BAHIR DAR UNIVERSITY INSTITUTE OF TECHNOLOGY
SCHOOL OF CIVIL AND WATER RESOURCE ENGINEERING
CIVIL ENGINEERING PROGRAM
STRUCTURAL DESIGN OF A G+7 MIXED USED BUILDING
REPORT SUBMITTED IN PARTIAL FULFILMENT OF
THE REQUIREMENT FOR THE DEGREE OF BACHELOR
OF SCIENCE IN CIVIL ENGINEERING
Advisor: Miss Misrak Tefera (MSc.)
Ahmed Wudmatas
025 /2000
Dagembirhan Assefa 093 /2000
Mearig Kahasay
222/2000
Temesgen Bogale
335 /2000
Wollelaw Abebe
365/2000
Structural Design of a G + 7 Mixed Use Building
Declaration
We undersigned, declared this project is ours and all sources of material used for the project has been
acknowledged.
Name;
1. Ahmed Wodmetas……………………………………………………..
2. Dagembirhan Assefa……………………………………………………
3. Mearig Kahasay………………………………………………………..
4. Temesgen Bogale………………………………………………………
5. Wollelaw Abebe………………………………………………………..
Advisor;
Miss Misrak Tefera (MSc.)……………………………………………
Bahir Dar University
Institute of Technology School of Civil and Water Resource Engineering
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Structural Design of a G + 7 Mixed Use Building
Abstract
This project is a structural design of a G+7 mixed – use building intended to provide shop, cafe and
restaurant, office and pension services. The proposed building is located within Addis Ababa.
The project document encompasses the analysis, design and detailed drawing of a mono pitch truss roof, a
solid slab, a ribbed slab, a stair case, beams, columns and foundation. Due to time constraints, we were not
able to include a shear wall design of the building.
The design philosophy adopted for the project is the limit state design for all aspects or parts of the
structure according to Ethiopian Building Code of Standards (EBCS). The frame and part of the roof
analysis were accomplished by employing SAP and ETABS design software.
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Structural Design of a G + 7 Mixed Use Building
Acknowledgement
First and foremost, we give thanks to God as none of this would have been a reality without God‟s willing.
It is, without doubt, God‟s plan for us to embark upon this project and accomplish it even with the ups and
downs that we faced within the project working time span.
As it was a necessity for as to have an advisor assigned to us by the university, we were more than lucky to
have Miss Misrak Tefera (MSc.) by our side from the commencing of the project up until the time we
accomplished our goal and completed the project in due time. Miss Misrak was the ideal advisor as she
was able to come up with ways that greatly reduced the gap that usually exists between instructors and the
student body by that helping us to communicate our ideas for the project freely that led to this success.
Our families, who were by our side in every step of the way, receive every bit of our gratefulness as they
guided us through our difficult days with helpful advices and morale. And everyone who contributed to the
successful finalization of the project; SCWRE staffs, friends and the university community in general, all
get what‟s ours to give, our deepest appreciation and thanks.
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Structural Design of a G + 7 Mixed Use Building
Material Properties and Specification
CONCRETE
Unit weight of normal concrete
Unit weight of reinforced concrete
Grade of concrete (class – I work)
Partial safety factor
Modulus of elasticity,
Characteristic strength,
Design strength;
STEEL
Grade of steel; S-400 and S-300
Characteristic yield strength;
Partial safety factor;
Design strength;
Modulus of elasticity;
Design philosophy: Limit State Design
Design code:
EBCS-1, 1995
EBCS-2, 1995
EBCS-3, 1995
EBCS-7, 1995
EBCS-8, 1995
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Structural Design of a G + 7 Mixed Use Building
Table of Content
Chapter -1........................................................................................................................................................ 1
1
Introduction ............................................................................................................................................. 1
Chapter-2......................................................................................................................................................... 5
2
Analysis and Design of Roof ................................................................................................................... 5
2.1
ROOF (I) .......................................................................................................................................... 5
2.2
ROOF-2 .......................................................................................................................................... 30
Chapter-3....................................................................................................................................................... 59
3
ANALYSIS AND DESIGN OF SLAB ................................................................................................. 59
3.1
Solid slab ........................................................................................................................................ 59
3.2
Ribbed slab ..................................................................................................................................... 92
Chapter-4..................................................................................................................................................... 116
4
Frame Analysis .................................................................................................................................... 116
4.1
Lateral Loading ............................................................................................................................ 116
4.2
Load transfer ................................................................................................................................ 140
Chapter-5..................................................................................................................................................... 146
5
Beam and Column Design ................................................................................................................... 146
5.1
Beam Design ................................................................................................................................ 146
5.2
Design of Column ........................................................................................................................ 197
Chapter-6..................................................................................................................................................... 228
6
Foundation Design ............................................................................................................................... 228
6.1
7
Structural Design of Isolated Footing .......................................................................................... 228
Reference ............................................................................................................................................. 234
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Structural Design of a G + 7 Mixed Use Building
List of Figures
Figure 2-1 Elevation of monopitch roof at 0o ................................................................................................. 7
Figure 2-2 Zones of monopitch roof at 0o ....................................................................................................... 8
Figure 2-3 Elevation for monopitch at 180o ................................................................................................... 9
Figure 2-4 Zones of monopitch roof at 180o ................................................................................................... 9
Figure 2-5 Zones of monopitch roof at 90o ................................................................................................... 10
Figure 2-6 lattice purlin ................................................................................................................................ 13
Figure 2-7 cross-section of outer & lower members of lattice purlin ........................................................... 18
Figure 2-8 cross-section of internal & diagonal members of lattice purlin ................................................. 20
Figure 2-9 truss-1 ......................................................................................................................................... 22
Figure 2-10 distribution of dead load on the truss rafter .............................................................................. 24
Figure 2-11 distribution of live load on the truss rafter ................................................................................ 25
Figure 2-12 distribution of wind load on the truss rafter .............................................................................. 26
Figure 2-13 distribution of wind load on the truss rafter .............................................................................. 27
Figure 2-14 cross-section of truss ................................................................................................................ 28
Figure 2-15 layout of roof-2 ......................................................................................................................... 31
Figure 2-16 Elevation for monopitch at 0o ................................................................................................... 32
Figure 2-17 zones of momopitch roof at 0o .................................................................................................. 33
Figure 2-18 Elevation for monopitch roof at 180o ........................................................................................ 36
Figure 2-19 zones of momopitch roof at 180o ............................................................................................. 37
Figure 2-20 zones of momopitch roof at 90o ................................................................................................ 38
Figure 2-21 lattice purlin .............................................................................................................................. 40
Figure 2-22 cross-section of lattice purlin .................................................................................................... 44
Figure 2-23 truss-2 ........................................................................................................................................ 46
Figure 2-24 dead load on rafter ..................................................................................................................... 47
Figure 2-25 distribution of live load on the truss rafter ................................................................................ 48
Figure 2-26 distribution of wind load on the truss ........................................................................................ 49
Figure 2-27 Suction....................................................................................................................................... 49
Figure 2-28 cross-section of truss-2 .............................................................................................................. 56
Figure 3-1 beam and panel layout ................................................................................................................. 59
Figure 3-2 panel-l layout ............................................................................................................................... 60
Figure 3-3 panel-2 layout .............................................................................................................................. 60
Figure 3-4 panel-3 & 9 layout ....................................................................................................................... 61
Figure 3-5 panel-4, 6, & 8 layout .................................................................................................................. 61
Figure 3-6 panel-5 & 7 layout ....................................................................................................................... 61
Figure 3-7 slab composite materials ............................................................................................................ 63
Figure 3-8 slab dead load .............................................................................................................................. 63
Figure 3-9 slab bending moment layout ....................................................................................................... 64
Figure 3-10 panel-10 layout .......................................................................................................................... 72
Figure 3-11 panel-11 layout .......................................................................................................................... 73
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Structural Design of a G + 7 Mixed Use Building
Figure 3-12 panel-18 & 19 layout ................................................................................................................. 74
Figure 3-13 strip of panel-18 & 19 ............................................................................................................... 76
Figure 3-14 panel-21 & 22 layout ................................................................................................................. 77
Figure 3-15 panel-20 layout .......................................................................................................................... 78
Figure 3-16 strip of panel-20 ........................................................................................................................ 80
Figure 3-17 bending moment of slab before adjustment .............................................................................. 82
Figure 3-18 bending moment of slab after adjustment ................................................................................. 91
Figure 3-19 panel-11, 12, &14 layout ........................................................................................................... 97
Figure 3-20 stair layout ............................................................................................................................... 110
Figure 4-1 projected plan ............................................................................................................................ 117
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Structural Design of a G + 7 Mixed Use Building
List of Tables
Table 2-1 Cpe,1 and Cpe,10 values for 0o ...................................................................................................... 8
Table 2-2, We values for 0o ............................................................................................................................ 8
Table 2-3 Cpe,1 and Cpe,10 values for 180o ................................................................................................ 10
Table 2-4 We values for 180o ....................................................................................................................... 10
Table 2-5 Cpe,1 and Cpe,10 values for 90o .................................................................................................. 11
Table 2-6 We values for 90o ......................................................................................................................... 11
Table 2-7 area of zones at 0o ......................................................................................................................... 35
Table 2-8 Cpe values at 0o ............................................................................................................................ 35
Table 2-9 We values at 0o ............................................................................................................................ 35
Table 2-10 area of zones at 180o ................................................................................................................... 37
Table 2-11 Cpe values at 180o ..................................................................................................................... 38
Table 2-12 We values at 180o ....................................................................................................................... 38
Table 2-13 area of zones at 90o ..................................................................................................................... 39
Table 2-14 Cpe values at 90o ........................................................................................................................ 39
Table 2-15 We values at 90o ......................................................................................................................... 39
Table 4-1 story shear force for each floor ................................................................................................... 126
Table 4-2 Ground and 1st floor column for center of mass calculation ...................................................... 127
Table 4-3 Ground to 7th floor beam for center of mass calculation ............................................................ 129
Table 4-4 2nd to 7th floor slab for center of mass calculation .................................................................... 130
Table 4-5 Ground floor slab for calculation center of mass calculation ..................................................... 131
Table 4-6 1st floor slab for center of mass calculation ................................................................................ 131
Table 4-7 2nd to 7th floor slab for center of mass calculation ...................................................................... 132
Table 4-8 Ground floor partition for center of mass calculation ................................................................ 133
Table 4-9 1st floor partition for center of mass calculation ......................................................................... 134
Table 4-10 2nd to 7th floor partition for center of mass calculation ............................................................. 134
Table 4-11 Ground and 1st floor shear wall for center of mass calculation ................................................ 135
Table 4-12 2nd t0 7th floor shear wall for center of mass calculation .......................................................... 135
Table 4-13 Ground and 1st floor stair for center of mass calculation ......................................................... 135
Table 4-14 2nd to 7th floor stair for center of mass calculation ................................................................... 135
Table 4-15 Roof center of mass calculation ............................................................................................... 137
Table 4-16 tanker slab mass center calculation .......................................................................................... 137
Table 4-17 building Center of mass calculation ........................................................................................ 138
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Structural Design of a G + 7 Mixed Use Building
Chapter -1
1 Introduction
About building structure
A building structure represents an assembly system that consists of components and their linkages. The
components or members may be rigid or flexible, linear, planar, or special. They may also be folded or
curved to form a two dimensional or three dimensional enclosures. The configuration of a structure and the
arrangement of its members can represent an equilibrium form, where the form of the structure makes a
natural equilibrium of external forces possible.
Generally, building structure components can be mainly classified as;
 Horizontal structures
 Vertical structures
Buildings basically consist of the support structure, the exterior envelope, the ceilings and the partitions.
The exterior envelope provides a protective shield against the outside environment and the
partitions
form interior space dividers.
Most buildings consist of;

horizontal planes (floors & roof structures)

The supporting vertical planes (walls, frames, etc.)

the foundations
The horizontal planes tie the vertical planes together to achieve frame effect, and the foundations make the
transition from the building to the ground possible.
The structure resists the vertical action of the gravity loads that is its own weight, as well as non-permanent
live or occupancy loads. It also resists the horizontal stability of the building.
The primary objective of structural components is to resist imposed and dead loads, by considering the
three fundamental principle of: stability, strength & Stiffness.
Basic structure components
The buildings super- structure & sub-structure are defined by geometry, i.e. lines, surfaces, spaces, and
bodies (solids).
The basic structural components in an ordinary building super structure are;
 the linear members of beams &columns
 the surface elements of slabs and walls
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1) Beams
Beams are linear members and they are distinguished in shape (like straight, tapered, and curved), cross
sections (rectangular, circular etc.), material (homogenous and composite) and support condition (simple,
continuous, and fixed).
Beams may be part of a repetitive grid (e.g. parallel or two-way joist system) or may represent individual
members. They may support ordinary floor and roof structures or span a stadium. They may form a stair, a
bridge, or an entire building. In other words, there is no limit to the application of the beam principle.
The effect of load action (eccentric vs. concentric) on beam behavior in response to member shape and
profile may be in;

simple bending

biaxial bending, or

unsymmetrical bending
Beams, in general, must be checked for the primary structural determinant of bending, shear, deflection,
possible load effect of bearing, and lateral stability.
Usually,
- Short beams are governed by shear,
- Medium-span beams by flexure, and
- Long-span beams by deflection.
The moment increase rapidly with the square of the span (L2) thus the required member depth (i.e. lever
arm of resisting internal forces, or moment of inertia I) must also correspondingly increase so that the
stresses remain within the allowable range. The deflection, however, increase with the span to the fourth
power (L4), clearly in dictating that with increase of span deflection becomes critical. On the other hand,
with decrease of span or increasing of beam depth (i.e. increasing of the depth-to-span ratio),the effect of
shear must be taken into account, which is a function of the span (L) and primarily dependent on the cross
sectional area of the beam (A).
Deflections in the elastic range are independent of material strength and are only a function of the stiffness
EI, while shear and bending are dependent on the material strength.
The potential internal forces that occur in the basic linear elements of beams and columns are;
o normal forces
o shear and
o Bending moment and occasionally torsion.
Once these forces are known, the minimum required member size can be found that should be capable of
responding to the maximum internal stresses caused by the internal forces.
Slab structures
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Floor structures consist of the slab and the framing. Occasionally, the slab is not supported by beams, as in
flat slab construction. The basic floor framing systems, as derived from the direction of their beam layout,
are arranged in parallel, radially, or diagonally, in one, two, or multiple directions.
The type of framing depends on the building shape, the type and loading, disturbance (e.g. openings), and
other functional and possibly aesthetical considerations. There is no magic formula for choosing a floor
structure.
The slab (i.e. deck or slab) may be a one-way or two-way structure. It is either directly supported on the
primary structural members (walls, columns, primary beams) or it rests on secondary filler beams or joists
(i.e. bay sub framing)
The familiar structural slabs are
 solid slab (e.g. one-way &two-way
 ribbed slab (e.g. one-way &two-way
 flat slab
 cantilever slab
One-way spanning slabs have always been designed as beams of considerable width. This involves
secondary distribution being provided to distribute temperature and shrinkage effects, to assist in fixing
and spacing the main steel, and to act distribution steel for concentrated loads.
Two –way spanning slabs are in-situ rectangular slabs supported on four, three, or two adjacent sides.
2. Columns
Reinforced concrete columns support loads in compression. They carried bending and axial compression
where the bending can be more important than the axial load.
Columns are the primary components of skeleton structures. They may carry an entire building.
Columns can be;
- Short or long
-slender or stocky
Reinforced concrete column may be separated from beams so that mainly axial forces are transferred, or
they may be continuous with beams to form beam-columns.
Analysis and Design Process
The overall structural analysis and design process typically consists of several steps
1. Geometry definition: - the basic geometry of structure is defined first, with particular attention paid
to member hierarchies (which member supports which other members) and spanning directions.
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Structural Design of a G + 7 Mixed Use Building
2. Load assessment: - the loads acting on the structure are determined next. Typically, this involves
determining loadings associated with the so called live loads on the structure resulting from its
occupancy (e.g. loadings do to wind and earth quake forces) and the so called dead loads associated
with the self waits of building elements
3. Modeling of the structure and boundary conditions:-the structure and its constituent elements are
modeled. Typically, such modeling includes characterizing complex real world construction
connections consisting of items such as anchor plates, bolts, etc as one or another an idealized set of
support conditions (e.g. pins, rollers, or rigid joints)
Objective of the project
This project will attempt to examine the integrated technique used in the design of multi-purpose building
which we have been taught through the past academic years. Its main purpose is to familiarize graduating
students with combined structural design aspect.
Slab design
Slabs are designed using the design tables provided on EBCS, 2, 1995. Slab depth requirements both for
service ability and limit states were checked. Partition walls on panels were converted to equivalent
uniformly distributed loads using approximate method. In solid slab design moments for each panel were
computed with the aid of the tables given on EBCS, 2, 1995.
After proper adjustment of support and fixed moments using method I & method II of EBCS, 2, 1995,
flexural reinforcements were provided to using general design tables provided EBCS, 2, 1995 (part two).
Cantilever slabs, stairs and landing slabs were designed as one -way slab.
Frame analysis
The restraint condition at the foundation would assume to be fixed or rigid. Loads were transferred to
beams from walls, slabs & Own weight of beams.
The section properties of beams and columns would be computed and the frames will be analyzed for
different combination of loading according to the provisions given on EBCS using SAP2000 program.
The frames are designed to resist the total lateral seismic force. The seismic force analysis will be done
according to EBCS, 8, 1995.
Design of beams and columns
The design of beams and columns will be done using the critical moments and shears from the combination
of loads. Beams will be designed using the chart method provided on EBCS, 2, 1995 (part two) and the
columns will be reinforced using the design charts prepared for it. [8]& [9]
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Structural Design of a G + 7 Mixed Use Building
Chapter-2
2 Analysis and Design of Roof
2.1 ROOF (I)
Loading
Characteristic live load
As per EBCS-1 table 2-13, Roofs are divided according to their accessibility into three categories. From
these categories out roof is categorized under h-category, i.e. roof not accessible except for normal
maintenance repair painting and minor repairs.
For category H-roof the following values are given on EBCS-1 1995 table 2.14.
(
= uniformly distributed load)
(
=concentrated load)
External Pressure
Wind pressure acting on the external surface of a structure
(We) is given by;
Where:is reference wind pressure
is exposure coefficient
is external pressure coefficient
Reference wind pressure,
The reference wind pressure (
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) is given by
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Structural Design of a G + 7 Mixed Use Building
Where:altitude of 2000m =0.94 kg/m3
= air density of the site (Addis Ababa) having an
Reference wind velocity
⁄
⁄
⁄
Exposure coefficient,
[
Where,
]
is the terrain factor
is roughness coefficient
is topography coefficient
Since Addis Ababa is urban areas in which at least 15% of the surface is covered with buildings and their
average height exceeds 15m, it is under terrain category IV/
The height of the building, =26.1m >
( ⁄ )
⁄
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Structural Design of a G + 7 Mixed Use Building
⁄
Since topography of our site is flat,
This is less than 0.05. Therefore
[
]
Since out roof is monopitch load is exerted in three wind directions,
Wind direction at
e is lesser of ,
Value is –
for area > 10m2
for area < 10m2
,for 1m2 < A < 10m2
Figure 2-1 Elevation of monopitch roof
at 0o
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Structural Design of a G + 7 Mixed Use Building
Figure 2-2 Zones of monopitch roof at 0o
Pitch
Zone For Wind direction
angel
F
G
-1.2
H
-1.7
-2.5
-1.64
-2.46 -1.17
-1.96 -0.58
-1.13
-0.9
-2.0
-1.5
-0.3
-0.8
-2.0
-0.6
-0.3
-1.2
Table 2-1 Cpe,1 and Cpe,10 values for 0 o
Zone Area(m2)
Cpe
F
7.396
2.395
G
14.792
-1.17
H
192.296
-0.58
⁄
Table 2-2, We values for 0o
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Structural Design of a G + 7 Mixed Use Building
Wind direction at
e = min (b, 2h)
e = b = 17.2m
Figure 2-3 Elevation for monopitch at 180o
Figure 2-4 Zones of monopitch roof at 180o
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Structural Design of a G + 7 Mixed Use Building
Pitch
Zone For Wind direction
angel
F
G
H
-2.3
-2.5
-1.3
-2.0
-0.8
-1.2
-2.315
-
-1.3
-2.0
-0.81
-1.2
-1.3
-2.0
-0.9
-1.2
2.522
-2.5
-2.8
Table 2-3 Cpe,1 and Cpe,10 values for 180o
Zone Area(m2)
Cpe
F
7.396
-2.326
G
14.792
-1.3
H
192.296
-0.81
⁄
Table 2-4 We values for 180o
Wind direction at
Figure 2-5 Zones of monopitch roof at 90o
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Structural Design of a G + 7 Mixed Use Building
Pitch
Zone For Wind direction
angel
F
G
H
-1.6
-2.2
-1.8
-2.0
-0.6
-1.2
0.5
0.5
-2.315
-2.522
-1.3
-2.0
-o.81
-1.2
0.5
0.5
-2.5
-2.8
-1.3
-2.0
-0.9
-1.2
-0.7
-1.2
Table 2-5 Cpe,1 and Cpe,10 values for 90o
Zone Area(m2)
F
8.3205
⁄
Cpe
-1.626
G
8.3205
-1.826
H
66.564
-0.615
I
138.675
0.5
219.4
Table 2-6 We values for 90o
From the above 3 possible cases, the maximum values are
⁄
For
⁄
⁄
⁄
Internal wind pressure
For closed buildings with internal partitions and openings the extreme values
or
⁄
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Structural Design of a G + 7 Mixed Use Building
⁄
⁄
Critical wind loads
⁄
⁄
⁄
⁄
2.1.1 Analysis and Design of purlin
Roof cover,
EGA-300, 0.3mm thick (size 0.9*1.9)
Unit weiht of EGA SHEET =
⁄
Weight per meter of EGA SHEET
⁄
⁄
Purlin is lattice purlin with size (30*30*1.5)mm upper and lower and (20*20*25)mm vertical and
Diagonal.
Truss Spacing = 133cm
(
)
( )
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Structural Design of a G + 7 Mixed Use Building
Figure 2-6 lattice purlin
Length of upper and lower purlin is equal to;
(
Length of vertical and diagonal lattice
(
)
)
Weight per meter of SHS 30*30*1.5
⁄
⁄
Weight of upper and lower purlin
=0.0379KN
⁄
Weight per meter of SHS 20*20*1.5
⁄
Mass of vertical and diagonal members of purlin
⁄
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Structural Design of a G + 7 Mixed Use Building
Weight of vertical and diagonal members of purlin
Weight per meter of vertical and diagonal members of purlin
⁄
⁄
Self-Weight of purlin
Purlin spacing =0.9m
Loads on the purlin
Dead load
Total dead load = Self weight of purlin + Dead load from EGA sheet
= 0.0376 + 0.021 = 0.0586
Live loads
According to Table 2.14 of EBCS – 1-1995, the imposed load on sloping roof of category H is,
⁄
Uniformly distributed load for sloping roof
⁄
Wind load

Pressure
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⁄
⁄
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Structural Design of a G + 7 Mixed Use Building

⁄
Suction
⁄
The above load s (DL and LL) shall be resolved parallel and perpendicular to the rafter so as to check the
purlin capacity in the two direction.
I)
Loads parallel to the rafter
⁄
⁄
II)
Load perpendicular to the rafter
⁄
⁄
Load Combinations
There are five possible load combinations
1/
I)
Parallel to the rafter
⁄
II)
Perpendicular to rafter
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Structural Design of a G + 7 Mixed Use Building
⁄
2/
I)
Parallel to the rafter
⁄
II)
Perpendicular to the rafter
⁄
3/
I)
Parallel to the rafter
⁄
II)
Perpendicular to the rafter
{
{
4/
I)
Parallel to the rafter
II)
Perpendicular to the rafter
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Structural Design of a G + 7 Mixed Use Building
,
⁄
(
⁄
)
5/
I)
Parallel to the rafter
⁄
II)
Perpendicular to the rafter
⁄
,
⁄
Critical load combinations
1) For load parallel to the load
⁄
2) For load perpendicular to rafter
⁄
Distribution of the maximum loading on the purlin
-
Exterior Nodes
-
Meddle Node
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Structural Design of a G + 7 Mixed Use Building
ANALYSIS RESULT
For the upper and lower members
For the vertical and diagonal members
Verification of the adequacy of the cross-section
-Check for outer and lower members
( 30*30*1.5mm )with property
-
h = 30mm
-
b = 30mm
-
A =1.65 cm2
-
r = 1.15cm
-
t = 1.5mm
Figure 2-7 cross-section of outer & lower members
of lattice purlin
Taking a steel grade Fe 510,
⁄
√
i) Check for tensile capacity
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Structural Design of a G + 7 Mixed Use Building
ii) Resistance of cross section for pure compression
Classification of the cross section
Flange:
Class-1, No local buckling
Web:
Class-1, No local buckling
iii) Check for flexural buckling;
√
√
Using EBCS-1995, table 4.11, we use buckling curve a.
For
=0.697 and buckling curve a, x = 0.85
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Structural Design of a G + 7 Mixed Use Building
Check for internal and diagonal members (20*20*1.5mm) with property
-
h= 20mm
-
A=1.05cm2
-
I =0.58cm2
-
r =0.74cm
-
t= 1.5mm
-
Figure 2-8 cross-section of internal & diagonal
members of lattice purlin
Taking a steel grade Fe510,
⁄
√
i) Check for tensile capacity
ii) Resistance of cross section for pure compression
Flange:
Class-1, No local buckling
Web:
Class-1, No local buckling
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iii) Check for flexural buckling
√
√
Using EBCS-1995, table 4.11, we use buckling curve a.
For
=1.05 and buckling curve a, x = 0.66
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2.1.2
TRUSS -1
Figure 2-9 truss-1
LOAD ON THE RAFTER
1. DEAD LOAD ON THE RAFTER

Self weight of purlin

Ega sheet weight
along the rafter

Self-weight of rafter
Using

SHS, weight per meter
Weight from Gypsum board
;
along the rafter
2. LIVE LOAD ON THE RAFTER


⁄

3. WIND LOAD ON THE RAFTER


Distribution of Dead Load on the Truss Rafter
1. ON THE UPPER NODES
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The loads that are applied on the upper nodes are: Weight of purlin, Weight of EGA sheet and
Weight from upper and partially diagonal members.




(
)
(

)
(

(
)
)
(
)

(
)

(
)

(
)

(

(

(
)
)
)

(
)

(
)

(
)
(

(

(
)
(
)
)
)
2. ON THE LOWER NODES
The loads that are applied on the lower nodes are: Weight of ceiling, Weight of upper, vertical and
diagonal (partially) members.
 Ceiling dead load
 Rafter dead load
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Structural Design of a G + 7 Mixed Use Building



(
)
(
)

(

(
)

(
)

)
(
)

(
)

(
)

(
)

(
)

(


)
(
(
)
)
Figure 2-10 distribution of dead load on the truss rafter
Distribution of Live Load on the Truss Rafter


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Structural Design of a G + 7 Mixed Use Building
(
)
(
)
(
)
⁄
⁄
⁄
Figure 2-11 distribution of live load on the truss rafter
(
)
Distribution of Wind Load on the Truss Rafter
Pressure
along the rafter
(
(
)
)
⁄
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Structural Design of a G + 7 Mixed Use Building
(
⁄
)
⁄
(
)
Suction
along the rafter
(
)
(
)
(
)
⁄
⁄
⁄
(
)
 Pressure and Suction forces are applied at joint normal to the roof but in order to make the
calculation easy it should be taken in components (X and Z axis on SAP)
Figure 2-12 distribution of wind load on the truss rafter
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Pressure (wind load)
Figure 2-13 distribution of wind load on the truss rafter
Suction (wind load)
LOAD COMBINATION
I.
Comb 1:
II.
Comb 2:
III.
Comb 3:
IV.
Comb 4:
(
)
V.
Comb 5:
(
)
SAP 2000 ANALYSIS RESULTS
⁄
⁄
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Structural Design of a G + 7 Mixed Use Building
Verification of the Adequacy of the Cross-Section
For
SHS, Fe 430 grade;








Figure 2-14 cross-section of truss
I.
CHECK FOR TENSILE CAPACITY
⁄
⁄
⁄
⁄
 OK!
II.
RESISTANCE OF CROSS-SECTION FOR PURE COMPRESSION
⁄
⁄
Cross-section classification:
Flange:
(
√
)
 Class 1: no local buckling
(
Web:
)
 Class 1: no local buckling
 Cross-section is class 1,
⁄
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 OK!
III.
CHECK FOR FLEXURAL BUCKLING
⁄
⁄
⁄
√
√
√
√
√
 From EBCS 3-1995-table 4.11, the buckling curve is curve a.
For =0.638 and buckling curve a,
⁄
⁄
 OK!
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Structural Design of a G + 7 Mixed Use Building
2.2 ROOF-2
WIND LOAD CALCULATION
 External wind pressure: the wind pressure acting on the external surface of a structure (WL) is
given by;
a) Reference wind pressure
⁄
⁄
b) Exposure coefficient,
[
]
 According to EBCS-1-1995 Addis Ababa is under terrain category IV, therefore the corresponding
values are:
(
)
(
)
 For flat topography with
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(
)
 Since our roof is monopitch roof load has exerted in three wind direction;
 Since Roof 2 has irregular shape, the sides should be protected to make it regular.
Figure 2-15 layout of roof-2
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I.
WIND DIRECTION AT
(
)
,
Figure 2-16 Elevation for monopitch at 0o
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Figure 2-17 zones of momopitch roof at 0o
⁄
{
⁄
⁄
(
⁄
⁄
)
 Since the different regions of the roof are irregular, the area is calculated by using AUTO-CAD
software.
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AREA
PITCH
ZONE FOR WIND DIRECTION,
ANGLE
F
G
⁄
⁄
H
⁄
⁄
⁄
⁄
Table 2-7 area of zones at 0o
EBCS-1995 APPENDIX A, TABLE A.3
ZONE
AREA
F
0.934
G
3.294
H
77.91
⁄
(
⁄
⁄
⁄
)
⁄
Table 2-8 Cpe values at 0o
(
External Wind Pressure,
ZONE
)
(
)
F
G
H
Table 2-9 We values at 0o
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II.
WIND DIRECTION AT
,
Figure 2-18 Elevation for monopitch roof at 180o
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Figure 2-19 zones of momopitch roof at 180o
PITCH
ZONE FOR WIND DIRECTION,
ANGLE
F
G
⁄
⁄
H
⁄
⁄
⁄
⁄
Table 2-10 area of zones at 180o
ZONE
AREA
F
0.805
G
9.42
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⁄
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H
71.12
⁄
Table 2-11 Cpe values at 180o
(
External Wind Pressure,
ZONE
)
(
)
F
G
H
Table 2-12 We values at 180o
III.
WIND DIRECTION AT
Figure 2-20 zones of momopitch roof at 90o
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Structural Design of a G + 7 Mixed Use Building
PITCH
ZONE FOR WIND DIRECTION,
ANGLE
F
G
⁄
⁄
H
⁄
⁄
⁄
I
⁄
⁄
⁄
4
Table 2-13 area of zones at 90o
ZONE
AREA
F
0
G
0.693
⁄
H
16.367
⁄
I
65.970
⁄
Table 2-14 Cpe values at 90o
(
External Wind Pressure,
ZONE
)
(
)
F
G
H
I
Table 2-15 We values at 90o
 From the above three possible wind direction cases, the maximum values are;

For suction:

For pressure:
INTERNAL WIND PRESSURE
 For closed buildings with internal partitions and opening windows the extreme values are;
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 Taking two extreme points, then:
CRITICAL WIND LOAD
2.2.1 Analysis and Design of Lattice Purlin
 Roof cover, EGA
thick
 Weight parameter of EGA sheet
 The purlin is lattice purlin with size
upper, lower, vertical and diagonal
elements
 Design for maximum truss spacing
Figure 2-21 lattice purlin
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(
(
)
)
(
)
LOADS ON PURLIN
1. DEAD LOAD
2. LIVE LOAD
According to table 2.14 0f EBCS 1-1995, the imposed load on sloping roof of category H is;


Uniformly distributed load (UDL) for sloping roof;
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3. WIND LOAD


The above forces, dead load and live load, shall be resolved parallel and perpendicular to the rafter so as to
check the purlin capacity in the two directions.
I.
II.
Loads parallel to the rafter
Loads perpendicular to the rafter
LOAD COMBINATION
I.
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II.
III.
IV.
[
]
V.
[
]
LOAD ON EXTERIOR NODES








LOAD ON INTERIOR NODES








Analysis result

⁄
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
⁄
Verification of the Adequacy of the Cross-Section
Figure 2-22 cross-section of lattice purlin
√
I.
Check for tensile capacity
⁄
⁄
⁄
II.
Resistance of cross-section for compression
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⁄
⁄
Cross-section classification for pure compression;
(
)
 Class 1: No local buckling
(
)
 Class 1: No local buckling

⁄
III.
Check for flexural buckling
⁄
⁄
√
⁄
√
 From EBCS-3-1995, table 4.11, we use buckling curve a

⁄
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2.2.2
TRUSS (II)
Figure 2-23 truss-2
Talking truss spacing at the of = 133cm
Loading on the Rafter
DL on the rafter
⁄
 Self-weight of purlin
⁄
 EGA sheet weight
 Weight from Gypsum board ceiling (12cm thick)
⁄
⁄
 Self-weight of the rafter
⁄
Using 40*40*2.4mm, weight per meter
⁄
Dead load on the Upper nodes
(
)
(
)
(
)
(
(
(
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(
)
(
)
(
)
(
)
Load on lower nodes
(
(
)
)
(
(
)
)
Figure 2-24 dead load on rafter
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Distribution of live load on the truss rafter
⁄
Load on the nodes
Figure 2-25 distribution of live load on the truss rafter
Distribution of wind load on the truss rafter
Pressure
Pressure = 0.571KN/m
Exterior nodes,
and
Interior node,
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Figure 2-26 distribution of wind load on the truss
Suction
Suction = -1.94 KN/m
Exterior Nodes,
Interior Nodes,
Figure 2-27 Suction
Load combination
1.
2.
3.
4.
5.
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ANALYSIS RESULT
From sap2000 analysis result comb 4 is the critical load combination
Checking the above result (for combination 4) using hand calculation
∑
∑
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Analysis of members using joint method
∑
Joint I
∑
JOINT J
∑
53.3
∑
Joint H
∑
∑
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JOINT K
∑
(
)
∑
Joint G
∑
JOINT L
∑
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JOINT F
∑
∑
JOINT M
∑
∑
JOINT E
∑
∑
JOINT N
∑
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Structural Design of a G + 7 Mixed Use Building
∑
JOINT D
∑
∑
JOINT O
∑
∑
JOINT C
∑
∑
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JOINT P
∑
∑
JOINT B
∑
From the above analysis
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Verification of the Adequecy of the Cross Section
For 40*40*2.5mm SHS, Fe 430 grade;







Figure 2-28 cross-section of truss-2
i) check for tensile capacity
ii) Resistance of cross section for pure compresion
Cross section classification
√
Flange:
(
√
)
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Cross section Class 1  No local buckling
Web:
Cross section Class 1  No local buckling
Cross section is Class 1 ,
iii) Check for Flexural Buckling
√
√
̅
√
√
From EBCS-3-1995 – table 4.11, buckling curve is “curve a”
For ̅=0.787 & buckling curve a, x = 0.81
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Chapter-3
3 ANALYSIS AND DESIGN OF SLAB
3.1 Solid slab
Concrete
Grade of concrete-C-25
⁄
Reinforcement
⁄
Steel grade-300,
⁄
The beam and panel layout
Figure 3-1 beam and panel layout
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Depth determination
For the determination of slab thickness, we use the following deflection equation.
As per EBCS-2 1995, equation 5.3 and the value of βa taken from table5.1
For panel-1(cantilever slab)
16.8m
1.8m
m
Figure 3-2 panel-l layout
For cantilever slab, βa=10
(
)
For panel-2 (end span)
Lx=4.2m
Ly=4.8m
4.2
m
𝐿𝑦
𝐿𝑥
4.8
Figure 3-3 panel-2 layout
For end span, βa=43.6
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(
)
For panel-3 & 9(end span)
Lx=4.2m
Ly=4.5m
4.2
𝐿𝑦
𝐿𝑥
4.5
Figure 3-4 panel-3 & 9 layout
For end span, βa=39.3
(
)
For panel-4, 6, &8 (interior span)
Lx=4.2m
Ly=4.8m
4.2
𝐿𝑦
𝐿𝑥
4.8
Figure 3-5 panel-4, 6, & 8 layout
For interior span, βa=38.6
(
)
For span 5, &7(interior span)
Lx=4.2m
Ly=4.5m
4.2
𝐿𝑦
𝐿𝑥
4.5
Figure 3-6 panel-5 & 7 layout
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For interior span, βa=44.3
(
)
For end and interior span
For cantilever slab
Loading
From EBCS-1 1995.Table2.1
⁄
⁄
⁄
⁄
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Figure 3-7 slab composite materials
material
Thickness(mm) Unit weight(KN/mm3)
Dead load(KN/mm2)
Cement screed
30
23
0.69
RC slab
120
25
3.0
plastering
25
23
0.575
Ceramic tile
3
27
0.081
total 4.35
Figure 3-8 slab dead load
Calculation of Support and Field Moments using Coefficient Method
Moments for individual panel with edges simply supported or fully fixed are calculated as:
Where;
Mi = is the design moment per unit width at the point reference
αi = is the coefficient given in EBCS-2 as a function of Ly/Lx and support condition
Lx = is the shorter span of the panel
Ly = is the longer span of the panel
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Pd = is the design load
Subscripts for moments and moment coefficient (αi) have the following meaning.
s = support
f = field
x = direction in shorter direction
y = direction in longer direction
Notations for different critical moments and edge moments are shown below. Division of slab
into middle and edge stirrup is given by the figure below.
Figure 3-9 slab bending moment layout
For panel -1
16.8m
Dead load
1.8
mm
⁄
⁄
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Structural Design of a G + 7 Mixed Use Building
⁄
⁄
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
⁄
⁄
This panel is considered as a cantilever and it is one way slab.
⁄
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Structural Design of a G + 7 Mixed Use Building
For Panel-2
Lx=4.2m
Ly=4.8m
4.2
m
𝐿𝑦
𝐿𝑥
4.8
Dead load
⁄
⁄
⁄
⁄
(
)
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
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Structural Design of a G + 7 Mixed Use Building
⁄
⁄
For calculation of moment we will use,
⁄
⁄
⁄
⁄
For Panel-3&9
Lx=4.2m
Ly=4.5m
4.2
𝐿𝑦
𝐿𝑥
4.5
Dead load
⁄
⁄
⁄
⁄
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Structural Design of a G + 7 Mixed Use Building
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
⁄
⁄
For calculation of moment we will use,
⁄
⁄
⁄
⁄
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For panel-4, 6, & 8
Lx=4.2m
Ly=4.8m
4.2
𝐿𝑦
𝐿𝑥
4.8
Dead load
⁄
⁄
⁄
⁄
(
)
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
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⁄
⁄
For calculation of moment we will use,
⁄
⁄
⁄
⁄
For panel-5, & 7
Lx=4.2m
Ly=4.5m
4.2
𝐿𝑦
𝐿𝑥
4.5
Dead load
⁄
⁄
⁄
⁄
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Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
⁄
⁄
For calculation of moment we will use,
⁄
⁄
⁄
⁄
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For Panel-10
16.8m
1.8
Figure 3-10 panel-10 layout
Dead load
⁄
⁄
⁄
⁄
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
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Structural Design of a G + 7 Mixed Use Building
⁄
⁄
This panel is considered as a cantilever and it is one way slab.
⁄
For panel-17
17.0m
1.8
mm
Figure 3-11 panel-11 layout
Dead load
⁄
⁄
⁄
⁄
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Structural Design of a G + 7 Mixed Use Building
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
⁄
⁄
This panel is considered as a cantilever and it is one way slab.
⁄
Panel-18 &19
Strip method is applicable for slabs have unsupported edge, hole, and irregular shape.
4.8
4.9
Figure 3-12 panel-18 & 19 layout
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Structural Design of a G + 7 Mixed Use Building
Dead load
⁄
⁄
⁄
⁄
Total point load
⁄
Total dead load
⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
⁄
⁄
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For panel-18and 19(using strip method)
Figure 3-13 strip of panel-18 & 19
X-direction middle strip
⁄

Hillerboreg notes that as a general rule for fixed edges, the support moment should be 1.5-2.5 times the
span moment in the strip.

⁄

⁄
X-direction edge strip

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
⁄

⁄
Y-direction middle strip
⁄


⁄

⁄
X-direction edge strip
⁄


⁄

⁄
For panel-21 & 22
4.9m
1.9
Figure 3-14 panel-21 & 22 layout
Dead load
⁄
⁄
⁄
⁄
Total dead load
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⁄
Live load
For bed room EBCS-1, 1995 table 2.1, EBCS-1 table 5.1
⁄
⁄
⁄
This panel is considered as a cantilever and it is one way slab.
𝐾𝑁⁄
𝑚
1.9m
⁄
Panel-20
Figure 3-15 panel-20 layout
Dead load
⁄
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Structural Design of a G + 7 Mixed Use Building
⁄
⁄
⁄
Total point load
⁄
Total dead load
⁄
Live load
⁄
⁄
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Structural Design of a G + 7 Mixed Use Building
For panel 20(using strip method)
Figure 3-16 strip of panel-20
X-direction middle strip
⁄

⁄

⁄


X-direction edge strip
⁄


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
⁄
Y-direction middle strip
⁄

⁄

⁄

Y-direction edge strip
⁄



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Figure 3-17 bending moment of slab before adjustment
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Moment adjustment for support and field using moment distribution method
For each support over which the slab is continuous, there will generally be two different support moment.
The difference may be distributed between the panels on either side of the support to equalize their
moments, as in the moment distribution method for frames.
Two methods of different accuracy are given here for treating the effects of this redistribution on moments
away from the support.
Method I
This method may be used when differences between initial support moments are less than 20% of the
larger moment. When method I is used dimensioning is normally carried out either using:
a. Initial moment directly
b. Based on the average initial moments at the support.
Method II
This method may be used when differences between initial support moments are greater than 20% of the
larger moment. In this method consideration of the effect of changes of support moments is limited to
adjacent spans. Since no effect on neighboring support section need to be considered, only a simple
balancing operation is required at each edge and no iterative process is involved.
The procedure for applying Method II is as follows:
a. Support span moments are first calculated for individual panels by assuming each panel to be
fully loaded, this is done by using the coefficient given EBCS-2, 1995.
b. The unbalanced moment is distributed using the moment distribution method. The relative
stiffness of each panel shall be taken proportioning to its gross moment moments of inertia
divided by respective span length.
c. If the support is decreased, the span moments Mxf and Myf are then increased to allow for the
changes of support moment. The following relation is used for adjustment.
Where;
If the support moment is increased, no adjustment shall be made to the span moment.
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Support moment adjustment
For section X-X
P10
P3
27.62
6.56
1.8
L
P2
6.56
P1
8.19
4.5
8.19
33.74
1.8
4.8
𝑀
𝑀
𝐾
𝐼
𝐿
0.56
I
0.22I
𝐷𝑓
0.21I
-
-
-
𝑀𝑎𝑑𝑗
0.56I
7.38
For section Y-Y
P10
P5
27.62
L
5.58
1.8
P4
5.38
6.72
4.5
P1
6.72
33.74
1.8
4.8
𝑀
𝑀
𝐾
𝐼
𝐿
0.56I
𝐷𝑓
𝑀𝑎𝑑𝑗
Bahir Dar University
0.22I
-
0.21I
-
0.56I
-
6.15
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For section Z-Z
P9
P7
7.73
5.97
4.2
L
P5
5.97
P3
5.97
4.2
5.97
7.73
4.2
4.2
𝑀
𝑀
𝐾
𝐼
𝐿
0.24I
𝐷𝑓
0.24I
0.24I
-
𝑀𝑎𝑑𝑗
1.76
-
0.24I
-
0.5
5.97
6.8
5
0.5
6.85
For section W-W
P8
P6
8.19
L
8.19
4.2
P4
8.19
8.19
4.2
P2
8.19
10.88
4.2
4.2
𝑀
𝑀
𝐾
𝐼
𝐿
0.24I
0.24I
0.24I
𝐷𝑓
-
-
𝑀𝑎𝑑𝑗
8.19
8.19
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-
0.24I
0.5
0.5
9.54
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For section W-W
P18
P20
5.12
L
3.04
4.9
P19
3.04
P8
5.12
4.7
5.12
8.19
4.9
4.2
𝑀
𝑀
2.08
𝐾
𝐼
𝐿
2.08
0.2I
0.21I
0.2I
-
𝐷𝑓
0.24I
-
0.49
𝑀𝑎𝑑𝑗
3.07
0.51
4.1
0.45
0.51
0.49
4.1
0.55
6.5
For section S-S
P10
P9
27.62
L
6.56
1.8
P8
6.56
6.72
4.5
P1
6.72
33.74
1.8
4.8
𝑀
𝑀
𝐾
𝐼
𝐿
0.56I
𝐷𝑓
𝑀𝑎𝑑𝑗
Bahir Dar University
0.22I
-
0.21I
-
0.56I
-
6.64
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Field moment adjustment
For panel-2
Since the support moment Mxs 10.88 is greater than the adjusted moment 9.54 and Mys 8.19 is greater than
the adjusted moment 7.38, it needs moment adjustment in the larger and the shorter side respectively.
From EBCS-2; Table A.2
⁄
⁄
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For panel-3 &9
Mxs changes from 7.73 to 6.85, it needs adjustment.
⁄
⁄
For panel-4, & 6
Mys changes from 6.72to 6.15, it needs adjustment.
⁄
⁄
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For panel-8
Mxs changes from 8.19 to 6.5, it needs adjustment.
⁄
⁄
Mys changes from 6.72to 6.64, it needs adjustment.
⁄
⁄
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For panel-18 &19
Mys changes from 5.12 to 4.1, it needs adjustment.
⁄
⁄
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Figure 3-18 bending moment of slab after adjustment
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3.2 Ribbed slab
Ribbed slab is economical for buildings where there are long spans and light and moderate live loads. The
ribbed slab which will be designed here is a series of in situ concrete, ribs cast between hollow block,
which remains part of the completed slab. Ribbed slab composed of ribs, toppings, and HCB. Ribs and
topping are composed to form T-section beams.
Size of the slab is shown below.
Size of the rib

Depth of the web
=210mm

Width of web
=80mm

Thickness of topping =60mm

c/c spacing of ribs

clear distance b/n ribs =320mm
=400mm
Size of HCB
Effective depth determination
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Taking a clear cover of 15mm and using 10 bars.
⁄
Depth for serviceability limit state requirement;
Considering the panel for cantilever and end span, we take the larger depth size.
For cantilever
(
)
Ribbed slabs are design as beam, so we used the βa value given for beams with different support condition.
For end span
(
)
But the effective depth provided is 250mm which is greater than 159.4mm.
Therefore, 250mm>159.4mm…………………………..OK!!
Checking the adequacy of rib and the topping dimension based on EBCS-2, 1995 Art, 7.2.3.1

Width of rib ≥ 70mm, 80mm > 70mm……………………………………………..ok!!

Depth of the rib (excluding topping) ≤ 4×70mm=280mm, 210mm ≤ 280mm………ok!!

The rib spacing shall not exceed 1.0m. 0.4m<1.0m…………………………………ok!!

The thickness of the topping ≥40mm or 1/10 times clear spacing of the ribs=1/10×320=32mm,
60mm ≥32mm…………………………………………….. Ok!!
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Load determination
Dead load
Unit weight of material are taken from EBCS-1, 1995 Art 2.4

Self-weight of the rib
⁄
⁄

Self-weight of HCB
⁄
Summation of self-weight
⁄
Finishing material (over rib length 0.4m)
⁄
30mm thick cement screed (under ceramic tile)
⁄
25cm thick plastering
⁄
Live loads according to EBCS-2, 1995, section2.6.3 buildings which are used as bed room areas are;
⁄
⁄
Partition load
For panel-11
⁄
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Per meter
⁄
For panel-12 & 15
⁄
Per meter
⁄
For panel-13 & 16
⁄
Per meter
⁄
For panel-14
⁄
Per meter
⁄
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Design load
⁄
⁄
⁄
⁄
By modeling the slab as continuous beam and loading with different load arrangement, we can easily
analyze it using SAP 2000, in order to get maximum stress. To draw the moment envelope we take load
cases into consideration as stated in EBCS-2, 1995 section 3.7.3.
The load cases are;

Design dead load on all spans with full design live load on two adjacent.

Design dead load on all spans with full live load on alternate spans.
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Determination of shear force and bending moment for each panel
Figure 3-19 panel-11, 12, &14 layout
Loading conditions
Case-1(all loaded)
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Case-2(no live load on p11 and p14)
Case-3(no live load onp11, p12, p14)
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Case-4(no live load onp11, p13, p14
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Design of ground floor
Since the floor is rested on the hardcore, this is supported by the soil under it. Minimum reinforcement
should be provided.
Reinforcement
Taking over all depth, D=100mm and
bar with clear cover 20mm.
{
Therefore, provide
c/c 200mm for each panel in both directions.
Design of solid slab (1st-7th floor)
Check for the depth adequacy
⁄
⁄
√
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⁄
⁄
√
√
Slab reinforcement
Reinforcement is calculated using design chart method.
B/n panel-1& (2, 4, 6, &8)
⁄
⁄
⁄
Minimum reinforcement
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{
⁄
From EBCS-2, 1995
In one way slab the ration of the secondary reinforcement to the main reinforcement shall be at least equal
to 0.2.
⁄
From EBCS-2, 1995
The spacing between secondary reinforcement shall not exceed 400mm.
⁄
For positive reinforcement
For panel-2
Reinforcement in X-direction
⁄
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⁄
⁄
Minimum reinforcement
{
Reinforcement in Y-direction
⁄
⁄
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⁄
Then we can do the others in the above way.
Then we can do the others in the above way.
Panel
1
2
Msd
-
8.79 6.02 6.99 4.51 6.44 6.8
Depth
160 100
100
100
100
100
100 160 160 100
100
160
Arequired
-
355
238
278
177
256
270 -
-
428
242
-
Aprovided
-
355
252
280
252
265
280 -
-
457
252
-
Srequired
-
140
210
181
284
197
186 -
-
117.6
208
-
Sprovided
-
140
200
180
200
190
180 -
-
110
200
-
8
17
18&19 20
-
2.82
3&9 4
5&7 6
8
10
17
18&19 20
-
-
10.59
21&22
6.07 -
Positive moment in X-direction
Panel
1
2
Msd
-
6.69 5.37 5.78 4.03 5.78 5.69 -
Depth
160 100
100
100
100
100
100
160 160 100
100
160
Arequired
-
280
212
229
169
229
225
-
-
169
169
-
Aprovided
-
300
252
252
252
252
252
-
-
252
252
-
Srequired
-
180
238
220
300
220
224
-
-
300
300
-
Sprovided
-
170
200
200
200
200
200
-
-
200
200
-
3&9 4
5&7 6
10
21&22
1.52 -
Positive moment in Y-direction
Msd
10.88 9.54 8.19 6.5
4.1
5.12 7.73 6.85
Depth
100
100
100
100
100
100
100
100
Arequired
444
386
331
261
167
204
331
274
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Aprovided
462
393
393
393
393
393
393
393
Srequired
177
204
238
300
470
386
253
330
Sprovided
170
200
200
200
200
200
200
200
Msd
5.97
7.38 6.15 6.64 20.43 21.30 27.62 33.74
Depth
100
100
100
100
160
160
160
160
Arequired
239
296
247
268
516
539
708
870
Aprovided
393
393
393
393
524
561
714
873
Srequired
330
266
318
295
153
146
111
90.4
Sprovided
200
200
200
200
150
140
110
90
Development length
From EBCS-2.1995, the development length will be;
Where:
=diameter of the bar
=design strength of the bar
= bond strength of the bar
Design of ribbed slab (1st-7th floor)
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Checking the depth for flexure
Using the bar diameter of 12mm for flexure.
⁄
√
√
Design of longitudinal reinforcement
(
⁄ )
A. Span moment
Assuming the neutral axis lies inside the flange.
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{
{
⁄
{
Checking the assumption
Design of rib
⁄
The assumption is correct, the neutral axis lies inside the flange.
⁄
According to EBCS-2 Art 2.7.2.11 the minimum, reinforcement required for longitudinal direction is;
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The other is done in the same way of the above.
b. Support moment
Design of shear reinforcement
Shear resistance of the beam concrete section shear capacity (Vc)
{
⁄
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To prevent diagonal compression failure;
The force is smaller, so provide the minimum stirrup.
From EBCS-2
The minimum reinforcement is provided according to EBCS-2 Art.7.2.3.2 = 0.00107 *sectional area i.e.
using 8 bar size.
Provide 8 c/c 125mm perpendicular to rib direction.
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Design of stair case
This staircase is Ground up to 7th floor typical staircase.
Figure 3-20 stair layout
Section X-X
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Section Y-Y
Depth determination
i). Depth for interior span, βa=38.75
(
)
(
)
Determination of the length of the flight
(
⁄
)
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Load of flight only
Dead load
⁄
⁄
⁄
⁄
⁄
⁄
⁄
Live load
⁄
⁄
Load for landing
⁄
⁄
⁄
⁄
⁄
Live load
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⁄
⁄
Typical floor staircase
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Design of stair
Main reinforcement
⁄
⁄
⁄
Secondary reinforcement
The ratio of secondary reinforcement to main reinforcement should at least be equal to 0.2.
⁄
Check for shear
Shear resistance of the beam concrete section shear capacity (Vc)
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⁄
⁄
The concrete shear resistance is greater than the design shear, so no need of stirrup.
To prevent diagonal compression failure;
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Chapter-4
4 Frame Analysis
4.1 Lateral Loading
We have two types of lateral loads in our region; Earth Quake and Wind load.
4.1.1 Wind load
External pressure (We)
⁄
⁄
⁄
From EBCS-1-1995table 3.2 recommendation, the project is classified under category IV and its
corresponding values given on table 3.3.
The height of building is =26m > Zmin=16m
⁄
Topography of our site is flat, then
[
[
Bahir Dar University
=1
]
]
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Since EBCS-1, 1995 provides pressure coefficient only for rectangular plan building, we need to project
our building‟s irregular shape plan in to rectangular.
Figure 4-1 projected plan
Wind Load In shorter direction
Plan View
h=26.1m
e is lesser of b or 2h
,

h=26.1m is lesser than b=38.18m, therefore
building shall be considered to be one part.
, thus the elevation view is as shown below.
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Case d > e
and
Using table A.1 of EBCS -1-1995, Cpe for vertical wall is as shown below.
zone
A
B*
D
E
d/h
Cpe,10
Cpe,1
Cpe,10
Cpe,1
Cpe,10
Cpe,1
Cpe,10
Cpe,1
0.834
-1
-1.3
-0.8
-0.1
0.8
1.0
-0.3
-0.3
zone
Area(m2)
Cpe
A
199.4
Cpe= Cpe,10=-1
B*
368.5
Cpe= Cpe,10=-0.8
D
996.5
Cpe= Cpe,10=0.8
E
996.5
Cpe= Cpe,10=-0.3
(N/m2)
Wind Load in Shorter Direction
b=21.76, h=26.1
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Since b<h<2b, analysis is carried out by dividing the building in to two parts.
,
Since d > e, the elevation view has the following pattern.
Elevation view for d > e case
Using table A.1 of EBCS-1-1995 and interpolating for d/h=1.463, the Cpe value for vertical wall is as
shown below.
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zone
A
B
C
D
E
d/h
Cpe,10
Cpe,1
Cpe,10
Cpe,1
Cpe,10
Cpe,1
Cpe,10
Cpe,1
Cpe,10
Cpe,1
1
-1
-1.3
-o.8
-0.1
-0.5
-0.5
0.8
1
-0.3
-0.3
1.463
-1
-1.3
-o.8
-0.1
-0.5
-0.5
0.77
1
-0.3
-0.3
4
-1
-1.3
-o.8
-0.1
-0.5
-0.5
0.6
1
-0.3
-0.3
We calculation for region-1
⁄
At z=21.76m→
*
Then
+
zone
Area(m2)
Cpe
A
113.54
Cpe= Cpe,10=-1
B
454.4
Cpe= Cpe,10=-0.8
C
428.56
Cpe= Cpe,10=-0.5
D
567.94
Cpe= Cpe,10=0.77
E
567.94
Cpe= Cpe,10=-0.3
⁄
We calculation for region-2
zone
Area(m2)
Cpe
A
113.54
Cpe= Cpe,10=-1
B
454.4
Cpe= Cpe,10=-0.8
C
428.56
Cpe= Cpe,10=-0.5
D
567.94
Cpe= Cpe,10=0.77
E
567.94
Cpe= Cpe,10=-0.3
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Internal pressure coefficient, Cpi
For closed building with internal partitions and opening windows, the extreme values
Cpi=+0.8 or Cpi=-0.5
Internal pressure
The wind pressure acting on the internal surface of a structure Wi, shall be obtained from
⁄
The net pressure
The net wind pressure across a wall or an element is the difference of the pressure on each surface taking
due to account of their signs (pressure towards the surface is taken as positive, and suction, directed away
from the surface as negative)
Net Pressure in the shorter direction
⁄
zone
⁄
⁄
D
351.1
-0.5
0.8
-219.4
351.1
570.5
0
E
-131.65
-0.5
0.8
-219.4
351.1
87.8
-482.8
Net pressure in the longer direction for region-1
zone
⁄
⁄
⁄
D
313.56
-0.5
0.8
-219.4
351.1
557.3
-13.2
E
-122.17
-0.5
0.8
-219.4
351.1
87.8
-482.8
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Net pressure in the longer direction for region-2
⁄
zone
⁄
⁄
D
337.9
-0.5
0.8
-203.6
325.81
517
-12.2
E
-122.17
-0.5
0.8
-203.6
325.8
81.4
-447.9
The wind pressure force acting on the frames are obtained by multiplying the pressure intensity and half
height of above the frame and half height below the frame system.
*
i‟e Wind Load
+
Wind Load in Shorter direction
Floor level Area(m2)
Wind pressure( ⁄
Wind load (KN)
Zone D
Zone E
Zone D
Zone E
roof
106.9
570.5
-482.8
60.99
-45.84
3th-7th
114.54
570.5
-482.8
65.3
-49.11
2th
120.3
570.5
-482.8
68.6
-51.58
1st
126
570.5
-482.8
71.9
-54
Wind Load in longer direction
Floor level Area(m2)
Wind pressure( ⁄
Wind load (KN)
Zone D
Zone E
Zone D
Zone E
557.3
-482.8
34
-29.5
35.1
-30.4
roof
61
7th
65.3
3rd-6th
65.3
517
-447.9
33.8
-29.2
2nd
68.5
517
-447.9
35.4
-30.7
1st
72
517
-447.9
37.2
-32.2
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Summary
Floor level
Shorter direction(KN)
Longer direction(KN)
roof
94.63
63.5
7th
104.12
65.5
3rd-6th
98.1
63
2nd
106.41
66.1
1st
112.3
69.4
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4.1.2 Earthquake load
The nature of supporting ground has influence on the seismic action. This shall generally be accounted for
by considering subsoil classes.
According to EBCS_1-1995,clause 1.3.1(4),for the ground condition in the absence of more accurate
information, the seismic action may be determined assuming ground conditions subsoil class B.
Addis Ababa is located at 09 02 N & 38 43 E under seismic zone B. (EBCS-8-1995-table 1.3)
By following linear structural analysis,
Sd(T) = αβγ
Sd(T), design spectrum at period T
α, ratio of design bedrock acceleration to g=9.8 ⁄
β, design response factor
α=αoI
I, importance factor
From EBCS-8-1995-table 1.1, αo=0.05
From EBCS-8-1995-table 1.4, our building is classified under category III and its corresponding
importance factor, I=1
β
S, site coefficient for soil characteristics
⁄
T, vibration period
From EBCS-8-1995-table 1.2, site coefficient, S=1.2
The height of our building is 26m, which is less than 80m.Therefore we can use approximate expression
for T.
⁄
H=26m
C=0.075(for RC moment resisting frames)
⁄
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β
⁄
Basic value of the behaviour factor, γ o =0.2 (for frame equivalent dual system)
Factor reflecting the ductility class, KD=2 (for DC‟‟L‟‟)
Factor reflecting the structural regularity, KR=1.25 (for non regular structures)
Factor reflecting the prevailing failure made in structural system with walls, KW=1 (for frame equivalent
dual system)
Seismic base shear force,
W=Total permanent load (for building without storage and ware house occupancies)
Concentrated force at the top,
∑
∑
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Lateral forces from earth quake loads at each floor are tabulated as shown below.
Floor level
hi(m)
Wi(m)
Wihi(KNm)
Fb-Ft(KN)
Fi(KN)
Tanker roof
27
126.4
3412.8
833.1
64.6*
Roof
24.6
678.26
16685.2
833.1
53.7
7th
21.6
2720.71
58767.4
833.1
189.1
6th
18.6
2720.71
50605.2
833.1
162.84
5th
15.6
2720.71
42443.1
833.1
136.57
4th
12.6
2720.71
34280.9
833.1
110.31
3rd
9.6
2720.71
26118.8
833.1
84.04
2nd
6.6
2720.71
17956.7
833.1
57.78
1st
3.3
2616.76
8635.31
833.1
27.79
Ground
0
2422.5
0
833.1
0
Table 4-1 story shear force for each floor
∑
*
∑
Comparing the summation of story shears of Wind load and Earth quake load, Earth quake load governs
the design.
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4.1.2.1 Mass center calculation
Ground and 1st floor column
Description γ(KN\m3)
W(KN)
X(m)
y(m)
Mx
My
C1A
25
13.2
0
0
0.00
0.00
C1B
25
13.2
0
4.8
0.00
63.36
C1C
25
13.2
0
9.3
0.00
122.76
C2A
25
13.2
4.5
0
59.40
0.00
C2B
25
13.2
4.5
4.8
59.40
63.36
C2C
25
13.2
4.5
9.3
59.40
122.76
C3A
25
13.2
9
0
118.80
0.00
C3B
25
13.2
9
4.8
118.80
63.36
C3C
25
13.2
9
9.3
118.80
122.76
C4A
25
13.2
13.4
0.67
176.88
8.84
C5B
25
13.2
13.87
4.8
183.08
63.36
C6A
25
13.2
18
4.1
237.60
54.12
C7C
25
13.2
11
10.8
145.20
142.56
C7B
25
13.2
15.3
9.5
201.96
125.40
C7A
25
13.2
20
9.1
264.00
120.12
C8A
25
13.2
21.12
12.1
278.78
159.72
C8B
25
13.2
16.52
13.5
218.06
178.20
C8C
25
13.2
12.22
14.8
161.30
195.36
C9A
25
13.2
22.34
16.1
294.89
212.52
C9B
25
13.2
17.75
17.5
234.30
231.00
C9C
25
13.2
13.45
18.8
177.54
248.16
C10A
25
13.2
23.57 20.11
311.12
265.45
C10B
25
13.2
19
21.57
250.80
284.72
C10C
25
13.2
14.7
22.82
194.04
301.22
C11A
25
13.2
24.8
24.2
327.36
319.44
C11B
25
13.2
20.21 25.53
266.77
337.00
C11C
25
13.2
15.91 26.84
210.01
354.29
∑=356.4
∑=4637.26 ∑=4155.1
Table 4-2 Ground and 1st floor column for center of mass calculation
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Ground to 7th floor beam
Description γ(KN\m3)
W(KN)
X(m) Y(m)
Mx
My
BA1-2
25
11.53
2.25
0
25.94
0.00
BA2-3
25
11.53
6.95
0
80.13
0.00
B1A-B
25
11
0
2.4
0.00
26.40
B1B-C
25
10.25
0
7.05
0.00
72.26
BB1-2
25
10.25
2.25
4.8
23.06
49.20
BB2-3
25
10.25
6.95
4.8
71.24
49.20
B2A-B
25
11
4.5
2.4
49.50
26.40
B2B-C
25
10.25
4.5
7.05
46.13
72.26
BC1-2
25
10.25
2.25
9.3
23.06
95.33
BC2-3
25
10.25
6.95
9.3
71.24
95.33
B3A-B
25
11
9
2.4
99.00
26.40
B3B-C
25
10.25
9
7.05
92.25
72.26
BA3-4
25
11
11.23
0.11
123.53
1.21
BA4-6
25
15
15.8
2.21
237.00
33.15
BA6-7
25
11
19
6
209.00
66.00
BB3-5
25
11.2
11.3
4.8
126.56
53.76
BB5-7
25
11.2
14.6
7.3
163.52
81.76
B4-5
25
9.4
13.66
2.8
128.40
26.32
B5-6
25
9.4
16
4.7
150.40
44.18
B7A-B
25
11
17.58
8.6
193.38
94.60
B7B-C
25
10.25
12.6
10.1
129.15
103.53
B8A-B
25
11
18.82 12.62
207.02
138.82
B8B-C
25
10.25
13.8
14.2
141.45
145.55
B9A-B
25
11
20
16.7
220.00
183.70
B9B-C
25
10.25
15
18.2
153.75
186.55
B10A-B
25
11
21.3
20.66
234.30
227.26
B10B-C
25
10.25
16.3
22.2
167.08
227.55
B11A-B
25
11
22.5
24.6
247.50
270.60
B11B-C
25
10.25
17.5
26.15
179.38
268.04
BA7-8
25
9.5
20.6
10
195.70
95.00
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BA8-9
25
9.5
21.8
14
207.10
133.00
BA9-1O
25
9.5
23
18
218.50
171.00
BA10-11
25
9.5
24.3
22
230.85
209.00
BB7-8
25
9.5
15.9
11.5
151.05
109.25
BB8-9
25
9.5
17.14
15.5
162.83
147.25
BB9-10
25
9.5
18.4
19.5
174.80
185.25
BB10-11
25
9.5
19.6
23.5
186.20
223.25
BC7-8
25
9.5
11.6
12.8
110.20
121.60
BC8-9
25
9.5
12.84
16.8
121.98
159.60
BC9-10
25
9.5
14
20.8
133.00
197.60
BC10-11
25
9.5
15
24.8
142.50
235.60
∑=426.6
∑=5629.89 ∑=4723.8
Table 4-3 Ground to 7th floor beam for center of mass calculation
2nd to 7th floor slab
Description γ(KN\m3) W(KN)
X(m)
Y(m)
Mx
My
C1A
25
12
0
0
0.00
0.00
C1B
25
12
0
4.8
0.00
57.60
C1C
25
12
0
9.3
0.00
111.60
C2A
25
12
4.5
0
54.00
0.00
C2B
25
12
4.5
4.8
54.00
57.60
C2C
25
12
4.5
9.3
54.00
111.60
C3A
25
12
9
0
108.00
0.00
C3B
25
12
9
4.8
108.00
57.60
C3C
25
12
9
9.3
108.00
111.60
C4A
25
12
13.4
0.67
160.80
8.04
C5B
25
12
13.87
4.8
166.44
57.60
C6A
25
12
18
4.1
216.00
49.20
C7C
25
12
11
10.8
132.00
129.60
C7B
25
12
15.3
9.5
183.60
114.00
C7A
25
12
20
9.1
240.00
109.20
C8A
25
12
21.12
12.1
253.44
145.20
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C8B
25
12
16.52
13.5
198.24
162.00
C8C
25
12
12.22
14.8
146.64
177.60
C9A
25
12
22.34
16.1
268.08
193.20
C9B
25
12
17.75
17.5
213.00
210.00
C9C
25
12
13.45
18.8
161.40
225.60
C10A
25
12
23.57 20.11
282.84
241.32
C10B
25
12
19
21.57
228.00
258.84
C10C
25
12
14.7
22.82
176.40
273.84
C11A
25
12
24.8
24.2
297.60
290.40
C11B
25
12
20.21 25.53
242.52
306.36
C11C
25
12
15.91 26.84
190.92
322.08
∑=324
∑=4243.86 ∑=3780.84
Table 4-4 2nd to 7th floor slab for center of mass calculation
Ground floor slab
Description γ(KN\m3) W(KN)
X(m)
panel 1
25
67.2
23.25 15.1
1562.40
1014.72
panel 2
25
46.5
21.92 22.8
1019.28
1060.20
panel 3
25
43.5
17.5
24.2
761.25
1052.70
panel 4
25
45.67
20.7
18.8
945.37
858.60
panel 5
25
42.7
16.2
20
691.74
854.00
panel 6
25
45.67
19.5
14.8
890.57
675.92
panel 7
25
42.7
15
16
640.50
683.20
panel 8
25
46.5
18.3
10.8
850.95
502.20
panel 9
25
43.5
13.8
12
600.30
522.00
panel 12
25
46.7
2.25
7.05
105.08
329.24
panel 13
25
50
2.25
2.4
112.50
120.00
panel 14
25
49.1
4.5
-1
220.95
-49.10
panel 15
25
46.7
6.75
7.05
315.23
329.24
panel 16
25
50
6.75
2.4
337.50
120.00
panel 17
25
57
16
3.7
912.00
210.90
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panel 18
25
48.5
11.45 2.68
555.33
129.98
panel 19
25
48.5
16.93 6.7
821.11
324.95
panel 20
25
20.25
15.1
305.78
64.80
3.2
∑=840.7
∑=11647.92 ∑=8850.76
Table 4-5 Ground floor slab for calculation center of mass calculation
1st floor slab
Description
γ(KN\m3)
W(KN)
panel 1
25
134.4
23.25
panel 2
25
69.8
panel 3
25
panel 4
X(m) Y(m)
Mx
My
15.8
3124.80
2123.52
21.92
22.8
1530.02
1591.44
65.3
17.5
24.2
1142.75
1580.26
25
68.5
20.7
18.8
1417.95
1287.80
panel 5
25
64.1
16.2
20
1038.42
1282.00
panel 6
25
68.5
19.5
14.8
1335.75
1013.80
panel 7
25
64.1
15
16
961.50
1025.60
panel 8
25
69.8
18.3
10.8
1277.34
753.84
panel 9
25
65.3
13.8
12
901.14
783.60
panel 12
25
70
2.25
7.05
157.50
493.50
panel 13
25
75
2.25
2.4
168.75
180.00
panel 14
25
73.6
4.5
-1
331.20
-73.60
panel 15
25
70
6.75
7.05
472.50
493.50
panel 16
25
75
6.75
2.4
506.25
180.00
panel 17 lft
25
23.3
11
-0.75
256.30
-17.48
panel 17 rght
25
23.3
20.21
6.11
470.89
142.36
panel 18 & 19
25
123
13.6
5.1
1672.80
627.30
∑=16825.83
∑=13699.85
∑=1203
Table 4-6 1st floor slab for center of mass calculation
2nd to 7th floor slab
Description γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
panel 1
25
134.4
23.25 15.8
3124.80
2123.52
panel 2
25
69.8
21.92 22.8
1530.02
1591.44
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panel 3
25
65.3
17.5
24.2
1142.75
1580.26
panel 4
25
68.5
20.7
18.8
1417.95
1287.80
panel 5
25
64.1
16.2
20
1038.42
1282.00
panel 6
25
68.5
19.5
14.8
1335.75
1013.80
panel 7
25
64.1
15
16
961.50
1025.60
panel 8
25
69.8
18.3
10.8
1277.34
753.84
panel 9
25
65.3
13.8
12
901.14
783.60
panel 10
25
69
4.4
10.3
303.60
710.70
panel 11
25
130.5
12.3
19.3
1605.15
2518.65
panel 12
25
70
2.25
7.05
157.50
493.50
panel 13
25
75
2.25
2.4
168.75
180.00
panel 14
25
73.6
4.5
-1
331.20
-73.60
panel 15
25
70
6.75
7.05
472.50
493.50
panel 16
25
75
6.75
2.4
506.25
180.00
Panel 17
25
114
16
3.7
1824.00
421.80
panel 18
25
72.75
11.45 2.68
832.99
194.97
panl 19
25
72.75
16.93
6.7
1231.66
487.43
panel 20
25
30.4
15.1
3.2
459.04
97.28
∑=1323.3
∑=22845.1 ∑=14126.9
Table 4-7 2nd to 7th floor slab for center of mass calculation
Ground floor partition
Description
γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
P1A-B
17
35.9
0
2.4
0.00
86.16
P1B-C
17
33.66
0
7.05
0.00
237.30
PC1-2
17
33.66
2.25
9.3
75.74
313.04
PC2-3
17
33.66
6.75
9.3
227.21
313.04
P3B-C
17
25.25
9
7.05
227.25
178.01
P2B-C
17
25.25
4.5
7.5
113.63
189.38
P7A-B
17
26.93
17.65
8.75
475.31
235.64
P7B-C
17
23.1
13.13 10.11
303.30
233.54
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P8A-B
17
26.93
18.83 12.77
507.09
343.90
P8B-C
17
23.1
14.35 14.14
331.49
326.63
P9A-B
17
26.93
20.1
16.79
541.29
452.15
P9B-C
17
23.1
15.69 18.15
362.44
419.27
P10A-B
17
26.93
21.29 20.81
573.34
560.41
P10B-C
17
23.1
16.92 22.23
390.85
513.51
P11A-B
17
30.67
21.23
25.6
651.12
785.15
P11B-C
17
30.67
18.03 26.29
552.98
806.31
PC7-8
17
28.12
11.62 12.79
326.75
359.65
PC8-9
17
28.12
17.14 15.49
481.98
435.58
PC9-10
17
28.12
21.1
18.77
593.33
527.81
PC10-11
17
28.12
22.33 22.84
627.92
642.26
∑=561.3
∑=7615 ∑=7363
Table 4-8 Ground floor partition for center of mass calculation
1st floor partition
Description γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
PC1-2
17
33.66
2.25
9.3
75.74
313.04
PC2-3
17
33.66
6.75
9.3
227.21
313.04
P2B-C
17
25.25
4.5
7.5
113.63
189.38
P7B-C
17
23.1
13.13 10.11
303.30
233.54
PC7-8
17
28.12
11.62 12.79
326.75
359.65
PC8-9
17
28.12
17.14 15.49
481.98
435.58
PC9-10
17
28.12
21.1
18.77
593.33
527.81
PC10-11
17
28.12
22.33 22.84
627.92
642.26
P11A-B
17
30.67
21.33
25.6
654.19
785.15
P11B-C
17
30.67
18.03 26.29
552.98
806.31
P1A-B
17
35.9
0
2.4
0.00
86.16
P1B-C
17
33.66
0
7.05
0.00
237.30
P3B-C
17
25.25
9
7.05
227.25
178.01
∑=384.3
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Table 4-9 1st floor partition for center of mass calculation
2nd to 7th floor partition
Description γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
P1A-B
17
22.1
0
1.45
0.00
32.05
P1B-C
17
33.66
0
7.05
0.00
237.30
PB1-2
17
25.25
2.25
4.8
56.81
121.20
PB2-3
17
25.25
6.75
4.8
170.44
121.20
P3A-B
17
16.55
9
1.45
148.95
24.00
P2B-C
17
25.25
4.5
7.5
113.63
189.38
P3B-C
17
25.25
9
7.05
227.25
178.01
P2A-B
17
16.55
4.5
1.48
74.48
24.49
P4-6
17
25.75
15.68
2.35
403.76
60.51
P7A-B
17
15.43
18.54
8.19
286.07
126.37
P7B-C
17
23.1
13.13 10.11
303.30
233.54
P8A-B
17
15.43
19.71 12.73
304.13
196.42
P8B-C
17
23.1
14.35 14.14
331.49
326.63
PB7-8
17
21.4
15.92 11.46
340.69
245.24
PB8-9
17
21.4
17.14 15.49
366.80
331.49
P9A-B
17
15.43
20.94
16.5
323.10
254.60
P9B-C
17
23.1
15.69 18.15
362.44
419.27
PB9-10
17
21.37
18.48
19.5
394.92
416.72
P10A-B
17
15.43
22.17 20.52
342.08
316.62
P10B-C
17
23.1
16.92 22.23
390.85
513.51
PB10-11
17
21.4
19.71 23.58
421.79
504.61
P11A-B
17
20.57
22.11 25.26
454.80
519.60
P11B-C
17
30.67
18.31 26.21
561.57
803.86
∑=506.45
∑=6195 ∑=6377.7
Table 4-10 2nd to 7th floor partition for center of mass calculation
Ground and 1st floor shear wall
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Description
γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
shear wall
25
155.3
12.22
7
1897.77
1087.10
∑=1897.766
∑=1087.1
∑=155.3
Table 4-11 Ground and 1st floor shear wall for center of mass calculation
2nd t0 7th floor shear wall
Description
γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
shear wall
25
141
12.22
7
1723.02
987.00
∑=1723.02
∑=987
∑=141
Table 4-12 2nd t0 7th floor shear wall for center of mass calculation
Ground and 1st floor stair
Description
γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
str lower
25
26.25
9.9
6.45
259.88
169.31
str middle
25
30
10.54
9.3
316.20
279.00
str upper
25
26.25
13.45
9.1
353.06
238.88
∑=82.5
∑=929.2 ∑=687.2
Table 4-13 Ground and 1st floor stair for center of mass calculation
2nd to 7th floor stair
Description
γ(KN\m3)
W(KN)
X(m)
Y(m)
Mx
My
str lower
25
24
10.2
6.6
244.80
158.40
str middle
25
30
10.54
9.3
316.20
279.00
str upper
25
24
13.31 9.11
319.44
218.64
∑=880.44
∑=656
∑=78
Table 4-14 2nd to 7th floor stair for center of mass calculation
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Roof
Weight of truss I ,W=7.28KN (From SAP result)
centroid of T1,=6.63 m from low cave side
Weight of truss II,W=5.37KN (From SAP result)
centroid of T2,=2.8m from low cave side
Description
W(KN)
X(m)
T 11
7.28
20.42
25
148.66
182.00
T 12
7.28
20
24
145.60
174.72
T 13
7.28
19.6
22.5
142.69
163.80
T 14
7.28
19.2
21.2
139.78
154.34
T 15
7.28
18.85
19.96
137.23
145.31
T 16
7.28
18.5
18.7
134.68
136.14
T 17
7.28
18.1
17.4
131.77
126.67
T 18
7.28
17.7
16.1
128.86
117.21
T 19
7.28
17.3
14.87
125.94
108.25
T110
7.28
16.91
13.6
123.10
99.01
T111
7.28
16.52
12.33
120.27
89.76
T112
7.28
16.13
11.1
117.43
80.81
T113
7.28
15.74
9.78
114.59
71.20
T 21
5.37
17.87
7.63
95.96
40.97
T 22
5.37
17.5
6.7
93.98
35.98
T 23
5.37
17
5.9
91.29
31.68
T 24
5.37
16.52
5.14
88.71
27.60
T 25
5.37
15.88
4.41
85.28
23.68
T 26
5.37
15.23
3.81
81.79
20.46
T 27
5.37
14.21
3.1
76.31
16.65
T 28
5.37
13.41
2.64
72.01
14.18
T 29
5.37
12.6
2.3
67.66
12.35
T210
5.37
11.69
2
62.78
10.74
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Mx
My
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T211
5.37
10.8
1.87
58.00
10.04
T212
5.37
9.61
1.74
51.61
9.34
T114
7.28
8.28
4.47
60.28
32.54
T115
7.28
6.95
4.47
50.60
32.54
T116
7.28
5.62
4.47
40.91
32.54
T117
7.28
4.29
4.47
31.23
32.54
T118
7.28
2.96
4.47
21.55
32.54
T119
7.28
1.63
4.47
11.87
32.54
T120
7.28
0.31
4.47
2.26
32.54
∑=210
∑=2854.6
∑=2130.7
Table 4-15 Roof center of mass calculation
tanker slab
Description γ(KN\m3)
slab
W(KN)
25
X(m) Y(m)
126.4
12
7.33
∑=126.4
Mx
1516.8
My
926.512
∑=1516.8 ∑=926.512
Table 4-16 tanker slab mass center calculation
Center mass calculation
∑Wi=Wcln+Wbeam+Wslab+Wshear wall+Wpartn wall+Wstair (ground _7th floor
∑Wi=Wtruss+Wtanker cln (roof)
∑Wi=Wtanker slab
(tanker slab)
X=∑WiXi/∑Wi
Y=∑WiYi/∑Wi
Floor level
∑Wi(KN)
∑WiXi(KNm)
∑WiYi(KNm
x(m)
y(m)
Ground
2422.5
32357.3
26866.96
13.36
11.09
1
2616.76
35038.88
28420.45
13.39
10.86
2
2720.71
41517.3
30652.24
15.26
11.27
3
2720.71
41517.3
30652.24
15.26
11.27
4
2720.71
41517.3
30652.24
15.26
11.27
5
2720.71
41517.3
30652.24
15.26
11.27
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6
2720.71
41517.3
30652.24
15.26
11.27
7
2720.71
41517.3
30652.24
15.26
11.27
roof
678.26
8973.1
7183.81
13.23
10.59
Tanker slab
126.4
1516.8
926.5
12.00
7.33
Table 4-17 building Center of mass calculation
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4.1.2.1.1 Accidental eccentricity
According to EBCS -8-1995 section2.3.2, in order to cover uncertainties in location of masses and in
special variation of the seismic motion action, the calculated center of mass at each floor shall be
considered displaced from its nominal location in each direction by an Accidentalaccidental eccentricity.
Where
all floors.
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4.2 Load transfer
The loads considered in this frame analysis are loads transferred to the beam from the slab, wall, stair and
roof and self-weight of the beam. The section properties of beams and columns would be computed and the
frames will be analyzed for different combination of loading according to the provisions given on EBCS8
using ETABS v 9.7 program.
The frames are also designed to resist the total lateral seismic force. The seismic force analysis will be
done according to EBCS8, 1995.
Loads transfer to beams
Load transferred from solid slabs
Panel-1 to beam (A& (11-7)
⁄
⁄
16.8m
1.8
Panel-2
⁄
Lx=4.2m
Ly=4.8m
4.2
m
𝐿𝑦
𝐿𝑥
4.8
⁄
⁄
⁄
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Panel-3&9
Lx=4.2m
4.2
Ly=4.5m
𝐿𝑦
𝐿𝑥
4.5
⁄
⁄
⁄
⁄
Panel-4, 6, &8
Lx=4.2m
Ly=4.8m
4.2
𝐿𝑦
𝐿𝑥
4.8
⁄
⁄
⁄
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Panel-5 & 7
Lx=4.2m
Ly=4.5m
4.2
𝐿𝑦
𝐿𝑥
4.5
⁄
⁄
⁄
Panel-10
⁄
16.8m
⁄
1.8
mm
Panel-17
⁄
17.0m
⁄
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Panel-18&19
Lx=4.8m
Ly=4.9m
4.8
𝐿𝑦
𝐿𝑥
4.9
⁄
⁄
⁄
Panel-20
Lx=3.5m
Ly=4.7m
3.5
𝐿𝑦
𝐿𝑥
4.7
⁄
⁄
⁄
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Panel-21 &22
⁄
4.9m
⁄
1.9
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Load transferred from ribbed slab beam
Beam axis A (1-3)
⁄
Beam axis B (1-3)
⁄
Beam axis C (1-3)
⁄
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Chapter-5
5 Beam and Column Design
5.1 Beam Design
According to EBCS-2, 1995, the following points should be considered when designing the beam for
flexure.
1. In the analysis of beams, a section of beam which has to resist a small axial load, the effect of the
ultimate axial load may be ignored if the axial load does not exceed 0.1fck times the cross-sectional
area.
2. The geometrical ratio of reinforcement and at any section of a beam where positive reinforcement
is by analysis shall not be less than given by
3. The reinforcement ratio
for either tensile or compressive reinforcement shall be 0.04.
For different combination different bending moment and shear force is obtained. For design we need to
consider the maximum bending moment and shear force.
In this project beams which have maximum bending moment and shear force is selected from the ETAPS
V7.9 analysis.
Flexural reinforcement
Depth determination
Effective depth for serviceability requirement (deflection)
(
)
(
)
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Effective flange width EBCS-2, 1995 Art 3.7.8
For positive bending moment, an effective depth beff is width when stressed uniformly to maximum at
center of beam. The maximum gives a compressive force as in actual developed in real compression zone
is:
{
{
But to be on the conservative side take beff=800mm
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Design of Beams on Axis-10 (between axis A&C)
{
⁄
=1065mm. but to be on the conservative side take
Support moment reinforcement design
Use

reinforcement bar


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Support C
No need for compression reinforcement
From Design Chart
Provide
Support B
No need for compression reinforcement
From Design Chart
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Provide
Support A
From Design charts
Provide
Span Moment Reinforcement Design
Span – A-B
No need for compression reinforcement
From design chart EBCS – 1995
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1
Provide
Span – B-C
No need for compression reinforcement
From design chart EBCS – 1995
Provide
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Design for Shear
No need of revising the section
Shear force developed by concrete
Where
⁄
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Axis 10 between B & C
– “d” distance from the support EBCS – 2 1995
d= 357mm
By similarity of triangles
At support
(from the flexural reinforcement)
Shear reinforcement is required
Vertical stirrups required to resist the excess shear force at this spacing is
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Maximum Spacing on stirrups
Use
stirrup
Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed
Since
use
Use
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Axis 10 between B & A
– “d” distance from the support EBCS – 2 1995
d= 357mm
By similarity of triangles
At support
(from the flexural reinforcement)
Shear reinforcement is required
Vertical stirrups required to resist the excess shear force at this spacing is
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Maximum Spacing on stirrups
Use
stirrup
Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed
Since
use
Use
Provide
⁄
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Design of Beams on Axis 2 between C-B and B-A
Support moment reinforcement design
Use

reinforcement bar


Support C
No need for compression reinforcement
From Design Chart
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Use As =
Provide
Support B
No need for compression reinforcement
From Design Chart
Use As =
Provide
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Support A
No need for compression reinforcement
From Design Chart
Use As =
Provide 3
Span moment Reinforcement
Span C-B
No need for compression reinforcement
From Design Chart
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Use As =
Provide 2
Span B-A
No need for compression reinforcement
From Design Chart
Use As =
Provide 2
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Design for Shear (Beams on Axis 2 between C &B)
According to EBCS-2, 1995, Art.4.5.2 to prevent diagonal compression failure in the concrete, the
resistance VRd of a section shall not be less than the applied shear force. Vsd
The shear force, Vc covered by concrete in members without significant axil forces shall be taken as;
Where;
Where;
As- area of tensile reinforcement at the intersection of the steel and concrete the possible 45o crack starting
from the face of the support
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No need of revising the section
Shear force developed by concrete
Where
⁄
⁄
Axis 2 between B & C
– “d” distance from the support EBCS – 2 1995
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d= 359mm
By similarity of triangles
At support
(from the flexural reinforcement)
We can provide Smax
Maximum Spacing on stirrups
Use
stirrup
Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed
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Use
Provide
⁄
Axis 10 between B & A
– “d” distance from the support EBCS – 2 1995
d= 359mm
2.96
By similarity of triangles
At support
(from the flexural reinforcement)
Since the concrete by itself can carry the shear force that occurs on the beam we provide only the
maximum spacing.
Maximum Spacing on stirrups
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Use
stirrup
Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed
Use
Provide
⁄
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Design of Beams on Axis-A
Axis (A) between 3&7

Maximum support moment= -138.45KNm( at axis 6)

Depth of beam
=450mm

Width of beam
=300mm

Effective depth
=450-20/2-8-25=407mm
The
depth
provided should be;
√
√
Using design chart No.-1 of EBCS-2, 995
Negative bending moments
N.A is in the web.
The section can be designed as a rectangular section.
Minimum reinforcement
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Maximum bending moment=61.33KNm (at axis -3)
N.A is in the web.
The section can be designed as a rectangular section.
Maximum bending moment=130.29KNm (at axis -4)
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N.A is in the web.
The section can be designed as a rectangular section.
Maximum bending moment=65.3KNm (at axis -7)
N.A is in the web.
The section can be designed as a rectangular section.
Positive bending moments
Between axis 3&4
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The depth of neutral axis;
N.A is in the flange
The section can be designed as a rectangular section.
Between axis 4&6
The depth of neutral axis;
N.A is in the flange
The section can be designed as a rectangular section.
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Between axis 6&7
The depth of neutral axis;
N.A is in the flange
The section can be designed as a rectangular section.
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Design for Shear (Beams on Axis A between 3&7)
1. Support 3right and support 4left
Maximum spacing of stirrup
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Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed;
{
2. Support 4right and support 6left
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Maximum spacing of stirrup
Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed;
{
,
3. Support 6right and support 7left
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Maximum spacing of stirrup
Maximum spacing of stirrups in the longitudinal direction when shear reinforcement is needed;
{
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Design of Beams on Axis-B between 5 and 11
 Negative Moments:






 Depth of the beam
 Width of the beam
 Effective depth,
The depth provided should be
√
√

1)
Using the general design chart number 1 of EBCS 2, 1995,
Depth of the neutral axis,
The section can be designed as a rectangular section,
Number of reinforcement provided:
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2)
 Depth of the neutral axis
The section can be designed as a rectangular section.
 Number of reinforcement
3)
 Depth of the neutral axis
The section can be designed as a rectangular section.
 Number of reinforcement
4)
 Depth of the neutral axis
The section can be designed as a rectangular section.
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 Number of reinforcement
5)
 Depth of the neutral axis
The section can be designed as a rectangular section.
 Number of reinforcement
 Positive Moments:





1)
 Depth of the neutral axis
The section can be designed as a rectangular section.
 Number of reinforcement
2)
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 Number of reinforcement
3)
 Have results similar to the previous Positive Moments;
 Number of reinforcement;
4)
 Depth of the neutral axis
The section can be designed as a rectangular section.
 Number of reinforcement
Shear Design of Axis B between (5) and (11)
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Shear design for 11left and 10right
 Shear force developed by the concrete;
Axis – B, between 11 and 10;
 By similarity of triangles;
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 At the support,
 From flexural reinforcement;
 Vertical stirrups required to resist the excess shear force at this spacing is,
Maximum Spacing of Stirrups;
 Maximum spacing of stirrups in the longitudinal direction where shear reinforcement is needed;
 Vertical stirrups required to resist the excess shear force is
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 Maximum spacing of stirrups;
 Maximum spacing of the stirrups in the longitudinal direction where shear reinforcement is needed;
Axis – B between 10 and 9
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 Maximum spacing of stirrups;
 Maximum spacing of the stirrups in the longitudinal direction where shear reinforcement is needed;
Axis – B between 9 and 8
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 Maximum spacing of stirrups;
 Maximum spacing of the stirrups in the longitudinal direction where shear reinforcement is needed;
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Axis between 8 and 7;
 Maximum spacing of stirrups;
 Maximum spacing of the stirrups in the longitudinal direction where shear reinforcement is needed;
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Axis – B between 7 and 5;
Maximum spacing of stirrups;
Maximum spacing of the stirrups in the longitudinal direction where shear reinforcement is needed;
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Design of Beam on axis-B between 1&5
Beam design for flexure
Design of beam for axis-B between support 1and 5 on the 1st floor
Depth of the beam=400mm
Width of the beam=300mm
Effective depth, d= 400-10-8-25=357mm (for Ø 20mm bar)
d=400-8-8-25=359mm (for Ø 16mm bar)
checking adequacy of the effective depth provided
Maximum moment capacity for the axis is, M=110.32KNm
√
√
dprovided > dcalculated…………………………………….OK
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Design for support moment
Support moment @ 1B=110.32KNm
Support moment @ 2B=88.76KNm
Support moment @ 3B=84.65KNm
Support moment @ 5B=74.8KNm
Design for support moment @1B
Since the floor near to the beam is ribbed slab, the beam is designed as rectangular beam.
using design chart No-1 of EBCS-2, 1995,
For
=0.255 → Kz=0.845
Reinforcement area calculation
,
→
⁄
⁄
govern the design
Reinforcement bar number calculation
Use 4 20mm bar
Design for support moment @2B
Using design chart No-1 of EBCS-2, 1995,
For
=0.2 → Kz=0.85
Reinforcement area calculation
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→
govern the design
Reinforcement bar number calculation
Use 3 20mm bar
Design for support moment @3B
Using design chart No-1 of EBCS-2, 1995,
For
=0.195 → Kz=0.85
Reinforcement area calculation
→
govern the design
Reinforcement bar number calculation
Use 3 20mm bar
Design for support moment @2B
Since the floor near to the beam is solid slab, the beam is designed as T beam.
⁄
,
⁄
To be on the conservative side, let take beff =800mm
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Using design chart No-1 of EBCS-2, 1995,
=0.17 →{
For
Neutral axis depth calculation
from bottom of the web.
Neutral axis lies inside the web…….OK
Reinforcement area calculation
→
govern the design
Reinforcement bar number calculation
Use 3 20mm bar
Design for Span Moment
Span moment between 1B and 2B, =50.27KNm
Span moment between 2B and 3B, =49.89KNm
Span moment between 3B and 5B, =48.00KNm
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Since the floor near to the beam between 3B and 5B is solid slab, the beam is designed as T beam.
Whereas the other two beam are adjacent to ribbed slab and designed as rectangular beam.
Design for span moment between 1B and 2B
Using design chart No-1 of EBCS-2, 1995,
=0.12 → Kz=0.93
For
Reinforcement area calculation
→
govern the design
Reinforcement bar number calculation
Use 3 16mm bar
Design for span moment between 2B and 3B
Using design chart No-1 of EBCS-2, 1995,
For
=0.11 → Kz=0.935
Reinforcement area calculation
→
govern the design
Reinforcement bar number calculation
Use 3 16mm bar
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Design for span moment between 3B and 5B
Using design chart No-1 of EBCS-2, 1995,
For
=0.04 →{
Neutral axis depth calculation
from top of the beam
Neutral axis lies inside the slab…….OK
Reinforcement area calculation
→
govern the design
Reinforcement bar number calculation
Use 2 16mm bar
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Beam on Axis B Design for shear
Shear force resistance developed by concrete alone:
⁄
Shear Force design for support 1B right and support 2B left
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-is at d distance from the support 1B

At support 1B,
<
→shear reinforcement is required
Shear force carried by the stirrup,
Shear reinforcement Spacing calculation
Calculation for maximum allowable spacing of stirrup
→
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{
Use
→
⁄
Shear Force design for support 2B right and support 3B left
-is at d distance from the support 3B

At support 3B,
<
→shear reinforcement is required
Shear force carried by the stirrup,
Shear reinforcement Spacing calculation
Bahir Dar University
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Structural Design of a G + 7 Mixed Use Building
Checking for allowable Smax
→
{
Use
(from previous calculation)
→
⁄
Shear Force design for support 3B right and support 5B left
-is at d distance from the support 3B

At support 3B,
<
→shear reinforcement is required
Shear force carried by the stirrup,
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Shear reinforcement Spacing calculation
Checking for allowable Smax
→
{
Use
(from previous calculation)
→
⁄
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5.2 Design of Column
Column is a vertical structural member which transmits loads from the roofs, slabs and beams to the
foundation. In the basis of manner by which lateral stability is provided to the structure as a whole, they
may be braced or unbraced.
Classification based on effective buckling length, the column may be considered as;
-Short column if
-slender column if
When; b=least lateral dimension
le=effective buckling length
Effective buckling length,
Bahir Dar University
[
]
[
]
, for non sway frame.
Institute of Technology School of Civil and Water Resource Engineering 197
Structural Design of a G + 7 Mixed Use Building
 The ETABS output are;



 Dimension of column.















 Limiting values of reinforcement;


 Inertia of column and beam



 Effective buckling length;

*
+
*
+
 Eccentricity
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Structural Design of a G + 7 Mixed Use Building
I.
Accidental eccentricity;
,
II.
;
√
√
For
[
]
[
]
III.
{
Total eccentricity,
Final design parameters,
Using bi-axial chart number 10,
Total area of steel,
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Design of shear
 Shear force carried by concrete
 Design shear forces are,
√
 According to EBCS – 2, 1995 Art 7.2.4.3 the shear reinforcement bar shall be less than,
{
{
Design of Column C-37 from
Floor
The analysis results are;





 Eccentricity,
I.
Accidental eccentricity;
Bahir Dar University
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{
II.
Second order eccentricity;
√
√
[
]
[
]
No need of second order eccentricity.
III.
Equivalent first order eccentricity.
{
 FINAL DESIGN PARAMETERS.
Using bi-axial chart number 10,
Total area of steel,
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Design of shear
 Shear force carried by concrete
 Design shear forces are,
√
 According to EBCS – 2, 1995 Art 7.2.4.3 the shear reinforcement bar shall be less than,
{
{
Design of Column C-37 from
Floor
The analysis results are;






Bahir Dar University
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For
[
]
[
]
{
Total eccentricity,
Final design parameters,
Using bi-axial chart number 10,

Total area of steel,
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Structural Design of a G + 7 Mixed Use Building
Design of shear
 Shear force carried by concrete
 Design shear forces are,
√
 According to EBCS – 2, 1995 Art 7.2.4.3 the shear reinforcement bar shall be less than,
{
{
Design of Column C-37 from
Floor
The analysis results are;






Bahir Dar University
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For
* +

*
+

{
Total eccentricity,
Final design parameters,
Using bi-axial chart number 10,
Total area of steel,
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Design of shear
 Shear force carried by concrete
 Design shear forces are,
√
 According to EBCS – 2, 1995 Art 7.2.4.3 the shear reinforcement bar shall be less than,
{
{
Design of Column C-37 from
Floor
The analysis results are;






For
[
]
[
]
{
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Total eccentricity,
Final design parameters,
Using bi-axial chart number 10,
Total area of steel,
Design of shear
 Shear force carried by concrete
 Design shear forces are,
√
 According to EBCS – 2, 1995 Art 7.2.4.3 the shear reinforcement bar shall be less than,
Bahir Dar University
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{
{
Design of Column 37 for G+ 4 Floor
Analysis results;
At bottom P=-1135.74KN
V2=-63.5KN,
V3=37.63KN
M2=54.55KNm,
At top
M3=-93.9KNm
P=-1373.3KN
V2=-63.5KN,
M2=-43.3KNm,
V3=37.63KN
M370.28KNm
Dimension of column is
25mm concrete cover
b‟=h‟=25+6+10=41mm
Limiting values for reinforcement
Area moment of inertia of column and beam
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Effective buckling length
Eccentricity calculation
Accidental eccentricity
{
First order eccentricity, for
{
,
Second order eccentricity, for
√
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Structural Design of a G + 7 Mixed Use Building
Second order eccentricity can be ignored.
Total eccentricity
,
,
First order eccentricity, for
,
Second order eccentricity, for
Second order eccentricity can be ignored.
Total eccentricity
,
,
Final design parameter
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Using biaxial chart no-10 →
………………….OK
Use 8
longitudinal bar
Design for shear force
Shear force carried by concrete
Design shear forces are:-
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√
…………………………..OK
According to EBCS-2, 1995 art 7.2.4.3 the shear reinforcement bar;
{
Use
shear reinforcement
Spacing
{
Use
C/C 240mm
Design of Column 37 5th to 6th Floors
Analysis results;
At bottom
P=-1083.1KN
V2=-64.2KN,
V3=34.6KN
M2=49.53KNm,
At top
M3=-95.4KNm
P=-1069.6KN
V2=-64.3KN,
V3=34.6KN
M2=-40.44KNm,
M3=71.74KNm
Dimension of column is
Effective buckling length,
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Eccentricity calculation
Accidental eccentricity
{
First order eccentricity, for
{
,
Second order eccentricity, for
√
Second order eccentricity can be ignored.
Total eccentricity
,
,
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First order eccentricity, for
,
Second order eccentricity, for
Second order eccentricity can be ignored.
Total eccentricity
,
,
Final design parameter
Using biaxial chart no-10 →
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………………….OK
Use 8
longitudinal bar
Design for shear force
Shear force carried by concrete
Design shear forces are:-
√
…………………………..OK
According to EBCS-2, 1995 art 7.2.4.3 the shear reinforcement bar ,
,
Use
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shear reinforcement
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Spacing
{
Use
C/C 240mm
Design of Column 37 7th to 8th Floors
Analysis results;
At bottom
At top
P=-784.76KN
V2=-63.54KN,
V3=30.62KN
M2=43.9KNm,
M3=-94.7KNm
P=-771.24KN
V2=-63.54KN,
M2=-35.71KNm,
V3=30.62KN
M3=70.513KNm
Dimension of column is
Effective buckling length,
Eccentricity calculation
Accidental eccentricity
{
First order eccentricity, for
{
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,
Second order eccentricity, for
√
Second order eccentricity can be ignored.
Total eccentricity
,
,
First order eccentricity, for
,
Second order eccentricity, for
Second order eccentricity can be ignored.
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Total eccentricity
,
,
Final design parameter
Using biaxial chart no-10 →
………………….OK
Use 8
longitudinal bar
Design for shear force;
Shear force carried by concrete
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Design shear forces are:-
√
…………………………..OK
According to EBCS-2, 1995 art 7.2.4.3 the shear reinforcement bar,
{
Use
shear reinforcement
Spacing
{
Use
C/C 240mm
Design of Column 37 7th to 8th
Analysis results;
At bottom
P=-491.82KN
V2=-67.75KN,
M2=39.14KNm,
At top
V3=27.1KN
M3=-97.7KNm
P=-478.3KN
V2=-67.75KN,
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M2=-33.01KNm,
M3=78.44KNm
Dimension of column is
Effective buckling length,
Eccentricity calculation
Accidental eccentricity
{
First order eccentricity, for
{
,
Second order eccentricity, for
√
Second order eccentricity can be ignored.
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Total eccentricity
,
,
First order eccentricity, for
,
Second order eccentricity, for
Second order eccentricity can be ignored.
Total eccentricity
,
,
Final design parameter
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Using biaxial chart no-9→
………………….OK
Use 8
longitudinal bar
Design for shear force;
Shear force carried by concrete
Design shear forces are:-
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√
…………………………..OK
According to EBCS-2, 1995 art 7.2.4.3 the shear reinforcement bar,
{
Use
shear reinforcement
Spacing
{
Use
C/C 240mm
Design of Column 37 for Tanker Floor
Analysis results;
At bottom
At top
P=-153.87KN
V2=-31.59KN,
V3=-25.42KN
M2=40.4KNm,
M3=-69.74KNm
P=-145.03KN
V2=-31.59KN,
M2=-32.84KNm,
V3=-25.42KN
M3=40KNm
Dimension of column is
Effective buckling length,
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Eccentricity calculation
Accidental eccentricity
{
First order eccentricity, for
{
,
Second order eccentricity, for
√
Second order eccentricity can be ignored.
Total eccentricity
,
,
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First order eccentricity, for
,
Second order eccentricity, for
Second order eccentricity can be ignored.
Total eccentricity
,
,
Final design parameter
Using biaxial chart no-9→
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………………….OK
Use 8
longitudinal bar
Design for shear force;
Shear force carried by concrete
Design shear forces are:-
√
…………………………..OK
According to EBCS-2, 1995 art 7.2.4.3 the shear reinforcement bar,
{
Use
shear reinforcement
Bahir Dar University
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Spacing
{
Use
C/C 240mm
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Chapter-6
6 Foundation Design
6.1 Structural Design of Isolated Footing
Depth Determination
Once the size of the footing is determined, the footing must be designed structurally for

Adequacy of the thickness of the footing
Check – punching shear (two way shear)
Diagonal tension (wide beam shear)

Providing the necessary reinforcement to withstand the bending moment
A) Punching Shear criteria

The critical section for punching is at a distance “1.5d” from the face of the
column (According to EBCS – 2, 1995)

The critical section for punching shear is at a distance of “0.5” from the face of
the column. (According to EBCS-2, 1985)
Therefore from the two codes we prefer to use the second one (EBCS-2, 1985) in footing depth
determination.
B) Wide Beam Shear Criteria
The critical section for wide beam shear is at a distance of “d” from the face of the column and it is a one
way shear consideration in both axis. (According to both EBCS-2, 1985, &1995)
N.B since we used the factored ETABS V 9.7 analysis data in order to avoid over conservative design we
didn‟t factor the bearing capacity of the ground soil.
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6.1.1
i.
FOOTING DESIGN
Proportioning of footing.
Assume the size of footing;
Check
Using flexural formula determine,













[
]
[
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[
]
[
]
[
]
Since there is no big difference between
ii.
, we take the average.
Structural design.
In this design of footing limited state design is used.
Depth determination;
a) Punching shear.
,
[
[
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]
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Structural Design of a G + 7 Mixed Use Building

b) Wide beam shear (diagonal tension)
*
*
+
+
The critical sections for wide beam shear are section 1-1 and section 2-2.
i.
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[
Comparing
]
[
]
punching governs.
c) Bending moment reinforcement.
In Y-Y and X-X direction














Using design chart,
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No need of compression reinforcement,
Check for minimum reinforcement,
Check bond length (development length)
(
)
√
√
(
)
The reinforcement bars should be bent at the end.
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7 Reference
1.
2.
3.
4.
5.
6.
7.
8.
EBCS-1, 1995
EBCS-2, 1995
EBCS-3, 1995
EBCS-7,1995
EBCS-8,1995
Joseph E .Bowles, P.E, S.E.‟‟ Foundation analysis and design.‟‟
Arthur H. Nelson, David Darwin, Charles Dolan, „‟Design of concrete structures.‟‟
Akbar Tamboli, Mohsin Ahmed, Michael Xing,‟‟ Standard book for civil engineers‟‟ McGraw-Hill
companies, USA, New Jersey, 2004.
9. W.F.CHEW, J.Y. Richards Liew,‟‟civil engineering hand book.‟‟, CRC Pre LCC. USA,2003
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