Comparative Study of Member Forces of Steel Building
with Reinforced Concrete Shear Wall in Different
Seismic Zones
Nay Myo Thu, Zaw Min Htun
Department of Civil Engineering
Mandalay Technological University
Abstract - This journal presents seventeen-storeyed steel
building with reinforced concrete shear wall which is
situated in seismic zone 4. And the structural member forces
and moments of proposed structure obtained from the
analysis of different seismic zones are compared. The overall
height of the building is 181 ft and it is rectangular-shape.
The parameters of the building are 84 ft in length and 86 ft
in width respectively. For dynamic analysis, response
spectra analysis is used in this paper. The building is
composed of special moment-resisting frame. The structural
elements are designed based on AISC-LRFD 1999. For
earthquake and wind forces, loading data were referenced
from UBC-97. Wind speed is used 80 mph. Dead loads and
live loads are used according to ACI code. The load
combination required for the whole structure is used
according to UBC. The structural steel used for the building
is A572 Grade 50 and wide flange W-section. Stability
checks such as overturning moment, storey drift, sliding and
torsional irregularity are also checked.
cause powerful twisting forces called torsion. These
forces can literally shear a building apart. When shear
walls are designed and constructed properly, they have
the enough strength and stiffness to resist unwanted
effects caused by the lateral forces. Therefore, shear walls
are essentially important in high-rise steel building
subjected to lateral forces mainly. The design of steel
structure is done with the aid of computer software
program named “ETABS”.
Keywords – AISC-LRFD 1999 code, ETABS software, UBC
97 code
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I. INTRODUCTION
Nowadays, like other countries, the growth of
population of Myanmar is getting more and more with a
high pace. The requirements of increased population and
natural geology of country highly demands the high-rise
building. Myanmar is situated in a secondary seismic belt
which is in the junction of two major belts. It is likely to
meet highly destructive damage of earthquake to the
buildings in some areas. Therefore, high-rise building
should be designed to resist the earthquake effects. To
save the construction time and other several factors, steel
structures are commonly designed. Steel structures are
more preferable than other structural materials. Steel
members are widely used all over the world because of
high strength, long life, ease of construction and fire
resisting. So, most people like steel structured buildings
because of less construction cost, light weight, easy
installation. And they can resist seismic force more than
reinforced concrete buildings.
In this paper, reinforced concrete shear wall is used as a
vertical structural resisting member to resist the lateral
load caused by the wind and earthquake.In building
construction, a rigid vertical diaphragm capable of
transferring lateral forces from exterior walls, floors and
roofs to the ground foundation in a direction parallel to
their planes. Lateral forces caused by wind and
earthquake and in addition to the own weight of structure
(1)
(2)
(4)
II. OBJECTIVE OF THE STUDY
The objectives of the study are as follow;
To collect information of actual behaviour of
high-rise steel building with reinforced concrete
shear wall
To know the usefulness and performance of
reinforced concrete shear wall
To acquire the more understanding of lateral force
resistant design with a better, safe and modernized
technique
To compare the results of structural member forces
and moments obtained from the analysis of different
seismic zones
III. DATA PREPARATION FOR DESIGN OF STRUCTURE
A. Structural Framing System
The proposed steel superstructure is designed as
Special Moment Resisting Frame and based on UBC1997. It is seventeen storeyed and located in seismic zone
4. The case study building is rectangular shape with an
overall height of 181 ft. Maximum length is 84 ft and
maximum width is 86 ft. ETABS-software is used to
analyse the structure.
B. Material Properties
The strength of a structure depends on the strength of
the materials from which it is made.
Analysis property data
- Weight per unit volume
- Modulus of elasticity for steel
- Poisson's ratio
- Coefficient of thermal expansion
Design property data
= 490 pcf
= 29×106 psi
= 0.3
= 6.5×10-6
- Concrete strength, fc '
- Yield stress
, Fy
- Tensile stress
, Fu
= 3.5 ksi
= 50 ksi
= 65 ksi
C. Loading Consideration
There are two kinds of load considered in this study
which is gravity load that includes dead and live load,
lateral load that includes wind and earthquake load.
Design load combinations are also used.
Gravity Load
All masses are attracted toward the center of the earth
by the gravitational force. Loads are defined as these
attracting forces acting upon their corresponding masses.
There are two different gravity loads: (1) Dead loads and
(2) Live loads.
1) Dead Load
Dead loads consist of the weight of all material and
fixed equipments incorporated into the building.
-
4.5 " thick wall weight
9" thick wall weight
superimposed dead load
unit weight of concrete
=
=
=
=
55 lb/ft3
100 lb/ft2
25 lb/ft3
150 lb/ft
2) Live Load
Live loads are gravity load produced by the used and
occupancy of the building and do not include dead
loads, construction load, or environmental loads such as
wind and earthquake loadings are based on to UBC-97.
- live load on residential
= 40 lb/ft2
- live load on stair case
= 100 lb/ft2
- live load on roof
= 20 lb/ft2
- unit weight of water
= 62.4 pcf
Lateral Load
1) Wind Load
The wind pressure on a structure depends on the wind
response of the structure. Required Data in designing for
wind load:
- Exposure type
= Type B
- Basic wind velocity
= 80 mph
- Total height of building
= 181 ft
- Method used
= Normal
Force Method
- Windward coefficient
= 0.8
- Leeward coefficient
= 0.5
- Importance Factor
= 1.0
2) Earthquake Load
The purpose of seismic design is to proportion the
structures so that they can withstand the displacements
and forces induced by the ground motion.
(i) Seismic Importance Factor, I
(ii) Seismic Zone Factor, Z
(iii) Soil Profile Types, S
(iv) Seismic Source Type
(v) Near - Source Factors, Na and Nv
(vi)Seismic Response Coefficients, Ca and Cv
(vii) Response Modification Factor, R
- Seismic zone
- Seismic Source Type
- Soil Type
- Structural frame structure
=
=
=
=
4
A
SD
Special Moment
Resisting Frame
- Zone Factor
= 0.4
- Importance Factor, I
= 1.0
- Response Modification Factor, R = 8.5
- Time period factor, Ct
= 0.035
IV. MODELLING OF THE PROPOSED STRUCTURE
The proposed steel superstructure is designed as
Special Moment Resisting Frame. The architectural view
of steel building with reinforced concrete shear wall is
shown in appendix.
-
Total height
Length
Width
Location
=
=
=
=
181 ft
84 ft
86 ft
Zone-4
V. DESIGN RESULTS OF PROPOSED STRUCTURE
In this paper, the design sections of proposed structure
with static analysis are shown in table I and II.
TABLE I
Column
Section
Column
Section
C1
12x19
C9
12x65
C2
12x22
C10
12x72
C3
12x26
C11
12x79
C4
12x30
C12
12x87
C5
12x35
C13
12x96
C6
12x45
C14
12x106
C7
12x53
C15
12x120
C8
12x58
Column section of proposed structure
TABLE II
Beam
Section
B1
10X12
B2
10X15
B3
10X17
B4
10X19
B5
10X22
B6
10X26
B7
10X30
Beam sections of proposed structure
VI. STABILITY CHECKING OF PROPOSED STRUCTURE
IN ZONE 2B
According to UBC-97, the stability for structure
has been checked in the following cases.
A. Checking for overturning moment
B. Checking for sliding
C. Checking for story drift
D. Checking for torsion
A. Checking for Overturning Moment
a) For X-direction
My
Total dead weight
= 347815.5 kip-in
= 7565.661 kip
Cumulated Center of mass
In X direction, XCCM = 522.179 in
Resisting Moment, M =0.9 x Total deadweight x XCCM
= 0.9 x 7565.661 x 522.179
= 3555566.366 kip-in
Factor of safety
=
Resisting moment
Overturning moment
= 3555566.366
347815.5
= 10.22 >1.5 OK
b) For Y-direction
My = 347816 kip-in
Total dead weight
= 7565.661 kip
Cumulated Centre of mass
In Y direction, YCCM = 522.238 in
Resisting Moment, M =0.9 x Total deadweight x YCCM
= 0.9 x 7565.661 x 522.238
= 3555968.102 kip-in
Factor of safety
=
Resisting moment
Overturning moment
= 3555968.102
347816
= 10.22 >1.5 OK
B. Checking for sliding
a) For X direction
Sliding force, Vx
= 229.15 kip
Friction coefficient, μ = 0.25
Total dead weight
= 7565.661 kip
Resistance due to
Friction
= μ × 0.9 × Total dead weight
= 0.25 × 0.9 × 7565.661
= 1702.27 kip
Factor of safety
= 1702.27
229.15
= 7.43 >1.5
No sliding occurs in X direction.
b) For Y direction
Sliding force, Vy
= 229.15 kip
Friction coefficient, u = 0.25
Total dead weight
Resistance due to
friction
= 7565.661 kip
= μ × 0.9 × Total dead weight
= 0.25 × 0.9 × 7565.661
= 1702.27 kip
Factor of safety
= 1702.27
229.15
= 7.43 >1.5
No sliding occurs in Y direction.
C. Checking for Story Drift
Period, T = Cth3/4 = 0.035 x 1813/4 = 1.73 >0.7 sec
Allowable story drift = 0.02h = 0.02 x 181 = 3.62
∆M = 0.7R∆s
∆M x = 1.62 <3.62 OK
∆M y = 1.27<3.62 OK
D. Checking for torsional irregularity
For point 5, Drift X = 0.001551 in, Drift Y = 0.001193 in
For point15, Drift X = 0.001624 in, Drift Y = 0.000849 in
(a) For X direction
Maximum Drift Ratio, max = 0.001624 in
Average displacement of two points,
avg = 0.001551  0.001193
2
= 0.0015875 in
 max = 0.001624 = 1.02 <1.2 OK
avg 0.0015875
(b) For Y direction
Maximum Drift Ratio, max = 0.001193 in
Average displacement of two points,
avg = 0.001193  0.000849
2
= 0.001021 in
 max = 0.001193 =1.17 <1.2 OK
avg 0.001021
Therefore, torsional irregularity does not exist in the
proposed building.
VII. COMPARISON OF STRUCTURAL PERFORMANCE
RESULTS OF PROPOSED STRUCTURE UNDER
DIFFERENT SEISMIC ZONES
In this journal, the proposed structure is analysed with
response spectra analysis. And, the structural
performance results of proposed building under different
seismic zones are compared by using the ETABS
Satisfactory
software.
Figure 1, Story drift in X direction for different seismic zones
Figure 4, Story moment for different seismic zones
Similar to story shear, maximum story
moment can be occurred at the bottom level,
that is, story 1. Due to the severe seismic
effectiveness of proposed structure, seismic
zone 4 has the greater story moment values than
that of others.
Figure 2, Story drift in Y direction for different seismic zones
VIII. COMPARISON OF STRUCTURAL MEMBER
FORCES UNDER DIFFERENT SEISMIC ZONES
From the above graphs, the maximum value
of storey drift can be found at storey level 8. As
a result of seismic effect on structures, the drift
formed at seismic zone 4 is greater compared
with other two seismic zones.
Figure e 5, Maximum axial force for three column types under
different seismic zones
Figure 3, Story shear for different seismic zones
From the chart, we can see the maximum
story shear at the bottom story level. The
applied forces on the members of all stories
transfer from the top most member to the
lowerest members. So, the maximum story
shear occurs at the bottom story level.
According to the bar chart, the
maximum axial force can be found at seismic
zone 4. The reason is because of the greater
effectiveness of the seismic force on the
proposed structure than the last two zones. In
addition, the column type that suffered peak
axial force is the exterior one. After the exterior
column type, the second greater axial force can
be occurred at corner types and the least value
can be seen at interior column one.
Figure e 6, Maximum bending moments for three types of column
under different seismic zones
Unlikely to the axial forces, the
maximum bending moment can be found at
interior column types. And the second greater
values occur at exterior column types and the
smallest values can be occurred at coner column
types. Similar to the others, the maximum
bending moment exists at the seismic zone 4
because of the greater seismic effectiveness on
the proposed structure.
Fig 8, Location of shear walls of Structure
APPENDIX
Fig 9, 3D View of Structure
IX.
CONCLUSIONS
Fig 7, Plan view of Structure
In this study, the seventeen storied steel building
with reinforced shear wall is analysed and the values of
structural member forces and moments for different
seismic zones are compared. From the analysis results,
the forces and moments of structural members are slowly
increasing from the lower to the higher level depending
on the respective seismic zone .The wind speed for the
design of structure is 80 mph. The structure is analysed
according to ETABS software and AISC- LRFD 1999
specifications. The static approach procedure was
analysed according to UBC-97.The stability checking,
such as story drift, overturning moment and sliding were
also checked in the design calculation.
ACKNOWLEDGEMENT
The author wishes to express her deep gratitude
to his Excellency, Minister Dr. Ko Ko Oo, Ministry of
Science and Technology, for opening the Master of
Engineering course at Mandalay Technological
University. The author is very thankful to Dr. Myint
Thein, Pro-Rector of Mandalay Technological University,
for his in valuable permission and kind support in
carrying out this research work. The author wishes to
record her thanks to Dr. Kyaw Moe Aung, Associate
Professor and Head, Department of Civil Engineering,
Mandalay Technological University, for his guidance,
suggestions and necessary advice. The author is deeply
indebted to her supervisor, Dr. Zaw Min Htun, Lecturer,
Department
of
Civil
engineering,
Mandalay
Technological University, for his careful guidance,
necessary advice and encouragement. The author also
wishes to thank all her friends for their helps and advices
on her studying. Finally, the author would like to express
grateful thanks to all teachers and parents for their
supports, kindness and unconditional love.
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Examples, (2010).
(3) Uniform Building Code, Volume 2. "Structural Engineering
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(5)
(6)
Design Provisions". 1997, 8th Ed. International Conference of
Building Officials.
Michael R. Lindeburg, PE with Majid Baradar: A Professional’s
Introduction to Earthquake Forces and Design Details, In Seismic
Design of Building Structures, 8th Ed., Professional Publications,
Inc., (2001).
Salmon, C. G. and J.E. Johnson, 1990, Steel Structures – Design
and Behavior, Third Edition, Harper & Row, New York, NY
Irwin, A. W. (1984). CIRIA Report 102. Design of Shear Wall
Buildings. London: CIRIA Publication.