CE415 CIVIL
ENGINEERING DESIGN I
FALL 2022-2023
LECTURE 1
DR. FEYZA SOYSAL ALBOSTAN
COURSE OUTLINE
COURSE OUTLINE
Please check your emails & webonline regularly!
CONTENT OF THE COURSE
• Design principles of structures
• Design loads for structures
• Preliminary design
• SAP2000 applications
• Seismic analysis & design per earthquake code
• Shear wall design
TODAY’S LECTURE
• Project introduction
• Design principles of structures
• Structural design process
• Structural members
• Load transfer mechanism
• Load carrying mechanism
• Irregularities in buildings
PROJECT INTRODUCTION
• Project alternatives:
• Hotel building
• Social facility building
• Select one of the projects, form project groups of 2 or 3
students and e-mail (fsoysal@cankaya.edu.tr) to me until
October 12, 2022
DESIGN PRINCIPLES OF STRUCTURES
Flow of work from planning of a structure to service:
Planning 
Design 
Construction 
CE415
Planning:
• Ownership & financing
• Approximate location
• Expected service lifetime (typically 50-100 years)
• Environmental evaluation
Maintenance
DESIGN PRINCIPLES OF STRUCTURES
Design: iterative process!
• Type of structure: R/C, steel, which materials to use?
• Performance requirements: defined in codes, based on the project
• Economy: building cost, construction cost
• Aesthetics
• Structural detailing: size of members,
vs
reinforcement
• Structural drawings
Image courtesy:
https://forum.donanimhaber.com/gecekonduapartman-dogurdu--6188620
Image courtesy:
https://www.archdaily.com/935777/cube-berlinsmart-office-building-3xn
DESIGN PRINCIPLES OF STRUCTURES
Construction:
Maintenance:
• Planning
• Assessment: investigation,
evaluation
• Construction
• Quality control
• Inspection
• Implementation of remedial
measures if necessary:
Bridges: repairing damaged steel
beams, damaged expansion joints
Base isolators: corrosion may occur,
dust accumulation
STRUCTURAL DESIGN PROCESS
Architect:
Structural engineer:
• Architectural drawings
• Preliminary design
• Decides on the form of the
structure
• Proposes a structural load carrying
mechanism based on the architectural plan
• Determines preliminary sizes of members
& reinforcement
• Proposes some dimensions on the
architectural plan
• Final design
• Final member sizes & reinforcement
• Selects the type of finish materials
• Final drawings
• Cost estimation
STRUCTURAL MEMBERS
• Slabs:
• Used to construct floors & ceilings
• Transfer the vertical loads to
beams, columns & shear walls
• Resist self-weight (dead load) &
live loads
Image courtesy: https://www.quora.com/What-are-beams-slabfootings-columns-in-construction
STRUCTURAL MEMBERS
• Beams:
• Flexural members
• Negligible axial force & resist loads
against bending
• Resist self-weight (dead load) &
dead and live loads transferred
from slabs
Image courtesy: https://www.quora.com/What-are-beams-slabfootings-columns-in-construction
STRUCTURAL MEMBERS
• Columns:
• Resist axial loading & bending
• Resist self-weight (dead load) &
dead and live loads transferred
from slabs and beams within a
tributary area
Image courtesy: https://www.quora.com/What-are-beams-slabfootings-columns-in-construction
STRUCTURAL MEMBERS
• Shear walls:
• Structural members
• Long side/Short side > 6 (TBEC2018)
• Resist in-plane shear & flexure
• Resist lateral load like wind & EQ
Image courtesy:
https://www.semanticscholar.org/paper/Study-onthe-Optimum-Location-and-Type-of-Shear-in-NajimAlAskari/e61b08f80aa959f7e697744c81df9b2d3744387
0
Image courtesy: https://www.quora.com/What-are-beams-slabfootings-columns-in-construction
LOAD TRANSFER MECHANISM
Two basic load paths: gravity load path & lateral load
path
Gravity load path:
Vertical loads such as dead load, live load or snow load
considered
Load  Roof surface  Roof slab  Beams 
Columns  Foundation  Soil
Slabs, beams & columns resist loading in gravity direction
Gravity load path depends on the type of floor slab (oneway, two-way)
Image courtesy:
https://www.engineersdaily.com/2014/05/how-loads-flowthrough-building.html
LOAD TRANSFER MECHANISM
Lateral load path:
Lateral loads due to wind & EQ transferred through
structure
Roof & floor systems (diaphragms) transfer the loads to
the walls &/or frames, which in turn transfer the load to
the foundations
Diaphragms take horizontal forces from the storeys at or
above their level & transfer to walls or frames in the storey
immediately below
Alternatively, lateral forces resisted by braces, which also
limit sway
Image courtesy:
https://www.engineersdaily.com/2014/05/how-loads-flowthrough-building.html
Image courtesy:
https://www.steelconstructio
n.info/Braced_frames
LOAD CARRYING MECHANISM
• You are given architectural drawings
• Floor plans, roof plan, elevation plans, section view
• In the architectural drawings, locations & dimensions of columns,
beams, slabs, shear walls (load carrying mechanism) are not shown
• There may be some architectural drawings with locations of columns.
Usually, architects & engineers decide together. If necessary, the
engineer can change the locations of columns
LOAD CARRYING MECHANISM
Types of structural systems for r/c structures:
• Moment frame system (beam, column, slab)
• Wall system (shear wall, slab)
• Dual system (beam, column, shear wall, slab)
Image courtesy:
http://www.seismicresilience.org.nz/topics/superstructure/seismi
c-design-concepts/moment-frames/
Usually selected
especially for EQ prone
regions
Image courtesy: https://gharpedia.com/blog/what-is-aframe-with-shear-wall-structural-system/
LOAD CARRYING MECHANISM
After the structural system is selected, propose a load carrying
mechanism  determine the places of beams, columns etc.
Keep in mind that both vertical & horizontal loads should be
transferred to the foundation by the shortest possible path.
LOAD CARRYING MECHANISM
Ideally:
• Slabs should be placed on beams
• Beams should be continuous throughout the plan
• Columns should be placed at both ends of beams
• Columns should be continuous throughout the elevation
• Sufficient shear walls should be placed for EQ loading
LOAD CARRYING MECHANISM
Step I: Place beams
Main purpose of beams is to carry slabs & walls
• Place beam below each exterior & interior walls
• Between beams, there will be slabs. Check the dimensions of slabs, if
there is a slab with shorter side greater than ~5 m, place additional
beams
• Check the place of beams, if there are beams with ~80 cm spacing,
delete some of them
LOAD CARRYING MECHANISM
Step II: Place columns / shear walls
Main purpose of columns is to transfer loads of beams to columns below & to
foundation
Shear walls transfer the lateral loads with the help of slabs & beams to columns
& foundation
• At the intersection of each beam, column is placed. But, throughout the
elevation the column place is checked so that columns will not pass through
doors, windows etc.
• For regular residential R/C buildings, limit the span length of beams to 6~7 m.
If there is a beam exceeding this span length, place additional column
LOAD CARRYING MECHANISM
• Check the place of columns. If there are too closely spaced columns,
columns may be removed or joined.
• Place columns symmetrically with respect to the geometrical centroid
• Place columns to have the same rigidity for each EQ loading direction.
If necessary, change the orientation & dimensions (without violating the
architectural plan)
LOAD CARRYING MECHANISM
• Locate approximately the center of mass & center of rigidity. Center
of mass is approximately at the geometrical centroid. The EQ loading is
applied to the center of mass. Center of rigidity is the stiffness centroid
& is closer to the denser locations of columns & shear walls. Try to
make mass & rigidity center as close as possible. The eccentricity
between these centers are limited in the EQ code.
Image courtesy:
https://taxonomy.openquake.org/terms/
torsion-eccentricity-tor
LOAD CARRYING MECHANISM
• Place the shear walls symmetrically. For each EQ direction, at least 2 shear
walls are required. Minimum area of shear walls are defined in EQ codes.
S4
S5
S6
In x-direction, which shear walls resist EQ?
b I=1/12bh3
h
h
b
S2,S5
y
S1
x
S2
S3
In y-direction, which shear walls resist EQ?
S1,S3,S4,S6
LOAD CARRYING MECHANISM
Step III: Place slabs
After placing the beams, place of slabs are already determined. But, be
careful with openings such as stairs or elevators
No slabs at openings
LOAD CARRYING MECHANISM
After placing the beams, columns, & shear walls, determine the initial
dimensions/sizes of members
At the preliminary design stage, estimate the dimensions. After you make
calculations, you can enlarge the cross-sections. Usually, you don’t
recalculate the static calculations
Based on the code requirements, you can estimate the cross-sectional
dimensions as the minimum dimensions defined in the codes
LOAD CARRYING MECHANISM
Min. cross-sectional dimensions of a column: 300x300 mm
Min. cross-sectional dimensions of a beam: 250x500 mm
Min. cross-sectional dimensions of a shear wall: 250x1500 mm
Since columns & shear walls mainly resist EQ forces, these min.
dimensions will be enlarged
LOAD CARRYING MECHANISM
Beams:
Min. width: 250 mm, min height: 500 mm
Beam height ~net span length/12
If you have a 7 m span length, height can be chosen as 600 mm
For schools & hospitals min dimensions can be 300x600 mm
LOAD CARRYING MECHANISM
Columns:
300x300 mm defined as a min in TBEC2018
Short side of column > column height/20
The cross-sections of columns can change from floor to floor but be
careful with the applicability & reinforcement
LOAD CARRYING MECHANISM
Shear walls:
Cross-section of a shear wall remains constant through the elevation
Min dimensions 250x1750 mm (TS500)
250x1500 mm (TBEC2018)
THINGS TO AVOID
IRREGULARITIES IN BUILDINGS
• Discontinuous slabs
• Discontinuous beams, columns
• Torsional irregularities
• Irregularities in plan
• Soft story
• Weak story
IRREGULARITIES IN BUILDINGS
• All columns & shear walls in the same direction
IRREGULARITIES IN BUILDINGS
• Discontinuous beams & beams
with abrupt changes in rigidity
• Single & mat foundation together
IRREGULARITIES IN BUILDINGS
• Not allowed in TBEC2018
•(a): column placed on a cantilever &
cantilever with a gusset
• (b): discontinuous columns
• (c): shear wall on a column
• (d): shear wall on a beam
IRREGULARITIES IN BUILDINGS
Image courtesy: http://helid.digicollection.org/en/d/Jh0683e/6.3.1.2.html