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Lateral Load Resisting Systems
Many slides from 2009 Myanmar Slides of Profs Jain and Rai 1
IITGN Short Course
Gregory MacRae

Lateral Loads
Wind Earthquake

Lateral Load Resisting Systems
Rai, Murty and Jain

Lateral Load Resisting Elements
Vertical Elements Moment-Resisting Frames
Walls
Bearing walls / Shear Walls / Structural Walls
Gravity Frame + Walls
Dual System (Frame + Wall)
Vertical Truss
Tube System
Bundled-Tube System
Floor/Diaphragm
Foundation various typesRai, Murty and Jain

Vertical Elements

Building Structures
Structural Systems
Frame with Concrete
Shear Walls
Concrete Moment
Resisting Frame
Steel Braced Frame
Concrete Frame with
Shear Walls Rai, Murty and Jain

Structural Systems
Building Structures
Rai, Murty and Jain

Evolution of Systems
Vertical ElementsMoment-Resisting FramesWalls (Bearing walls / Shear Walls / Structural Walls)Gravity Frame + Walls Dual System (Frame + Wall)Vertical TrussTube SystemBundled-Tube System
Rai, Murtyand Jain

U.S. Buildings, Zones 3 and 4
9Sudhir K Jain

Bearing/Shear Wall System
Variations in LFRS Selection among seismic countries, Zones 3 and 4
Countries CHILE, US, PERU, COLOMBIA, MEXICO

Building Frame /Shear Wall System

Moment Resisting Frame System

Wall/Frame Dual System

Bearing/Shear Wall Building Frame/Shear Wall
14Sudhir K Jain

Moment-Resisting Frame Wall/Frame Dual Frame
15Sudhir K Jain

STRUCTURAL FORMS
Approximate Analysis of:
- Moment Frames
- Walls
Approximate analysis allows to get a simple
estimate of member sizes and to check the
magnitude of computer analysis results
16Sudhir K Jain

Moment Resisting Frame
Components
Beams
Columns
Joints
Joints: Most frames have joints where the angle
between the connecting members in maintained,
i.e., rigid joints.
h
P
2/Ph 2/Ph2/Ph 2/Ph
2/P 2/P
17Sudhir K Jain

Frame with rigid joints and with very flexible beams.
18Sudhir K Jain
BMD

Deflected shape due to flexural deformation of columns
Deflected shape due to flexural deformation of columns and beams.
Deflected shape due to flexural deformation of columns and beams, axial deformation of columns.
19Sudhir K Jain

Frame with rigid joints and with infinitely rigid beams
20Sudhir K Jain
BMD
For such a frame with different flexibility beams, what is the range of column base moments?

Moment Pattern
Under Lateral Forces
21Aseismic Design Analysis of Buildings, by Kiyoshi Muto; Maruzen Company, Ltd.,
Tokyo, 1974 xiv q-361 pp.
Hinges (locations of zero moment) Midpoints of Beams
htop
hbot
hmid
hmid 0.5hmid
0.5hmid
0.7htop
0.7hbot
0.5LbeamLbeam

Shears on Different Columns
22Aseismic Design Analysis of Buildings, by Kiyoshi Muto; Maruzen Company, Ltd.,
Tokyo, 1974 xiv q-361 pp.
Lateral Forces Lateral Shears
Exterior Columns Assumed to Carry One Half Shears of Internal Columns

Shears on Different Columns
23Example: If the storey shear at the top level is 120kN say, then the shear force on
an internal column in 20kN, and on an external column is 40kN.
Lateral Forces Lateral Shears
Exterior Columns Assumed to Carry One Half Shears of Internal Columns
120kN20kN20kN 40kN 40kN
40kN80kN80kN40kN240kN

Shears on Different Members
24
20kN20kN 40kN 40kN
40kN80kN80kN40kN
Example:
Top right beam shear is found by
considering a free body. The beam
axial force is first computed from .
horizontal equilibrium as 20kN. Then,
by taking moments about the column
mid-height, the beam shear is
20kNx0.3*3.6m /(0.5x7.2m)= 6kN.
20kN
20kN
6kN
0.3 x 3.6m
0.5 x 7.2m
6kN

Forces on Different Members
25A similar process may be used to obtain all moments, shears and axial forces throughout
the frame.
20kN20kN 40kN 40kN
40kN80kN80kN40kN
Example:
The beam moment demand is therefore
0.5 x 7.2m * 6kN = 21.6kNm due to
earthquake loads. This can be
combined with gravity loads for design.
20kN
20kN
6kN
0.3 x 3.6m
0.5 x 7.2m
6kN
21.6kNm
21.6kNm

Forces on Different Members
Seismic axial forces in columns
are generally small in the internal
columns since the shears in the
beams either side of the column
tend to cancel out. They are
generally greater in the external
columns

Degree of Freedom in 2-D Frame
Degrees of freedom (3 per joint) Degrees of freedom after neglecting axial deformations
(one per joint +one per floor)
27Sudhir K Jain

Degree of Freedom in 3-D Frame
28Sudhir K Jain

Plan of a three-storey building having three two-bay frame in they-direction, and by two four-bay frames in the x-direction
x
y
29Sudhir K Jain

Plan of a three-storey building having three two-bay frame inthe y-direction, and by two four-bay frames in the x-direction
30Sudhir K Jain

Bearing wall / structural (shear) wall
Shear wall shear beam
Large width-to-thickness ratio; else like a column
Height-to-width
small ( 1) Mainly shear deformations
large ( 4) Mainly flexural deformations
in-between Shear and flexural deformation
Foundation
rigid body rotation
Walls
31Sudhir K Jain

Walls
32
Wall with Shear
Deformation
Wall with Flexural
Deformation
Wall with both
Shear and Flexural
Deformation
Sudhir K Jain

Stiffness due to point load at the top
4m
14m
0.4m
0.4m 0.4m
3.6m
Wall Section
Area = 860,000 mm2
Shear Area = 540,000 mm2 (= 0.15m x 3.6m)
Moment of Inertia = 1.867 1012 mm4
E = 25,500 MPa
G = 10,500 MPa
0.15m thick
Example
33Sudhir K Jain/MacRae

mmWW
GA
WH
mmWW
EI
WH
s
shear
flexure
6
6
12
33
1046.2500,10000,540
14000
106.1910867.1000,253
14000
3
Total Deflection = flexure + shear = 22.1X10-6 W mm
mkNmmNW
Wkwall 320,45320,45
101.22 6
Example
34MacRae/Sudhir K Jain

4m
Footing
8m
Shear wall
Winklers Foundation
Sub grade modulus for some soils300030 m/kN,k
M k(x ). 4dx
x
Rocking of Footing
35Sudhir K Jain

Rocking stiffness of footing
Rocking moment M causes rotation
Restoring moment
Rocking stiffness of footing
Horizontal load W acting 14m above
Moment applied on footing = 14W kNm
kNmdxxxkmM 64
4
1012.54
rad/kNm.M 610125
Rocking of Footing
36Sudhir K Jain

Rotation of footing
Wall displacement at roof level
Total deflection
Wall stiffness
radiansW..
W 66
1073210125
14
mWWrocking56 1083.3141073.2
mWX
mWXmWX
shearflexurerockingtotal
5
85
1083.3
1021.21083.3
mkNWX
Wkwall /110,26
1083.3 5
Rocking of Footing
37Sudhir K Jain
Ro
ckin
g g
over
ns
def
lect
ions
and s
tiff
nes
s!!!
It m
ust
be
consi
der
ed

Issues
Stiffness calculations
Force resultants/stresses
Detailing
Stiffness
Small Opening
Ignore reduction in lateral stiffness due to opening
Large Opening
Behaves as two walls connected with a coupling beam
Shear Wall with Openings
38Sudhir K Jain

Shear Wall with Openings Issues
beam
beam
beam
Imaginary
beam
Shear panels
ColumnColumn
Column
Ib
I = I =
Analysis
Model
Wall
39Sudhir K Jain

Example
4m 3m 6m
BB
AA
14m
Beam size 200 1100
0.4m

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