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Earthquake Methods

This document discusses determining earthquake loads and lateral forces on buildings. It provides two methods - the static force procedure and Rayleigh's formula - to calculate minimum design lateral forces for buildings. It also works through an example problem to calculate the base shear and seismic coefficients for a 3-story commercial building in the Philippines, determining its earthquake load. Key steps include calculating the total building weight, importance factor, seismic coefficients, and applying formulas to determine minimum lateral forces.

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Cesar Malenab
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197 views24 pages

Earthquake Methods

This document discusses determining earthquake loads and lateral forces on buildings. It provides two methods - the static force procedure and Rayleigh's formula - to calculate minimum design lateral forces for buildings. It also works through an example problem to calculate the base shear and seismic coefficients for a 3-story commercial building in the Philippines, determining its earthquake load. Key steps include calculating the total building weight, importance factor, seismic coefficients, and applying formulas to determine minimum lateral forces.

Uploaded by

Cesar Malenab
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Earthquake Load

Determination
Earthquake Loads
Problem 1
Adjust Load Combination given by Equation 203-5.

Solution:
Simplified Static
Simplified Design Base Shear

  W = total weight
R = numerical coeff. representative of
R the inherent overstrength and global
ductility

Vertical Distribution

 
 
Problem 2
Determine the minimum design lateral forces for a three-
story commercial building located in Lucena, Quezon. The
building is constructed using building frame systems with
ordinary reinforced concrete shear walls.
Deck
3rd
2nd

GF
3m 150T
3m 150T
3m 200T
Static Force Procedure
I. Method A

Ct = 0.035 for steel moment frames


= 0.030 for concrete moment frames ENGLISH SYSTEM
= 0.035 for eccentric moment frames
= 0.02 for all other buildings

hn hn hn
hn

n = no. of storey
II. Method B

Reyleighs Formula
Problem 3
Wihi Fx

950 3.6 950 (38.4) 78.487

1800 3.6 1800(34.8) 134.771

1800 3.6 1800(31.2) 120.829

1800 3.6 1800(27.6) 106.887

1800 3.6 1800(24) 92.94

2600 3.6 2600(20.4) 114.116

1850 3.6 1850(16.8) 66.869

1850 3.6 1850(13.2) 52.54

1950 3.6 1950(9.6) 40.276

2000 6 2000(6) 25.818


__________
387,420
Problem
Example. 4
Location: Cubao, Q.C.
Occupancy: Hospital
Structure: SMRF Concrete Special
Moment Resisting Force system
Soil Profile: Guadalupe Tuff - C
Seismic Source type A

Deck 3m 100T
4th 3m
3rd 3m
150T
2nd 3m 150T
GF 3m 200T
  Cv= 0.56Nv
Nv=1.6(≤5km)
Cv= (0.56)(1.6) = 0.896

Ca= 0.4Na
Nv=1.2(≤5km)
Cv= (0.4)(1.2) = 0.48

Importance factor, I =1.15

W, Total weight = 600T

R= 0.85

T= Ct(hn)3/4
hn=12, Ct = 0.0731
T= 0.731(12)3/4 Wihi Fx
0.471sec < 0.7sec ; Ft=0
950 (38.4) 78.487
1800(34.8) 134.771
1800(31.2) 120.829
1800(27.6) 106.887
Σ=387,420

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