ctural Geometry
Structure
Plate-Frame (d) 3D Frame
WARNING:
Computers assist the structu phase of the design process rearranges system componen rearranges system componen and behavior. Therefore any substitute for informed huma be used by competent desi experience necessary to information generated byg y PERFORM-3D.
ural designer in the creative s, but it is the designer who nts so as to optimize both cost nts so as to optimize both cost y structural software is not a an judgment and should only igner with the training and evaluate and verify any the software tools like
Example Application:
Example Application:
Problem
A basic seven-story RC moment resistb s c seve s o y C o e es s traditional linear-static and linear-dyn ETABS, is subjected to earthquak performance of the building using stat performance of the building using stat uniform distribution of lateral load patt nonlinear time history analysis) based o form of 1940 El Centro ground motion approximate level of the design respo using the computer software EZ-FRISKg p
: 3D Concrete Building : 3D Concrete Building
ting building frame was designed byg bu d g e w s des g ed by namic lateral load methods using ke ground motion. Evaluate the tic nonlinear pushover analysis with tic nonlinear pushover analysis with terns and dynamic analysis (inelastic on an earthquake ground motion in a n record (accelerogram) scaled to the onse spectrum by spectral matching K v7.32.
Typical Floor Plan and Elevation
0m
Columns: 70cm x Rebar: 24 – #8 Ties: #3 @0.10 W-E beams: 45cm
6.00m
W E beams: 45cm Top End Rebar Bottom End R Top Midspan R Bottom Midsp Ti #3 @0 10
6.0 Ties: #3 @0.10
N-S beams: 45cm Top End Rebar Bottom End R Top Midspan R Top Midspan R Bottom Midsp
6.0m 5.0m 6.0m
Rebar: 2 – #8 pan Rebar: 3 – #8
0m
Seismic Design Criteria and Design E Seismic Design Criteria and Design E
Understanding the fundamentals of the Code and the behavior of the proposed structural developed for the proposed structural system’s developed for the proposed structural system s The first design parameter is an explicit s defining performance levels, as shown in Table
Design Earthquake Level 1
(Moderate Earthquake)
Table 1 Desig
( q )
Performance Level No Damage
Earthquake Levels Earthquake Levels
requirements in terms of strength and ductility system, two sets of design parameters were s seismic performance
s seismic performance.
et of quantifiable acceptable Design Criteria e 1.
Repairable Damage No Collapse
Th d t f d i t i th D The second set of design parameter is the De relates the seismic load design levels stated in peak ground motion based on the seismic zones to the seismic zones from the UBC 1997 can to the seismic zones from the UBC 1997 can ground acceleration (associated with an earth exceeded in 50 years) expressed as a functio absence of site specific study, the following eff absence of site specific study, the following eff used, as shown in Table 2.
Seismic Risk
Table 2 Effec
Zone 1 Minor damage; maximum groun 4.9 of Richter Scale
Z 2 Moderate damage; maximum gro
Zone 2 g ; g
to 5.9 of Richter Scale
Zone 3 Major damage; maximum ground 6.9 of Richter Scale
Zone 4 No collapse; maximum ground a corresponds to magnitude 7 and
i E th k L l ( t lid ) th t
esign Earthquake Levels (see next slide), that the Table 1 of Design Criteria to the effective s. The values of this seismic zone factor related be considered to represent the effective peak be considered to represent the effective peak hquake that has a 10% probability of being on of the acceleration due to gravity. In the fective peak ground acceleration (PGA) can be fective peak ground acceleration (PGA) can be
Seismic Damage ctive PGA
g
nd acceleration is 0.07g; corresponds to magnitude 4 to ound acceleration is 0.15g; corresponds to magnitude 5 g; p g
d acceleration is 0.30g; corresponds to magnitude 6 to acceleration is estimated to be approximately 0.55g;
higher of Richter Scale
T bl 3 D i Levels of
Earthquake Loads by their Intensities
FEMA Qualitative Description
Pro Occ 5 Table 3 Design
by their Intensities 5
Level 1: MMI VII
Frequently level Occasional Level 2: MMI VIII
Level 2: MMI VIII
Design Intensity level Rare Level 3: MMI IX
Severity level Very Rare
Severity level
The level 1 earthquake is similar in magnitude earthquake, which is the serviceability state
E th k L l obability of
currence in 50 years
Return Period (Year)
Corresponding Effective PGA
(g) n Earthquake Level
50 years (g)
50% 72 0.12
10% 475 0.25
2% 2475 0.50
e to the Code level elastic design in a moderate event (Immediate Occupancy). The level 2
One often asks: Can my building withst the M7.2 earthquake causes different sh and the damage induced in buildings and the damage induced in buildings indeed it is particular levels of inte structures are designed to resist, and n ground acceleration (PGA), i.e., maxi ground during shaking, is one way the severity of the ground shaking (seismicy g g (
Approximate Empirical Correlations Be
tand a magnitude 7.2 earthquake? But, haking intensities at different locations, at these locations is different Thus at these locations is different. Thus, ensity of shaking that buildings and not so much the magnitude. The peak imum acceleration experienced by the e engineers and scientists quantify the c intensity).y)
etween the MMI Intensities and the PGA
Seismic Design Loading Seismic Design Loading
Using the above-mentioned perform equivalent static lateral force analysis used to size all the structural member stage of design, the nonlinear pushove history analysis were used to understa history analysis were used to understa system for its compliance with the desi Static seismic load: UBC 1997 Soil Pro
Seismic Zone Fact Distance To Know Distance To Know
mance based approach; a Code based s and response spectrum analysis were rs using ETABS. Following this initial er analysis and inelastic nonlinear time and the global behavior of the structural and the global behavior of the structural
ign criteria.
ofile Type = Sc
or = 0.40 Seismic Source Type = A wn Seismic Source = 10 km
wn Seismic Source 10 km
Dynamic seismic load:
Earthquake record: Pair of El Cen Earthquake record scaled to matc
Se Se Earthquake record scaled to matc
ntro Site, 180 degrees and 270 degrees ch UBC 97 Response spectrum with:
eismic Coefficient Ca = 0.40 eismic Coefficient Cv = 0.672
ch UBC 97 Response spectrum with:
Note:
1. Ca and Cv are the earthquake nea response within the acceleratio
Acceleration controlled range of the spectrum
Velo con of th
response within the acceleratio design response spectrum.
ar-source effect that defines ground motion n and velocity controlled ranges of the
ocity
ntrolled range he spectrum
n and velocity-controlled ranges of the
Note:
2. The El Centro ground motion r and amplitude of acceleration w and amplitude of acceleration w produce a response spectra comp the design of the building).
El Centro E-W component Spectrum
record (accelerogram) frequency content will be altered so that the accelerogram will be altered so that the accelerogram parable to the UBC 97(which was used in
m Match Graph Using EZ-FRISK v7.32
Live load: Roof LL = 1.0 kPa F Gravity Loading
Materials
Dead load: Floor wt + toppings = 3.6 kP Materials
Concrete: 24.131 MPa Reinforcing st
Make sure that you read through the sections of or its updated version FEMA 356 before you procedures discussed here automate the proces the method to ensure valid results Finally the method to ensure valid results. Finally, documentation for the nonlinear analysis is n computational details of nonlinear analysis, capabilities of PERFORM-3D in the nonlinear structures.
Floor LL = 2.4 kPa
Pa Partitions: 1 kPa
teel: ASTM Grade 60 fy = 415 MPa
f the FEMA-273 Guidelines and Commentary u attempt to apply the NSP and NDP. The s but you still need a thorough knowledge of it is emphasized that the PERFORM 3D it is emphasized that the PERFORM-3D not intended to, and does not, document the , but rather is intended to document the analysis and performance assessment for 3D