Seismic Calculations for UBC 1997 Static Process for Regular Buildings
Dear ETABS users, this is coolest bliss and in this tutorial we will solve an example by UBC method and then we’ll compare it with ETABS. Remember, it is a very simple example, just to clear the concepts of ETABS new users.
In the following pages, you will see some pictures and notes.
Want more? Join CIVILEA group! & visit my blog
To understand this example, you will need at hand following things:-
1- UBC Seismic Calculation Sheet; CB Seis Ver 2.0 Download it. Excel-2007 Format or Excel-2003 Format If you want Visual Basic .EXE file download it from here.
2- UBC-97 Code (Chapter 16) 3- ETABS (Version 9.5.0)
And of course, A GOOD BRAIN….:-)
We will make a modelwith these parameters.
*2D model in XZ*24ft wide bay*12ft high four storeys
*Start a new model.*Units kip-ft*4 Storeys*Each storey 12ft high*Grid Only
24x24Bays
2-Selectbeamoption
1-Change thisto ALLSTORIES3-Draw beam from
grid B to grid C asshown
4-Selectdrawcolumnoption
5-Draw 2columnshere.
1-Selectelevationshortcut. 2-Goto
Elevation 3
Selectthis lineanddelete.
Goto thisoption
Make self weight multiplier "ZERO" toneglect self weights.
Select MASS SOURCEOPTION
1-Select "FROM LOADS" because we will notput any additional mass in this example andno self weight...We will only put DL and LL soselect this option.
2-Enter these valuesbecause we want ourseismic weight W = 100%DL + 25% LL(See UBC code)
Select all 4 lines to apply load
"4 LINESSELECTED"
we willput UDL
Put 2 kip/ft as DL towardsGRAVITY. Other values shouldbe as shown.
GET PREVIOUSSELECTION
Dead Load =2kip/ft
Keep all otheroptions same asthat of DL inprevious step andput 1 kip/ft as LIVELOAD
Goto DEFINE>STATIC LOAD CASESand define two new cases as1-EQX as QUAKE according to UBC 97and2-EQY as QUAKE according to UBC 97
For EQX put allvalues as shown inform
Similarly for EQY...everything same,except the direction....(YOU CAN EVEN OMIT THIS EQYLOAD CASE because we will runour model as 2D only in XZdirection.
Our model coordinates...XY...as 2D
Click set analysis option
UNCHECKDYNAMIC &PDELTAOPTIONS..
SelectXZ Plane
SAVEYOURMODEL
RUNANALYSIS
DEFLECTED SHAPE INEQX
2-Clickshowtables
1-UNITSshouldbe Kip-ft
SelectSTORYSHEARS
12 ft
For each storeyDL = 2x24 = 48 KIPandLL = 1x24 = 24 KIP
Before going to next step. Fill all the datain this sheet
Notethesetwovalues
Notestoreyshears
Check DL and LLis same as youput in excelsheet.
Forgetabout TOP& BOTTOMlocation..they aresame in thisexample
On the bottomstorey(Storey-1, seeDL=192 andLL=96) sameas in excelsheet.
compare THICK RED CIRCLE storeyshears with excel sheet...storeyshear...they are same!
Compare!
Display>Story Response Plots
Check story shear this time
Display>ShowLoads>Joint/Points>select EQx....compare with previouspage
Show reactionsfor EQX
This time...checkstorey moment withEXCEL SHEET
1-Rightclick onjoint
Value of DELTA S.you have to put thisvalue in excel sheet
Story drift ratio = Storydrift / Story Height
This is thevalue of deltaS.
This isthe valueof storydrift ratio
Building Location: Pasrur, District Sialkot, Pakistan
Seismic Zone: II-B Soil Profile Type: SD
Seismic Zone Factor Z: 0.2
Seismic Coefficients
Ca: 0.28 Na: 0
Cv: 0.4 Nv: 0
No. of Storeys: 4 Importance Factor: 1
Building Height: 48 Ct : 0.02
Building Period: 0.36 Response Factor: 5.5
Building Dead Load: 192 Building Live Load: 96
Seismic Weight, W = 1 x DL + 0.25 x LL = 216
Eq 30-4: 43 Design Base Shear: 27
Eq 30-5: 27 Ft: 0
Eq 30-6: 7
Example-1
30-Sep-10
UBC Seismic CalculationsPrepared By: coolest bliss Job:
SITE�DATA
BUILDING�DATA
LOADING
BASE�SHEAR
Checked By: - Date:
CB Seis. Ver 1.0
Input data printed from excel sheet
CB Seis. Ver 1.0
Building / Frame DataHeight
h
Dead Load DL
Live Load LL
Seismic Weight
wx
Total Height
hxwx.hx
Lateral Force
Fx
Storey Shear
Vx�s Overturning
MomentStorey Drift
Drift Limit
ft kip kip kip ft kip-ft kip kip in kip-ft in in
� 48.00 192 96 216 6480 27.49 82
Storey 1 12.00 48 24 54 12.00 648 2.75 27 0.40396 660 0.40396 3.60 OK 0.00281
Storey 2 12.00 48 24 54 24.00 1296 5.50 25 0.62030 363 0.21635 3.60 OK 0.00150
Storey 3 12.00 48 24 54 36.00 1944 8.25 19 0.76972 132 0.14942 3.60 OK 0.00104
Storey 4 12.00 48 24 54 48.00 2592 11.00 11 0.85990 0 0.09018 3.60 OK 0.00063
Storey Drift Ratio
UBC Seismic Calculationscoolest bliss
-
Example-1
30-Sep-10
Job:
Date:
Prepared By:
Checked By:
LevelDrift
Check
Calculate
PRINT SUMMARYREPORT
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 1
PROJECT INFORMATION
Company Name = Omrania & Associates
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 2
S T O R Y D A T A
STORY SIMILAR TO HEIGHT ELEVATION
STORY4 None 12.000 48.000 STORY3 STORY4 12.000 36.000 STORY2 STORY4 12.000 24.000 STORY1 STORY4 12.000 12.000 BASE None 0.000
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 3
S T A T I C L O A D C A S E S
STATIC CASE AUTO LAT SELF WT NOTIONAL NOTIONAL CASE TYPE LOAD MULTIPLIER FACTOR DIRECTION
DEAD DEAD N/A 0.0000 LIVE LIVE N/A 0.0000 EQX QUAKE UBC97 0.0000 EQY QUAKE UBC97 0.0000
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 4
A U T O S E I S M I C U B C 9 7 Case: EQX
AUTO SEISMIC INPUT DATA
Direction: X Typical Eccentricity = 5%
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt (1 of 6) [9/30/2010 11:12:36 AM]
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt
Eccentricity Overrides: No
Period Calculation: Program Calculated Ct = 0.02 (in feet units)
Top Story: STORY4 Bottom Story: BASE
R = 5.5 I = 1 hn = 48.000 (Building Height)
Soil Profile Type = SD Z = 0.2 Ca = 0.2800 Cv = 0.4000
AUTO SEISMIC CALCULATION FORMULAS
Ta = Ct (hn^(3/4))
If Z >= 0.35 (Zone 4) then: If Tetabs <= 1.30 Ta then T = Tetabs, else T = 1.30 Ta If Z < 0.35 (Zone 1, 2 or 3) then: If Tetabs <= 1.40 Ta then T = Tetabs, else T = 1.40 Ta
V = (Cv I W) / (R T) (Eqn. 1) V <= 2.5 Ca I W / R (Eqn. 2) V >= 0.11 Ca I W (Eqn. 3)
If T <= 0.7 sec, then Ft = 0 If T > 0.7 sec, then Ft = 0.07 T V <= 0.25 V
AUTO SEISMIC CALCULATION RESULTS
Ta = 0.3647 sec T Used = 0.5106 sec W Used = 216.00
V (Eqn 1) = 0.1424W V (Eqn 2) = 0.1273W V (Eqn 3) = 0.0308W
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt (2 of 6) [9/30/2010 11:12:36 AM]
Check withexcelsheet
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt
V (Eqn 4) = 0.0465W
V Used = 0.1273W = 27.49
Ft Used = 0.00
AUTO SEISMIC STORY FORCES
STORY FX FY FZ MX MY MZ
STORY4 11.00 0.00 0.00 0.000 0.000 -527.825 STORY3 8.25 0.00 0.00 0.000 0.000 -395.869 STORY2 5.50 0.00 0.00 0.000 0.000 -263.913 STORY1 2.75 0.00 0.00 0.000 0.000 -131.956
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 5
A U T O S E I S M I C U B C 9 7 Case: EQY
AUTO SEISMIC INPUT DATA
Direction: Y Typical Eccentricity = 5% Eccentricity Overrides: No
Period Calculation: Program Calculated Ct = 0.02 (in feet units)
Top Story: STORY4 Bottom Story: BASE
R = 5.5 I = 1 hn = 48.000 (Building Height)
Soil Profile Type = SD Z = 0.2 Ca = 0.2800 Cv = 0.4000
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt (3 of 6) [9/30/2010 11:12:36 AM]
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt
AUTO SEISMIC CALCULATION FORMULAS
Ta = Ct (hn^(3/4))
If Z >= 0.35 (Zone 4) then: If Tetabs <= 1.30 Ta then T = Tetabs, else T = 1.30 Ta If Z < 0.35 (Zone 1, 2 or 3) then: If Tetabs <= 1.40 Ta then T = Tetabs, else T = 1.40 Ta
V = (Cv I W) / (R T) (Eqn. 1) V <= 2.5 Ca I W / R (Eqn. 2) V >= 0.11 Ca I W (Eqn. 3)
If T <= 0.7 sec, then Ft = 0 If T > 0.7 sec, then Ft = 0.07 T V <= 0.25 V
AUTO SEISMIC CALCULATION RESULTS
Ta = 0.3647 sec T Used = 0.5106 sec W Used = 216.00
V (Eqn 1) = 0.1424W V (Eqn 2) = 0.1273W V (Eqn 3) = 0.0308W V (Eqn 4) = 0.0465W
V Used = 0.1273W = 27.49
Ft Used = 0.00
AUTO SEISMIC STORY FORCES
STORY FX FY FZ MX MY MZ
STORY4 0.00 11.00 0.00 0.000 0.000 395.869 STORY3 0.00 8.25 0.00 0.000 0.000 296.902 STORY2 0.00 5.50 0.00 0.000 0.000 197.935 STORY1 0.00 2.75 0.00 0.000 0.000 98.967
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt (4 of 6) [9/30/2010 11:12:36 AM]
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 6
M A S S S O U R C E D A T A
MASS LATERAL LUMP MASS FROM MASS ONLY AT STORIES
Loads Yes Yes
M A S S S O U R C E L O A D S
LOAD MULTIPLIER
DEAD 1.0000 LIVE 0.2500
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 7
A S S E M B L E D P O I N T M A S S E S
STORY UX UY UZ RX RY RZ
STORY4 1.678E+00 1.678E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 STORY3 1.678E+00 1.678E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 STORY2 1.678E+00 1.678E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 STORY1 1.678E+00 1.678E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 BASE 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 Totals 6.713E+00 6.713E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 8
MODAL INFORMATION
Modal Analysis not done.
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 9
TOTAL REACTIVE FORCES (RECOVERED LOADS) AT ORIGIN
LOAD FX FY FZ MX MY MZ
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt (5 of 6) [9/30/2010 11:12:36 AM]
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt
DEAD 4.441E-16 0.000E+00 1.920E+02 9.216E+03 -6.912E+03 -1.421E-14 LIVE 2.220E-16 0.000E+00 9.600E+01 4.608E+03 -3.456E+03 -7.105E-15 EQX -2.749E+01 0.000E+00 0.000E+00 0.000E+00 -9.897E+02 1.320E+03 EQY 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 10
S T O R Y F O R C E S
STORY LOAD P VX VY T MX MY
STORY4 EQX 1.776E-15 -1.100E+01 0.000E+00 5.278E+02 5.684E-14 -1.320E+02 STORY3 EQX 3.020E-14 -1.924E+01 0.000E+00 9.237E+02 1.478E-12 -3.629E+02 STORY2 EQX 2.132E-14 -2.474E+01 0.000E+00 1.188E+03 9.095E-13 -6.598E+02 STORY1 EQX 0.000E+00 -2.749E+01 0.000E+00 1.320E+03 0.000E+00 -9.897E+02 STORY4 EQY 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 STORY3 EQY 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 STORY2 EQY 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 STORY1 EQY 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00
ETABS v9.5.0 File:STATIC Units:Kip-ft September 30, 2010 9:21 PAGE 11
STORY DRIFTS
STORY DIRECTION LOAD MAX DRIFT
STORY4 X EQX 1/1597 STORY3 X EQX 1/964 STORY2 X EQX 1/666 STORY1 X EQX 1/356
file:///C|/Documents%20and%20Settings/waseem.sarwar/Desktop/New%20Folder/Static.txt (6 of 6) [9/30/2010 11:12:36 AM]
Top Related