ubc earthquake etabs

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 well 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.

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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:

SITEDATA

BUILDINGDATA

LOADING

BASESHEAR

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

Vxs Overturning Moment

Storey 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


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


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


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]


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


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


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



AUTO SEISMIC CALCULATION FORMULAS

Ta = Ct (hn^(3/4))

If Z >= 0.35 (Zone 4) then: If Tetabs



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


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


MODAL INFORMATION

Modal Analysis not done.


TOTAL REACTIVE FORCES (RECOVERED LOADS) AT ORIGIN

LOAD FX FY FZ MX MY MZ



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


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


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
