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ETABS Example RC Building Seismic Load _Response_

Seismic Analysis &
Design of
10 Story RC Building

(Modal Response Spectra Analysis)

Using ETABS
(Metric Units)
ACECOMS, AIT



Table of Content
Objective

5

Problem

5


Step by Step

11

1. Open Existing Model and Unlock Model

11

2. Delete Existing Seismic Static Load Case

14

3. Define Response Spectrum Function

15

4. Specify Response Spectrum Cases

17

5. Run Analysis

21

6. View Modal Analysis Results

24

7. View Results for Response Spectral Analysis

27

8. Run Concrete Frame Design and View Results

36

9. Run Shear Wall Design and View Results

42



ETABS Tutorial Example

ACECOMS, AIT

Objective
To demonstrate and practice step-by-step on modal
response spectra analysis and design of 10 story RC
building.

Problem
Carry out modal response spectra analysis, and
design of 10 story RC building as shown in following
details based on IBC2000.

3D View

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Plan View (Unit in m)

6.00 m

6.00 m

6.00 m

6.00 m

2.00 2.00 2.00

2.00 2.00 2.00

6.00 m

6.00 m

BASE – STORY 7
6.00 m

6.00 m

6.00 m

6.00 m

2.00 2.00 2.00

2.00 2.00 2.00

6.00 m

6.00 m

STORY 8 – STORY 10

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Elevation View

Material Properties for Concrete (Unit in kg and cm)

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Section Properties
Member

Dimension

Beam (width x Height)

30 x 60 cm

Column

50 x 50 cm

Slab

Thickness = 15 cm

Shear wall

Thickness = 20 cm

Story Height Data
Story

Height

Typical Story

3.00 m

Story at base of building

4.00 m

Static Load Cases
Load
Name

DEAD

LIVE

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Load Type

Dead Load

Reducible
Live Load

Details

Value

Self Weight of Structural Members
Calculate automatically using Self
Weight Multiplier in ETABS

-

Uniform Load on Slabs:
(Finishing + Partition Load)

0.20 t/m2

Uniform Load on Beams:
(Wall Load)

0.50 t/m

Uniform Load on Slabs:
(Use Tributary Area: UBC97)

0.25 t/m2

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Modal Response Spectra Parameters (IBC2000)

Parameter

Values

Note

Damping

0.05

For RC building

Modal Combination

SRSS

Directional Combination

SRSS

Site Class

E

Response Acceleration
for Short Period (Ss)

0.45

Response Acceleration
for 1 Second (S1)

0.18

Site Coefficient of
Response Acceleration
for Short Period (Fa)

1.86

Table 1615.1.2 (1)

Site Coefficient of
Response Acceleration
for 1 Second (Fv)

3.26

Table 1615.1.2 (2)

Maximum Response
Acceleration
for Short Period (SMS)

0.84

SMS = Fa x SS
(Equation 16-16)

Design Response
Acceleration
for 1 Second (SM1)

0.59

SM1 = Fv x S1
(Equation 16-17)

Design Response
Acceleration
for Short Period (SDS)

0.56

SDS = (2/3) x SMS
(Equation 16-18)

Maximum Response
Acceleration
for 1 Second (SD1)

0.39

SD1 = (2/3) x SM1
(Equation 16-18)

Table 1615.1.1
(Soft Clay)

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Wind Load Cases (UBC97)

Load Case
Parameter

Wind Direction

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WINDX

WINDY

X

Y

Wind Speed

90 mph

Exposure Type

B (Suburban area)

Importance Factor

1 (Building normal importance)

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Step by Step

1. Open Existing Model and Unlock Model
Step 1-1: Open Existing Model
Start up screen of ETABS, click on Open button
file from previous example.

or go to File >> Open and find

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ETABS Tutorial Example

ACECOMS, AIT

Step 1-2: Save As to New File
Go to File >> Save As and specify new file name.

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Step 1-3: Unlock Model
Click on Unlock Model button

Click on “OK” to confirm to unlock the model and delete all analysis results

Note: ETABS has locked the model automatically from previous. Model has to be
unlocked first before do any modification by clicking on Unlock Model
button
. ETABS will delete all analysis and design results after unlock.

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ETABS Tutorial Example

ACECOMS, AIT

2. Delete Existing Seismic Static Load Case
Step 2-1: Delete Existing Seismic Static Load Case
Go to Define >> Static Load Case, select “EQXA” and click on “Delete Load”
Repeat this step to delete “EQXB”, “EQYA” and “EQYB”

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

3. Define Response Spectrum Function
Step 3-1: Add New Response Spectrum Function
Go to Define >> Response Spectrum Function and select “Add IBC2000
Spectrum” from drop-down menu.

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Step 3-2: Enter Response Spectrum Function for IBC2000
Specify response spectrum function for IBC2000 as shown in figure below

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

4. Specify Response Spectrum Cases
Step 4-1: Add New Response Spectrum Case
Go to Define >> Response Spectrum Cases and click on “Add New Spectrum”

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Step 4-2: Specify Response Spectrum Case Data for “EQX”
Enter response spectrum case data as shown in figure below

Note: ETABS will treat response spectrum case as unfactored seismic load (E) in
ACI load combination for RC frame and shear wall design but response
spectrum load from IBC2000 is factored load then “Scale Factor” in
response spectrum case should be divided by load factor (1.4) to change
from factored load to unfactored load.

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Step 4-3: Add and Specify Response Spectrum Case for “EQY”
Repeat Step 4-1 and Step 4-2 for response spectrum case (“EQY”)

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Step 4-4: Deactivate Special Seismic Load Effect
Go to Define >> Special Seismic Load Effect and select “Do Not Include Special
Seismic Design Data”

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

5. Run Analysis
Step 5-1: Set Dynamic Analysis Parameters
Go to Analyze >> Set Analysis Options, select “Dynamic Analysis”, click on “Set
Dynamic Parameters” and specify dynamic analysis parameters as shown in figure
below

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

Step 5-2: Start Analysis
Go to Analyze >> Run Analysis or click on Run Analysis button
to start
analysis. ETABS will display deformed shape of model when analysis complete.

Note: ETABS will lock the model automatically from undesired changes. Model
will be unlocked by clicking on Unlock Model button
. ETABS will delete
all analysis and design results after unlock.

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Step 5-3: Check Error from Analysis Run Record
Go to File >> Last Analysis Run Log and scroll down to check error message.

Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)

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ETABS Tutorial Example

ACECOMS, AIT

6. View Modal Analysis Results
Step 6-1: Display Mode Shape in 3D View
Select 3D view window, go to Display >> Show Mode Shape or click on Show
and select desired mode.
Mode Shape button
To view deformed shape in animation, click on “Start Animation”.

Note: Time Period of current mode shows at top of 3D window

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Seismic Analysis & Design of 10 Story RC Building (Modal Response Spectra)


ETABS Tutorial Example

ACECOMS, AIT

Step 6-2: Display Modal Displacement at Particular node
Right click on desired node to display modal displacement at current mode shape

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