Static and Dynamic Analysis by ETABS

Linear Elastic Static and Dynamic Analyses by ETABS THE UNIVERSITY OF HONG KONG Dr. Ray Su Department of Civil Engineering

Get started with ETABS

Procedure for using ETABS          

Select Unit Define Grid and Storey Data Define Material Properties Define Frame, Wall or Slab Sections Define Structural Form Assign Mass Wall Assign Restraints Assign Loadings Perform Analysis Present Results

column lines

Node

storey

id Gr

E.L. Wilson (2000) Three Dimensional Static and Dynamic Analysis of Structures, A Physical Approach with Emphasis on Earthquake Engineering, Computers and Structures, Inc. Berkeley California, USA.

s il ne

Static Lateral Load and Free Vibration Analysis Example 1

Model 1

3-storey RC Building 93 kN

16 tonne (Mass)

3.5m

300 x 500 RC beam

62 kN

16 tonne

3.5m

300 x 500 RC beam

16 tonne

300 x 300 RC column

31 kN

300 x 500 RC beam

Z

3.5m fixed base

X

fixed base

6.0 m

E=27.4×109N/m2

Start ETABS Select Unit

Define Grid and Storey Data (Uniformly Spaced Grid and Storey Data)

Define Material Properties

For dyn. analyses

For static analyses (weight will be generated automatically Unit=N/m3)

Define Frame Sections (Beam)

Define Frame Sections (Column)

Define the Structural Form (Column)

(Select COLUMN Properties)

Define the Structural Form (Beam)

(Select BEAM Properties)

Define the Structural Form

Assign Mass (16Tonnes=16000kg; 16000/6=2667 kg/m)

Select Beam Elements

Assign Mass (16000/6=2667 kg/m)

Assign Support Restraints

Assign Support Restraints

Assign Point Loads

WIND

Assign Point Loads

Perform the Analysis

Allowable DOF

Present Results (Show Mode Shapes)

Mode 1= 0.69 sec (ETABS) Mode 1= 0.67 sec (from Hand Calculation)

Present Results (Show Mode Shapes)

Dynamic Response =

Mode 1

T1=0.69 s By Excel calculation (p111) (0.67s)

+

Mode 2

T2=0.23 s (0.25s)

++

Mode Mode3 3

T3=0.14 s (0.18s)

Present Results (Show Output Data-Displacement)

WIND

Present Results (Show Output Data-Displacement)

WIND WIND WIND WIND WIND WIND WIND WIND

Present Results (Show Output Data-Displacement) 3 Hand Calculation ETABS

Storey

2

1

0 0

10

20

30

40

Displacement (mm)

50

60

70

Example 2

Model 2

9-storey MRF Building 3.5m

93 82.5 72 62 51.5 41 31.5

typical RC beam 300 x 500

21.5 11 6m

6m

6m

typical RC column 500 x 500

Example 2 ETABS Model

Example 2 Fundamental Period & Displacement

Mode1=1=1.43 1.43sec sec(ETABS) (ETABS) Mode Mode1=1=1.40 1.40sec sec(Hand (HandCalculation) Calculation) Mode

9 Hand Calculation

8

ETABS

7

Storey

6 5 4 3 2 1 0 0

10

20

30

40

50

60

Displacement (mm)

Mode ModeShape Shape(first (firstmode) mode)

70

80

90

Example 3

Model 3

9-storey Wall Building 3.5m

93 82.5 72 62 51.5 41 31.5 21.5

0.3m thick x 4m long RC wall

11 4m

Example 3 Define Wall Sections

Deformed shape

Z X Membrane action

Z X Bending action

Example 3 Draw Rectangular Areas

Example 3 ETABS Model

Example 3 Fundamental Period & Displacement

Mode 1= 1.12 sec (ETABS) more flexible, usually more 9 accurate Hand Calculation

Mode 1= 1.06 sec (Hand Calculation)

8

ETABS

7

Storey

6 5 4 3 2 1 0 0

10

20

30

40

Displacement (mm)

Mode Shape (first mode)

50

60

70

Example 4

Model 4

9-storey Dual-System 3.5m

93 82.5 72 62 51.5 41 31.5 21.5 11

link

Example 4 ETABS Model

Rigid Link

Example 4 Fundamental Period & Displacement

Mode 1= 0.81 sec (ETABS)

9

Mode 1= 0.77 sec (Hand Calculation)

8

Hand Calculation ETABS

7

Storey

6 5 4 3 2 1 0 0

10

20

Displacement (mm)

Mode Shape (first mode)

30

40

Analysis Results (Show Mode Shapes)

Mode 1

Mode 2

Mode 3

T1=0.81 s

T2=0.17 s

T3=0.07 s

Excel calculation T1= 0.80s ,

T2=0.17s

T3=0.06s

Return period = 475 years Medium-field

Acceleration Response Spectra For HK Rock sites Far-field

Return period = 2475 years Near-field

Far-field

Spectrum & Time History Analyses Response Spectrum & Time History Functions Medium Field (Return Period: 475 yrs) 10% exceedance in 50 yrs 1.0

(5% damping ratio)

10MF18.dat

0.5

Acceleration (m/s^2)

Spectral Acceleration (g)

0.3

0.2

0.1

0.0

-0.5

0.0

-1.0 0.0

0.5

1.0

1.5

Period (sec)

2.0

2.5

3.0

0

5

10

Time (sec)

15

20

Spectrum & Time History Analyses Response Spectrum & Time History Functions Far Field (Return Period: 2475 yrs) 2% exceedance in 50 yrs (5% damping ratio)

1.0

02FF18.dat

0.5

Acceleration (m/s^2)

Spectral Acceleration (g)

0.3

0.2

0.1

0.0

-0.5

0.0

-1.0 0.0

0.5

1.0

1.5

Period (sec)

2.0

2.5

3.0

0

10

20

Time (sec)

30

40

Spectrum Analysis-Example 4 (ETABS) Define Response Spectrum Functions

Spectrum Analysis-Example 4 (ETABS) Define Response Spectrum Cases

2

Spectrum Analysis-Example 4 (ETABS) Results-Displacement

(m)

Spectrum Analysis-Example 4 (ETABS) Results-Storey Shear

(N)

Time History Analysis-Example 4 (ETABS) Define Time History Functions

m/s^2

Time History Analysis-Example 4 (ETABS) Define Time History Cases

Time History Analysis-Example 4 (ETABS) Results-Displacement

(m)

Time History Analysis-Example 4 (ETABS) Results-Storey Shear

(N)

Comparison of Simulation Results (ETABS) Spectrum Analysis & Time History Analysis

Medium Field, Return Period: 475 years (5% damping ratio)

Displacement

9

Storey Shear

9

Spectrum Anlysis

8

8

7

Time History Analysis

7

6 5

Storey

Storey

6

4

5 4

3

3

2 Spectrum Anlysis

1

2

Time History Analysis

0

1 0

5

10

Displacement (mm)

15

20

0

100

200

Storey Shear (kN)

300

400

Comparison of Simulation Results (ETABS) Spectrum Analysis & Time History Analysis

Far Field, Return Period: 2475 years (5% damping ratio)

Displacement

9

Storey Shear

9

8

8

7

7

6 5

Storey

Storey

6

4

5 4

3

3

2 Spectrum Anlysis

Spectrum Anlysis

2

1

Time History Analysis

Time History Analysis

0

1 0

5

10

15

20

Displacement (mm)

25

30

0

100

200

Storey Shear (kN)

300

400

End

Assignment 2 Lateral Load Analysis of a Frame using ETABS

h

P3

h

P2

h

P1

Pinned supports X

s

y

Z

d

A two-dimensional reinforced concrete frame building subjected to a set of lateral loads is shown. The sectional sizes of beams (b×d) and columns (x×y), the floor height (h), the beam span (s) and the applied lateral loads (P1, P2, P3) are listed in Table 1. The material properties of all structural members are constant: the Young's Modulus E = 25GPa and Poisson's ratio v = 0.2. For lateral load analysis, you may assume the concrete weight per unit volume to be 0 N/m3.

b

x

Assignment 2 Lateral Load Analysis of a Frame using ETABS

Table 1. Dimension and Loading Schedule

Last number of your U.No. 0 1 2 3 4 5 6 7 8 9

h (mm) 3500 3500 3500 3500 3500 4000 4000 4000 4000 4000

s (mm) 6000 6000 6000 6000 6000 6000 6000 6000 6000 6000

b×d (mm) 300×500 300×500 350×550 350×550 350×550 300×500 300×500 350×550 350×550 300×500

x×y (mm) 450×550 450×550 500×500 500×500 500×600 450×550 450×550 500×500 500×500 500×600

P1 (kN) 20 30 20 30 30 20 30 20 30 30

P2 (kN) 40 50 40 50 50 40 50 40 50 50

P3 (kN) 70 70 70 70 70 70 70 70 70 70

Assignment 2 Lateral Load Analysis of a Frame using ETABS

Setup the computer model of the building using the computer software ETABS (which is available in Manusell Laboratory) and (a) determine the deformed shape of the frame; (b) show the bending moment diagram of the frame; (c) check the global force equilibrium of the frame; (d) check if the drift ratio (Δroof / Hb) ≤ 1/500, where Hb is the building height and Δroof is the roof lateral displacement; and (e) suggest four practical ways to reduce the drift ratio of the building.

Due date:8th April 2013