-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
1/12
4/5/20
Using SAP2000 Software Package in
Earthquake Engineering (Part II: Pushover)
Sameframebut
differentloading
QD=4.5kips/ft
QD=10.5kips/ft
QD=10.5kips/ft
Loads on structures:
- Static (e.g. self-weight)- Dynamic (e.g. earthquake)
Structures response:-- Nonlinear (variable stiffness)
Structural Analysis Approaches:
- Linear static (ELF)
(least accurate; least complex)
- Linear dynamic (response spectra)- Nonlinear static (pushover)
- Nonlinear dynamic (time history)
(most accurate; most complex)
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
2/12
4/5/20
Pushover analysis:
Applying a force distributionforce distribution to the structure in an
incremental fashion while monitoring theoccurrence of nonlinear behaviornonlinear behavior and plotting the
base shear (Vb) versus control nodecontrol node displacement
(uN).
compromise the simplicity of linear static approaches
and accuracy of nonlinear dynamic methods.
1- Nonlinearity sources:
- Geometrical (P-Delta effects)(consider or not: codes)
- Material
2- Nonlinearity modeling:
- Concentrated - Distributed
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
3/12
4/5/20
Plastic hinge properties:
- running section analysis and coming up with M- curves
Plastic hinge properties:- using codes tabulated properties
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
4/12
4/5/20
3- Lateral load pattern:
- a single concentrated force at the top(good for one-story buildings)
- in proportion to the standard code procedure:
/x x x x xF w h w h V
-
predominant mode shape of the elastic model of the
structure
/x x x x xF w w V
4- Control node:- For common buildings, the control node could be
selected as roof (top) story node
- Pushover analysis is stopped when the structure reaches:
pre-defined displacement
or
ultimate capacity
5- Gravity loads should be applied prior to the
application of lateral loads
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
5/12
4/5/20
6- Check at performance point :
The global response of the structure and individualcomponent deformations are compared to limits in
g o e spec c per ormance goa s o e sys em
Using SAP2000 for Pushover Analysis
We will use the same frame (elastic beams), justmodify dead loads:
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
6/12
4/5/20
1- Run Modal Analysis
( 1 )
1 . 0
0 . 7 5 9
0 . 3 4 5
1 0 0 0
Select lateral load pattern:
7 5 9
3 4 5
xF k i p s
2- Lateral Load Case
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
7/12
4/5/20
3- Modify Dead Load Case
3- Define Push Load Case
1
2
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
8/12
4/5/20
3- Define Push Load Case
1 2
4- Assign Plastic Hinges
Select column elements:
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
9/12
4/5/20
4- Assign Plastic Hinges
4- Assign Plastic Hinges
Select beam elements:
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
10/12
4/5/20
5- Run
6- Results Output
Display displacement:
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
11/12
4/5/20
6- Results Output
Display pushover curve:
7- Checking Hinges Status
Looking for 0.5 ft roof displacement:
-
7/25/2019 Using SAP2000 Software Package in Earthquake Engineering (Part II Pushover)
12/12
4/5/20
7- Checking Hinges Status
At 0.5 ft roof displacement: the performance levelof the system is Collapse Prevention (CP)