# Practical three dimensional nonlinear static pushover analysis

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Practical Three Dimensional Nonlinear Static Pushover Analysis
By Ashraf Habibullah, S.E.1, and Stephen Pyle, S.E.2 (Published in Structure Magazine, Winter, 1998)
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Figure 1: Force-Deformation For Pushover Hinge for both two and three-dimensional buildings. The following steps are included in the pushover analysis. Steps 1 through 4 discuss creating the computer model, step 5 runsthe analysis, and steps 6 through 10 review the pushover analysis results. 1. Create the basic computer model (without the pushover data) in the usual manner as shown in Figure 2. The graphical interface of SAP2000 makes this a quick and easy task.

Figure 2: Basic SAP2000 Model (Without Pushover Data)

2.

Define properties and acceptance criteria for the pushover hinges as shown inFigure 3. The program includes several built-in default hinge properties that are based on average values from ATC-40 for concrete members and average values from FEMA-273 for steel members. These built in properties can be useful for preliminary analyses, but userdefined properties are recommended for final analyses. This example uses default properties. Locate the pushover hinges on the model byselecting one or more frame members and assigning them one or more hinge properties and hinge locations as shown in Figure 4. Define the pushover load cases. In SAP2000 more than one pushover load case can be run in the same analysis. Also a pushover load case can start from the final conditions of another pushover load case that was previously run in the same analysis. Typically the first pushoverload case is used to apply gravity load and then subsequent lateral pushover load cases are specified to start from the final conditions of the gravity pushover. Pushover load cases can be force controlled, that is, pushed to a certain defined force level, or they can be displacement controlled, that is, pushed to a specified displacement. Typically a gravity load pushover is force controlled and...