Expert Tips: Plastic Hinges
Author: Yong Yang
Publish Date: 18 Nov, 2020
Pushover analysis has become an essential tool for the design and analysis of nonlinear bridge structures, and plastic hinges are used in midas Civil to simulate the non-linear behavior of structural elements. In this session, Yong Yang, principal structural engineer from Jacobs, will be demonstrating how plastic hinges can be set up quickly by the automatic determination of cross-sectional properties and member material through midas Civil's general section design (GSD) module.
Step 1: We can set up pushover hinge properties here, or we can go to the main menu on the top under Pushover tab.
Step 2: Find "Yield Surface Properties", we can use data generated from the next step to populate the yield surface properties
Step 3: Obtaining moment-curvature data through midas Civil's general section design (GSD) module.
After we have obtained the moment curvature data, we input into yield surface properties in midas Civil (shown in the next step), and we are able to see the directional properties of pushover hinge in terms of curves. (from Y-axis button on the top right.)
Step 4: Populating the yield surface properties from data obtained in GSD module.
Finally, after the pushover hinge properties are defined as shown above, you can select part of the structure that is pre-determined/predicted to be the location of plastic hinges, and drag and drop the defined property from the model tree to the view box.
One thing to note, some codes only allow part of the structure to be the location of plastic hinges, for example top and bottom columns. Meaning they do not allow plastic hinges to happen on the superstructure or on the drill shaft or any other places on the column. Therefore, we can assign the plastic hinges on these locations, and after the pushover analysis we check if the members defined as plastic hinges exceed the yield limit. If so we need to redesign the structure. Another alternative is we can assign hinge to the entire structural member (entire column/shaft). After the pushover analysis, we need to observe where do plastic hinges form. If they form at the column then this structural member needs to be redesigned.
Editor: JC Sun