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[GEN/Pushover]Points to Consider When Selecting Load Patterns in Pushover Load Cases

Question

What should I pay attention to when selecting a Load Pattern in the Pushover Load Case?

 

Answer

The method for setting Load Patterns in a Pushover Load Case includes (1) Static Load Case, (2) Uniform Acceleration, (3) Mode Shape, and (4). Here are some considerations for each method

1. Static Load Case uses static loads as the load distribution shape. Uniform Acceleration distributes loads based on the inertial forces generated in the structure when subjected to constant acceleration. Mode Shape determines the load distribution shape using the mode shapes of the structure.

2. When choosing Static Load Case as the Load Pattern, it typically involves using static seismic loads (excluding accidental eccentricity conditions). The displacements due to static seismic loads are calculated, and the performance of the structure is evaluated as multiples of these displacements, setting the target displacement.

3. When setting the Load Pattern using Mode Shape, it's important to choose a mode shape that represents the typical 1st mode shape bending in the direction of the load. If the selected mode shape exhibits torsion or deformation in directions perpendicular to the load, it may not be suitable for use.

4. Normalized Mode ShapeMass utilizes the normalized mode shapemass to determine the load distribution shape.

[Image 1] Pushover Laod Case

[Image 2] Normalization of Mode Shape

[Image 3] Lateral Load Pattern of "Mode Shape*Mass

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