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Target Displacement

 

The fundamental question in the execution of the pushover analysis is the magnitude of the target displacement at which seismic performance evaluation of the structure is to be performed. The target displacement serves as an estimate of the global displacement of the structure is expected to experience in a design earthquake. It is the roof displacement at the center of mass of the structure. In the pushover analysis it is assumed that the target displacement for the MDOF structure can be estimated as the displacement demand for the corresponding equivalent SDOF system transformed to the SDOF domain through the use of a shape factor. This assumption, which is always an approximation, can only be accepted within limitations and only be accepted within limitations and only if great care is taken in incorporating in the predicted SDOF displacement demand all the important ground motion and structural response characteristics that significantly affect the maximum displacement of the MDOF structure. Inherent in this approach is the assumption that the maximum MDOF displacement is controlled by a single shape factor without regards to higher mode effects.

Under the Non-linear Static Procedure, a model directly incorporating inelastic material response is displaced to a target displacement, and resulting internal deformations and forces are determined. The mathematical model of the building is subjected to monotonically increasing lateral forces or displacements until either a target displacement is exceeded, or the building collapses. The target displacement is intended to represent the maximum displacement likely to be experienced during the design earthquake.

Adaptabitility of computer programs

It is well known fact the distribution of mass and rigidity is one of the major considerations in the seismic design of moderate to high rise buildings. Invariably these factors introduce coupling effects and non-linearities in the system, hence it is imperative to use non-linear static analysis approach by using specialized programs viz., SAP2000,STAADPRO2005,ETABS,IDARC,NISA-CIVIL,etc., for cost-effective seismic evaluation and retrofitting of buildings.
 

Non-Linear Static Analysis for Buildings

 

 



Introduction to Non-Linear Static Push-over Analysis

What is Non-Linear Static Push-over Analysis?

Purpose of Push-over Analysis

Target Displacement

Non-Linear Static Analysis for Buildings

Case Study of Non-Linear Static Analysis using SAP2000

Limitations of Non-Linear Static Push-over Analysis

Conclusion & References