Evaluation of combination rules for maximum response calculation in multicomponent seismic analysis

2001 ◽  
Vol 30 (9) ◽  
pp. 1379-1398 ◽  
Author(s):  
Oscar A. López ◽  
Anil K. Chopra ◽  
Julio J. Hernández
Keyword(s):  
Seismic Analysis ◽  
Maximum Response ◽  
Combination Rules ◽  
Multicomponent Seismic

Preliminary Study of the Unsteady Response Spectrum Based on Time-Varying

2011 ◽  
Vol 346 ◽  
pp. 58-62
Author(s):  
Pei Qiang ◽  
Ping Guan ◽  
Jing Tian ◽  
Er Liang Chen
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Maximum Response ◽  
Time Varying ◽  
Structural Failure ◽  
Time Duration ◽  
Structure Response ◽  
Preliminary Study ◽  
The Relationship

Engineering characteristics of ground motion can be defined by three factors that are respectively amplitude, frequency and duration. Any one of them in isolation are not fully made known for the ground notions affecting on the structure. Response spectrum theory is one of the principal methods in seismic analysis. The maximum response of structure under earthquake input is only varying with period in traditional response spectrum during the whole time duration. The relationship between the maximum response and duration can not be shown in the response spectrum of earthquake. The concept of unsteady response spectrum is based on moveable spectrum in this paper. Based on the conventional response spectrum, the factor of time is taken into account in unsteady response spectrum research. Then the response spectrum can be studied according to time varying. As examples for strong motion records obtained from WenChuan earthquake, two methods are proposed to research the effect of duration on response spectrum. The result of unsteady response spectrum can play an important role in the further study of the structural failure mechanism and cumulative damage under earthquake loadings.

A Clarification of the Orthogonal Effects in a Three-Dimensional Seismic Analysis

1995 ◽  
Vol 11 (4) ◽  
pp. 659-666 ◽  
Author(s):  
Edward L. Wilson ◽  
Iqbal Suharwardy ◽  
Ashraf Habibullah
Keyword(s):  
Structural Design ◽  
Reference System ◽  
Theoretical Basis ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Response Spectra ◽  
Perpendicular Direction ◽  
Combination Rules ◽  
Seismic Forces ◽  
Selection Of

For response spectra analyses it is shown that the “design of elements for 100 percent of the prescribed seismic forces in one direction plus 30 or 40 percent of the prescribed forces applied in the perpendicular direction” is dependent on the user's selection of the reference system. These commonly used “percentage combination rules” have no theoretical basis and can underestimate the design forces in certain members and can produce a member design which is relatively weak in one direction. It is proven that the alternate code approved method, in which a SRSS combination of two 100 percent spectra analyses with respect to any user defined orthogonal axes, will produce design forces which are not a function of the reference system and results in a structural design which has equal resistance to seismic motions from all directions.

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