engleski

Multimodal Pushover Target Acceleration Method Versus Dynamic Response of R/C Frames

A multimodal pushover target acceleration method for the non-linear analysis of reinforced concrete (R/C) frames subjected to seismic action is presented in paper. One aim of research shown in paper was to find the influence of multimodal combinations, based on linear combination (L) and square root of sum of square combination (SRSS), in assessing the bearing capacity of R/C frames, and to make the verification of multimodal combinations. This paper presents the procedure of searching the target ground acceleration as a measure of the lowest seismic resistance what is reached by the envelope principle. In accordance with the Eurocode 8 rules, application of pushover method favours access utilizing the first mode. Examples of presented R/C frames show the significant influence of the higher modes and that the L combination of modes is more unfavourable than the SRSS combination. Failure ground acceleration in multimodal pushover analysis is significant less, even multiple of less than acceleration for single mode. Verification of L and SRSS combination on the linear and non-linear level of single degree of freedom system are taken as the obtained modes for observed R/C frames. As seismic excitation eight real earthquake accelerograms are taken. Test on them shows that the linear combination is more probable. The formulation to obtain the equivalent viscous damping of system by equalizing the dissipated energy during one cycle of vibration of the non- linear system and the equivalent linear system is presented in paper. Target ground acceleration for the linear combination of modes was determined with an elastic spectrum with realistic viscous damping. This paper presents results of dynamic response of R/C frames analyzed by software package for non-linear analysis. On the basis of the results obtained by non-linear dynamic time- history analysis validation of the procedure of searching the target ground acceleration was made.

Pushover ; Target Acceleration ; Dynamic Response ; R/C frame

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