Evaluation of equivalent pulses to predict the inelastic response of generic frames subjected to near-fault ground motions

Student: Rajesh Rupakhety
Supervisors: Prof Apostolos S. Papageorgiou


ABSTRACT

Engineering structures in the vicinity of causative earthquake faults have experienced severe damage during strong earthquakes of the past decade. Forward directivity and fling effects have been identified by the seismologists as the primary characteristics of near-fault ground motions. It has been observed that the near-fault ground motions with forward rupture directivity are characterized by a large pulse, which is mostly oriented perpendicular to the fault. Because of the unique characteristics of the near-fault ground motions and their potential to cause severe damage to structures designed to comply with the criteria mostly based on far-field earthquakes, it is necessary to characterize and parameterize these special types of ground motions by simple and reliable mathematical models having input parameters which have clear physical meaning and scale to the earthquake magnitude. One of the most successful models available in the literature is the one proposed by Mavroeidis and Papageorgiou (Mavroeidis & Papageorgiou, 2003). The main objective of this study is to investigate if such simplified models, which have been proved to be effective and accurate for SDOF systems, are capable of predicting the response of MDOF systems. Generic frame models with 6 different heights and three levels of design ductility have been used to evaluate their response to 20 actual near-fault ground motions and the corresponding pulses calibrated to them. It has been found that the equivalent mathematical model being evaluated in this work is capable of estimating, fairly accurately, the base shear demand, the maximum inter-story drift and the height-wise distribution of inter-story drifts for the regular plane moment resisting frames used in this work.