Near-Fault Effects on RC Buildings’ Demand in Linear and Nonlinear Analyses

Abstract

Abstract. Strong ground motions of near-fault earthquakes are mostly generated by forward-directivity effects. Forward-directivity effects develop energetic pulses particularly in horizontal velocity history of fault-normal component. The narrow-band nature of the pulses results in revealing at least two peaks on the response spectra and also increasing seismic demand especially for mid-rise and high-rise buildings.Iranian seismic code (IS 2800-14) presents the coefficient N, for considering near-fault effects. It seems that the N is not efficient for designing in near-fault zone. The accurate near-fault demands can be determined by using nonlinear response history analyses. In the present paper, two 3-D reinforced concrete framed structures (RC buildings) are designed according to ACI 2014 and IS 2800-14. Then, the demands are estimated by employing linear response history analysis (LRHA) and also nonlinear response history analysis (NRHA) under an ensemble of 11 near-fault ground motions. The results reveal that the design spectrum of IS 2800-14 is incompatible with near-fault spectra and underestimates demands in the long periods range. Further, implementation of LRHA using response modification factor (R u ) and deflection amplification factor (C d ) leads to insufficient inter-story drift ratios. Finally, the 2 influence of enhancing ductility is studied by determining ductility reduction factors for near-fault records.

Near-Fault Response and Loading Protocols of Box Columns in Steel Frames with Self-Centering Braces to Provide Recentering Capability

“…Baker [17] revealed that near-fault motions increase the elastic seismic demand of structures with similar periods. Mohammadi et al [18] studied the response of structures under near-fault earthquakes and reported that the velocity pulse would lead to ineffectiveness of the structural ductility and damage of structure. Gillie et al [19] indicated that nearfault earthquakes increase the inelastic seismic demand of structures.…”

Evaluation of the response modification factor of RC structures constructed with Bubble Deck system

“…The at slabs are normally used together with the lateral force-resisting structural members like shear walls or Moment-Resisting Frame (MRF) structures [23]. Mohammad et al [24] studied two 3-D RC framed structures designed according to ACI-318-14 and IS 2800-14 codes employing Linear Response History Analysis (LRHA) as well as Non-linear Response History Analysis (NRHA) under an ensemble of 11 near-fault ground motions. The obtained results revealed that the design spectrum of IS 2800-14 was incompatible with near-fault spectra and underestimated demands in long-period ranges.…”