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Summary: The selection of representative input ground motions (IGMs) is important for a proper nonlinear response time history analysis (NLRHA) of modern structures. The prevailing IGM selection procedure requires that the response spectra of selected ground motions are matched with the code‐specified design spectra, while the effect of the frequency contents combination in the time domain on the multimode interactions is not considered. Ignoring the effect of the frequency contents combination in the time domain of IGMs may cause significant variations in the analysis results for selected IGMs, although they are matched to the same design spectrum. In this paper, a modal‐based ground motion selection (MGMS) procedure is proposed as a supplement to spectrum matching‐based IGM selection procedures for selecting proper IGMs that can sufficiently induce the multimode interactions. In the proposed procedure, three equivalent single‐degree‐of‐freedom (ESDOF) systems are developed by pushover analysis. NLRHA is then conducted for these ESDOF systems with a set of 20 seed IGMs chosen by the spectrum‐matching–based selection procedure. Finally, seven IGMs are selected from the seed IGMs for NLRHA in the full structural model. To verify MGMS, seismic demands of high‐rise buildings were computed by NLRHA with seven MGMS‐selected IGMs, seven IGMs with closest spectrum matching, and groups of seven randomly selected IGMs derived from three different sets of 20 seed IGMs. The computed seismic demands with MGMS‐IGMs show very good agreement with the mean demands determined using the whole set of seed IGMs, while the deviation is much lesser compared with those groups of randomly selected IGMs. [ABSTRACT FROM AUTHOR]

Unreinforced masonry (URM) infill panels are widely used as partitions in RC frames and typically considered as non-structural elements in the design process. However, observations from recent major earthquakes have shown that under seismic excitation, the structural interaction between columns and infill walls can significantly alter the structural behaviour, thus causing catastrophic consequences. The purpose of this research was to propose and test an innovative low seismic damage detailing method, which isolates the infill panel from bounding columns with finite width vertical gaps during the infill panel construction phase and deploys steel wire connections in mortar layers anchored to columns. Taking into account the similitude requirements, a total of six one-third scale, single-storey single-bay RC frames with different infill configurations and flexible connection details were carefully designed and tested on a shake-table. Three real earthquake records were selected and scaled to ascending intensity levels and used as input signals. A series of thorough investigations including dynamic characteristics, hysteretic behaviour, failure mechanisms, out-of-plane vulnerabilities and the effect of different gap filling materials and load transfer mechanisms were rigorously studied. The experimental results indicate that the undesirable interaction between infill panels and bounding frame is significantly reduced using the proposed low seismic damage detailing concept. Direct shear failure of columns at an early stage is prevented, and structural redundancy at high levels of excitation can be provided. In general, the structural stability and integrity, and displacement ductility of infilled RC frames can remarkably be improved. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]