Abstract
This study proposes a new structural design of the first-story isolation system in reinforced concrete (RC) structures. Compared to the conditional buildings with independent columns, this new design integrates the independent columns with beams to increase the seismic capacity of the building by increasing the integrated stiffness of the coupled columns and the stability of the isolation system. The seismic responses of the proposed structure and the corresponding isolation effect were investigated by performing a series of numerical simulation and shaking table tests on a typical 7-story RC frame structure. The structure models were subjected to four earthquake waves with two PGAs (peak ground acceleration) of 0.30 g and 0.40 g for seismic analysis regarding the peak acceleration and inter-story displacement. Both simulation and testing results showed that the story acceleration and inter-story displacement of the superstructure in the isolated model decreased significantly. While the substructure below the isolation layer had a negligible decrease of acceleration. The connection of beams with concrete columns significantly increases the seismic capacity of the RC frame buildings compared to non-isolated frame buildings. The coupled beam-column connections could thus be potentially adopted in the practical first-story isolation system to avoid the requirements of large column stiffness and large column size.
Highlights
The seismic performance of frame structures has been continually investigated by researchers, mainly through developing structures with maximum energy dissipation capacity [1,2,3,4,5,6,7,8,9]
Designers and researchers believed that the soft first story is like a soft spring that has a positive isolation effect on the whole structure and it can alleviate the seismic response of the superstructure above the soft first story [12]
This study proposes a new structural design of the first-story isolation system in an reinforced concrete (RC) frame building, where the RC columns connecting with isolation rubber bearings are inter-connected by
Summary
The seismic performance of frame structures has been continually investigated by researchers, mainly through developing structures with maximum energy dissipation capacity [1,2,3,4,5,6,7,8,9]. Who applied the soft-first-story idea by lifting the structure off the ground. A series of earthquake incidents showed that the soft first story was severely damaged after the earthquake, though the superstructures above the first story were only slightly damaged [13,14]. This result could be caused as the lateral stiffness of the soft first story was abruptly decreased from that of the superstructures, resulting in a weak connection between the first story and its above stories.
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