| Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 103 === Since 2007 in Taiwan, the National Center for Research on Earthquake Engineering (NCREE) has launched the Taiwan New RC Project. This study, belonged to one of topics in the project, was designed four rectangular cantilever beams with a/d=3.0 and different stirrup layouts. The objective of this study is to investigate the seismic behavior of these specimens.
The shear strength of the beam HRB-S1b, which had shear stirrups with the combination of U-shape ties and lateral 90°-135° degree tie bars on the top of U-shape ties, did not show significantly different in comparison with the beam HRB-S1a, which had standard close-type stirrups, when the hysteresis loop sustained until DR(drift ratio)=3.5%. However, after DR=3.5%, the beam HRB-S1b had earlier shear degradation comparing with the beam HRB-S1a.
The other two specimens (HRB-S2a and HRB-S2b) were the beam HRB-S2a, which had shear stirrups with 90°-135° degree hook vertically taking turn to tie the middle flexural bar, and the beam HRB-S2b, which had no take-turn 90°-135° hook arrangement in a substandard method. The beams HRB-S1 series had contrary results to the beams HRB-S2 series. That is, the beam HRB-S2b had lower shear strength than the beam HRB-S2a when the hysteresis loop reached DR=3.5%. However, they (HRB-S2a and HRB-S2b) had similar tendency in the shear strength degradation.
Test results indicated that the measured maximum stress of stirrups of all the specimens ranges from 680MPa to more than 895MPa (the actual yielding stress). In the fore-mentioned specimens, concrete still had shear contribution in plastic hinge zone.
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