Studies on Seismic-Inelastic Behavior of Reinforced Concrete Spandrel-Beams

(1)研究目的本研究的重点是讨论钢筋混凝土悬臂梁的抗震性能受各种参数的影响：1)梁截面的高宽比。2)剪跨比。3)腹板配筋率。另一个重点是通过试验观测来研究梁在弯曲裂缝后的轴向变形行为。进行了27根不同参数的钢筋混凝土悬臂梁的静力破坏试验，并对试验结果进行了分析。将模拟结果与试验结果进行了对比。(3)研究结果总结如下。1)轴向配筋为多层配筋的钢梁的弯曲屈服点由梁筋的偏移量确定。2)在轴向约束变形的情况下，腹梁的抗弯强度得到提高。假定轴力是由轴向变形约束形成的，则极限理论可用于抗弯承载力的估算。3)采用刚体模型可以方便地计算出随弯曲变形而增大的约束力。4)楼板对轴向变形的约束作用不大，但与梁的抗弯能力有关。5)当延性要求大于1/100时，需要的抗剪钢筋超过构件的抗剪设计要求。6)为了防止屈曲和改善延性，箍筋间距应小于压筋直径的6倍。

(1) PURPOSES A focus of this study is to discuss the seismic-inelastic behavior of reinforced concrete spandrel-beams which are affected by the varius parameters : 1) depth-width ratios of the beam cross-section. 2) shear span ratios. 3) web reinforcement ratios. etc. Another focus is to investigate the behavior of axial beam-deformation after flexural cracks by the test obsevation. And to simulate the strength-deformation relationships of the beams whose axial deformation is restrained externally.(2) METHOD The static failure tests of 27 reinforced concrete spandrel-beams with various parameters are conducted, and the results are analized. The simulation for the strength-deformation relationships of spandrel-beams is compared with the results observed by the tests.(3) RESULTS The results obtained from this study are summarized as follows. 1) The flexure-yield-point of spnaderel-beams, whose axial steel-bars are placed as multi-layer reinforcement, is identified by the yieding of beam-bars. 2) The spandrel-beams whose deformation are restrained axially develop their flexure-strength. Being assumed the axial forces developed by the restraint of axial deformation, the ultimate theory becomes available for the estimation of the flexure-capacity. 3) The restraint-forces increased with the flexure deformation are assumed easily by the use of the rigid-body-model. 4) The floor-slabs don't affect the restraint of axial deformation, but they relate the flexure-capacity of the spandrel-beams. 5) The shear reinforcements are needed more than those required by shear-design of the member, in case that the ductility are required more than 1/100. 6) The interval of the stirrups should be less than six times of the diameter of the compression-bar for buckling-prevention and ductility-improvement.