Study on reinforcement methods for enforcrment of sbear strengrh and improvement of ductility ofoiers made of reinforced concrete

在1994年远东地震和1995年兵库县南部地震中，钢筋混凝土结构发生了多次破坏，为了保护结构内的人员，保持结构的最小功能，要求钢筋混凝土结构即使在超过设计荷载的地震力作用下，仍能保持其形状和最小剩余强度的抗震能力，并能在地震后的紧急情况下使用。临时修复后。本文针对上述问题，对钢筋混凝土结构中柱的抗剪承载力和延性进行了研究，比较了不同配筋方式的加固效果，设计了合理的配筋方式，（φ 150 mm，h300 mm），方形（133 x 133 mm，高300 mm）和矩形（188 x 98毫米，h 300 mm）柱进行抗压试验，其混凝土强度指标为280 kgf/cm ^2，水灰比为55%结果表明，尽管模型的最大荷载和剩余强度都较大，但箍筋越多，在最大荷载后，各强度都急剧下降，而对于矩形柱，箍筋作用较小，螺旋布置较好，钢筋与主轴筋连接牢固，双筋保持架最大荷载后的强度和剩余强度表现良好，斜向布置和一组轴筋也较好有效认为抗剪钢筋应在主轴向钢筋周围的正方形内连接牢固，现场预制双笼或一组轴向钢筋是有效和经济的。

There occured many collapes of reiforcd concrete (RC) stru in the 1994 Far-Off Sanniku and the 1995 Hyougoken-Nanbu Earthquakes.To protect people inside of structures and keep their least functions, it is requested that RC structures shall maintain sbear resistance ststaining their shapes and the minimum residual strength even against seismic force more than the design load.These structures shall be able to use emergency after after temporary repair. This study aims enforcement of shear strength and improvement of ductility, of columns mainly in RC structures, to reply the above-mentioned.To compare the effect of different reinforcements and to devise rational arrangements, reinforced models of circular (phi150mm, h300mm), square (133 x 133mm, h 300mm) and rectangular (188 x 98mm, h 300mm) columns are prepared for compression test.Their specified strength of concrete is 280kgf/cm^2 and W/C is 55%.The diameters of main and hoop bars are 6mm and 3mm As results, aithough the maximum loads and residual sltenhths of the models are the stronger, the more hoop bars, each strength goes down suddenly after the maximym load.But in case of the rectangular columm, hoop bars are less effectixe and spiral arrangement is better.The stirrup shall be firmly connected with main axial bars.The double bar cage shows excellant behavior of the strength after the maximum load and the residual strength.Diagonal arrangement and a group of axial bars are also effective. Is is concluded that the reinforcement to shear force shall be firmly connected within square surrounding the main axial bars and a double cage or a group of axial bars prefabricated, shall be effective and economical at site.