Evaluation method and improvement of energy absorption of RC and PC structure member by using DFST

钢筋混凝土和混凝土结构在地震、落石等冲击荷载作用下发生脆性破坏。提出这种发生概率低、能量大的荷载应由结构的塑性变形吸收。为此，开发具有良好吸能性能的结构构件并建立其评价方法是必不可少的。本研究采用钢管混凝土(CEST)代替钢筋混凝土和PC构件中的压筋，研制了一种新型组合结构构件，并将其应用于耗能要求较高的结构中。本报告围绕以下事项进行安排：1.钢管混凝土与混凝土砌块粘结强度的推出试验(1)钻孔钢管形成的混凝土销钉对钢管与混凝土砌块之间的粘结强度是有效的。(2)钢管表面喷砂处理和/或在其上涂抹粘结剂增加了钢管与混凝土的粘结。对钢管混凝土加固组合梁进行了静力弯曲试验和冲击荷载试验。证实了钢管混凝土作为受压补强材料的韧性(变形性)得到了提高。在钢管-混凝土组合柱上施加静弯荷载和轴力。当柱子承受循环荷载时，钻孔钢管的孔洞成为缺陷。在半尺寸模型上进行了静载试验，以模拟真实结构，即岩棚。

The RC and PC structures subjected to the impact-load such as earthquake and rock-fall are destroyed in brittleness. It is proposed that such a load having a low occurrence probability and huge energy should be absorbed by the plasticity deformation of structure. The development of structure members with excellent energy absorption and the establishment of its evaluation method are indispensable for that. This study has developed a new composite structure member by using concrete-filled steel pipe (CEST) instead of the compression steel-bars of RC and PC members and applied it to the structure which needs the high energy absorption. This report is arranged about the following items.1. Push-out tests concerning bond strength of concrete-filled steel pipe (CFST) and the concrete block(1)The concrete dowels, which are formed by using the bored steel-tube, are effective for the bond strength between the steel-tube and concrete block.(2)The adhesion of steel-tube and concrete has been increased by the sand blasting processing of the steel-tube surface and/or by spreading adhesive agent on it.2. Static bending test and impact load test on the composite beam reinforced with CFST were done. It was confirmed that toughness (deformability) was improved by using CFST for compression reinforcements.3. Static bending load and axial force were applied on steel-tube and concrete composite column. The hole of the bored steel-tube becomes a defect, when the column is subjected to cyclic load.4. Static load tests were done on a half-size model to simulate the real structure, i.e. rockshed.