结构抗震除需避免罕遇地震作用的倒塌,还应尽量减小设防地震作用下结构的残余变形,以便震后结构修复。普通钢筋混凝土框架结构由于使用材料的强度都比较低,强震作用下结构容易形成倒塌破坏机制,即使没有发生倒塌破坏也会产生残余变形,使得结构修复难度增大。根据采用高强配筋减小结构震后残余变形的方法,以两跨三层的钢筋混凝土框架为研究对象,研究这种自复位结构在低周反复水平荷载作用下的抗震性能。试验结果表明,在柱中配置高强钢绞线的混凝土框架可以显著减小结构的残余变形,并可降低结构在罕遇地震下的破坏程度,从而可以降低震后加固和维修的难度及费用,同时由于底层柱下端钢筋屈服明显推迟,高强钢筋配筋框架结构因柱端产生塑性铰而形成楼层倒塌破坏机构的机率大大减小,提高了结构的抗震能力。
Abstract: One of the important objectives of anti-seismic design is to ensure sufficient anti-collapse capability in severe earthquakes, and to reduce residual deformation in moderate earthquakes so that the damage can be easily repaired. Because ordinary reinforced concrete frames are reinforced with low strength rebars, collapse mechanism maybe easily formed in severe earthquakes, and even if the frame survived,its residual displacements would be very large. According to the method of reducing seismic residual deformation of the structure reinforced with high-strength steel, two sets of two-span and three-story frames were studied with low-cyclic reversed horizontal load to compare the anti-seismic performance of the frames. The experimental results show that the residual displacement of the frame reinforced with high strength strands was very small with a low level of damage, which would reduce the difficulty and cost of rehabilitation. In addition, because of delayed yielding in the reinforcement in the columns of the bottom story, the collapse probability of frame reinforced with high strength strands is greatly reduced.