单侧面加固钢筋混凝土框架梁抗震性能研究

Seismic performance study on reinforced concrete frame beam strengthened by single side beam section

采用单侧面不对称方式增加补强截面对钢筋混凝土框架梁进行抗震加固,可提高既有钢筋混凝土框架梁的抗震性能。文章设计了4个单侧面加固梁试件,即1个原梁和新梁整体现浇试件,1个植筋方式连接试件和2个螺栓紧固方式连接且新梁采用有粘结预应力试件,并进行了低周反复加载试验,采用了预应力加固梁先预后紧和先紧后预两种连接方式研究了新增截面中预应力筋张拉及与原梁拼接先后顺序的不同对试件抗震性能的影响,在试验的基础上,对比分析了加固梁的破坏特征、滞回曲线特性、承载力、延性和强度退化特征。结果表明:加固梁均为弯曲破坏具有良好的抗震性能且新增截面施加预应力后残余变形约降低40%左右,植筋方式得到的加固梁试件整体变形能力优于螺栓紧固连接试件,二者延性系数最大相差31%。

The existing reinforced concrete frame beam could be retrofitted by adding new RC section only on one lateral side. The low cycle reversed loading experiment is launched on four specimens to study the seismic performance of the retrofitted beam. One specimen is that the original beam and the new beam is overall cast-in-situ, one specimen is that the new beam is connected to the original beam by the anchorage steel bars, two specimens are that the new beam is connected to the original beam by the high strength bolts and the new beam is also prestressed. Two connection type is further considered for the prestressed specimen to study the influence rule of different order of bolt-tightening and the process of prestressed loading to the seismic performance. Based on the test, the failure mode, characteristic of the hysteretic curves, bearing capacity, ductility, strength degradation is studied. Test results show that the failure mode of all specimen is flexural failure and the retrofitted beam has good seismic performance, the residual deformation is reduced by degree of 40% for the existence of prestress, the deformation capacity of planting bar sepcimen is superior to the high strength bolts connection specimen and the deference of ductility between them is 31%. Experiment results would provide good references for practical retrofit engineering.