Experimental study on seismic behavior of circular RC columns strengthened with pre-stressed FRP strips

Bonding fiber reinforced polymer （FRP） has been commonly used to improve the seismic behavior of circular reinforced concrete （RC） columns in engineering practice. However, FRP jackets have a significant stress hysteresis effect in this strengthening method, and pre-tensioning the FRP can overcome this problem. This paper presents test results of 25 circular RC columns strengthened with pre-stressed FRP strips under low cyclic loading. The pre-stressing of the FRP strips, types of FRP strips and longitudinal reinforcement, axial load ratio, pre-damage degree and surface treatments of the specimens are considered as the primary factors in the tests. According to the failure modes and hysteresis curves of the specimens, these factors are analyzed to investigate their effect on bearing capacity, ductility, hysteretic behavior, energy dissipation capacity and other important seismic behaviors. The results show that the initial lateral confined stress provided by pre-stressed FRP strips can effectively inhibit the emergence and development of diagonal shear cracks, and change the failure modes of specimens from brittle shear failure to bending or bending-shear failure with better ductility. As a result, the bearing capacity, ductility, energy dissipation capacity and deformation capacity of the strengthened specimens are all significantly improved.

高强型钢混凝土柱抗震性能影响因素研究

通过对已完成试验的7根型钢混凝土柱在低周反复荷载下的受力性能模拟分析,验证OpenSees非线性有限元软件能够对高强钢混凝土柱截面的抗震性能进行分析。采用OpenSees软件建立了考虑型钢和箍筋对混凝土约束作用的有限元分析模型,以剪跨比、轴压比、配箍率和含钢率为参数,对21个高强型钢混凝土压弯滞回试件进行抗震性能影响因素参数分析。结果表明,大剪跨比、低轴压比、高配箍率及高含钢率的高强钢SRC柱试件滞回环更趋于较为饱满的梭形,试件极限变形能力更强:随着剪跨比的提高,试件极限承载力显著下降,延性性能先大幅提高再逐渐降低;随着轴压比的增大,试件极限承载力小幅下降,而延性性能下降显著;随着配箍率和含钢率的提高,试件的极限承载力和延性性能均有所提高,且变化幅度均较小。