配置高强箍筋混凝土框架梁端抗震性能试验研究

进行15个框架梁端试件的低周反复加载试验，其中试件的剪跨比包括1.4、2.5和3.4，试件的受力纵筋为HRB500级钢筋，箍筋为970MPa级PC钢棒和HRB400级钢筋。研究配置高强纵筋和高强箍筋的混凝土框架梁端的破坏特征、滞回曲线、骨架曲线、位移延性和刚度退化等抗震性能和极限承载力，分析平均约束应力（ ）的影响，并利用试验结果对比分析了中国、美国和日本相关标准的受剪承载力计算公式。结果表明：提高 可限制试件裂缝开展，降低破坏程度，使试件滞回曲线饱满，并可提高其抗震性能与极限承载力，但对受弯破坏试件的承载力和位移延性的提高幅度不大，且过大的 会使梁身过强而出现梁端结合面破坏；达到极限承载力时，所有试件的受力纵筋均屈服，受剪破坏试件中PC钢棒箍筋的实测最大应变值为 ；当取 为钢筋实测屈服强度且 ≤3.5MPa时，按《混凝土结构设计规范》（GB 50010-2010）和《高强箍筋混凝土结构技术规程》（CECS 356-2013）计算受剪承载力与试验值之比平均分别为0.91和0.87。

Experimental research on seismic behaviors of concrete frame beam-end with high-yield-strength stirrup

Quasi-static tests were carried out on fifteen frame beam-end specimens with longitudinal HRB500 reinforcements and 970MPa-PC-steel-bar stirrups. The shear ratios of specimens were 1.4, 2.5 and 3.4, respectively. Seismic behaviors, including failure pattern, hysteresis loops, skeleton curves, displacement ductility, stiffness degradation and ultimate bearing capacity of concrete frame beam-end with high-yield strength stirrups and high-yield strength longitudinal reinforcements, were studied. The influence of mean confinement stress ( ) was analyzed. Then the test results were used to analyze the diagonal bearing capacity calculation formulations in relative standards of China, Japan and America. The results show that the increasing mean confinement stress could limit the crack width, reduce the damage degree, make the hysteresis loops plump, and improve the seismic behaviors and ultimate bearing capacity of specimens. However, the increase of ultimate bearing capacity and displacement ductility of bending failure specimens is tiny. Unreasonable mean confinement stress would lead to joint surface failure. The longitudinal reinforcements of all specimens and PC steel bar stirrups in the diagonal tension failure specimens yielded at the peak load. But PC steel bar stirrups in the shear compression failure and diagonal compression failure specimens did not yield，whose maximum stirrup strains were between   and  . When   was taken as the measured yield strength and   was less than 3.5MPa, the average ratios of calculation value calculated by Code GB 50010-2010 and specification CECS 356-2013 to the experimental value were 0.91 and 0.87 respectively.