RC梁的变形性能指标限值研究与试验验证

Experimental study on deformation limits of RC beams

为建立钢筋混凝土(RC)梁的变形性能指标限值,对RC梁的分类方法、性能状态划分方法及各性能状态变形限值的确定方法进行了研究.对于RC梁的分类方法,基于收集的103个RC梁的低周往复荷载试验结果对RC梁破坏形态的影响因素进行研究,将RC梁划分为弯控及剪控两类,并以剪跨比和弯剪比为参数给出两类构件的划分准则.对于RC梁的性能状态及其变形限值,根据中国现行规范将RC梁的抗震性能状态划分为7个等级,基于构件的力-位移角骨架曲线的3个关键性能点(屈服点、承载力退化20%点及丧失承载能力点)提出了RC梁各性能状态变形限值的确定方法.在此基础上,对103个RC梁试验结果进行多组不同参数的回归分析,获得弯控及剪控RC梁3个关键性能点变形限值的控制参数及回归公式,依此建立了弯控及剪控RC梁的变形指标限值.为进一步验证提出的RC梁变形指标限值合理性,进行了9个RC梁的拟静力试验,将试验位移角限值与提出的变形限值进行了对比,结果表明,本文提出的RC梁变形性能指标限值的准确性、离散性及超越概率均在合理范围内.

To establish deformation limits of reinforced concrete（ RC） beams,study on the method for classification of RC beams,definition of performance states and determining the deformation limit of specific performance state was conducted. As for the classification of RC beams,parameters affecting the failure modes of RC beams were investigated using collected test data for 103 RC beams tested under low frequency cyclic loading. A method was proposed to classify the failure modes into flexure-controlled and shear-controlled based on shear span ratio and moment shear ratio of beams. As for the performance states of RC beams and their deformation limits,the performance states of RC beams were divided into seven levels with reference to the current Chinese codes for seismic design,and the method for determining the deformation limits of these levels was put forward,which is based on three key performance points（ point of yielding,point of losing 20% load capacity,point of losing bearing capacity） of the force-drift ratio backbone curves. With the test data of 103 RC beams,regression analysis of deformation limits was performed on multiple sets of parameters,key parameters and formula of deformation limits of the three key performance points were found for the flexure-controlled and shear-controlled RC beams. Deformation limits of flexurecontrolled and shear-controlled RC beams were then put forward. To further verify the proposed deformation limits,quasi-static test of 9 RC beams was conducted,test deformation limits of three key performance points were obtained and compared to the proposed performance limits. The results show that the accuracy,discreteness and failure probability of the proposed RC beam deformation limits are all within reasonable range.