多齿块厚板锚固区足尺试验和有限元分析

Full-Scale Test and Finite Element Analysis of Thick Plate Anchorage Zone with Multiple Blocks

为了探究预应力混凝土多齿块厚板锚固区的受力分布特征,以上海大歌剧院旋转楼梯中最长一根悬挑梁的锚固区为研究对象,进行了足尺试验。通过对各齿块预应力筋分批施加张拉力,得到了拉应力集中位置处钢筋和混凝土的应力发展规律。建立了有限元模型并进行了参数分析,得到了多齿块厚板锚固区的力流分布特征和各因素对锚固区局部作用效应的影响规律。试验和有限元计算结果表明:多齿块厚板锚固区中局部弯曲效应不明显,且只有最后的齿块存在锚后牵拉效应;各齿块的锚下劈裂效应、悬臂效应和径向力效应相互独立;板内抵抗水平剪力的箍筋应力随着各齿块预应力筋的张拉而不断累积;厚板中锚下劈裂效应引起的拉应力流主要分布在锚下一半齿块长度范围内;锚后牵拉效应力存在分叉的现象;齿块角度越大,锚后牵拉效应和悬臂效应越小;板厚越小、齿块距离板前端越远,局部弯曲效应越大。

In order to investigate the stress distribution characteristics of the prestressed concrete thick plate anchorage zone with multiple blocks,a full-scale test was carried out on the anchorage zone of the longest cantilever beam in the staircase of Shanghai Grand Opera House.The stress development of the reinforcement and concrete at the location of the tensile stress concentration was obtained by tensioning the prestressed tendons in batches of each block.The finite element model was established and the parameters were analyzed.The force flow characteristics and the influence of various factors on the local action effect in the anchorage zone were obtained.The results of test and finite element calculation showed that the local bending effect was not obvious in the thick plate anchorage zone,and only the last anchor block had the tieback tension effect.The bursting effect,root tension effect and deviation force effect of each anchor block were independent of each other.The stress of the stirrups resisting horizontal shear in the plate accumulated with the tension of the prestressed tendons of each anchor block.The tensile stress flow caused by the bursting effect in the thick plate anchorage zone was mainly distributed in the tension end to the half of the block length.And there was a bifurcation phenomenon of the tie-back tension effect force.The tie-back effect and root tension effect decrease with the increase of the angle of the block.The local bending effect increased with the decrease of the plate thickness and the increase of the distance from the block to the front end of the plate.