预应力混凝土箱梁桥腹板竖向预应力回缩损失控制与测试分析

摘要

竖向预应力损失过大是导致混凝土箱梁腹板开裂的主要原因之一，在竖向预应力损失中钢筋回缩损失占绝大部分。本文提出一种操作简单、传感器可以重复使用的竖向预应力回缩损失测量方法，对6座实桥竖向预应力回缩损失进行实测，共获得239个实测样本。样本检验表明竖向预应力回缩损失服从皮尔逊Ⅲ曲线 y＝f （X珡，Cy ，Cs）分布，得到满足工程可靠度0.95的竖向预应力损失值为73.6 kN。%An excessive loss of vertical prestresses is one of the major causes leading to cracking in the webs of a concrete box girder ,and the main reason leading to the excessive loss of vertical prestresses is anchorage slip.In this paper ,a simple test method with which sensors can be reused was proposed to test vertical prestress losses due to anchorage slip.With this method ,tests of vertical prestress losses were conducted on six bridges ,and 239 samples were obtained.The samples indicate that the vertical prestress losses follow the distribution of Pearson type Ⅲ curve y= f (X ,Cv ,Cs )and the magnitude of vertical prestress loss corresponding to the engineering reli-ability level of 0.95 is 73.6 kN.