先张预应力混凝土板梁梁端横裂病害原因分析及处治对策研究

Diseases Causes and Countermeasures of Beam Transverse Crack of Pre-tensioning Prestressed Concrete Slab Beam

对先张预应力混凝土板梁梁端横裂进行了理论计算及加固试验,分析梁端横裂病害产生原因,先张法预应力钢绞线采用分批混凝土自锚固,引起锚固区混凝土出现先期局部微裂缝,运营期间梁体出现支座脱空和饺缝破损等病害,及活载超载作用下,引起局部微裂缝扩展,引起部分梁体出现梁端横裂病害。针对梁端横裂病害,研究了换梁或新建中先张板梁梁端增加局部纵筋,改进后对结构微裂缝控制及梁端抗剪承载能力提高效果明显。对运营期间存在梁端横裂的先张预应力混凝土板梁,利用替换下的单梁,进行贴黏钢板加固的理论分析和荷载试验研究,在满足锚固长度要求的条件下,黏钢加固可以较好的处理梁端横裂病害。

The theoretical calculation and reinforcement test of the beam transverse crack of the pre-tensioning prestressed concrete slab beam were carried out,and the causes of the transverse crack at the beam end were analyzed.The pre-tensioning prestressed steel strand was self-anchored by batching concrete,which caused the local micro-cracks of concrete in the anchorage zone.During the operation,the diseases such as the beam bearing cavity and the hinge joints damage appeared,and caused the expansion of local micro-cracks and the transverse crack at the beam end under the action of overloading of live load. In the light of the beam transverse crack disease,adding local longitudinal reinforcement at the end of pre-tensioning beam during beam replacement or new construction was studied,and the control of micro-cracks in the structure and the shear bearing capacity of the beam end were obviously improved after the improvement. Aiming at the pre-tensioning prestressed concrete slab beam with transverse crack at the beam end during the operation,a single beam under replacement was used to carry out the theoretical analysis and load test of bonding steel plate reinforcement.In the case that the length of anchorage was satisfied,bonding steel plate reinforcement can deal with the transverse crack of the beam end better.