某大跨径连续刚构桥底板崩裂后的结构损伤评估

Assessment of Structural Damage of a Long Span Continuous Rigid-Frame Bridge with Bursting Cracks in Its Bottom Slab

为评估某大跨径预应力混凝土连续刚构桥[跨度为(96+132+96)m]底板崩裂后(崩裂长度最长为26.0m,崩裂厚度最大达30cm)的结构损伤程度,确定合理的处理方案,采用MIDAS Civil 2010建立全桥有限元模型,分析了桥梁各种损伤量化参数,建立了损伤模型,对损伤前、后主梁的顶、底板应力进行计算分析。结果表明,在主力+附加力作用下,损伤后主梁底板出现拉应力(0.25 MPa),桥梁损伤较为严重,不能满足《铁路桥涵钢筋混凝土和预应力混凝土结构设计规范》的设计要求。建议后续不仅要对崩裂底板进行修复,而且要对桥梁进行全面的加固改造(如设置体外预应力,增加顶板厚度等),以提高其整体刚度和承载力,保证桥梁结构后续运营的安全。

To assessthe structural damage degree of a long span prestressed concrete continu‐ous rigid‐frame bridge with span arrangement （96 m＋132 m＋96 m） with bursting cracks in its bottom slab （the maximum bursting crack length and depth respectively being 26 .0 m and 30 cm） and to determine the rational scheme for handling the cracks ,the MIDAS Civil 2010 was used to set up the finite element model for the w hole bridge of the bridge and the various quantitative pa‐rameters of the damage of the bridge were analyzed .The damage models were set up as well and the stress of the top and bottom slabs of the main girder of the bridge before and after the bridge was damaged was calculated and analyzed .The results of the calculation and analysis indicate that under the action of the main force＋additional forces ,the tensile stress （0 .25 M Pa） occurs in the bottom slab of the damaged bridge ,the damage of the bridge is rather severe and can not meet the design requirements in the Code for Design on Reinforced and Prestressed Concrete Structure of Railw ay Bridge and Culvert .It is hence proposed that the bursting cracks in the bottom slab should not only be repaired immediately but also the bridge should be all‐roundedly strengthened （such as adding of the external prestressing and increasing of the depth of the top slab） so as to im‐prove the global rigidity and bearing capacity of the bridge and ensure the operation safety of the bridge structure in the future .