预应力混凝土连续箱梁桥施工中临时中支墩垮塌对主梁的影响及对策研究

发布时间：2018-01-17 23:31

本文关键词：预应力混凝土连续箱梁桥施工中临时中支墩垮塌对主梁的影响及对策研究　出处：《长安大学》2014年硕士论文　论文类型：学位论文

【摘要】：预应力混凝土连续箱梁桥以受力合理、结构刚度大、行车平顺性好、造型美观和养护简单等特点，成为被广泛应用的桥型之一。但这种桥型在施工中，往往会因为施工方式、施工过程中自然灾害等因素的影响导致主梁出现裂缝，这严重影响了桥梁的使用性和耐久性。因此研究桥梁施工时出现裂缝后的应对措施对桥梁的使用性和耐久性有重要意义。本文以采用支架整体现浇法施工的甘肃某桥为例，通过ANSYS建立三维实体模型，研究了采取不同顶推截面数、不同顶推力、预先张拉不同位置的预应力钢筋和不同预应力大小、以及粘贴不同厚度钢板和不同厚度碳纤维的应对措施对中跨主梁的受力影响，主要成果如下：（1）随着中跨主梁贝雷梁临时支架下顶推截面数的增加，，主梁的最大拉应力在不断减小，并且承受较大拉应力的区域也在不断缩小。（2）中跨临时中支墩处顶推力对主梁的受力有明显的影响，在一定范围内，随着顶推力的不断增加，中跨主梁的最大挠度值和最大拉应力值在都不断减小。（3）当采取张拉单根预应力钢筋的应对措施时，越是张拉远离底板位置处的预应力钢筋，主梁腹板位置处的最大拉应力和挠度减小的越明显；而采取同时张拉所有预应力钢筋的应对措施时，对主梁的强度和刚度产生的效果明显优于采取单独张拉任何位置处预应力钢筋产生的效果；随着张拉预应力的增加，主梁的最大拉应力值和最大挠度值在不断减小。（4）采取粘贴钢板和粘贴碳纤维的应对措施对主梁的挠度和应力几乎没有改善，效果不明显。（5）当中跨临时中支墩处顶推力为250t，并且张拉所有预应力钢筋50%预应力时，该桥的强度和刚度都得到了较好的改善。
[Abstract]:Prestressed concrete continuous box girder bridge is one of the widely used bridges because of its reasonable force, large structure stiffness, good ride comfort, beautiful shape and simple maintenance. Often because of the construction mode, construction process of natural disasters and other factors resulting in cracks in the main beam. Therefore, it is of great significance to study the measures to deal with the cracks in the construction of bridges, which is of great significance to the use and durability of the bridges. In this paper, a bridge in Gansu Province which is constructed with support monolithic cast-in-place method is taken as an example. The three-dimensional solid model is established by ANSYS, and the different pushing cross sections and different top thrust are studied. The main results are as follows: (1) the effects of pre-tensioning different positions of prestressed steel bar and different prestressing force size, as well as different thickness of steel plate and different thickness of carbon fiber on the stress of the mid-span main beam are as follows: 1) with the increase of the number of pushing sections under the temporary support of Beilai beam with medium span, the maximum tensile stress of the main beam is decreasing continuously, and the region bearing the larger tensile stress is also shrinking. The top thrust of intermediate span temporary middle pier has obvious influence on the force of the main beam, and in a certain range, with the increasing of the top thrust. The maximum deflection value and the maximum tensile stress value of the middle span main beam are both decreasing. 3) the more the prestressed steel bar far away from the bottom plate is tensioned, the more obvious the maximum tensile stress and deflection of the main girder web are reduced when the measures are taken. The effect on the strength and stiffness of the main beam is obviously better than that of the prestressed steel bar at any position of the single tensioning when the corresponding measures are taken to stretch all the prestressed steel bars at the same time. With the increase of tensioning prestress, the maximum tensile stress and maximum deflection of the main beam are decreasing. 4) the deflection and stress of the main beam are hardly improved by the measures of sticking steel plate and carbon fiber, and the effect is not obvious. The strength and stiffness of the bridge are improved better when the top thrust is 250 t and 50% prestressing bar is tensioned.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.35;U445.7

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