【作者】 闫龙；

【导师】 梁力；

【作者基本信息】 东北大学 ， 结构工程， 2008， 硕士

【摘要】 体外预应力加固技术是后张预应力体系的重要分支之一,在桥梁加固中起着非常重要的角色。体外预应力加固技术是先在梁体上固定钢锚箱,然后通过钢锚箱张拉预应力筋,并固定于钢锚箱上,根据需要人为的引入某一数值与分布的内应力,改变了混凝土内部的应力状况,用以部分或全部抵消外荷载应力的一种混凝土加固方法,属于主动加固方法。本文利用大型通用计算软件ANSYS,以辽宁省辽阳市朴沟桥采用体外预应力进行加固改造和提高荷载等级为研究背景,建立了体外预应力混凝土结构分析的有限元模型,考虑了几何和材料非线性特性,并将试验数据与本文有限元分析数据进行了对比；分析了加固前后T型桥在汽车荷载作用下抗弯性能,评价了加固效果,并且分析了预应力度、预应力筋面积、转向块的高度及体外预应力筋锚固点位置等参数对结构受力及极限承载力的影响。朴沟桥加固分析表明采用体外预应力加固可以有效改善桥梁的抗弯工作性能、提高桥梁的极限承载能力。随着体外预应力筋有效预应力的增加,梁体混凝土的开裂荷载提高,所加固桥的刚度、结构的破坏荷载都得到不同程度的提高；在保持总张拉力不变的前提下,随着体外预应力筋面积的增大,梁体的极限承载力提高；转向块的高度对跨中水平段体外预应力筋合力作用点到原梁换算截面重心轴的距离有影响,转向块的高度越大跨中水平段体外预应力筋合力作用点到原梁换算截面重心轴的距离越大,在同等荷载作用下梁体的挠度变小,但是转向块高度比较小时对梁的抗弯极限承载力影响不大；体外预应力筋在钢锚箱上的锚固点到梁体翼缘板底部的垂直距离越近,缩短了体外预应力筋在钢锚箱的锚固点到原梁换算截面重心轴的距离,虽然梁体的挠度变化不是很大,但是当梁达到破坏时,其极限荷载增加。更多还原

【Abstract】 External prestressing technique which is one important branch of post-tensioned prestressmg system takes great part of reinforcing bridge. External prestressing technique is a method of reinforcing concrete which hauls prestressing reinforcing steel, fixes prestressing reinforcing steel bar onto the steel anchor box to import(introduce) a man-made numerical value of distributing inner stress in need and changes the stress of concrete in order to partly or fully counteract the stress which is begeted by outer load.It belongs to initiative reinforcing method.This article’s background is the Pu Gou bridge of Liaoyang in Liaoning Province which was strengthened by external prestressing technique to upgrade the load grade. The finite element models of nonlinear analysis of external prestressing concrete bridge is finished by the finite element analytical software of ANSYS. Also nonlinear effects of material, geometry and boundary conditions are taken into account in these models.For analyzing the resisting-bend behaviors of inforced T beam bridge contrast against the initial bridge uninforced and evaluating enforcing impact, datas produded by finite element models is contrasted with a great number of measureed datas. The effectiveness of the location of steel anchor box and deviaror, effective prestressing force, the area of prestressing tendon and the position of load on the behaviors and the ultimate loading capacity of T-beam bridge have been fully discussed.Results of analysis indicate external prestressing technique can improve the behaviors of the T-beam bridge and increase the ultimate loading capacity of bridge.The actual prestressing and area of prestressing reinforcing steel bar have great influence on bridge.With the actual prestressing and area increasing, the ultimate loading capacity of bridge will also be argumented.The height of the deviator can change the offsetting of bridge.If the height is heightened,the carrying capacity of bridge is also argumented.The setting location of prestressing reinforcing steel bar impacts the ultimate loading capacity of bridge.更多还原