体外预应力加固RC梁受力性能试验

发布时间：2019-05-07 19:46

【摘要】：为了确定合适的张拉控制应力和束高,为体外预应力加固提供合理的参数,制作了7根缩尺试验梁,分别开展了不同张拉控制应力和束高下的体外预应力加固RC梁受力性能、破坏模态和极限承载力的试验研究,测试了荷载、挠度、应变、裂缝的发生以及发展状况等。同时,依据承载力理论计算得到各试验梁的理论承载力,利用ANSYS软件将试验值与计算值进行对比分析。研究结果表明:被加固梁破坏模态与未加固梁类似,均呈现显著的塑性破坏特征,二者破坏前有明显的裂缝发生、发展过程,但持续时间较未加固梁大大增加;增大束高有利于提高梁的承载能力,但束高增大到一定程度后,由于挠度增加导致钢束对梁体二次效应显著,梁体承载能力的增大效应显著削弱;张拉控制应力越大,被加固梁开裂荷载与极限荷载越大,钢绞线应力增量越小,较大的张拉控制应力有利于充分发挥体外预应力加固效应,但当张拉控制应力小到一定程度时,改变张拉控制应力大小对被加固梁承载力几乎无影响;相比于变化张拉控制应力,束高的改变对梁体受力性能的影响更加显著;体外预应力加固在提高原梁承载能力的同时,显著改善了其延性,破坏时梁体塑性发展更加充分。
[Abstract]:In order to determine the appropriate tension control stress and beam height, and to provide reasonable parameters for external prestressing reinforcement, seven scale test beams were fabricated, and the mechanical properties of externally prestressed RC beams strengthened by external prestressing under different tensile control stress and beam height were carried out respectively. The failure mode and ultimate bearing capacity are tested. The load, deflection, strain, crack occurrence and development are tested. At the same time, the theoretical bearing capacity of each test beam is calculated according to the theory of bearing capacity, and the experimental value is compared with the calculated value by ANSYS software. The results show that the failure modes of the strengthened beams are similar to those of the unreinforced beams, showing significant plastic failure characteristics. There are obvious cracks and development processes before the two failures, but the duration of the strengthened beams is much longer than that of the unreinforced beams. Increasing the beam height is beneficial to improve the bearing capacity of the beam, but when the beam height increases to a certain extent, the secondary effect of the beam is obvious due to the increase of the deflection, and the increasing effect of the bearing capacity of the beam is weakened significantly. The larger the tension control stress is, the greater the crack load and ultimate load are, the smaller the increment of steel strand stress is, the larger the tension control stress is beneficial to give full play to the external prestressed reinforcement effect, but when the tension control stress is to a certain extent, the stress increment of steel strands is smaller, but when the tension control stress is small to a certain extent, Changing the tensile control stress has little effect on the bearing capacity of reinforced beams. Compared with the change of tension and controlling stress, the influence of beam height on the mechanical behavior of beam is more obvious, while the bearing capacity of the original beam is improved, the ductility of the beam is greatly improved by external prestressed reinforcement, and the plastic development of beam body is more sufficient when the beam is destroyed.
【作者单位】：华中科技大学土木工程与力学学院;宁德市公路局;湖北工业大学土木建筑与环境学院;
【基金】：国家自然科学基金项目(51678264) 福建省交通运输科技发展重点项目(201435)
【分类号】：U445.72

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