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为有效检测竖向预应力筋的有效张拉力并提高竖向预应力的施工质量,解决箱梁由于竖向预应力损失过大而导致箱梁腹板开裂的工程难题,基于结构动力学理论,视竖向预应力精轧螺纹钢筋外露段为悬臂梁,将锚固段用一个刚臂和两个弹性支承模拟,建立竖向预应力筋的平面弹性支承模型。结合模型试验数据,建立精轧螺纹钢筋张拉力P与平面弹性支承刚度K的非线性关系模型。通过室内模型试验及锚固段刚度增大系数法验证本研究方法的有效性,并进行工程应用。引入竖向预应力张拉力无损检测方法进行箱梁竖向预应力张拉施工质量的监测,张拉力合格率由58.0%提高至96.8%,有效提高了竖向预应力的施工质量。同时提出了箱梁施工期需要提高锚垫板安装精度的工程措施。
In order to effectively detect the effective tension of vertical prestressing tendons and improve the construction quality of vertical prestressing, the engineering problems of box girder web cracking caused by the excessive loss of vertical prestressing are solved. Based on the structural dynamics theory, As the vertical prestressed threaded bars exposed steel cantilever beams, the anchorage section with a rigid arm and two elastic support simulation, the establishment of vertical prestressed tendons plane elastic support model. Combined with the model test data, a nonlinear relationship model between the tensile force P and the elastic stiffness K of the plane rolling rebar is established. Through the indoor model test and the coefficient of increase of the anchorage section stiffness, the validity of the method is verified and the engineering application is carried out. The vertical prestressing tensile testing method was introduced to monitor the quality of vertical prestressed concrete box girders. The passing rate of tensile force was increased from 58.0% to 96.8%, which effectively improved the construction quality of vertical prestressing. At the same time, the engineering measures for improving the installation accuracy of the anchor plate during the construction period of the box girder are put forward.