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大跨预应力砼连续刚构桥在中国应用广泛,普遍使用三向预应力体系,其中竖向预应力体系的使用可有效减小腹板的主拉应力,对箱梁腹板斜裂缝具有控制性作用。但在实际工程中,竖向预应力钢筋在张拉后的预应力常常不足甚至处于无拉力状态,这势必会削弱设置竖向预应力筋的目的,增加腹板斜裂缝产生的风险,对桥梁的耐久性和外观有着较大影响。因此,需在施工期对竖向预应力进行有效检测。工程中常用精轧螺纹钢筋作为竖向预应力筋,为有效检测竖向精轧螺纹钢筋的张拉力,文中在视竖向精轧螺纹钢筋外露段为悬臂梁的基础上,将锚固段用刚臂和两个弹性支承模拟,同时考虑精轧螺纹钢筋本身的刚度,建立竖向精轧螺纹钢筋的平面弹性支承物理模型;结合现场模型试验数据,建立竖向精轧螺纹钢筋的张拉力P与平面弹性支承刚度K的非线性数学关系;通过与平面弹性支承(钢筋为刚体)法对比验证文中所提方法的有效性,同时进行工程应用,为箱梁竖向精轧螺纹钢筋张拉力现场测试提供理论基础。
Long-span prestressed concrete continuous rigid frame bridge is widely used in China, commonly used three-way prestressed system, in which the use of vertical prestressed system can effectively reduce the web of the main tensile stress, the web box slab cracks have control Sexual function. However, in practical engineering, the vertical prestressing tendons tend to be under tension or even no tension after tensioning, which will inevitably weaken the purpose of setting vertical tendons and increase the risk of oblique cracks in webs. Durability and appearance have a greater impact. Therefore, vertical prestressing needs to be effectively tested during construction. In order to effectively detect the tensile force of the vertical finishing rolling rebar, as the vertical pre-rolling rebar exposed section is the cantilever beam, Arm and two elastic supports, taking into account the rigidity of the finished rebar itself, the physical model of plane elastic support of the vertical finishing rebar was established. Based on the field model test data, the tension P of the vertical finishing rebar was established, The nonlinear mathematical relationship between the plane elastic support stiffness K and the plane elastic support (rigid steel body) method to verify the effectiveness of the method proposed in this paper, while engineering applications, the box beam vertical finishing threaded tensile testing site Provide a theoretical basis.