半整体桥梁搭板的内力计算方法研究

发布时间：2019-05-22 07:47

【摘要】：对于有缝桥梁来说,桥头搭板是近台端简支于桥台牛腿上、远台端简支于枕梁或自由搁置台后路基上的单向受力板。其内力计算方法是将搭板横桥向划分成单位板宽的搭板条,降维成简支梁或弹性地基梁进行计算。而在半整体式桥台桥梁中(后面简称半整体桥梁),搭板的近台端与主梁相连,搭板会受到主梁伸缩、梁端弯曲变形等影响,故搭板除了受搭板自重、车辆荷载等竖向荷载外,还会受到主梁传递至搭板端部的荷载。该荷载的种类、大小、以及该端部荷载对搭板内力计算的影响是桥梁设计中一个值得探讨的课题。首先,验证既有有缝桥梁的搭板内力计算方法在半整体桥梁中的适应性。利用有限元软件ABAQUS对主梁和搭板的连接处(简称桥头节点)进行模拟,分别施加搭板端部弯矩、剪力和水平力并运算模型得出结果。分析结果得到各荷载对搭板内力计算的影响程度,判别出搭板内力计算中搭板端部的最主要因素是端部水平力。继而利用MIDAS建立搭板整体模型,通过计算在不同参数情况下搭板端部水平力对搭板内力计算的影响程度,从而分析得出：既有有缝桥梁搭板的内力计算方法不适用于半整体桥梁的搭板设计。然后,在搭板内力计算的简支梁法基础上,提出针对半整体桥梁搭板内力计算的简支梁修正法。简支梁修正法是通过两个搭板长度修正系数α和β来考虑半整体桥梁搭板的实际受力情况,修正系数α和β分别等效搭板底部地基土对搭板的支撑作用和搭板端水平力对搭板内力计算的影响,最后对该两个修正系数取乘积即得出综合修正系数γ。半整体桥梁的搭板内力计算中,只需将预设搭板长度与综合修正系数γ相乘,得出搭板计算长度,并根据搭板计算长度按照简支梁法进行计算,即可得出半整体桥梁的搭板内力。最后,将简支梁修正法的理论计算值和有限元计算值对比,验证简支梁修正法的正确性。对应简支梁法、弹性地基梁法和简支梁修正法分别对三种方法进行搭板试设计,并根据试设计分别建立搭板有限元实体模型。在不同参数组合情况下运算模型并得出计算结果,提取搭板底缘应力,搭板挠度和搭板受拉区钢筋应力作为参考指标,对比分析三种搭板内力计算方法的优劣。得出结论：在三种搭板内力计算方法中,简支梁修正法是最适用于半整体桥梁的搭板设计。
[Abstract]:For sewn bridges, the bridge head slab is a one-way stress plate simply supported on the platform cow leg near the platform, and simply supported on the pillow beam or on the roadbed behind the free shelving platform at the far end of the bridge. The internal force calculation method is to divide the transverse bridge direction into the strip with unit plate width, and to reduce the dimension into simply supported beam or elastic foundation beam. In the semi-integral bridge (hereinafter referred to as the semi-integral bridge), the near end of the slab is connected to the main beam, and the slab will be affected by the expansion of the main beam and the bending deformation of the beam end, so the slab is not only subjected to vertical loads such as the self-weight of the slab and the load of the vehicle. It will also be subjected to the load transferred by the main beam to the end of the slab. The type and size of the load and the influence of the end load on the internal force calculation of the slab are a topic worthy of discussion in bridge design. Firstly, the adaptability of the internal force calculation method of the existing jointless bridge in the semi-integral bridge is verified. The finite element software ABAQUS is used to simulate the joint of the main beam and the slab (bridge head joint). The bending moment, shear force and horizontal force at the end of the slab are applied to calculate the results respectively. The analysis results show that the influence of each load on the internal force calculation of the slab is obtained, and it is concluded that the horizontal force at the end of the plate is the most important factor in the calculation of the internal force of the slab. Then the whole model of the lap plate is established by using MIDAS, and the influence degree of the horizontal force at the end of the lap plate on the internal force calculation of the slab under different parameters is calculated. It is concluded that the internal force calculation method of existing jointless bridges is not suitable for the design of semi-integral bridges. Then, on the basis of the simple supported beam method for calculating the internal force of the slab, a simple supported beam correction method for the calculation of the internal force of the semi-integral bridge is proposed. The simply supported beam correction method takes into account the actual force of the semi-integral bridge slab by two plate length correction coefficients 伪 and 尾. The correction coefficients 伪 and 尾 are equivalent to the supporting effect of the foundation soil at the bottom of the lap plate and the influence of the horizontal force at the end of the slab on the calculation of the internal force of the slab, respectively. finally, the comprehensive correction coefficient is obtained by taking the product of the two correction coefficients. In the calculation of the internal force of the semi-integral bridge, it is only necessary to multiply the preset plate length with the comprehensive correction coefficient 纬 to obtain the calculated length of the slab, and to calculate the length of the slab according to the simply supported beam method. The internal force of the slab of the semi-integral bridge can be obtained. Finally, the theoretical calculation value of the simply supported beam correction method is compared with that of the finite element method, and the correctness of the simple supported beam correction method is verified. Corresponding to the simply supported beam method, the elastic foundation beam method and the simply supported beam correction method, the three methods are designed, and the finite element solid models of the slab are established according to the trial design. Under the condition of different parameter combination, the calculation model is obtained, and the stress at the bottom edge of the lap plate, the deflection of the slab and the stress of the steel bar in the tension zone of the lap plate are extracted as the reference indexes, and the advantages and disadvantages of the three internal force calculation methods of the slab are compared and analyzed. It is concluded that among the three internal force calculation methods, the simply supported beam correction method is the most suitable for the design of semi-integral bridge.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441

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