混凝土公路桥梁墩身刚度及开裂对整体受力影响的有限元分析

Finite Element Analysis of the Effect of Pier Stiffness and Cracking on the Integral Force of Concrete Highway Bridges

以辽宁某混凝土公路桥梁为研究对象,对其墩身开裂影响整体受力的有限元进行了分析。结果表明,横隔板及腹板交接倒角处以及腹板内侧面和外侧面,都会有局部拉应力的出现,预应力损失值的不断增大,将会进一步扩大拉应力的范围,同时也将降低顶板压应力,但在这个过程中结构应力分布状态并不会出现明显的变化。如果底板损失值与顶板束损失值之间表现出一致性时,此时对比二者的挠度值可以发现后者的更大,也就是对主梁刚度降低而言,顶板束预应力损失具有更大的影响,竖向预应力损失不断增加对主梁刚度的影响较小。在下部结构刚度变化时,对上部结构竖向位移的影响较小。上部结构挠度受墩身刚度的影响较小,但对上部结构应力具有显著影响,因此适当将下部结构刚度减小,从而减小上部结构的不利弯矩。最后根据桥梁开裂情况,提出混凝土构件表面,采用表面涂抹治理、玻璃纤维布治理、充填治理、灌浆治理等方法治理开裂。

In this paper,a concrete highway bridge in Liaoning Province is taken as the research object,and the influence of pier cracking on the overall force is analyzed by the finite element method.The results show that the local tensile stress occurs at the chamfer of the diaphragm and web joints on the inner and outer sides of the web.The range of the tensile stress increases with the increase of the loss value of prestress,while the compressive stress of the roof decreases gradually,but the stress distribution of the structure remains basically stable.When the loss value of roof bundle is consistent with that of bottom bundle,the deflection value caused by the loss of roof bundle is larger,that is to say,the loss of prestress of roof bundle has greater influence on the reduction of stiffness of main beam,while the increasing loss of vertical prestress has less effect on the stiffness of main beam.When the stiffness of the lower structure changes,the influence on the vertical displacement of the upper structure is small.The upper structure deflection is less affected by pier stiffness,but it has a significant impact on the stress of the upper structure.Therefore,the lower structure stiffness should be reduced appropriately,so as to reduce the unfavorable bending moment of the upper structure.Finally,according to the cracking situation of the bridge,the surface of concrete component is put forward,and the cracking is treated by surface coating,glass fiber cloth,filling and grouting.