低配筋率高速铁路桥墩抗震延性分析

发布时间：2018-10-22 20:00

【摘要】：受刚度控制等因素的制约,我国铁路桥墩很多都采用了少配筋的重力式桥墩,包括低配筋率的高速铁路桥墩。这些低配筋率桥墩(配筋率在0.5%以内)很难像公路规范或其他国外规范那样进行延性设计;另一方面,由于铁路桥桥墩截面尺寸大,即使进入塑性,其塑性变形也很小。这就意味着低配筋率铁路桥墩的延性性能如何以及抗震能力需要开展研究。本文研究的主要内容包括:(1)利用有限元分析软件ANSYS建立了高速铁路桥墩的实体模型,与实验数据进行对比,验证了模型的正确性;计算了不同配筋率、配箍率以及剪跨比下桥墩的各项延性性能以及破坏过程,并对结果进行了对比。结果表明:桥墩的滞回曲线均表现出明显的捏拢效应,当配筋率小于0.3%时,桥墩延性性能差,表现为脆性破坏;当配筋率大于0.4%时,桥墩才表现出良好的塑性性能。(2)分析了剪跨比、纵筋配筋率与配箍率对桥墩各项延性指标的影响。结果表明:纵筋配筋率是影响桥墩延性性能最主要的因素。纵筋配筋率的增加,可以明显提高桥墩的极限位移以及位移延性系数;桥墩的滞回耗能能力也得到明显的增强,还能够有效减缓桥墩刚度退化的速度。剪跨比的增加可以明显提高桥墩的屈服位移,并且对桥墩的极限位移、位移延性系数以及滞回耗能能力有一定的帮助,但不如配筋率的影响作用明显。相比较来说,配箍率对于桥墩的延性性能影响不大。(3)利用ANSYS建立了一座两跨32m的简支梁桥的有限元模型,并对其在纵桥向进行了动力非线性时程反应分析。得到了不同墩高的桥墩在不同地震波、不同加速度峰值下,桥墩墩顶的位移反应。将得到的墩顶最大位移反应与桥墩纵桥向极限位移进行对比,给出了桥墩在不同加速度峰值下最低配筋率的建议值。并验证了现行高速铁路通用图桥墩的抗震性能。
[Abstract]:Restricted by stiffness control and other factors, many railway piers in China adopt gravity piers with less reinforcement, including high-speed railway piers with low reinforcement ratio. It is very difficult to design the ductility of these piers with low reinforcement ratio (less than 0.5%) as the highway code or other foreign codes. On the other hand, due to the large section size of the piers of railway bridges, the plastic deformation of the piers is very small even if they enter into plasticity. This means that the ductility and seismic capacity of railway piers with low reinforcement ratio need to be studied. The main contents of this paper are as follows: (1) the solid model of bridge pier of high-speed railway is established by using the finite element analysis software ANSYS, and the validity of the model is verified by comparing with the experimental data, and the different reinforcement ratio is calculated. The ductility and failure process of piers under hoop ratio and shear span ratio are compared. The results show that the hysteretic curves of the piers show obvious pinch effect. When the reinforcement ratio is less than 0.3, the ductility of the piers is poor and the ductility is brittle, and when the reinforcement ratio is greater than 0.4, the ductility of the piers is poor, and when the reinforcement ratio is greater than 0.4, the ductility of the piers is poor. (2) the influence of shear span ratio, reinforcement ratio of longitudinal reinforcement and hoop ratio on ductility index of pier is analyzed. The results show that the reinforcement ratio of longitudinal reinforcement is the most important factor affecting the ductility of pier. The ultimate displacement and displacement ductility coefficient of bridge piers can be obviously increased with the increase of longitudinal reinforcement ratio, and the hysteretic energy dissipation capacity of bridge piers is also obviously enhanced, and the speed of stiffness degradation of piers can be effectively slowed down. The increase of shear span ratio can obviously increase the yield displacement of pier, and it is helpful to limit displacement, displacement ductility coefficient and hysteretic energy dissipation ability of bridge pier, but the effect of reinforcement ratio is less obvious than that of reinforcement ratio. By comparison, the hoop ratio has little effect on the ductility of piers. (3) the finite element model of a two-span simply supported beam bridge with 32m is established by using ANSYS, and the dynamic nonlinear time-history response analysis is carried out on the longitudinal bridge. The displacement responses of piers with different piers are obtained under different seismic waves and different acceleration peaks. The maximum displacement response of the pier top is compared with the ultimate displacement of the longitudinal bridge of the pier, and the minimum reinforcement ratio of the pier under different acceleration peaks is given. The seismic performance of the universal map pier of the current high-speed railway is verified.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U442.55

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