预应力混凝土连续梁桥在车辆荷载作用下的疲劳特性研究
发布时间：2018-11-19 21:27
【摘要】：随着高速公路的发展，预应力混凝土连续梁桥以其桥墩少、受力合理等独特优势而被广泛使用。预应力混凝土连续梁桥主梁连接部负弯矩区压应力的储备，克服了自重大的难题，使其极限承载能力得到普遍认可。但这并不代表它具有良好的疲劳耐久性，尤其在密集的车流量长期作用下，其疲劳强度能否满足使用要求仍然存在疑虑。因此，本文重点以预应力混凝土连续梁桥——重庆石柱桥为原型，利用有限元软件模拟分析预应力混凝土连续梁桥在车辆荷载作用下的疲劳性能，主要研究内容及结论如下： ①建立石柱桥有限元实体模型，对施加预应力后的连续梁桥进行模态分析，根据固有振型确定桥梁刚度薄弱部位、应力集中部位即为疲劳破坏危险部位。 ②运用MATLAB软件编程以实现服从对数正态分布的随机车辆荷载谱模拟，将该荷载谱随机作用于桥面行车道上，对预应力混凝土连续梁桥进行瞬态（Transient）动力分析，计算车辆荷载对桥梁上部结构的动力响应。 ③基于混凝土及预应力钢绞线的疲劳S—N曲线分析理论，将求解的结果通过雨流计数法处理，计算出该桥梁危险截面材料的等效常幅应力水平、等效常应力幅和循环次数等相关参数；根据线性疲劳累积损伤理论，计算危险部位材料的疲劳寿命和疲劳损伤度，分析得到：在车辆荷载谱作用下，，预应力混凝土连续梁桥的疲劳寿命取决于混凝土材料的疲劳寿命；车辆荷载引起高应力状态下预应力筋的疲劳损伤度比混凝土小；跨中部位预应力筋的动力响应比支座部位大。 ④基于前人实际调查统计的车辆荷载谱，采用与随机车辆荷载谱相同的车流量和加载方式将其作用于桥面行车道上，计算预应力混凝土连续梁桥危险部位材料的疲劳寿命和疲劳损伤度；比较两种荷载谱作用下桥梁疲劳参数的计算结果得到：两种荷载谱引起桥梁的动力响应特性较为接近，甚至服从正态分布的随机车辆荷载谱比按统计调查比例分布的车辆荷载谱模拟加载结果更保守，可见用于验算分析预应力混凝土连续桥梁的疲劳特性是可行的。
[Abstract]:With the development of expressway, prestressed concrete continuous beam bridge is widely used because of its unique advantages such as less piers and reasonable force. The storage of compressive stress in the negative moment region of the main girder connection of prestressed concrete continuous beam bridge overcomes the self-important problem and makes its ultimate bearing capacity generally accepted. However, this does not mean that it has good fatigue durability, especially under the effect of dense traffic flow for a long time, whether its fatigue strength can meet the requirements of use is still doubtful. Therefore, this paper focuses on the prestressed concrete continuous beam bridge-Chongqing stone column bridge as the prototype, using finite element software to simulate the fatigue performance of prestressed concrete continuous beam bridge under vehicle load. The main research contents and conclusions are as follows: 1 the finite element solid model of stone column bridge is established, the modal analysis of prestressed continuous beam bridge is carried out, and the weak position of bridge stiffness is determined according to the inherent mode of vibration. Stress concentration is the dangerous part of fatigue failure. (2) the MATLAB software is used to realize the simulation of random vehicle load spectrum with logarithmic normal distribution. The load spectrum is applied randomly on the carriageway of the bridge deck, and the transient (Transient) dynamic analysis of prestressed concrete continuous beam bridge is carried out. The dynamic response of the vehicle load to the superstructure of the bridge is calculated. Based on the theory of fatigue S-N curve analysis of concrete and prestressed steel strands, the equivalent constant amplitude stress level of the dangerous section material of the bridge is calculated by the method of rain flow counting. Equivalent constant stress amplitude and cycle number and other related parameters; According to the theory of linear fatigue cumulative damage, the fatigue life and the degree of fatigue damage of materials in dangerous parts are calculated. It is concluded that under the action of vehicle load spectrum, the fatigue life of prestressed concrete continuous beam bridge depends on the fatigue life of concrete material; The fatigue damage of prestressed tendons caused by vehicle load is smaller than that of concrete, and the dynamic response of prestressed tendons in mid-span is larger than that in support. (4) based on the vehicle load spectrum investigated by predecessors, the vehicle flow and loading mode which is the same as the random vehicle load spectrum is applied to the bridge deck carriageway. The fatigue life and fatigue damage degree of the material in the dangerous part of prestressed concrete continuous beam bridge are calculated. Comparing the calculation results of the fatigue parameters of the bridges under two load spectra, it is concluded that the dynamic response characteristics of the bridges caused by the two kinds of load spectra are close. Even the random vehicle load spectrum with normal distribution is more conservative than the simulation result of vehicle load spectrum which is distributed in proportion to the statistical investigation. It can be seen that it is feasible to analyze the fatigue characteristics of prestressed concrete continuous bridge by checking calculation.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.35;U441.4
本文编号：2343469
[Abstract]:With the development of expressway, prestressed concrete continuous beam bridge is widely used because of its unique advantages such as less piers and reasonable force. The storage of compressive stress in the negative moment region of the main girder connection of prestressed concrete continuous beam bridge overcomes the self-important problem and makes its ultimate bearing capacity generally accepted. However, this does not mean that it has good fatigue durability, especially under the effect of dense traffic flow for a long time, whether its fatigue strength can meet the requirements of use is still doubtful. Therefore, this paper focuses on the prestressed concrete continuous beam bridge-Chongqing stone column bridge as the prototype, using finite element software to simulate the fatigue performance of prestressed concrete continuous beam bridge under vehicle load. The main research contents and conclusions are as follows: 1 the finite element solid model of stone column bridge is established, the modal analysis of prestressed continuous beam bridge is carried out, and the weak position of bridge stiffness is determined according to the inherent mode of vibration. Stress concentration is the dangerous part of fatigue failure. (2) the MATLAB software is used to realize the simulation of random vehicle load spectrum with logarithmic normal distribution. The load spectrum is applied randomly on the carriageway of the bridge deck, and the transient (Transient) dynamic analysis of prestressed concrete continuous beam bridge is carried out. The dynamic response of the vehicle load to the superstructure of the bridge is calculated. Based on the theory of fatigue S-N curve analysis of concrete and prestressed steel strands, the equivalent constant amplitude stress level of the dangerous section material of the bridge is calculated by the method of rain flow counting. Equivalent constant stress amplitude and cycle number and other related parameters; According to the theory of linear fatigue cumulative damage, the fatigue life and the degree of fatigue damage of materials in dangerous parts are calculated. It is concluded that under the action of vehicle load spectrum, the fatigue life of prestressed concrete continuous beam bridge depends on the fatigue life of concrete material; The fatigue damage of prestressed tendons caused by vehicle load is smaller than that of concrete, and the dynamic response of prestressed tendons in mid-span is larger than that in support. (4) based on the vehicle load spectrum investigated by predecessors, the vehicle flow and loading mode which is the same as the random vehicle load spectrum is applied to the bridge deck carriageway. The fatigue life and fatigue damage degree of the material in the dangerous part of prestressed concrete continuous beam bridge are calculated. Comparing the calculation results of the fatigue parameters of the bridges under two load spectra, it is concluded that the dynamic response characteristics of the bridges caused by the two kinds of load spectra are close. Even the random vehicle load spectrum with normal distribution is more conservative than the simulation result of vehicle load spectrum which is distributed in proportion to the statistical investigation. It can be seen that it is feasible to analyze the fatigue characteristics of prestressed concrete continuous bridge by checking calculation.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.35;U441.4
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