中小跨径公路坡桥动力特性及车载响应分析

发布时间：2018-07-04 18:50

本文选题：坡桥 + 动力特性　；参考：《长安大学》2015年硕士论文

【摘要】：坡桥在我国西南山区应用越来越多,近年来坡桥发生局部破坏的现象较一般桥梁严重;同时在长下坡路段为了达到减速目的,不得不在桥梁上设置振动减速带,目前其设置具有较大的随意性,关于坡桥减速带对桥梁结构动力特性的影响研究较少,因此对坡桥动力特性及车载响应展开分析非常必要。以国家自然科学基金项目《随机车载下高墩大跨弯连续刚构桥冲击系数研究》的后续研究及中央高校基金《长大坡桥动力分析》资助项目为依托,运用有限元程序对不同坡度、不同支座设置形式下的简支梁、连续梁坡桥自振特性展开理论研究,并通过室内试验验证了理论研究的正确性。基于现行《公路桥涵设计通用规范》(JTG D60-2004)对简支梁、连续梁坡桥的冲击系数展开研究,在此基础上,利用车-桥耦合振动原理分别研究了连续纵坡在车辆作用下的挠度、弯矩响应,得到了桥梁结构在不同车速、不同行驶方向下的时程曲线,按照传统计算方法求解桥梁结构的冲击系数,分析了单向纵坡、双向纵坡、桥面不平整度对连续坡桥冲击系数的影响,并和规范法冲击系数进行对比分析。基于车-桥耦合振动原理研究了不同坡度和行驶速度下减速带设置数量、设置间距、设置位置对坡桥动力特性及冲击系数的影响,并对坡桥减速带的合理设置提出建议。研究结果表明坡桥振型与相应平桥相同,支座的布置方式对桥梁的频率有一定影响,当支座水平方向设置时坡桥频率比相应平桥的小,当支座垂直主梁方向设置时坡桥基频与相应平桥相同;坡桥宜将固定支座设在较低墩台处。基于规范法得到简支梁、连续梁纵坡坡度对桥梁冲击系数影响很小;车-桥耦合振动下单、双向纵坡形式对连续梁桥冲击系数有一定影响;减速带的设置增大了坡桥结构的动力响应,在条件允许时建议不设减速带;若必须设置则建议采用8组减速带、减速带组间距为,且减速带距梁端8m为宜。论文研究成果可为坡桥桥梁结构的动力评估及交通设施安全提供依据和参考。
[Abstract]:The slope bridge is applied more and more in the mountainous area of southwest China. In recent years, the phenomenon of local damage of the slope bridge is more serious than that of the ordinary bridge. At the same time, in order to achieve the purpose of deceleration, vibration reducers have to be set up in the long downhill section of the bridge. At present, there is much randomness in the design of the bridge, so it is necessary to analyze the dynamic characteristics and the vehicular response of the bridge because of the little research on the influence of the slope-bridge reducer on the dynamic characteristics of the bridge structure. Based on the project of National Natural Science Foundation, "Research on impact coefficient of long span continuous rigid frame bridge with high piers under random vehicle" and the project of "dynamic Analysis of long Slope Bridge" funded by the Central University Foundation, the finite element program is used to analyze the different slopes. The theoretical study on the natural vibration characteristics of continuous beam sloping bridges with simple supported beams with different support forms is carried out and the correctness of the theoretical research is verified by laboratory tests. Based on the current General Code for Highway Bridge and culvert Design (JTG D60-2004), the impact coefficient of simply supported beam and continuous beam slope bridge is studied. On this basis, the deflection of continuous longitudinal slope under the action of vehicle is studied by using the coupled vibration principle of vehicle-bridge. Bending moment response, the time history curve of bridge structure under different speed and different driving direction is obtained. According to the traditional calculation method, the impact coefficient of bridge structure is solved, and the unidirectional longitudinal slope and bidirectional longitudinal slope are analyzed. The influence of deck irregularity on impact coefficient of continuous slope bridge is analyzed and compared with that of code method. Based on the principle of vehicle-bridge coupling vibration, the effects of the number of reducers, the setting distance and the setting position on the dynamic characteristics and impact coefficient of the slope bridge under different slope and driving speed are studied, and some suggestions are put forward for the reasonable setting of the deceleration belt of the slope bridge. The results show that the mode of vibration of the slope bridge is the same as the corresponding horizontal bridge, and the arrangement of the support has a certain influence on the frequency of the bridge. When the support is set horizontally, the frequency of the slope bridge is smaller than that of the corresponding horizontal bridge. The base frequency of the slope bridge is the same as that of the corresponding horizontal bridge when the support is set in the direction of the main beam, and the fixed support should be set at the lower pier abutment. Based on the code method, the simple supported beam is obtained, the longitudinal slope gradient of continuous beam has little effect on the impact coefficient of bridge, the order of vehicle-bridge coupling vibration is given, and the impact coefficient of continuous beam bridge is influenced by the form of two-way longitudinal slope. The installation of the reducer increases the dynamic response of the slope bridge structure, and it is suggested that no reducer should be set when the conditions permit; if necessary, 8 sets of reducers should be adopted, with a spacing of 8 m between the reducers and the end of the beam. The research results can provide the basis and reference for the dynamic evaluation of bridge structure and the safety of traffic facilities.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.3

【共引文献】