轻型立转开启桥设计参数研究

轻型立转开启桥是以尽可能减少开启部分的结构重量为目标而设计的一种新型开启桥。与传统开启桥相比,它采用了结构新颖,形态优美的无背索斜塔斜拉桥作为其开启结构,达到平衡压重与结构有机融合的目的,利用了移动兼作减振功能的开合压重以调整结构重心,达到开合的目的,并采用接触弹簧对开启结构进行辅助开合,达到了进一步减轻结构重量的目的。从建立该类开启桥的力学模型出发,对开合过程中结构各部分设计参数应满足的条件进行了分析,并通过一个算例说明了该类开启桥的初步设计过程,同时对结构的振动控制方案作了探讨。     

临海高等级公路灌河大桥钢锚梁及钢牛腿制造

介绍了灌河大桥钢锚梁与钢牛腿的结构特点,结合生产实际情况,分析了钢锚梁及钢牛腿制造过程中的关键工艺及控制要点,以提高制造精度,消减焊接变形,从而保证钢锚梁、钢牛腿结构的质量。     

某斜拉桥在高温季节混凝土的配制研究

结合某斜拉桥在高温季节的施工情况，就高温条件下混凝土原材料和试配以及施工时采取的措施进行了研究，并提出了混凝土施工技术要求，通过严格控制，工程取得了良好的效果。     

朝天门大桥关键临时结构的施工与监控

重庆朝天门大桥为世界最大的公轨两用钢桁架拱桥,主桁拱采用平衡悬臂拼装法施工,施工阶段中最大悬臂长度276m。为解决大悬臂施工难题,朝天门大桥建设采用新颖的带铰斜拉扣挂系统和临时系杆。通过对斜拉扣挂系统、临时系杆的施工及监控,并对索力、应力、位移进行动态监测,结果表明:主桁拱、斜拉扣挂系统和临时系杆线型和应力均处于安全受控状态。朝天门大桥已于2009年4月底建成通车,对大跨度临时结构的施工与监控具有借鉴意义。     

Safety Analysis of Moving Road Vehicles on a Long Bridge under Crosswind

This paper presents a safety analysis of high-sided road vehicles running on a long span cable-stayed bridge when the road vehicle enters a sharp-edged crosswind gust while the bridge is oscillating under fluctuating winds. Road vehicle accidents, including overturning, excessive sideslip, and exaggerated rotation, are defined first. The mathematical model and the equation of motion of coupled road vehicle–bridge systems under crosswind are then established, which include road surface roughness, vehicle suspension, and the sideslip of the vehicle tire relative to the bridge deck in the lateral direction. A case study using a real long cable-stayed bridge and a high-sided road vehicle is finally conducted, and an extensive computational work is performed to obtain a series of accident vehicle speed against mean crosswind speed, by which the decision on the threshold of mean wind speed above which the bridge should be closed to the road vehicle can be made. The obtained accident vehicle speeds are also compared with those for the same vehicles running on the ground. It is shown that the oscillation of the cable-stayed bridge will lower the accident vehicle speed when wind speed reaches a certain level.     

大跨度斜拉桥风振响应研究进展

介绍了大跨度斜拉桥风振响应研究的现状及发展，对各种风振分析方法进行了评述，并对大跨度斜拉桥风振研究中存在的一些问题，提出了作者的观点。     

Vibration of Tensioned Beams with Intermediate Damper. II: Damper near a Support

Analytical solutions are used to investigate the free vibrations of tensioned beams with a viscous damper attached transversely near a support. This problem is of particular relevance for stay-cable vibration suppression, but no restrictions on the level of axial load are introduced, and the results are quite broadly applicable. Characteristic equations for both clamped and pinned supports are rearranged into forms suitable for numerical solution by fixed-point iteration, whereby the complex eigenfrequencies and corresponding damping ratios can be accurately computed within a few iterations. Explicit asymptotic approximations for the complex eigenfrequencies are also obtained, subject to restrictions on the closeness of the eigenfrequencies to their undamped values. These asymptotic approximations are expressed in the same “universal” form identified in previous studies. It is observed that the maximum attainable modal damping ratios and the corresponding optimal values of the damper coefficient can be significantly affected by bending stiffness and by the nature of the support conditions, and a nondimensional parameter grouping is identified that enables an assessment of when bending stiffness should be considered.     

用于斜拉桥抖振控制的多重调质阻尼器性能研究

多重调质阻尼器(MTMD)控制技术是近年来兴起的一种有效的被动控制方法.MTMD克服了过去常采用的STMD(单调质阻尼器)在结构频率发生漂移时控制效果不稳定的缺点,在工程上具有良好的应用前景.本文通过对杨浦大桥抖振在MTMD控制下的计算,着重分析了考虑背景响应的情况,对MTMD的各个参数分别进行了研究,得出了一些在MTMD设计和评价中有益的结论.     

采用振动台阵的超大跨斜拉桥大比例全模型试验研究

强震作用下超大跨斜拉桥的结构响应与其结构体系密切相关,且受基础和场地土特性影响较大,然而目前为止,因试验条件和技术所限,尚缺乏相关的全桥模型振动台试验研究。以一座试设计的主跨1400m超大跨斜拉桥为原型,设计一座几何相似比为1/70、包括桩基础和场地土的全桥模型;采用振动台阵试验技术,研究El Centro波、人工波、Mexico City波等三种典型地震一致激励下不同结构体系的地震响应特性及影响机理,所研究的结构体系包括：纵向半漂浮体系、纵向弹性约束体系、以及本文作者提出的纵向辅助墩耗能体系和横向耗能体系;探讨不同纵向结构体系的抗震性能以及附加在上塔柱间的耗能构件对斜拉桥横向地震响应的控制效果。试验结果表明：土-结构相互作用对上部结构地震响应的影响不可忽视;主塔地震响应受高阶振型的影响明显;在PGA为0.4g以下的El Centro波和人工波、以及PGA为0.2g的Mexico City波作用下,结构响应仍处于弹性状态;纵向弹性约束体系和纵向辅助墩体耗能系可有效减小主塔位移和塔-梁间纵向相对位移响应,其中作者提出的纵向辅助墩耗能体系的抗震性能更好;附加耗能构件可有效降低主塔的弯矩应变响应,实现分散主塔受力和附加耗能作用,但对主塔加速度和位移响应的控制有限。     

剪力滞对斜拉桥中Π形主梁弯曲刚度影响分析

按实际施工动态过程分析剪力滞对Π形结合梁斜拉桥中主梁弯曲刚度的影响。基于能量变分法引入简化的剪力滞翘曲位移函数,导出一种可以考虑剪力滞与Π形结合梁弯曲刚度耦合影响的实用梁单元。该方法每节点采用两个剪力滞自由度,可以处理斜拉桥中集中弯矩引起的剪力滞位移边界条件突变和施工动态过程中荷载和剪力滞位移边界条件不断变化的问题。结合某Π形结合梁斜拉桥进行数值分析并与实测数据比较,验证了本文方法的有效性与准确性。研究表明,剪力滞效应使斜拉桥中主梁的抗弯刚度减小,且在悬臂施工阶段比成桥阶段的影响更大;相对于简支箱梁和连续箱梁而言,剪力滞对Π形结合梁斜拉桥主梁弯曲刚度的影响相对小一些,在悬臂施工阶段其对中跨的影响约为2%~7%,对边跨的影响约为3%~12%。