负荷钢桁桥节点连接加固设计方法研究

负荷钢桁桥节点连接在受力情况下加固,面临着加固件及原构件受力不同步、原构件不可随意拆卸、加固后传力路径复杂等问题。钢桁桥设计往往采用“强节点,弱杆身”的原则,节点连接加固的同时,其连接杆身往往需要一起加固,两者不可分割,连接构造对传力效果及其有效性起到关键性作用。依托上海市松浦大桥大修工程,以控制既有原构件满足现行规范要求为原则,围绕负荷钢桁桥节点连接加固设计展开研究。首先,对4种节点连接加固构造方案进行了分析,指出负荷钢桁桥节点连接加固设计应尽量避免原连接件的拆除,并应与杆身加固件的连接构造统筹考虑;然后,基于构造方案4,给出3种节点连接加固计算方法及流程,并通过算例说明了3种方法的不同之处,提出节点连接加固后应为杆身加固件传力提供足够的支撑刚度,避免在杆身端部加固件内力向原构件转移;最后,通过成桥试验结果,对设计进行校正,论证了设计方法的正确性。

Study on Design Method of Joint Connection Reinforcement of Loaded Steel Truss Bridge

The joint connection of loaded steel truss bridge is reinforced under stress, which is faced with the problems that the reinforcing member and the original component are not synchronized, the original component cannot be arbitrarily removed, and the force transmission path is complex after reinforcement. The principle of "strong joint, weak rod body" is often adopted in the design of steel truss bridge. When the joint is connected and reinforced, to connect the rod body often needs to be reinforced together. The two are inseparable. The connection structure plays a key role in the force transmission effect and its effectiveness. Based on the overhaul project of Songpu Bridge in Shanghai, the joint connection and reinforcement design of loaded steel truss bridge is studied according to the principle of controlling the existing original components to meet the requirements of current specifications. Firstly, four kinds of joint connection reinforcement schemes are analyzed. It is pointed out that the joint connection reinforcement design of load steel truss bridge should avoid the removal of the original connectors as far as possible, and should be considered as a whole with the connection structure of the rod reinforcement. Then, based on the construction scheme 4, three kinds of calculation methods and processes of joint connection reinforcement are given. And the differences of the three methods are illustrated by an example. It is proposed that the joint connection reinforcement should provide the sufficient support stiffness for the force transmission of the rod reinforcement in order to avoid the transfer of the internal force of the reinforcing member to the original member at the end of the rod. Finally, through the test results of the finished bridge, the design is corrected, and the correctness of the design method is demonstrated.