64 m跨简支栓焊钢桁梁桥在新规范下的运行状态

研究目的：随着列车速度的提升，对铁路钢桥的要求越来越高，一些既有线路的老式钢桥是否能够满足现有规范的设计要求是一个迫切需要解决的问题。本文通过对64m跨下承式简支栓焊钢桁梁桥在新规范下的运行状态进行分析以得出它是否满足新规范的要求。 研究方法：通过比较铁路桥梁钢结构设计的新旧规范，找出它们之间的主要差异。然后通过理论计算，分析老式钢桥是否满足新规范的要求。 研究结果：得出新规范在纵向联结系的长细比限值、中心压杆轴向容许应力折减系数、各种构件疲劳容许应力的检算和横向刚度的规定等诸多方面更加严格的结果。通过进一步分析得出64m跨下承式简支栓焊钢桁梁桥主要杆件的内力、构造和整体结构的横向自振频率等方面无法满足新规范要求，而强度也几乎达到新规范的临界值的结果。 研究结论：随着高速铁路的发展和列车运载量的提升，需要对老式钢桥进行加固处理，以满足列车安全运营的要求。

The Running Status of 64 m Simply Supported Bolted and Welded Steel Truss Girders Bridge by the New Code

Research purposes:The promotion in the speed of train required more load-carrying capacity of the steel bridge in railway.Code formulation department summarized the experience and lesson in our country railway construction,studied and referred advanced standard in the world,modified and completed the existing code.Whether the load-carrying capacity of some old steel bridge satisfied the design requirement of the existing code required settlement urgently.This paper analyzed the running status of 64 m simply supported bolted and welded steel truss girders bridge by the new code and obtained whether its strength satisfied the requirement of the new code.Research methods:Compared the new and old design standards on steel structure of Railroad Bridge,this paper found out the main difference,and analyzed whether the load-carrying capacity of some old steel bridge satisfied the design requirement of the new code through theory calculation.Research results:This paper found out the main difference between the new and old design standards in the respect of the longitudinal join slenderness ratio limit,the center pressure bar axial-allowable stress discount factor,the checking computation of various components fatigue allowable stress,lateral rigidity,and also obtained stricter result from the new code.Through further analysis,this paper got that the major components inner force and the transverse direction natural vibration frequency of the 64 m simply supported bolted and welded steel truss girders bridge,and found out this bridge did not satisfy the design requirement of the new code in the respect of lateral rigidity and constructional detail,and the strength reached the critical value which defined in the new code.Research conclusions:The promotion in the speed of train and the capacity of the train carriage required strengthen on the old steel bridge for train safe service.