极限状态法和容许应力法对高架车站轨道梁设计的影响分析

按目前规范的要求,轨道交通高架车站结构需要采用极限状态法和容许应力法两种不同的方法进行计算。设计人员对这两种方法的本质及计算结果的差异往往缺乏足够的认识。为厘清两种方法对设计结果的影响,以钢筋混凝土轨道梁为研究对象,对两种计算方法的计算结果进行比较分析。另外,对规范给出的基本公式进行推导,以期得到适用性更广泛的结论。结果表明,容许应力法的计算结果更为保守。计算结果的差异与配筋率和材料强度有关,当配筋率较大时,计算结果差异随配筋率增大而增大;当钢筋强度不变时,计算结果差异随混凝土强度的增大而减小。研究成果有利于简化高架车站轨道梁等受弯构件的设计,同时也为将来铁路规范的修订提供参考。

Influences of Limit State Method and Allowable Stress Method on Designing of Track Beam in Elevated Station

According to current codes,the elevated station structure of rail transit needs to be designed with two different methods: the limit state method and the allowable stress method. Engineers usually lack sufficient knowledge about the essence of the two methods and the calculation difference derived from them. To find out how these two methods influence the design,they are applied to reinforced concrete track beam and the results are compared and analyzed. In addition,the fundamental equations in codes are used to obtain more widely applicable conclusions. The result reveals that the allowable stress method is more conservative. The differences in calculation results are related to reinforcement ratio and material strength. When reinforcement ratio is at a higher level,the differences increase. When rebar strength is constant,the difference decreases as concrete strength increases. The conclusions are helpful in simplifying the designing of bending members such as track beams,and provide references for the revision of railway codes.