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我国现行的《铁路工作技术规范·桥涵篇》简称《桥规》第2—205条中规定,预应力混凝土梁须按公式K_fσ≤σ_h+γR_l计算抗裂性。此公式用弯矩表达则为K_f=M_f/M=W_0(σ_hγR_l)/M≥[1.2],这就是五十年代初照搬苏联设计预应力结构的公式(仅安全系数有所不同),我国铁路使用已近30年了。近年来我国铁路一些设计单位在设计槽形粱时发现γ<1的情况(根据设计T形或箱形
China’s current “technical specifications of railway work · Bridge culvert” referred to as “Bridge Regulation” Article 2-205 stipulates that prestressed concrete beams shall be calculated according to the formula K_fσ ≤ σ_h + γR_l crack resistance. This formula is expressed as bending moment K_f = M_f / M = W_0 (σ_hγR_l) / M≥ [1.2], which is the formula of Soviet-designed prestressed structure in the early 1950s (only the safety factor is different) Used for nearly 30 years. In recent years, some design units of China’s railways found γ <1 when designing slotted beams (according to the design of T-shape or box shape