【摘要】 我国现行公路桥梁结构设计规范采用分项系数法。用几个分项系数建立的设计表达式在不同材料、受力状态、荷载比等条件下的最小可靠指标与目标值间有不同误差。该文用一次可靠度方法(FORM)计算了现行规范的各类构件各种设计表达式的最小可靠指标,发现对不同材料、受力状态、荷载比的误差达2.98,此误差还受材料等级、配筋率、偏心距的影响。因此它们不能用来评定即有桥梁结构,也不能做出具有均衡安全度的加固设计。该文全面考虑上述6项因素的影响,细化回归了各分项系数,使可靠指标误差在±0.1范围内。使用新的分项系数,这些设计表达式可以用于评定和加固旧桥。更多还原

【Abstract】 The current code for design of highway RC bridges in China is based on the Level I reliability method with a few partial safety factors determined on the minimum root-mean-square errors in the reliability index. Using FORM, this paper examines errors between the predicted target and minimum values of reliability indexes corresponding to the different design formulae in the code with errors as large as 2.98, depending on not only the types of the action and material as well as the ratio of load effects, but also the reinforcement ratio, material grades and eccentricity. Thusly, such formulae can not be used for evaluating and strengthening existing bridges. The paper gives new values of the partial safety factors considering the six factors with the regression. With these new values, the errors in the reliability index of the different design formulae are in a range of ±0.1.更多还原