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为研究结构安全评估工作中荷载效应分项系数的合理取值,首先基于可靠度理论推导均值与标准值定义下分项系数的数学表达,并分析了荷载效应变异系数、目标可靠指标、活恒载比值等对分项系数取值的影响,最后,以一个实例梁进一步阐述了不同分项系数取值对评估结果的影响。结果显示:工程应用中恒载效应变异系数对分项系数的取值影响较小;活载效应变异系数的增大将使得活载效应分项系数呈现先增后减的趋势,峰值点位于0.7附近,而恒载效应分项系数变化较小;恒载效应及活载效应分项系数均随目标可靠指标的提高而增大,且活载分项系数增幅更加明显;活恒载标准值之比增大时,活载效应分项系数明显增大,而恒载效应变异系数呈缓慢下降趋势;不同的分项系数取值将对结构安全评估结果产生明显影响,我国现行规范分项系数取值略显保守。结构评估规范中分项系数取值的优化应同时考虑实际荷载的变异性、结构具体形式及目标可靠指标的合理选择。
In order to study the reasonable value of the sub-coefficient of load effect in structural safety assessment work, the mathematical expression of sub-coefficient under the definition of mean value and standard value was derived based on the reliability theory. The coefficient of variation of load effect, target reliability index, Load ratio on the value of the sub-coefficient, and finally, an example beam further elaborated on the different sub-coefficient values on the evaluation results. The results show that: the coefficient of variation of constant load effect in engineering application has a small effect on the value of sub-coefficient; the increase of coefficient of variation of live load effect will increase the sub-coefficient of live load firstly and then decrease, the peak value is around 0.7 , While the constant-load effect has a small change in the sub-coefficient. The constant-load effect and the live-load effect sub-coefficient all increase with the improvement of the target reliability index, and the live-load sub-coefficient increases more obviously. When it increases, the partial coefficient of live load increases obviously, while the coefficient of variation of permanent load shows a slow downward trend. Different partial coefficient values will have a significant impact on the results of structural safety assessment. Slightly conservative. The optimization of the value of the sub-coefficient in the structure evaluation criterion should take into account the variability of the actual load, the specific structure of the structure and the reasonable choice of the target reliable index.