Sensitivity Study Of RC Members' Reliability To Random Parameters

Sensitivity analysis to random variables of the structural reliability is one of the important aspects of the reliability study. Sensitivities of in-service structure reliabilities are of great significance to structure quality control.This study includes: statistically analyse the data characteristics of the resistance of in service reinforced concrete (RC) structures; study the sensitivities of reliabilities with and without time varying of reinforce concrete structure and members to random variables are studied in this paper; Based on the statistical data of in-service RC structures, anlyse the sensitivities of reliabilities of in-service RC structures.The value of sensitive factors greatly affects reliability calculation results in structure reliability analysis. The sensitivity indexes without dimension are respectively defined about distributing parameters sensitivity and parameters sensitivity in limit state functions so as to compare the magnitude of sensitivity to reliability index from random variables. These factors must be accurately determined and studied to improve the accuracy of calculated results. Based on the analysis of existing sensitivity calculation methods, a new practical sensitive factor analysis method was put forward to analyzing sensitive factors in structural strength reliability calculations. The dimensionless sensitive indexes of structural reliability were defined in the new method to compare the influence degree of random parameters to reliability. And the method was applied to analyze sensitivity under two conditions of the structural resistance decreasing and not changing with time.Random variables, defined by their probability distribution and corresponding distribution parameters, were used to describe uncertainties in the reliability calculation. In the terms of sensitivity indexes, sensitivities of reliabilities are analyzed for reinforcement concrete (RC) axial-compressive members, flexural members, and big and small excursion-compressive members, in which resistances are respectively considered to be varying and to remain constantly with time. And sensitivity rules for these members are summed up due to large numbers of calculating examples.Different forced state RC columns were taken as examples to analyze the structural sensitivity, and sensitive factors affecting the columns'structural reliability were obtained. The results show that the reliability of time-varying structure has descended to some extent compared with and without time-varying structure, and the effect from the random parameters to reliability index. The example and theory demonstrate the feasibility and rationality of the new method. This article has certain reference value to the structure design, construction and detection. Some problems for futher study are put up in the end of the paper.