Abstract：In order to study the reliability index calculation method in engineering structure,the calculation problem of structural reliability index( RI) was converted to a corresponding unconstrained optimization problem by means of structural reliability concept and the penalty function method of optimization theory. In the solving process,the shuffled complex evolution( SCE) algorithm was adopted because of its better global search ability. The special codes SCE-RI and MC-RI based on the SCE algorithm and Monte Carlo method were designed through the platform of Matlab. And these programs were used to compute the reliability index of a circular tunnel. By comparing with the calculation ones obtained by other methods,the results show that the SCE-RI algorithm can not only avoid the difficulty of function derivation operation but also have good performance in precision and efficiency. Moreover,the SCE-RI algorithm proposed for structural reliability index calculation is feasible and has certain application value for other similar projects.

Keyword：penalty function method;shuffled complex evolution(SCE) algorithm;function derivation;reliability index;