A method for reliability-based economic design of building structures

In limit states design codes for building structures, the load and resistance factors are derived based on a 'target' reliability index, which is determined based on a code calibration process. It is not clear whether the target reliability index selected through the code calibration is optimal with respect to the cost, because through calibration the structural safety is achieved quantitatively while the economic aspects are only considered qualitatively. The intention of the present paper is to formulate a basic approach to reliability-based economic design, based on structural reliability theory. The focus of the paper is to derive an analytical solution to optimized reliability index. A parametric study is conducted for sensitivity analysis of the optimal reliability index to different variables. Finally, the application of the solution to design codes, i.e. determining load and resistance factors in design formulae, is outlined.