Abstract: Ratio of safety margin (RSM) provides a useful tool to bridge safety criteria of deterministic design method based on safety factor and reliability-based design (RBD). Generalized reliability RSM(RRSM) overcomes the limitation on the distribution type of uncertain parameters, which restricts the application of the principle of the ratio of safety margin (RSM), and makes the RSM principle feasible in general design situations. This paper proposes a calibration method and framework for determining the allowable safety factor (FSa) based on generalized RRSM for a given target failure probability (or target reliability index). The proposed approach is applied to study the safety criteria for foundation bearing capacity. The FSa values of foundation bearing capacity are calibrated for the traditional method based on the ratio of resistance over load and strength reduction method, respectively. The proposed approach is illustrated using a design problem of foundation bearing capacity, and the relationship between RRSM and generalized RRSM is also discussed. And then, the influence of different parameters and calculation models on the allowable safety factor of foundation bearing capacity is discussed. It is shown that the feasible design domains of the deterministic design method based on FSa values calibrated from the proposed approach are identical to those of RBD under different design situations. This validates the proposed method for bearing capacity design problems.

Key words: factor of safety, reliability, ratio of safety margin, safety criteria, bearing capacity