Probabilistic analysis of obliquely loaded strip foundations

摘要

This paper presents a probabilistic analysis at the ultimate limit state of a shallow strip footing resting on a (c, φ) soil and subjected to an inclined load. The system response considered in the analysis is the safety factor obtained using the strength-reduction technique. The deterministic model makes use of the kinematic approach of the limit analysis theory. The Polynomial Chaos Expansion (PCE) methodology is employed for the probabilistic analysis. The soil shear strength parameters and the footing load components are considered as random variables. A reliability analysis and a global sensitivity analysis are performed. Also, a parametric study showing the effect of the different statistical characteristics of the random variables on the variability of the safety factor is presented and discussed. It is shown that the use of the safety factor (based on the strength-reduction technique) for the system response is of significant interest in the reliability analysis, since it takes into account the simultaneous effect of soil punching and footing sliding and it requires a unique reliability analysis for both failure modes. Furthermore, it allows the rigorous determination of the zones of predominance of soil punching and footing sliding in the interaction diagram for different cases of soil and/or loading uncertainties. Finally, it is shown that the loading configurations located in the zone of the footing sliding predominance exhibit a more significant variability in the safety factor compared to those located in the zone of the soil punching predominance.