Sensitivity analysis of steel frames subjected to progressive collapse

Progressive collapse refers to a phenomenon in which a local damage of a primary structural element due to abnormal loads, leads to the failure of partial or whole structural system. Abnormal loads are those loads which are not considered in normal analysis of structures but if applied to the structure, the final damage is not proportional to initial damage. Although most researches in this field are based on deterministic analysis and by using median or nominal values of analysis parameters, for more realistic results, it would be better to consider uncertainty in material specifications and loads. In this regard sensitivity of the response to analysis parameters and loads should be specified. In this paper sensitivity analysis is performed to investigate the uncertainty effects of live load, dead load, modulus of elasticity and steel yield stress on the column removed point displacement. For sensitivity analysis, three methods, Monte Carlo simulation, tornado diagrams and First Order Second Moment (FOSM) method, are used. According to the results, the displacement of the structure is more sensitive to variation of dead load and steel yield stress.