Reliability analysis of net cross-section resistance with accidental eccentricity of holes

The aim of the research was to determine reliability function of net cross-section resistance in relation to accidental eccentricity of nominally centric holes. The response surface method was used by taking into account the relevant Eurocode design provisions and reliability requirements. Within the response surface method, the central composite design method and the least square method were used with the employment of Monte Carlo simulations. The probable distributed variables such as strength f _y, breadth b, thickness t, diameter d ₀ and eccentricity e were determined by the central composite design method. 280 different numerical simulations were set up with varying variables. A log-normal distribution for strength (f _y) and a normal distribution for geometrical variables (b, t, d ₀,e) were employed by taking into account the coefficients of variations: V _fy=0.07, V _b,=0.005, V _l=0.05 and V _d0=0.005. In order to determine the influence of eccentricity on partial safety factor, several normal distributions with different variation factors were applied in the analysis. The influence of the edge distance of the hole e ₂ over d ₀ ratio on the partial safety factor was determined by varying mean values of variable b. For comparison, two types of steel were used: structural steel S235 and high strength steel S690. Numerical simulations of the net cross-section resistance F _u were performed with ABAQUS 6.7. The response surface for the net cross-section resistance was determined by introducing a quadratic approximation function and by applying the least square method. The partial safely factor was then (statistically) obtained by means of robust Monte Carlo simulations on the calculated response surface.