Uncertainty and sensitivity analysis of time-dependent effects in concrete structures

The purpose of this paper is to propose the method of uncertainty and sensitivity analysis of time-dependent effects due to creep and shrinkage of concrete in concrete structures. The uncertainty and sensitivity analyses are performed using the Latin Hypercube sampling method. For each sample, a time-dependent structural analysis is performed to produce response data, which are then analyzed statistically. Two measures are examined to quantify the sensitivity of the outputs to each of the input variables. These are partial rank correlation coefficient (PRCC) and standardized rank regression coefficient (SRRC) computed from the ranks of the observations. Three possible sources of the uncertainties of the structural response have been taken into account — creep and shrinkage model uncertainty, variation of material properties and environmental conditions. The proposed theory is applied to the uncertainty and sensitivity of time-dependent axial shortening and time-dependent prestress forces in an actual concrete girder bridge. The numerical results indicate that the creep model uncertainty factor and relative humidity appear to be the most dominant factors with regard to the model output uncertainty. The method provides a realistic method of determining the uncertainty analysis of concrete structures and identifies the most important factors in the long-term prediction of time-dependent effects in those structures.