Time-dependent effects in continuous composite girder bridges

摘要

The paper describes the effects of creep and shrinkage on the redistribution of internal moments, stresses, and deformations resulting from the different stages of construction in composite concreteconcrete girder bridges. First, the method used for prediction of creep and shrinkage of the high-performance concrete used for HPC girders is discussed, and a brief description of the method of analysis for the timedependent moments, stresses and deformations is presented. Second, the values of the time-dependent effects due to the different causes are calculated. Time-dependent stresses and deformations originate from: dead loads and multiple stages of prestressing, applied before and after continuity has been provided at different ages of the concrete; redistribution of stresses from the concrete to the non-prestressed steel, if any; shrinkage of the girder and differential shrinkage between the girder and deck concretes; and last but not least, redistribution of moments due to creep after the longitudinal girders have been made continuous. A brief discussion of the sensitivity of the results concludes the paper.