Calculation of Deflection and Stress of Assembled Concrete Composite Beams under Shrinkage and Creep and Its Application in Member Design Optimization

摘要

There are a large number of concrete bonding interfaces in assembled concrete structures. Moreover, the problems of deformation and coordination at the interfaces lead to weak bonding under shrinkage and creep. The theoretical methods and analytical solutions for the long-term performance of composite structures in recent literatures are relatively complicated for the review or optimization in the design stage. Hence, a method for calculating the mid-span deflection of and the cross-sectional stress on composite beams under shrinkage and creep was developed based on the average curvature method. The calculation method was then verified by the experiments and the numerical simulations. Further, factors affecting the deflection of and the stress on the assembled concrete composite beams, including the loading age, the reinforcement ratio, the section dimensions, and the surface area in contact with the atmosphere were analyzed by using the developed method. The results revealed that the adjustment of the section dimensions and the loading time is the effective optimization approach. A framework for review or optimization of composite concrete beams based on the sensitivity analysis is proposed and a case study is carried out. The results of this work can helpfully be used to control the risk of additional deflections or cracking during the long-term operation of buildings.