Experimental and numerical investigation of the creep response of precast concrete sandwich panels

Abstract A numerical model is developed in this paper for investigating the time-dependent creep and shrinkage response of precast concrete sandwich panels made with diagonal-bar shear connectors. The material model uses the fixed smeared cracking approach and the modified principle of superposition in its integral form. It is incorporated into the finite element package ABAQUS to build a structural model that considers concrete cracking, tension stiffening, aging, creep, shrinkage and geometric nonlinearity. The time-dependent behaviour is described via a time-stepping analysis. An experimental study that includes testing of four panels under sustained loading for a period of four months is reported. Two panels were subjected to 4-point bending and the other two were loaded under eccentric axial compression. The test results show that creep has led to a reduction of up to 27% in the residual capacity of the axially loaded panels. A good correlation between the numerical model and the experimental results is obtained. The numerical model is further used for conducting parametric studies. The results provide an insight into the critical parameters that govern the time-dependent behaviour of concrete sandwich panels, which include the diameter of the shear connectors, sustained load level, loading eccentricity and concrete strength. It was found that global creep buckling of the investigated panels can occur under eccentric axial load levels that are as low as 60% the load carrying capacity.