Experimental Study On Dynamic Hysteretic Rule Of Reinforced Concrete Columns Under Rapid Loading

Concrete is a kind of rate sensitive material.Not only the dynamic effect of whole structure should be considered,but also the loading rate effect to concrete constitutive should be considered while the structure is under dynamic loading.Most existing researches focused on the strain effect to the concrete constitutive and dynamic performances of columns under impact loading.But researches on mechanical properties of columns under rapid loading,the levels of whose rate are within seismic strain rate range are relatively few. As the main load-bearing components of reinforced concrete frame and bridge structures,reinforced concrete columns show significant elastic-plastic characteristics under strong dynamic loadings such as severe earthquakes.The performances of reinforced concrete columns such as loading capacity, the ductiliy have become important indicators of seismic and wind resistance.Precisely prediction for the behavior of reinforced concrete structures under severe earthquakes or strong winds is important to assess the safety of reinforced concrete structure.Against this background,the rapid longding test of reinforced concrete columns under seismic strain rate rang has important theoretical and practical engineering value.The reinforced concrete columns subjected to rapid loading were investigated in this paper. It can be expected to make a rational assessment of the seismic performances of reinforced concrete columns.The experimental researches also can be used as a basis for making a rational repairing planning.The dynamic constitutive model of concrete with the consideration of strain rate effects was introduced to the fiber model of reinforced concrete columns.A dynamic fiber model was constructed and employed to forecast the dynamic performance of the reinforced concrete column specimens.The damage process of reinforced concrete column was monitored with the PZT smart aggregates.The main work is summarized as following:Rapid loading test was conducted with three reinforced concrete specimens.The loading rate effect to loading capacity, stiffness,ductility and energy dissipation capacity of reinforced concrete columns was analyzed and investigated on the basis of test results.Wrote the calculation program using Fortran.The program adopted dynamic fiber model considering strain rate effect can simulate the dynamic monotonic properties of reinforced concrete columns.Simulation results show good agreements with the test results.The validated dynamic fiber element model is employed to further numerically study the dynamic monotonic properties of reinforced concrete columns under different axial compression ratios and subjected to different load rates in order to investigate the loading rate effect to the load-carrying-capacity of reinforced concrete columns.The PZT smart aggregates were applied to detect the damages of reinforced concrete column.