MATERIAL MODELING FOR TRANSIENT DYNAMIC ANALYSIS OF REINFORCED-CONCRETE STRUCTURES

Reinforced concrete is a composite structural material which has been the subject of extensive research since it was first used. When consid ering the rational properties, the research has mainly centred on the behaviour of the concrete, that of the reinforcing steel and the inter action between the steel and the surrounding concrete subject to stati c loading. The behaviour of reinforced concrete, and, in particular, t hat of the concrete itself when subject to dynamic loading has been le ss thoroughly studied. This paper proposes a material model for the co ncrete which includes the effect of high strain rate upon both the sti ffness of the material and upon the crushing strength. It proposes exp ressions for the yield and failure surfaces of the concrete which acco unt for the effects of high strain rate and then incorporates this mat erial model into an existing finite element program to compare with a series of test results. The paper illustrates that this improved mater ial model can now produce a displacement/time history for reinforced c oncrete elements which is very close to that observed in tests on elem ents which are far outside the elastic range.