ABSTRACT
One of the most important prerequisites of reinforced and most prestressed concrete construction is the bond between steel and the concrete. A considerable amount of work on the static bond strength between steel and concrete has been done, but very little attention has been given to the dynamic bond characteristics. Although nowadays there is a greater risk of structures being exposed to impact loading, with disastrous consequences, the knowledge about bond under such loading is still very limited. In fact very few researchers have investigated the behaviour of steel-concrete bond when subjected to high rates of loading. Hanson and Liepins (1962) and later Vos and Reinhardt (1982) found that there was a negligible effect of loading rate on bond of smooth bars and prestressing strands. There was, however, a strong influence in the case of the deformed bars. This was mainly due to the fact that both the compressive and the tensile strength of concrete and mortar increase with increasing loading rate. In other words this apparent bond strain-rate sensitivity can be attributed to the concrete itself as deformed bars produce more cracking in the surrounding concrete or mortar.
