Response of reinforced high-strength concrete beam–column joints under load reversals

With the increasing use of high-rise reinforced concrete structures, high-strength materials, smaller member sections and larger reinforcing bars should be employed. Therefore, the stress resistance capacity of a joint is also required to be increased over other parts of a structure. The application of high-strength concrete has progressively increased in many structures, and it has now been used in many parts of the world. Previous research^1–3 has shown that the behaviour of a reinforced high-strength concrete structure subjected to monotonic or earthquake-type loading is significantly different from that of a reinforced normal-concrete structure. It tends to be brittle when overloaded to failure, and to show a more sudden appearance of microcracking. Lack of ductility in concrete members raises serious concerns for structural safety. The behaviour of reinforced high-strength concrete members and joints must be accurately assessed before high-strength concrete can be used with confidence in reinforced concrete frame structures. The objective of this experimental research was to study the behaviour of reinforced high-strength concrete beam–column joints, and to develop a new approach for the design of such joints in high-rise reinforced concrete buildings.