Numerical and experimental study on the steel-concrete connection for supporting structure of current power system

Tidal current energy is recently regarded as a vital source of ocean energy, because it is not only reliable and renewable but also its capacity is predictable compared to the other ocean energy sources including offshore wind and wave. Since the tidal current power systems are commonly installed at the rapid flow water area, it requires the safe and reliable supporting as well as the steady and high-efficiency current power generator. In addition, the rational construction and maintenance methods should be prepared to reduce the total cost of tidal current power generation systems. Until now, various types of current power structures have been developed such as pile-type, gravity-type, and jacket-type and so on, considering performance for construction work as well as soil and marine conditions.Among these, the gravity-type is regarded as the most costeffective and reliable one, since there is no need to use large scale marine equipments such as pile driving vessels, cranes and so on. Generally, the structure of gravity-type is composed of a steel column supporting, the current power generator and a concrete basement providing the structural stability of the whole system due to its self-weight. The most failures of support structures occur at the steel-concrete connection part due to the shear forces and the fatigue loads. Therefore, the safety of steel-concrete connection is the most important to secure the overall safety of supporting structure. In this study, the structural details and failure mode of steelconcrete connections for the gravity type have been investigated. Also, the numerical analysis and the static loading test for the scaled model have been carried out to evaluate the structural behaviors according to connection details. The analysis and test results indicate that the connection detail using circular ribs is more effective to resist against the tensile forces than the other connection details. Thus, it is concluded that this connection detail c- n be usefully applied to the supporting structures subjected to the thrust forces induced by blades as well as the horizontal current forces.