Investigation of Multi Plastic Hinge Approach in Reinforced Concrete Core-Wall Tall Building under Near Fault Records

Utilizing tall building with reinforced concrete core-wall is propagating nowadays. In this paper the response of a tall building of this type is studied. First, a 40-story tall building with reinforced concrete core-wall is analyzed and designed by the response spectrum procedure. Then the lower stories of the core-wall are modeled by nonlinear fiber elements and the remaining stories are modeled by elastic elements. The Nonlinear Time History Analyses is performed for a set of near fault ground motions. The results show that the overall trend of the moment diagram along the height of the structure has not agreement with the results obtained from the response spectrum analysis. In the median of the height the amount of the moment demand in the Nonlinear Time History Analyses is about the 3.5 times of the moment demands in the response spectrum analysis. In this subject the moment demand of meddle height is very big and it is very hard to remain it in the elastic region and it will need a lot of reinforcements to remain elastic. To reduce the moment demand for these areas, first one and then two plastic hinges is planned along the height of the system. The Nonlinear Time History Analyses is performed for these cases. The results show that dual and triple plastic hinge approach will reduce the moment demand about 28 and 42 percent.