Seismic plastic design of RC frame structure based on energy balance

This research focused on the development of plastic design methodology under strong earthquakes using energy balance concept for reinforced concrete frame structures. The strong-column weak-beam mechanism was selected as the basic failure mode of plastic design through the multiple failure mode analyses. From the differential equation of motion, the structural energy equilibrium equation was derived, and the elastic vibration energy and earthquake input energy were given. In order to reflect the deterioration of load-carrying capacity, stiffness degradation and pinching effects, the modified energy equilibrium equation was proposed. Based on the fact that the external work equals the internal work, the lateral forces could be obtained, taking into account the P-Δ effects. Then, the sectional internal forces of beams and columns could be calculated through the energy dissipating mechanism. A seven-story RC frame structure was designed based on the plastic design method and the performance of plastic design structure was compared with that of elastically designed structure. The results show that the plastically designed structure can fully develop the strong-column weak-beam yielding mechanism and have a better ductility performance and uniform maximum story drift along the height, indicating the effectiveness of the proposed plastic design method.