Nonlinear Dynamic Analysis of Isolated and Fixed-Base Reinforced Concrete Structures

Earthquakes are a major threat to human lives and to the integrity of the infrastructures in seismic regions. Structures are the worst hit with the phenomenal damages due to ground motions resulting from earthquakes. Recent research and studies have led to new techniques to reduce the damages caused by earthquakes on structures and these techniques are applied for innovative structural design. One of the techniques is the base isolation method, which is used to design structures against earthquake damages by using seismic isolators to change the dynamic characteristics of a structure. In this study, three bay 4-and8- storey reinforced concrete structures are designed as isolated and fixed-base. Lead-rubber bearing (LRB) is used as an isolation system. Nonlinear behavior of both isolation system and super-structure are considered in the modeling. The behaviors of designed models under dynamic loads are analyzed using Ruaumoko computer software. Erzincan, Marmara and Duzce Earthquakes are chosen as the ground motions. At the end of analysis, period, storey accelerations, inter-storey deformations, base shear forces, plastic hinge locations and weighted damage histories are compared for isolated and fixed-base structures. As a result, the advantages of isolated reinforced concrete structures against fixed-base structures under earthquake are shown.