A Joint Optimization Framework Towards Finding Optimal Lead Rubber Bearing (LRB) Properties

The technology of base isolation is widely adopted as a practical and efficient measure to protect the structure from the devastating affects of earthquake forces. The isolation systems achieve desired performance by decoupling the superstructure from the foundation through energy dissipation and avoiding the dominant frequency of the earthquake by elongating the fundamental period of the structure. Hence, to achieve an effective isolation system design, one needs to account for various performance measures to maintain a balance between multiple conflicting objectives. This paper proposes a novel joint optimization approach to find the optimal isolation system parameters that aims to simultaneously minimize the Maximum Interstorey Drift Ratio (MIDR), top floor acceleration (TFA) and base displacement (BD)s. We have chosen Lead Rubber Bearing (LRB) as the isolation system in the present study which is modeled in OpenSees. A popular multi-objective evolutionary algorithm, more specifically NSGA-II is employed to optimize the objective functions simultaneously; though, any other suitable optimization algorithm can be applied. It has been observed that the optimal parameters found with the proposed joint optimization approach performs well.