Civil Engineering Association

Optimum design of base isolated RC structures

The main idea of the study is the optimum design and the economic evaluation of reinforced (RC) conventional and isolated structures. For the purpose of the study two symmetrical RC structures were studied, designed both with and without seismic isolation, following a performance based concept. The seismic isolation was accomplished by the use of Lead-Rubber Bearings (LRB) and High Damping Rubber Bearings (HDNR).
In the first chapter, the seismic isolation technique is described, as well as the conditions and the applications of the method worldwide, along with the types of the isolation devices.
In the second chapter, the modeling, the preliminary design and the final design of the bearings is described.
In the third chapter, the analysis procedures are presented, and specifically the Linear Static Procedure (LSP), the Nonlinear Static Procedure (NSP) according to the recommendations of FEMA-356 and the Nonlinear Dynamic Procedure (NDP).
Thereafter, in the fourth chapter the structural optimization problem is described, along with the history of the technique and the formulation of the problem. The design variables, the objective function and the constraint functions are defined, as well as the three types of optimization. Finally, the Evolutionary Algorithms (EA) are presented, with emphasis to the Differential Evolution (DE).
In the fifth chapter the procedure of Life-Cycle Cost Analysis (LCCA) is presented, which can be used as an assessment tool of the response of the building during its expected lifetime. The calculation of the procedure is analyzed, as well as the steps to incorporate the nonlinear dynamic analysis in the calculation procedure.
Subsequently, in the sixth and seventh chapter the test cases of the study are presented analytically, along with the conclusions that are obtained from this process.