Full Session with Abstracts
Seismic events are economically devastating and may be fatal. The seismic design in building codes has made large strides toward reliable life safety design but the enormous economic loss remains an issue in need of attention. Aiming to minimize the estimated seismic economic loss to a structure can be quite expensive as well. This leaves capital holders in an economic dilemma, spend now or risk large losses in the future. Furthermore, the capital holders usually do not have enough structural knowledge and are not given the necessary information when decisions must be made.
In recent years, many studies have proposed methodologies for optimal seismic design and seismic retrofitting (of frames) using fluid viscous dampers. The optimal solution in these methodologies can usually be classified to one of two categories, optimal initial cost of the seismic retrofitting or optimal seismic performance.
In the present work, a multi-objective optimization is performed facing the initial realistic retrofitting cost with the seismic life-cycle cost as two opposing objective functions. The initial realistic cost is directly related to the topology and the sizes of the dampers while using limited number of dampers’ size-groups. The life-cycle cost is defined by the estimated seismic loss considering the performance of the retrofitted structure to seismic excitation for the defined structural life cycle. Rather than resulting with a single optimal solution, this platform presents a set of Pareto-optimal solutions (also known as the Pareto front) is obtained and presented.
The loss estimation analysis is a stochastic computation procedure accounting for geotechnical and structural uncertainties, using multiple ground motions for the structural performance while addressing non-linearity of the structure. Integration of the hazard curve, probabilities of global structural performance and specific element fragility curves, leads to a calculated measure of the estimated loss. The problem is solved using a first order optimization method. The gradients for both objective functions are derived using the adjoint analytical method and are used to create a computational efficient solution procedure.
This lecture/paper/presentation is intended for both practitioners and researchers who deal with earthquake engineering or structural optimization. Design engineers are expected to learn a new optimal seismic design approach that leads to better communication with the decision makers in a retrofitting projects. Researchers will see a first step towards making complex engineering concepts accessible for decision makers. The multi-objective optimization creates a powerful knowledge platform in simple terms for decision makers. A set of options presenting both the initial cost and the estimated losses hold the information needed to make the economically wise decision.