Performance-based design in earthquake engineering is a structural optimization problem that has, as the objective, the determination of design parameters for the minimization of total costs, while at the same time satisfying minimum reliability levels for the specifi ed performance criteria. Total costs include those for construction and structural damage repairs, those associated with non-structural components and the social costs of economic losses, injuries and fatalities. This paper presents a general framework to approach this problem, using a numerical optimization strategy and incorporating the use of neural networks for the evaluation of dynamic responses and the reliability levels achieved for a given set of design parameters. The strategy is applied to an example of a three-story offi ce building. The results show the importance of considering the social costs, and the optimum failure probabilities when minimum reliability constraints are not taken into account.

The time history analysis of the linear and non-linear response of earthquake resistant structures is a tool increasingly used in practice and required by codes. In this paper, a set of 12 accelerograms was generated numerically with the spectral representation methodology. Another set of 15 accelerograms were selected from a database of earthquake records and scaled with a uniform factor so that the mean spectrum fits the design one. The non-linear dynamic response of two frames of different stiffness and resistance was obtained under the action of the two sets of accelerograms. The global force - displacement results showed a higher coefficient of variation for the set of recorded accelerograms, especially for the structure of lower resistance that has a strong non-linear incursion. The same tendency was obtained for the moment - curvature relationships of beam and column sections, with higher dispersions compared to the global results. In addition, the influence of the vertical acceleration component was analyzed, resulting in a higher incidence in the interior columns of the frames.