1st Croatian Conference on Earthquake Engineering 1CroCEE 2021

In this paper a fully automated optimization procedure of reinforced concrete structures exposed to earthquakes by using genetic algorithm-GA optimization method is implemented. Given the highly stochastic nature of the earthquake, its extreme effects and possible catastrophic consequences, special attention must be paid to solving this problem. The behaviour of structural systems was assessed employing nonlinear dynamic analysis. Localized nonlinearities are taken into account by using finite elements that are able to realistically describe the hysteresis behaviour of reinforced concrete structures under cyclic loading. The problem of structural optimization comes down to achieving the optimal response under earthquake load with minimal material consumption. However, the main goal of optimization is to achieve a favourable response in the sense of performance-based design and the minimum consumption of materials is a criterion of lesser importance. Seismic load is modelled using an artificially generated accelerogram whose response spectrum closely approximates the design acceleration spectrum defined by relevant seismic code. The optimization procedure defines the target performance levels, with the imposed limits of the largest interstory drifts. The first target performance level refers to earthquakes of lower intensity and shorter return periods and must prevent excessive damages. The second target performance level represents earthquakes with the highest expected intensity in the observed area. Damage limitation is the primary goal of the optimization procedure, which is then followed by ultimate limit state verification. Numerical examples cover both simple, geometrically regular and uniform systems as well as irregular structures. For all analysed examples, optimization by using the GA method resulted in structures that fully meet the SLS and ULS constraints. Structures optimized in this manner easily achieve a desired response to earthquakes.