Fragility Curves for Concrete Frame Buildings with Passive Controllers

Fragility curves present the probability of a structure exceeding a certain limit state in terms of a seismic intensity parameter function. The seismic demand varies from very low to maximum intensity. The fragility curves are developed from the adjustment of the function distribution of the results obtained. This article presents a set of fragility curves for concrete frame buildings of mid rise and high rise elevations based on the HAZUS classification in order to obtain the level of damage of a structure. The frames have the principal characteristic of having installed passive controllers of variable orifice in each level. Different dampers configurations were considered in the analysis, such as Diagonal, Chevron, Lower Toggle, among others. To develop the fragility curves the maximum drift of the top floor was obtained for each frame based on a nonlinear time history analysis using records of four earthquakes, i.e., El Centro, San Fernando, Loma Prieta, and an earthquake artificially generated. The earthquakes used were escalated from 0.1g to 1.5g with of an increase of 0.1g based on their maximum PGA. To simulate the nonlinearity of the structure the Bouc-Wen model was used. Finally, the curves illustrate the advantages of using dampers to reduce the level of damage in a structure, in which the results demonstrate that the most efficient configurations are the Lower Toggle and the Scissor-Jack.