Modelación y análisis por desempeño de una estructura de acero, considerando deterioro para la predicción del colapso

Abstract

In seismic design, codes handle the concept of transforming complicated nonlinear dynamical behaviors of structures during earthquakes into equivalent linear problems, even assigning arbitrary load reduction coefficients for analysis. In this work, the performance analysis at drift level of a special seismic steel system is proposed, based on non-linear dynamic analyzes. It also shows the execution of a series of checks through nonlinear dynamic and static analysis to verify the correct behavior of the model. The analyzes will be carried out in OpenSees. The prototype to be used comes from an example of collapse evaluation used in the ATC-76-1 project. The model generated has concentrated plasticity, with plastic hinges in beams and columns, following the modified deterioration theory of Ibarra-Medina-Krawinkler. The geometric non-linearity, PDelta effect, is included through modeling a column without lateral resistance, leaning column, loaded with the weight of the non-tributary area of the lateral system. Three levels of seismic intensity were analyzed, corresponding to earthquakes with return periods of 72, 475 and 2500 years (service, design and MCE), on the model calibrated with two capacity reduction strategies by the interaction of the axial load - moment. The results show that the service objectives are not met while the design objectives do meet the requirements of drifts. For the MCE intensity the effect of the capacity reduction is more evident, fulfilling the performance requirements only for strategy 2 (axial load due to gravity loads).