Análisis sismo-resistente de edificios mixtos de acero y hormigón armado

Abstract

In this study it was assessed the seismic behavior of framed buildings with composite structure of steel and reinforced concrete (RC) in a specific configuration formed with lower levels with RC (primary structure) and higher levels with steel (secondary structure) as structural materials for components. Levels with steel elements correspond to the higher or two higher levels of the buildings. Static and dynamic nonlinear analyses were conducted to determine the parameters of capacity, fragility and damage of structural systems. These analyses were based on criteria and methodologies such as Spectrum-Capacity, Adaptive Pushover and the Capacity Parametric Model. The difference in performance was remarkable in some models depending on rigidities and the heights of models. Fragility curves and damage indices were determined using two different methodologies in order to assert the behavior in terms of reliability and it was evidenced that in some structural systems there is a great probability of zero damage while in others predominate a high probability of reach moderate, severe or collapse damage states. In Time-History and Incremental Dynamic analysis, were used 5 real and 5 synthetic accelerograms. Numerical results show that most of the models suffer significant lateral deformations, often reaching beyond acceptable limits states from the Venezuelan normative. It was performed a experimental test of a two level frame with Steel elements in the higher level and Reinforced Concrete elements in the lower level. Another experimental test was performed on a full-scale mixed Steel-Reinforced Concrete joint. Both tests were subjected to cyclic lateral loads in order to determine its characteristics, behavior and capacity to histeretics actions in terms of stiffness degradation and damage evolution. Concerning to capacity and damage indexes, it was showed the influence of horizontal relative displacements of each level and the stiffness degradation as key parameters in determining the damage to a building. All this was revalidated with a probabilistic approach to the Damage Index. Experimental results showed very similar values in absolute and relative terms to those obtained in the numerical models. In these numerical and experimental process was used the Capacity Parametric Model (CPM) and the fragility and damage models associated with this methodology. Too achieve structural continuity at the structural joint of steel columns with reinforced concrete elements, it was evidenced that it can be used the AISC and ASCE design criteria for base-plates for steel columns

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