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Base Isolation for Seismic Retrofitting of a Multiple Building Structure: Evaluation of Equivalent Linearization Method
Full text linkAlthough the most commonly used isolation systems exhibit nonlinear inelastic behaviour, the equivalent linear elastic analysis is commonly used in the design and assessment of seismic-isolated structures. The paper investigates if the linear elastic model is suitable for the analysis of a seismically isolated multiple building structure. To this aim, its computed responses were compared with those calculated by nonlinear dynamic analysis. A common base isolation plane connects the isolation bearings supporting the adjacent structures. In this situation, the conventional equivalent linear elastic analysis may have some problems of accuracy because this method is calibrated on single base-isolated structures. Moreover, the torsional characteristics of the combined system are significantly different from those of separate isolated buildings. A number of numerical simulations and parametric studies under earthquake excitations were performed. The accuracy of the dynamic response obtained by the equivalent linear elastic model was calculated by the magnitude of the error with respect to the corresponding response considering the nonlinear behaviour of the isolation system. The maximum displacements at the isolation level, the maximum interstorey drifts, and the peak absolute acceleration were selected as the most important response measures. The influence of mass eccentricity, torsion, and high-modes effects was finally investigated
Confined Masonry Members: A Method for Predicting Compressive Behaviour up to Failure
No full textThe behaviour of masonry elements confined with steel tied plates and subjected to axial compression is faced in this paper. The problem is investigated by means of an analytical approach, calibrated against the results of a non linear F.E.M. numerical analysis, carried out with the ABAQUS code. The theoretical procedure allows the evaluation of the effect of confinement in both horizontal directions, accounting for the inelastic behaviour of both masonry and steel. In spite of the reduced number of factors involved, the proposed model proves to be reliable in the prediction of the main behavioural aspects of confined masonry and, for this reason, it can be considered as an useful tool for practical calculations
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