Seismic Damage Analysis of Reinforced Concrete Building Considering Member Fracture

Abstract


The Great Hanshin Earthquake, which occurred in January 1995, damaged a wide area. The structural design guidelines for buildings especially against vertical seismic wave has been thoroughly reconsidered. Therefore, the arrival of a convenient technique to analyse collapse modes of structural objects under three-directional excitation, is now desired. However, generally used finite element code needs some extra complicated processes to simulate this kind of dynamic collapse problem which contain strong nonlinearity and discontinuity, such as member fracture occurred in flexural damage or shear damage in reinforced concrete members.
The Adaptively Shifted Integration (ASI) technique, which produces the highest computational efficiency in the finite element analyses of framed structures including static and dynamic collapse problems, is applied to the seismic damage analysis of a reinforced concrete building. In this technique, the numerical integration points in an elastically deformed element are placed at the optimal points for linear analysis, while the integration points are shifted immediately after the occurrence of a fully-plastic section in the element to form a plastic hinge exactly at the position of that section. Thus the technique produces higher computational accuracy with fewer elements than the conventional finite element code. By expressing an explosion or a fracture by a plastic hinge located at the exact position with a simultaneous release of resultant forces on the element, discontinuous problem such as this can be easily analysed even by the conventional finite element code with the displacemental form. By using the ASI technique, sufficiently reliable solution for the practical use has been obtained in the seismic damage analysis of a five stories-five span reinforced concrete building. The present technique can be easily implemented with a minimum effort into the existing finite element codes utilizing the linear Timoshenko beam element.


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