Modeling of existing and rehabilitated reinforced concrete buildings

Abstract

<p>There are many existing buildings which have been designed according to earlier codes. In these codes, either design for seismic loads was not a requirement or design was for lower levels of seismic forces. One of the major challenges that faces structural engineers is to determine the seismic capacity of an existing building and to rehabilitate these buildings to upgrade their seismic capacity if needed. At present, there are no guidelines available for the rehabilitation of existing structures and for the design of different retrofitting techniques. One of the most effective ways of rehabilitation is the addition of reinforced concrete (RC) walls. Until now, there is no robust analytical model available to study the effect of adding RC walls on the building behaviour up to failure. To determine the building seismic capacity and to study the effect of adding RC walls, the analytical model used should be capable of representing all the deficiencies in existing buildings. Moreover, it should be able to represent all possible failure modes such as beam-column joint shear failure, cumulative concrete crushing and bond slip failure. The objective of the present research is to evaluate the behaviour of buildings retrofitted by the addition of reinforced concrete structural walls. This was done by the development of a suitable analytical model that fully describes the behaviour of existing buildings before and after rehabilitation using RC structural walls. This model was verified using test results on specimens representing existing structures and found to give results that are closely correlated to the experimental results. The model was able to detect the failure mechanisms observed in the experiments. This model was used in the analysis of an existing three-storey building to determine its seismic capacity. The effect of ignoring the beam-column joint shear deformations, bond slip and concrete crushing was studied. Ignoring any of these parameters can change the building failure mechanism which could lead to misleading results. After that, a suitable rehabilitation technique using RC walls was chosen and the building behaviour after rehabilitation was studied.</p>