SEISMIC RETROFIT OF DEFECTIVE EXTERIOR RC CEILING-COLUMN

The present work investigates the seismic vulnerability of in-situ concrete column-ceiling connections. Improper implementation of beam-column and ceiling connections in in-situ reinforced concrete buildings are known as the most important weak points with the potential of failure in reinforced concrete moment frames subjected to seismic loading and hence the work presented herein investigates the performance of the imperfect concrete beam-column connection and provides a method with which to improve the behavior of the connection. To retrofit the said connection, steel plates in conjunction with bolts and straps are used. The analyzed connection is one of the connections of the building of a high school in the city of Kermanshah in Iran which has been inadequately implemented. In this study, different parameters such as the dimensions of the steel plate, the number and the different pre-stressing percentages of the bolts, configuration of the steel straps and the selection of the suitable pre-stressing percentage for the bolts are studied. It needs to be mentioned that all of the parameters used in the analyses have been obtained based upon the actual behavior of the material through tests such as the Schmidt hammer and core extraction for the concrete and tensile tests for the steel bars. Finally, based on the results from the load-displacement diagrams, the optimum design with high ductility and load bearing capacity is proposed.

Keywords:

Defective exterior ceiling-column , Finite element method , Seismic Retrofit , Brittle behaviour of RC joint , Core sample