To assess seismic vulnerability of existing reinforced concrete buildings in Iran, cyclic and monotonic load tests on seven columns have been carried out. Four specimens represent existing buildings with deficient seismic details. Three others represent well proportioned constructions in accordance with provisions of intermediate ductility, ACI318–99, which is a common reference in Iran. Both types of columns are in similar positions in the reference building and are subject to similar seismic demand. Based on test results, hysteresis curves, backbone curves, and idealized curves are established. The deficient specimens show 35% reduction in both strength and initial stiffness and 37% loss of energy dissipation capacity in comparison to the well proportioned specimens. The length of plastic hinge of most tested columns is almost equal to full depth of the section. The maximum measured shear force is at least 20% greater than the shear force derived from expected nominal flexural strength.
In recent years, there has been a growing seismic demand for existing bridges and the final redesign of bridges, especially after a major earthquake One method to strengthen concrete frames on bridges is to use steel sheets or profiles to use the confining force. During this study, a sample at 30% scale under gravity and lateral cycle loading was examined within the laboratory. A finite element model is additionally used to compare the behavior of laboratory samples. The laboratory sample was a model of a typical bridge in iran that was generally designed with deficient detailing requirements in agreement with the typical regulations of the 1970s. A finite element analysis set was used to evaluate various parameters in improving the behavior of the laboratory sample. The finite element model correctly predicted the weakness of the model. Subsequently, a reinforced specimen was investigated by increasing the prestressing force within the concrete beam and the thickness of the frp sheets utilized in the bridge pier by the finite element method. The results show the energy absorbed within the hysteresis curves improved the propagation of the failure. The result also showed that a 100% increase in the prestressing load caused a 67% increase in resistance .
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