Single story precast structures in seismic zones - I

The theoretical and experimental research performed recently in the Structural and Earthquake Engineering Laboratory of Istanbul Technical University on prefabricated square columns will be presented here as a set of complementary research work. The deformability limits, failure modes of columns, the performance of columns exhibited under the different type of cyclic displacement protocols versus monotonic loading, rehabilitation by different type of complete and partial jacketing with and without CFRP sheets using both ordinary or self-leveling-self compact concrete, damping ratios and Earthquake Load Reduction Factors based on experiments, plastified regions observed etc. were taking place in this research program. The investigation essentially covers the test results of 1/1 scale 13 specimens with different cross sections and longitudinal reinforcement ratios. Nine of them were tested again after having applied different types rehabilitation referring to the corresponding displacement protocols. The presented part of the research covers the test results of virgin specimens, displacement ductilities obtained, overstrength factors and hence earthquake load reduction factors. An attempt to find out the most probable displacement demands of precast individual square columns has been presented as well in order to set up a more reliable design philosophy based on dynamic displacement considerations. The purpose is to find ways of overcoming the selection of initial stiffness and displacement ductility. In order to does that, 12 groups of earthquake records cover the cases of far field, near field, firm soil, soft soil possibilities for 2/50, 10/50 and 50/50 earthquakes with minimum scale factors. The selection has been done by using two different approaches which suggest modifying the frequency content of the record or not.