Akademik Veri Yönetim Sistemi
9th US National and 10th Canadian Conference on Earthquake Engineering 2010, Including Papers from the 4th International Tsunami Symposium, Toronto, Kanada, 25 - 29 Temmuz 2010, cilt.2, ss.839-849
Performance of post installed internal steel frames (ISFs) to upgrade the existing deficient reinforced concrete (RC) frames was investigated experimentally in this study. Three strengthened and one as-built reference portal frame specimens were tested under constant gravity load and reverse cyclic lateral displacement excursions. ISFs connected to RC frames with and without anchors were tested. Test results indicated that placing an interior steel frame without any anchors as a new lateral load resisting system can increase the lateral stiffness and strength significantly. The strength increase was found to be limited by the horizontal joint shear strength of the RC frames. On the contrary, higher strength enhancements were observed upon using anchor connections between RC and steel frames. It was found that if the lateral strength needed is less than the horizontal joint shear strength, it is more practical and economical to use anchorless internal steel frames. However, if the lateral strength demand on the steel frame exceeds the horizontal joint shear capacity of the frames, it is preferable to use ISF with internal anchor connectors. It was also observed that ISFs also perform as means of gravity collapse prevention systems under the conditions of severe strength degradation and second order effects at high drift deformation demands. Finally the available drift capacity of strengthened frames in relation with the drift limits given in seismic rehabilitation design guidelines is discussed.