چكيده لاتين :
In recent years, composite frames that are consist of reinforced concrete column and steel beam, have been attended by researchers due to their economic efficiency as well as their effect on improving the behavior of tall structures. In such frames, using of concrete in columns, due to the compressive strength of concrete and using of steel in the element of beam, due to high tensile strength of steel, result in reduction of elements section and structure weight and also improving its performance. Previous studies have shown that the most important issue in these frames is their connections. Moment connections of such frames are through-beam-type and through-column-type connections. Details of these connections should be in such a way that prevent the formation of plastic hinge in panel zone, and besides, has adequate ductility. Most studies, so far, have been done on the details of through-beam-type and little researches have been done on the plans of through-column-type connection. Nonetheless, determination of beam-column connection with appropriate seismic performance and also force transmission mechanism is necessary. In this study, amount of the effect of proposed composite connection consist of through-reinforced concrete column and attached steel beam with peripheral diaphragms and inter plates, on the improvement of the behavior of composite moment frames than conventional concrete frames has been investigated that the sample of this connection has been made and tested, laboratorial, by the authors. The survey has been conducted on the amount of displacement and drift of frame’s stories and also on the loading capacity, ductility and energy absorption of frames. For this purpose, firstly, a composite frame of one story-one span with the proposed connection has been modeled by two finite elements softwares called Abaqus and SeismoStruct and the displacement control has been analysed under pushover lateral loading, and its results have been compared with the results of reference concrete frame. To ensure of the accuracy of the modeling that has been done, load-displacement curve that is the resultant of the connection model of Abaqus and SeismoStruct, has been compared with experimental results. Then, three concrete frames and three composite moment frames with four, seven and ten stories, with four 5-meters spans, 3 meters in height of each story, that had been selected from the meddle frame of a construction with dimensions of 20 meters by 20 meters in plan, and had been designed for area with high seismic risk, were modeled by SeismoStruct software, and were analysed under mentioned loading. The results showed appropriate performance of composite moment frames which are consist of mentioned connection, especially in frames with high number of stories. In this study, the drift of the frame and the relative drift of stories, have been reduced in composite moment frames than conventional concrete frames. Moreover, using the proposed composite connections in composite frames has resulted in the increase of the loading capacity of the frame so that the maximum of force that is tolerated by composite frames with 1,4,7 and 10 stories has been increased, respectively, by 59%, 49%, 67% and 46% than concrete frames. In addition, ductility of composite frames with 1,4,7 and 10 stories has been increased, respectively, by 65%, 50%, 37% and 30% than concrete frames with similar number of stories. The results have indicated the increase in initial and final stiffness of composite frames than concrete frames, in average, by 62% and 10%, respectively. Furthermore, a 116% increase in the energy absorption of composite frames than concrete frames has been observed.
