| Eccentrically braced frame is a new lateral-loads-resisting system developed recently for buildings in high-intensity earthquake regions and in which D-type eccentrically braced structure is one of the most commonly used structures for resisting seismic.In this thesis,we first present the theory and features of D-type eccentrically braced frame,as well as its disadvantages,based on recent research and studies in the field.We analyze factors affecting its performance of seismic-resisting.Based on the analysis we further build the 1/3 scale models of traditional D-type EBF,D-type EBF of add side-plate to beam-column connection and D-type EBF of add ribbed plate to beam-column connection,which are then used to study the seismic-resisting performance,with the method combining both experiments and finite element analysis. The results demonstrate that compared to traditional eccentrically braced frame,the new scheme can relax the local deformation constraint exerted by column to flange of link. Since it moves link away from column so as to allow link have more rotation,resulting in sufficient development of plastic deformation and exhibiting better seismic-resisting capacity.It also avoids link near the column premature yielding,keeping plastic hinge away from welds of link,reducing the concentration of stress and strain in the top flange caused by the welds,and the possibility of brittle failure as well.Then this thesis conducts elastic-plastic time-history analysis with both traditional D-type EBF and the improved D-type EBF by finite element analysis software.Feeding both with a typical record of high-intensity earthquake,we compare their seismic response,and study their influence on the entire structure by changing the length of strengthening connection and modifying arrangement of link.The research result provides theoretical and practical basis for the application of the improved D-type eccentrically braced frame,and also serves as the basis for the future research. |
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