Effect of Variation of EBF Link Length along the Frame Height on High-Rise Building Performance and Damage Index

Eccentric braced frame is one of the most reliable seismic systems in steel buildings. If the moment frames are combined with eccentric braced frame, an effective seismic resistance system is obtained. In the eccentric braced frame, depending upon its length, the link may dissipate seismic energy either by developing plastic hinges or by yielding of the web in shear. In the seismic design issues, the binding of the link length has not been determined and its designation and consequently the choice of the type of link performance from the perspective of the formation of flexural or shear plastic hinge is the responsibility of the designer.
We have tried to investigate the effect of changing the length of the link at the structural height on the structure performance. For this purpose, 12 frames of 15, 20, 25 and 30 stories are designed to have links with variable length in each group. Then these frames have been analyzed by pushover, and their performance has been evaluated and compared. In evaluating the performance of the frames, the results of the contribution of the moment frames to story shears, drifts of the frames, the ductility, and their resistance are presented based on acceptance criteria in pushover.
Based on the obtained results, the frames with decreasing link lengths have the lowest damage index and fixed-length frames have the highest damage index. Frames with decreasing link length have the best performance in terms of bearing highest base shears and more displacements at all performance levels.