CYCLIC BEHAVIOUR OF KNEE-RING BRACED FRAMES

Seismic resistant structures are expected to maintain adequate stiffness and energydissipation during earthquake. In this paper, new seismic resisting structural system ispresented investigating different stiffness related structural performance level and energydissipation requirements simultaneously. This system, called Knee-Ring Frame dissipatesearthquake energy through large inelastic deformation occur within Knee and Ring elementsaccording to each one stiffness. Knee-Ring is designed to be the first line of dissipation ofenergy during severe earthquakes. The Knee-Ring acts as a none-elastic fuse against lateralcyclic displacement. This paper aims to find out key issues influencing cyclic behavior ofknee braced frames and knee-Ring braced frames. Knee-Ring frames are as same parallelsprings with equal none-elastic deformation, so each one is stiffer, produce’s larger reactionforce. Results of analysis of analytical models with finite element method of knee-Ringbraced frames indicate stable hysteretic behavior and have rather energy dissipation capacityof KBF simultaneously. This comparison discuss analytical models to evaluate lateralstiffness alongside of energy dissipation of knee frames with analysis several kind of Knee-Ring braced frames and compare hysteresis curves of knee frame and Knee-Ring frames withdifferent place of Ring along knee member. Finally, results of compare hysteresis curves ofKnee Braced Frame and by adding Ring to different places into diagonal brace and calculateenclosed area of hysteresis curve of last loading cycle, indicate disposable seismic energy ofKnee-Ring frames more rather than Knee Braced Frame, models with shorter distance ofRing to diagonal brace along knee, are rather stiffness and energy dissipation. Furthermore aswell as stiffness and energy dissipation of Knee braced frames depends on length of Knee,stiffness and energy dissipation of Knee-Ring Braced frames depends on distance of Ringinto diagonal brace.

کلیدواژه ها:

stiffness ، hysteresis curve ، energy dissipation ، structural performance level ، cyclic displacement ، Knee-Ring braced frames