EVALUATION THE EFFECTOF LINK BEA MS' STIFFE NERS WITH DIFFERENT CROSS-SECTIONS

Link beams of eccentrically braced frames similar to ductile fuses, in addition to avoiding bracing buckling, attract earthquake energies. Link beams' stiffenershave significant effect in earthquake energy dissipation and their suitable arrang ement, causes increasing the rotation capacity of link beams.In this investigation, link be ams with tubular and I-shaped cross-sections that are similar in area, moment of inertia, length and stiffener spacing, were compared together and the eff ect of link beam section and its stiffeners on the rotation c apacityof link beams has been studied. Also in this study, tubular link beams for different values of flang e compactness ratio and web compactness ratio were compared together and this question has been answer ed that the flange compactness ratio has more impact on the rotation capacity of tubular link beams or w eb compactness ratio?In this investigation, the li nk beams were modelled in ABAQUS and in order to loa ding, AISC-2005 loading protocol was used. In this modelling, shell elements for flanges, webs and stiffeners have been utilized and also the nonlin ear kinematic hardening plasticity material model has been used.The result of this investiga tion indicates that, if link beams with vari ous cross-sections have geometrical similarity, I-shaped lin k beams will have approximately two times more rotation capacity than tubular link beams and it will be more significant with increasing of flange com pactness ratio and link beamlength. Also it can be concluded that flange compactness ratio has more impact on the rotation capacity of tubular link beams, in a way that for one web compactness ratio, with increasing of flange compactness ratio, the rotation capacity decreases approximately 69% but for one flange compactness ratio, with increasing of web compactness ratio , the rotation capacity decreases approximately 36%.

Keywords:

Link Beam , Stiffener , C ross-Section