Behavior of Shear Link of WF Section with Diagonal Web Stiffener of Eccentrically Braced Frame (EBF) of Steel Structure

Abstract

This paper presents results of numerical and experimental study of shear link behavior, utilizing diagonal stiffener on web of steel profile to increase shear link performance in an eccentric braced frame (EBF) of a steel structure system. The specimen is to examine the behavior of shear link by using diagonal stiffener on web part under static monotonic and cyclic load. The cyclic loading pattern conducted in the experiment is adjusted according to AISC loading standards 2005. Analysis was carried out using non-linear finite element method using MSC/NASTRAN software. Link was modeled as CQUAD shell element. Along the boundary of the loading area the nodal are constraint to produce only one direction loading. The length of the link in this analysis is 400mm of the steel profile of WF 200.100. Important parameters considered to effect significantly to the performance of shear link have been analyzed, namely flange and web thicknesses, , thickness and length of web stiffener, thickness of diagonal stiffener and geometric of diagonal stiffener. The behavior of shear link with diagonal web stiffener was compared with the behavior of standard link designed based on AISC 2005 criteria. Analysis results show that diagonal web stiffener is capable to increase shear link performance in terms of stiffness, strength and energy dissipation in supporting lateral load. However, differences in displacement ductility’s between shear links with diagonal stiffener and shear links based on AISC standards have not shown to be significant. Analysis results also show thickness of diagonal stiffener and geometric model of stiffener to have a significant influence on the performance of shear links. To perform validation of the numerical study, the research is followed by experimental work conducted in Structural Mechanic Laboratory Center for Industrial Engineering ITB. The Structures and Mechanics Lab rotary PAU-ITB. The experiments were carried out using three test specimens with model and dimension identical to the model in the numerical study. Experimental testing apparently has shown results of the same behavior as predicted in the numerical study. However, when it is compared to the shape of the hysterical curve, a slight difference is apparent. This is due to the influence of stiffness of bolt joints and the supports which is difficult to model precisely in the numerical studies

Comparison of WF & Tubular Links on the Eccentrically Brace Frame System due to Cyclic Loads

“…To reduce this, it can be controlled by placing web stiffeners on the link beam although it is not very efficient because of the influence of torque. Yurisman et al [14] and Budiono et al [4] perform experimental testing and numerical analysis of short-link beam elements (shear links) and long links (bending links) using diagonal web diagonals (diagonal web stiffeners). Suswanto [2] said Link with classification as a short link, will have a higher ductility than the long link.…”

Behavior of Modified Long Links with Supplemental Double Stiffeners on Eccentrically Braced Frames

“…Several researchers showed some variation in results related to long links indicated that its performance could still be improved. Berman [11], Danesmand [5], Mohebkhah [12], Okazaki [13] and Yurisman [14] suggest that the value of the rotation and strength can be increased which improves the overall performance of the long links. Rotation of the link can still exceed the minimum threshold required, 0.02 rad, and the overstrength can exceed 1.0.…”

“…Mohebkhah [12] found an average overstrength value of 1.4 with inelastic rotation ranging from 0.04 to 0.09 rad. However, the weakness in the long link is caused by the formation of a plastic hinge on the flange in the welding zone at the end of the link with is then accompanied by failure caused by lateral torsional buckling, and fracture and buckling of the flange [4], [5], [9], [12], [14], [16], [17], [18], [19]. Some researchers suggested that avoid this weakness through limiting the slenderness of the flange.…”

“…Some research has been done to avoid failure due to bending dominant force by adding stiffeners to the web and flange. Yurisman [14] conducted a study on short links that were added diagonal stiffeners on the web. Danesh [20] reported utilizing diagonal stiffeners on the web and supplemental stiffeners on the flange.…”

“…Stephens and Dusicka [22] reported that the use of continuous stiffeners on the short link could improve its performance, exceeding the standard shear link performance according to the requirements of AISC 341-10. Furthermore, Yurisman [14] and Danesh [16] reported that retrofitting the link delayed failure at the end of the link. Reinforcement at the ends of long links prevents the early failure that is preceded by the formation of the plastic hinge on the flange.…”