BEHAVIOR OF MODIFIED LONG LINKS WITH SUPPLEMENTAL DOUBLE STIFFENERS ON ECCENTRICALLY BRACED FRAMES

• Main Author: - NIM: 35013005, MUSBAR
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29404
• Institution: Institut Teknologi Bandung

<p align="justify">Link elements in eccentrically braced frame (EBF) structure falls into three categories: short links (shear links), medium links (intermediate links) and long links (flexural links). Initial failure of long links caused by fracture and buckling occurs on the flange and web at the end of the link. Local damages are mostly caused by dominant bending moments, compared to shear forces. When tested for ductility, energy absorption, rigidity and strength, the long link performed poorly compared to short ones. However, long links are popular among architect because they allow for larger opening in rooms. Research on improving the performance of long link is relatively few compared to research on short and the medium link. The focus of this study is to provide information on using supplemental double stiffeners on both sides of the web at the ends of the long links without changing its behavior. Using supplemental double stiffeners increases the capacity of the plastic modulus (Zp) in resisting flexural force as well as increasing its capacity to withstand shear forces. <br /> <br /> <br /> This study used supplemental double stiffeners that are connected between each end of the link and the intermediate stiffeners. Providing slide open holes on both the outer side of the double stiffeners decreases the plastic modulus as well as further decreasing the effects of shear force. By varying the thickness (ts), vertical hole width (Th), longitudinal hole width (Bh) and the distance of the double stiffeners from the outer side of the flange (Js), the specimen can be conditioned to have longer plastification zone and ductility. The classification for obtaining the long link modification performance with the supplemental double stiffeners can be distinguished based on the percent range of increasing the plastic modulus (Zp) against standard link model. Research on the improvement of long links performance has been done through numerical and experimental analysis. The experimental study was carried out on four long link models consists of a standard model and models modified by the addition of supplemental double stiffeners at the flange. Selection of the experimental model was based on the results of the numerical analysis which represented the best model to resist loading. The numerical analysis of the modified long link was conducted by ANSYS 17.0. The steel profile used for the numerical and experimental study is WF 200.100.5,5.8, which met the requirements for slenderness and the capacity of the power tools used in laboratory testing. Link length ratio (&#61554;) analyzed was 3.03 of 100 cm, complying with the requirements of AISC 341-10. <br /> <br /> <br /> The results of the numerical and experimental analysis showed that the failure of the long links occurred under three conditions. First, failure occurred in a zone close to the ends of links without the extension of the plastification zone. Second, the failure occurred in the zone near the confluence with the extension of the plastification zone. Third, failure shifted towards the middle of the link without plastification at the ends. The addition of the supplemental double stiffeners can improve the performance of long links by preventing earlier failure due to buckling and fracture that occurs on the flange on the pedestal link. Thickness (ts) and vertical hole width (Th) in the supplemental double stiffeners served as the main parameter to control the type failure. The role of these two variables is crucial in obtaining the best modified long link model as well as maintaining its behavior. The best performance of modified long links is to extend the plastification zone from both ends of the link inwards, not by moving the plastification zone from the ends toward the inside. Supplemental double stiffeners can also be use for WF profiles that do not meet slenderness requirements on the flange since early occurrence of lateral torsional buckling can be prevented. The supplemental double stiffeners are an alternative to improving long link performance, making it more effective in its application in steel construction.<p align="justify"> <br />