Advances and Challenges in Design of Connections in Steel-Braced Frame Systems with In-Plane Buckling Braces

Abstract

A new type of connection has been developed for steel-braced frame systems that allows the brace members to undergo compression buckling in the in-plane direction. In addition to the inherent benefits of in-plane buckling (IPB) braces that help in reducing the extent of damage to the non-structural components, the IPB brace system is also considered to be an efficient way of retrofitting existing seismically deficient structures. The use of the compact and thicker gusset plate prevents the distortion of the free edges and the additional torsional force demand on beams and columns. However, IPB braced frame systems are not frequently used in practice, primarily due to the absence of limit state design criteria. As a result, some prominent failure modes observed in IPB frame systems are out-of-plane brace buckling, yielding of gusset plates, interface weld failure, and fracturing of knife plates. Recent studies on the IPB braced system have resolved some of these problems, such as design criteria being developed to prevent OOPB (out-of-plane buckling) of the IPB braced system. Other challenges need to be studied to achieve reliable performance of the braced frame system. This study focuses on recent advances and potential areas of improvement to achieve an efficient IPB braced system in highly seismic areas.

Experimental Investigation of Seismic Vulnerability of Braces under Hazard Consistent loading sequences

“…One type of building that has not received much attention in this area is braced steel buildings, which are most commonly used lateral force resisting system and are particularly vulnerable to low-cycle fatigue induced by seismic damage [9][10][11]. Therefore, the objective of this study is to investigate how earthquake duration affects the seismic performance of steel braced frames, with a particular focus on the effects of low-cycle fatigue behaviour of the open section braced members.…”

Influence of Slenderness Ratio and Sectional Geometry on the Behavior of Steel braced Frames

“…Previous seismic events have revealed that brace frame systems are vulnerable to premature collapse. Several undesirable failure modes, including the fracture of the interface weld of the gusset plate, tearing of the gusset plate, buckling of the gusset plate, net section failure of the brace cross-section, and premature failure of the brace section, have been observed [16]. Based on the data gathered from both real seismic events and experimental assessments [17][18][19][20], it has been determined that there are three specific locations within the braced frame that are susceptible to damage [19].…”