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Non-structural members, such as roofs and ceilings, become affixed to main beams that are known as structural members. When such main beams experience bending or compressive forces that lead to lateral buckling, non-structural members may act to restrain the resulting lateral buckling deformation. Nevertheless, neither Japanese nor European guidelines advocate for the utilization of non-structural members as lateral buckling stiffeners for beams. Additionally, local buckling ensues near the bolt apertures in the beam–roof folded plate connection due to the torsional deformation induced by the lateral buckling of the H beam, thereby reducing the rotational stiffness of the roof folded plate to a percentage of its ideal stiffness. This paper conducts torsional experiments on roof folded plates, and with various connection methods between these plates and the beams, to comprehend the deformation mechanism of roof folded plates and the relationship between their rotational stiffness and the torsional moment. Then, the relationship between the demand values against restraining the lateral buckling of the main beam and the experimentally determined bearing capacity of the roof folded plate is elucidated. Results indicate the efficacy of utilizing the roof folded plate as a continuous brace. The lateral buckling design capacity of H beams that are continuously stiffened by roof folded plates is elucidated via application of a connection method that ensures joint stiffness between the roof folded plate and the beam while using Japanese and European design codes. [ABSTRACT FROM AUTHOR]

Buckling-restrained braced frames (BRBFs) are attracting interest worldwide by virtue of their extraordinary response reduction performance. The system relies strongly on the energy dissipation of buckling-restrained braces (BRBs). Therefore, the surrounding members (beams, columns, or gusset plates) must sustain the force imposed by a BRB. Notably, beams are not designed primarily to support the axial force. The sections consequently tend to become deep and slender to enhance the flexural strength and stiffness effectively, thereby leading to local buckling, which lessens the reaction force to the BRB. Moreover, the instability is activated by the compressive axial force transferred from the BRB. However, beams in the BRBFs generally become composite beams through an assemblage with a concrete slab by stud shear connectors. The concrete slab shifts the neutral axis of the beam, which imposes more strain on the bottom flange. The BRB axial force and composite effect therefore influence the steel beam buckling behavior. Eventually, the beam might be subjected to instability at a smaller-than-expected deformation. However, the rotation capacity of the composite beam in BRBFs has not been clarified yet. To address this concern, this study established a finite-element analysis (FEA) model referring to a former specimen and an experiment scheme. Additionally, a parametric study of the influential factors was conducted using the experimentally validated FEA model. This study examined a proposed evaluation equation of an apparent axial force issued from the composite effect based on the obtained results. An earlier evaluation index established for bare steel beams was ultimately modified to include the axial force influence. Eventually, the results demonstrated that the structural performance can be assessed appropriately using the existing evaluation equations proposed using a steel frame subassembly. [ABSTRACT FROM AUTHOR]