This eliminated the fire resistance reduction caused by thermal bowing deformations and provided an improved fire performance than cavity insulated LCS stud walls. However, a different thermal behaviour was observed when SHS/RHS studs were used in cavity insulated walls, as the hollow cavity reduced the temperature difference between the stud hot and cold flanges. The test results showed that CFS SHS/RHS stud walls achieved a higher FRL due to the superior elevated temperature mechanical properties of CFS SHS/RHS, while the temperature development exhibited good similarity with uninsulated LCS stud walls of the same wall configuration. Four full-scale load-bearing standard fire tests were therefore conducted to investigate the performance of cold-formed steel SHS/RHS stud walls exposed to fire. However, the fire resistance of LSF walls made of SHS/RHS studs has not been investigated yet, so their fire resistance levels (FRLs) are unknown, restricting their use in mid-rise buildings. Currently, LSF walls made of lipped channel section (LCS) studs are commonly used in low-rise buildings, but with the expansion of CFS applications to mid-rise buildings, cold-formed steel square and rectangular hollow section (SHS/RHS) studs are being used to meet the higher load capacity demands. Their fire safety has thus become an important consideration for designers. The testing provides needed characterization of cold-formed steel floor-to-wall performance and is augmented by improved design methods for this detail.Light gauge steel frame (LSF) walls as primary load-bearing components have been increasingly used in the construction of cold-formed steel (CFS) buildings. Design methods to support strength predictions consistent with the observed limit states are developed and assessed. However, ledger-to-stud screw pull-out, ledger flange buckling, and stud web crippling limit states are all observed in the testing. Current design for this connection assumes a pure shear condition governed by screw shear capacity. The results indicate how the connection details and loading conditions drive the moment-rotation response in addition, several limit states not checked in current design were also observed. The test matrix is designed to evaluate the presence of OSB floor sheathing, applied moment/shear ratio of the joist, joist-to-ledger clip angle location (inside or outside of the joist section), presence of top and bottom screws connecting the joist and ledger flanges, and location of the joist relative to the studs. Monotonic and cyclic full-scale connections were tested and reported here to examine the connection strength and stiffness, so that this hypothesis may be explored further in the future. One hypothesis is that the stiffness of the floor-to-wall connections, and the repetitive nature of this connection, provided beneficial semi-rigid frame response that augmented the designed shear walls.
Recently completed research employing full-scale shake table tests on a two-story ledger-framed cold-formed steel framed building utilizing oriented strand board (OSB) sheathed shear walls and floors exhibited beneficial lateral system response that exceeded predictions.
The objective of this paper is to investigate the moment-rotation behavior of floor-to-wall connections used in ledger-framed cold-formed steel building construction with full-scale experiments.
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