Connection Strength of Hold-Down Component Used for Steel Framed House

Abstract

Light gage bearing wall is usually designed as a cantilever column. Therefore, due to overturning moment from the upper floors, high axial force must be considered at the base. Hold-down components are used to connect the bearing wall to the foundation to resist these high axial forces; it is one of the most important seismic element to guaranty the structural safety. The purpose of this study is to clarify the connection strength of the hold-down component which is connected by drill screws. Finally, design formula than can evaluate the shear lap joint connected by drill screws was proposed, and the validity of the proposed formula was also demonstrated with the test results.

Required number of self‐drilling screws for built‐up column comprising cold‐formed lipped channel sections to ensure flexural buckling as a single unit member

“…Assuming the BUC, in which n b fasteners are joined in the same cross-section, the strain energy ΔU c owing to the flexural buckling deformation of chords 1 and 2 can be expressed as in Equation (21). The strain energies of the rotational (ΔU r ), shear (ΔU s ), and axial (ΔU h ) springs are given by Equations ( 22)-(24), respectively, and the work ΔT done by the external force can be expressed by Equation (23).…”

“…The effects of the axial stiffness k h are shown in Figure 14. Figure 14A shows the change in the flexural buckling strength ratio P cr,c /P cr,b for each flexural stiffness ratio, I 1 /I 2 , with the horizontal axis representing the axial stiffness ratio γ h , as expressed in Equation (21). For I 1 /I 2 = 1.0, the flexural buckling strength ratio was constant regardless of the axial stiffness ratio.…”

“…All information and data are given in the text completely. The region around the self-drilling screw was modeled, 21 as shown in Figure A1, and the rotational stiffness k r around the self-drilling screw was derived. In this model, a bending moment acts around the self-drilling screw such that the bending moment becomes zero in the middle of the interval.…”

“…The interval length, a, is calculated as 100 mm. 1,12 The rotational stiffness of the frequently used self-drilling screw DNH4819 (nominal, and thread trough diameters of 4.8 and 3.58 mm, respectively) used in previous studies 2,3,11,12,19,21 as the fastener is in the range up to 0.13 kN.m/rad.…”