Tension: wood — analysis. Find the capacity (safe load) of a 6x8 Hem-Fir No.1 tension element connected with two lines of 3/4"-diameter bolts. The bolt holes are drilled through the short dimension of the 6x8. The duration of load factor can be taken as 1.0 (i.e., only live and dead loads are present).
Tension: wood — design. A roof is supported by wooden trusses spaced at 10-feet on center. The roof load consists of a dead load, D = 30 psf, a snow load, S = 20 psf, and a construction/maintenance roof load, LR = 30 psf. Assume that the governing load is applied to the top chord of the truss at the truss "nodes" only, and that the loads at these nodes can be found using tributary areas. Also assume that the tension member is a single 2x Hem-Fir No.1, and that it is spliced together at mid-span with 2 lines of 3/4"-diameter bolts. Determine the size of the tension chord.
Tension: steel — analysis.
a) Find the capacity of the threaded rod hangers shown in the image below. Assume 5/8"-diameter "double" rods, A-36 steel, and an allowable stress, Ft = 0.33Fu on the unthreaded part of the rod. Assume that the rods are spaced at 8-feet on center. See text, p. 63, for more information on threaded rods in tension.
NY Times Headquarters (Renzo Piano, Architect), photo by J. Ochshorn
b) As shown in the diagram below, the mezzanine span is assumed to be 20-feet. If the mezzanine supports a dead load, D = 45 psf, and a live load, L = 100 psf (with no live load reduction permitted), are the hangers acceptable?
Tension: steel — design. Assume that the tension force in the vertical first-floor chord of a lateral-force-resisting truss is 136 k. Select (design) the lightest acceptable W8 member to resist this tensile force. To begin, assume the tension element is connected with four lines of 5/8-diameter bolts (with 6 bolts per line), that the flange thickness is 1/4", and that the steel used is A-992. After selecting a provisional cross-section, check the section using its actual dimensions. Revise your selection if necessary and re-check.
