Question

Standard design practice, as exhibited by the solutions to Probs. 8-66 to 8-70, is to assume that the bolts, or rivets, share the shear equally. For many situations, such an assumption may lead to an unsafe design. Consider the yoke bracket of Prob. 8-61, for example. Suppose this bracket is bolted to a wide-flange column with the centerline through the two bolts in the vertical direction. A vertical load through the yoke-pin hole at distance B from the column flange would place a shear load on the bolts as well as a tensile load. The tensile load comes about because the bracket tends to pry itself about the bottom corner, much like a claw hammer, exerting a large tensile load on the upper bolt. In addition, it is almost certain that both the spacing of the bolt holes and their diameters will be slightly different on the column flange from what they are on the yoke bracket. Thus, unless yielding occurs, only one of the bolts will take the shear load. The designer has no way of knowing which bolt this will be In this problem the bracket is 8 in long, Ai, B 3 in, C 6 in, and the column flange isin thick. The bolts are in-13 UNC x 1 in SAE grade 4. The nuts are tightened to 75 percent of proof load. The vertical yoke-pin load is 2500 lbf. If the upper bolt takes all the shear load as well as the tensile load, determine a static factor of safety for the bolt, based on the von Mises stress exceeding the proof strength Problem. 8-66 The figure shows a bolted lap joint that uses SAE grade 5 bolts. The members are made of cold- drawn AISI 1020 steel. Assume the bolt threads do not extend into the joint. Find the safe tensile shear load F that can be applied to this connection to provide a minimum factor of safety of 2 for the following failure modes: shear of bolts, bearing on bolts, bearing on members, and tension of members in 16 t in-20 UNC in T in

Answer 1

-Q.GI KİPS 6 2. Leanin) em bolts, 2. ce.aing am rymba, = 3.5% Kips o 25(s7.) -7.13 kiP