Chapter 1, Problem 1.10.15P

An elevated jogging track is supported at intervals by a wood beam AB (L = 7.5 ft) that is pinned at A and supported by steel rod BC and a steel washer at B. Both the rod (d_BC= 3/16 in.) and the washer (d_B= 1.0 in.) were designed using a rod tension force of T_BC=415 lb. The rod was sized using a factor of safely of 3 against reaching the ultimate stress tr_u— 60 ksi. An allowable bearing stress s_ba= 565 psi was used to size the washer at B.

A small platform HF is suspended below a section of the elevated track to support some mechanical and electrical equipment. The equipment load is uniform load q = 50 lb/ft and concentrated load W_E= 175 lb at mid-span of beam HF. The plan is to drill a hole through beam ABaX £land install the same rod (d_BC) and washer) d_B) at both D and F to support beam HF.

(a) Use s and to check the proposed design for rod DF and washer d,: are they acceptable?

(b) Re-check the normal tensile stress in rod BC and bearing stress at 8 if either is inadequate under the additional load from platform HF. Re-design them to meet the original design criteria.