Question

An overhead crane runs on rails attached to structural columns by means of 25 mm thick mild steel brackets. The brackets are riveted to the column as shown using five 14 mm diameter rivets. The rivets have a shear strength of 100 MPa. Determine if the bracket can safety carry a downwards vertical load of P=20 kN. 1. If the bracket can safely carry the load, determine the factor of safety against eventual failure. 2. If you determine that the bracket will fail, then recommend changes to improve the situation. 100-- 450 P = 20KN 2501 125 Dimension in mm.

Answer 1

P- 20KN 100 450 in shear load рхе where K = ñ - Ps, = Ps2 = Ps3 = Psy = Pss = f = 4kn. Secondary shear load Ps,' = ksi Psa' = K2 Pass = K 93 Psu = k oly dipe: eccentricity (450+50) = 500 mm B = k rs of = 502 + 62.521 - 80.039 mm = 9ly = 50%+12521 - 134.629 mms - 1 = 50 mm . R (20KN) (500mm) (20.029) + (24.629)* +502 +€124.629)* 680.0394 = 0.1939 KN mm

Finding critical element The congle between the primary shear load and Secondary shear load is Smaller than that is critical givet. . are critical Therefore Rlvet We consider river and o - 15:52 KN. i's, -K9 = 0.1939 x 20.039 Resultant shean load PSRI = V p, ² + Psi + 2 Ps, Psi cose" Coser som = 0.6247 - 0.6247 er 80.039 Psre = 42+15.52% + 2x 4x15252 X 0.6247 18.28 KN. PSRI For safe design fos d: 14 mm Ssy = 100mpa 4 x 1828 KN TX 142 mmt 100 Nimmm2 tos =

100 X 1X142 0.242 fos = 4x18 22 X1000 Tmax = ''She = 118.749 mpa y Ssy = 100 mpo. so it will fail I → To use same material, the chiameter of rivet may increase to avoid failure TO Lise Same diameter rivets, the material having higher shear strength would preffered.