Question

2. The box beam is subjected to the loading shown. Determine the principal stresses in the beam at point A, marked in red. 800 lb 1200 lb 5 in. . A 5 in.I A18 in. 8 in. 63 -3 ft- -5 ft 42.5 4-1-2.5 t-

Answer 1

600 lb 1200 lb А C -Rx 1 Rz 4-3 ft 5 ft 2.5ft 25ft RE moment Equilibzium about B EMB P 1200x13 -RX10 + 800X520 R = 196016 EF:0 = Rit R2 = 1200+800 3 Efc=0 R2-40 1b. at cross-section at A. Shear force - VA P 2 VA = -40 16 Bending moment MA-40x2.5 = 100 lb-ft 1200 lb-in Cross-section- 45 INA (8x8°- 5x5°) 289.25 in 4 1. E A 1 8 QA = Aų = 8X1.5X(4-19) 39 in P-5”

Normal stress at A My IN-A 1200 X 2:5 289.25 5--10,37165 psi (compression) 2 shear stress Tu=0 Exey? It 404 39 289 25x3 Exy - 1.7977 psi Principal stress Vretazny 121-10-37165 + J610-37165)+ 481-7977 % L-10137165 40.977157 + 2 T7 -0.30275 psi - 10 - 6744 psi 22
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