2. The beam shown is prestressed using a bonded (stress relieved tendons) with a specified tensile strength of prestressing tendons fpu = 1350 MPa, a fc' = 35 MPa. The area of prestressed reinforcement in tension zone Aps = 1000 mm2. The specified yield strength of prestressing tendons fpy = 1160 %3D MPа. 0.85fc' a 430 NA. -- (d-a/2)

H.W 3 Two aluminum alloy plates (2) are attached to the sides of a wooden beam (1) as shown in Figure 3. mensions of the composite cross section are b1 = 80 mm, d¡ = 240 mm, b2 = 10 mm, d2 = b2 The di- |di 120 mm, and a = 60 mm. Deter- (2) (2) %3D mine the maximum bending (1) a stresses produced in both the wooden beam and the aluminum b1 plates if a bending moment FIGURE 3 +6,000 N m is applied M2 %3D about the z axis. Assume that Ej = 12.5 GPa and E2 = 70 GPa.

The composite beam is made of steel (A) bonded to brass (B) and has the cross section shown. It is subjected to a moment of M = 6.3 kN?m .Ebr = 100 GPa, Est = 200 GPa A: Determine the maximum bending stress in the brass. B:Determine the maximum bending stress in the steel. C: Determine the stress in the brass at the seam where the brass and steel are bonded together. D:Determine the stress in the steel at the seam where the brass and steel are bonded together. B M 175 mm 150 mm 200 mm

A composite beam is made of two brass [E = 112 GPa] bars bonded to two aluminum [E = 69 GPa] bars, as shown. The beam is subjected to a bending moment of 350 N-m acting about the z axis. Using a = 15 mm, b = 115 mm, c = 25 mm, and d = 65 mm, calculate (a) the maximum bending stress in the aluminum bars. (b) the maximum bending stress in the brass bars. Z Aluminum с Aluminum Answers: (a) Jal= (b) Obr= Brass i y i b Brass a a MPa MPa