- 4 3 A Double T Pretensioned Roof Beam Is Shown In Figure P4 3 It Has A Simple Span Of 74 Ft 22 6 M And Carries Superi 1 (181.46 KiB) Viewed 32 times
4.3 A double-T pretensioned roof beam is shown in Figure P4.3. It has a simple span of 74 ft (22.6 m) and carries superimposed service live and dead loads of 60 psf (2,873 Pa; WSD part of load = 25 psf). It also carries a 2-in. (5.1 cm) concrete topping. Design the prestressing reinforcement and the ap- propriate eccentricities using 270-grade prestressing strands (fp = 1,862 MPa) with a total prestress loss of 20 percent. Use the appropriate percentage of nonprestressed mild steel for partial pre- stressing behavior at the limit state at failure. Assume the strands to be harped at midspan, and sketch the reinforcing details including the anchorage zone strands. Also, draw the distribution of stresses for the various loading stages in your solution. The following data are given: fpu = 270,000 psi, stress-relieved strands (1,862 MPa) Eps 28 x 106 psi (193 x 10³ MPa) = fé = 5,000 psi (34.5 MPa) normal-weight concrete f for topping = 3,000 psi (20.7 MPa) normal-weight concrete f'a = 4,000 psi 15252 SSANGY 43" Figure P4.3 Double-T cross section. e₂ = 17.71 in. Untopped Topped 567 in.² (3,658 cm²) 4 55,464 in.* 71,886 in.4 21.21 in. 23.66 in. C₁ 10.79 in. 10.34 in. Sp 2,615 in.³ 3,038 in.³ 5,140 in.³ 6,952 in.³ WD 591 plf 791 plf I NEED STEP BY STEP PROCEDURE ON A4 PAGE NOT ONLY A TABLE IF YOU DONT SOLE ON A4 PAGE STEP BY STEP THEN NO NEED TO POST TABLE BECAUSE IT IS ALREADY POSTED ON answers Ac Ic Cb V/S = 1.79 in. 8'-0" 73"- 32"