360R-06 Design of Slabs-on-Ground
DESIGN OF SLABS-ON-GROUND 360R-41
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| DESIGN OF SLABS-ON-GROUND 360R-41
9.7—Residential slabs with post-tensioned reinforcement for structural action 9.7.1 Soil properties—The designer should have the following information about soil properties: • Allowable soil bearing pressure q allow , lb/ft 2 (N/m 2 ); • Edge moisture variation distance e m (ft [m]), center lift, and edge lift; • Differential soil movement y m (in. [mm]), center lift, and edge lift; and • Slab-subgrade friction coefficient μ. 9.7.2 Structural data and materials properties—The necessary data for design is: slab length L, ft (m); beam spacing S, ft (m); overall depth h, in. (mm); width b (in. [mm]) of the stiffening beams; and the perimeter loading P, lb/ft (N/m). Required material properties: • Specified 28-day compressive strength of concrete f c ′ , psi (MPa); • Type, grade, and strength of the prestressing steel; and • Type and grade of nonprestressed reinforcement. 9.7.3 Design stresses for the concrete—The following stresses are used when designing by the PTI method: Allowable tensile stress f t = 6 (in.-lb) (9-3) f t = 0.5 (SI) Allowable compressive stress f c = 0.45f c ′ (9-4) Estimated tensile cracking stress f cr = 7.5 (in.-lb) (9-5) f cr = 0.62 (SI) Allowable shear stress v c = 1.7 + 0.2f p (in.-lb) (9-6) v c = 0.14 + 0.2f p (SI) Allowable concrete bearing stress at anchorages: At service load (9-7) At transfer (9-8) Allowable stresses in prestressing steel: Allowable stress due to tendon jacking force f pj = 0.8f pu ≤ 0.94f py (9-9) Allowable stress immediately after prestress transfer f pi = 0.7f pu (9-10) tải về 2.35 Mb. Chia sẻ với bạn bè của bạn:
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