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1;:��s►: ' <br /> �2 • (6)M�/b(tt) • (6)191249308/137(144)(1) • 342 <br /> M . • 18.Sft <br /> The alternative to a Plata concrete bulkhead is to install tensile <br /> reinforcement to carry the tensile bending stresses. The NCI capacity <br /> reduction factor for bending in reinforced concrete (ACI, 1983, sec 9.3.2.1) <br /> is 0.". The method employs the rectangular compressive stress distribution <br /> approximation. The ACI method is described in sec 10.2 and assumes that a <br /> uniform compressive stress equal to 0.85 times the specified concrete <br /> compressive strength acts over an area i ft wide by 0.05 times the centroidal <br /> distance in depth (a) below the loaded surface. The constant, O.aS, Is - <br /> reduced 0.05 for each 19000 psi the concrete strength exceeds 4.000 Psi. The <br /> method, as further described by Yang and Salmon (198S, p 43-44). assumes the <br /> tensile reinforcing.steel Yields before the concrete mashes under bending <br /> Induced compressive stress. ' • - <br /> �� ?he tensile reinforcement design for the 14-ft thick Friday Lowden. <br /> Bulkhead follows: - <br /> Compressive for (C) • 0.85090ba (16) <br /> • Tensile.force (T) - Asfy (17) <br /> b - beam width (in.) <br /> a - compression mne depth (im.)•• <br /> As - steel area (sa in./ft) . <br /> fy • steel yield stress (psi) <br /> f'c - concrete strength (Psi) - <br /> The method Presented by Yang and Salmon (1985) assumes that the <br /> compressive stress concrete area is no deeper into the beam than necessary to <br /> tarry the bending moment developed compressive*fora at the ACI specified <br /> compressive stress of•0.85 times the specified compressive strength. The <br /> } calculations for the Friday Lowden bulkhead follow. <br /> Equating C to T using equations (16) maid (17): <br /> -11- <br />