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involves the conservative assumption that the bulkhead carries load from side <br /> to side acting as a one-Tray slabg but no load from roof to floor of the <br /> tunnel. The design procedure further uses a one-foot wide strip of the <br /> slab. The critical section for design is defined as 0.15 times the span is <br /> from the ribside for uniformly loaded beans, 1.5 ft in the case of the 10-ft <br /> wide Friday lorries Tunnel. The ACI specified shear strength (vc) that is <br /> available at the critical section for unreinforced deep beams with a span to <br /> depth ratio of less than five is: <br /> vc - K(1.9 rf'c) . (4) <br /> f'c • design concrete strength (Psi) . <br /> vs • vc (5) <br /> 0.8S capacity reduction factor for concrete in shear <br /> vs • nominal available shear strength (Psi) <br /> K • 3.5 - 2-9%/Vu(d) (6) <br /> !V • critical section moment (ft-lb)' <br /> Vg - critical section shear (lb) <br /> d - beam depth (ft), plug length <br /> Except K cannot exceed 2.5 and vc cannot exceed 6 ME <br /> For the Friday Lowden bulkhead No is 372,708 ft-lb, as follows: <br /> Pv - (wi/2)(0.151) - w(0.151)(0.151)/2 <br /> w • hydrostatic load (lb/ft) - <br /> ! - tunnel width (ft) <br /> My • 0.075w1= - 0.01125wi' - 0.06375w1= <br /> -7- - <br />