Laserfiche WebLink
%, <br /> Shear Strength_Design <br /> lbe length of a bulkhead must be sufficient to keep the shear stress <br /> developed in the bulkhead concrete below the ACT limits (ACT, 1983ts ,S c H- <br /> and the shear stress in the adjacent rock to well Hof the design 3,000 psi <br /> hear <br /> strength. The ACT estimated minimum shear strength <br /> cooipressive strength concrete for the Friday Lowden bulkhead is: <br /> v . 2 110 psi (2) <br /> c <br /> The owner required additional factor of safety of 2 reduced the design shear <br /> strength to SS psi. Applying the same design method to the 1S9S70 psi <br /> uniaxial compressive strength of the rock adjacent to the planned Fridag Friday the <br /> Lowden bulkhead results in a design shear strength of 12S psi. Inc for the rat <br /> additional factor of safety of 2. This calculated shear strength <br /> sees to be extremely low, which is probably actually oa the order of <br /> approximately 2,000 psi. Irregardlesse the concrete shear strength will <br /> n govern the shear design for the Friday Lowden Tunnel bulkhead. <br /> '- assuming shear would take place just <br /> The simple shear strength design, • <br /> inside the concretafrock interface, is as follows: <br /> Required plug length (ft) - pab/2(a+b)vc (3� <br /> p - pressure head (psi) <br /> a - width (ft) <br /> b - height (ft) <br /> •c - shear strength (psi) <br /> Regnired plug length (ft) • 290(10)(10)/2(10+10)SS • W ft . <br /> for the pressure gradient criteria is <br /> Therefore, the. 14-ft design plug length . . <br /> acceptable-for r9mide shear.ACI (1983, sec 1i.8) prov h shear <br /> The ides guidance for ultimate strength <br /> divided by the beam depth ratio is less <br /> design for deep beams. where the span tanned 14- <br /> than S. The Friday Lowden spWdepth ratio for the 10-ft span by P <br /> ten lug, deep beams is 0.T1. Using the ACI deep beam design-procedure <br /> ft length P <br />