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Project Design Mogul Tunnel Bulkhead <br />8' x 8' (9' Thick, Station 2+41) <br />By JFA Date 7/4/03 <br />Sheet 4 of 6 <br />Reinforced concrete deep-beam bending stress design for earthquake acceleration: <br />C = ~ ,~ f ~ bw a = 0.85 (3000) 12 a = 30600 a <br />C= T 30600 a= 60000 A 5 <br />Mn <br />Factored earthquake bending M ~ :_ - <br />moment, 0.9 <br />Minimum concrete rebar cover, d := 12 L t - m o <br />T=ASf y=60000 A$ <br />a = (60000 A x/30600 = 1.961 A s <br />M u = 209985 <br />d = 104.5 in <br />M „ = A s f ~, (d - a/2) = 60000 A s (d - 1.961 A ~I2) = 60000 A s d - 58830 A SZ <br />58830 A 52 -60000 A s d + M „" 12 = 0 C 1 := 58830 C 2 :_ -60000 •d <br /> C 1 = 58830 C 2 =-6270000 <br />z <br />A ._-C2- C2 -4•C1•C3 A =0.403 in2 <br />s 2•C 1 s <br />ft-Ib <br />C3:=M~•12 <br />C 3 = 2519823 <br />One cage of #b bars (0.44 in2 per bar, 0.750-in diameter) on 12-in c-c (I 1.25-in between bars) <br />provides 0.44 in2/ft of steel area. <br />Thercforc, A s := 0.44 inz <br />Check for adequacy, <br />Allowable factored bending moment, A ~ :_ -C I • ~A s`z - C 2•A <br />Design factored bending moment, M u~12 = 2519823 in-lb <br />A <br />Factor of safety, FS := u FS = 1.09 <br />MU~12 <br />A ^ = 2747411 <br />in-(b <br />t+~. -~ ~''~'~h~"& { '.~... F •Mgfgkdl~mod9/IUI9011121 PM <br />:a:. ,.Y.. -...... .. .. <br />