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, <br /> American Tunnel bulkheads #2 & #3 Page 12 January 15, 2001 <br /> Appendix A. American Tunnel Bulkhead #2 design calculations (Continued) <br /> C =T; 30600a= 60000A8; a= 60� = 1.961 AS <br /> co=U= 1.4p(144) = 1.4(277)144 = 55,800(s <br /> M. = 8z = ssaoo(13s2) = 1,271,000 ft-lb <br /> M„ = Mn — 12711 = 1,412,000 ft-lb (16,940,000 in-lb) <br /> 0.9 — 0.9 <br /> M„-Asfy(d—2); d =L - m, = 10(12) - 3.5 = 116.5 in <br /> M„= 60000A,(d—2) = 60000A,(116.5— 1.16IA.\ = 6990000A8—58800A, <br /> Therefore: 16,940,000 = 6990000A,- 58,800Ag <br /> 58,800A2- 6,990,000A3 + 16,940,000 =0 <br /> As= 2.475 a steel area required for outbye (downstream) side of 10-ft thick bulkhead <br /> #10 bars (1.270 in per bar) on 6-in c-c provides 2.540 ft steel area <br /> Check for adequacy <br /> Allowable M„=-58,800Ag +6,990,000OA,= 17,380,000 in-lb <br /> Design Mu = 16,940,000 in-lb <br /> FS = 1 1946940000 0000 = 1.03 for outb3'a (downstream) side of 10-ft thick bulkhead <br /> Critical section shear strength for American Tunnel Bulkhead #2, 10-ft thick deep-beam <br /> bulkhead <br /> Deep beam defined as a < 5 (ACI 318-95, Sec 11.8.1). Critical section shear at 0.151 (1.90 <br /> ft) from ribside(ACI 318-95, Sec 11.8.5), with#10 bars on 6-in c-c, there will be 2.540 ft <br /> of steel per ft of beam width, d = 116.5 in(9.71 ft). <br /> Detailed shear strength at critical section(ACI 318-95, Sec 11.8.7) <br /> Q — 1166..5 <br /> 13 2c-3. = 1 <br /> d — [10(121-3.5] = 1.39 < 5 Therefore, reinforced concrete bulkhead <br /> is a deep beam for design! <br />