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Unformatted text preview: Lecture 18 Design Lecture 18 Design July 18, 2003 CVEN 444 Lecture Goals Lecture Goals Slab design example Total beam design OneWay Slab Example OneWay Slab Example The cross section of a continuous oneway solid slab in a building is shown. The slabs are supported by beams that span 24 ft. Between simple supports. The dead load on the slabs is that due to selfweight plus 60 psf; The live load is 120 psf. Design the continuous slab and draw a detailed section. Given: f c = 3 ksi, f y = 40 ksi. OneWay Slab Example OneWay Slab Example Determine the thickness of the slab. 12 ft. Minimum thickness of interior bay: 12 in. 12 ft 1 ft. 5.14 in. 28 28 L h = = = OneWay Slab Example OneWay Slab Example Use h= 6 in. Dead weight b coverage 2 0.5 in. 6 in. 0.75 in. 5.0 in. 2 d d h = = = ( 29 sl 3 2 2 1 ft 6 in. 150 lb/ft 60 lb/ft 12 in. 135 lb/ft DL h DL = + = + = OneWay Slab Example OneWay Slab Example Determine the load on the floor For slab design is seldom > 0.01. Use c/d = 0.2 ( 29 ( 29 2 2 2 2 1.2 1.6 1.2 135 lb/ft 1.6 120 lb/ft 354 lb/ft 0.354 k/ft U DL LL = + = + = ( 29 ( 29 ( 29 ( 29 ( 29 1 u c 1 0.85 1 2 0.85 0.2 0.85 3 ksi 0.85 0.2 1 0.397 ksi 2 k R f k = = = OneWay Slab Example OneWay Slab Example Find the coefficient of the moment diagram The maximum moment is ( 29 2 2 2 u n u 0.354 k/ft 11 ft. 10 10 4.28 kft/ft w l M = = = OneWay Slab Example OneWay Slab Example Find the design d for a onefoot strip If b =12in. then d = 3.46in., which for c/d = 0.2, so d = 5in., the slab is OK. u 2 u 3 12 in. 4.28 kft/ft ft 0.9 R 0.397 ksi 143.9 in /ft M bd = = = OneWay Slab Example OneWay Slab Example Find the coefficient of the shear The maximum shear is ( 29 2 u u v 0.354 k/ft 11 ft. 1.15 2 2 2.24 k/ft w l V C = = = OneWay Slab Example OneWay Slab Example Check the shear capacity of the slab ( 29 ( 29 ( 29 ( 29 u c w 0.75 2 0.75 2 3000 12 in. 5 in. 4930 lb. 4.93 k > 2.24 k V f b d = = = = Use h = 6in., d = 5in. and w u = 0.354 k/ft OneWay Slab Example OneWay Slab Example Minimum about of steel is (use ACI 7.12 ) ( 29 ( 29 ( 29 s min 2 0.0020 0.002 12 in. 6 in. 0.144 in A bh = = = Moment capacity of the slab (12in. beam) u s y 2 a M A f d = ( 29 0.925 0.925 5 in. 4.625 in. 2 a d d 2245 = = Assume OneWay Slab Example OneWay Slab Example Compute the moments Moment capacity of the beam A B C D E l n 11 ft. 11 ft. 11 ft. 11 ft. 11 ft. M coef 1/24 1/14 1/10 1/11 1/16 M u 1.78 kft 3.06 kft 4.28 kft 3.89 kft 2.68 kft A min 0.144 in 2 0.144 in 2 0.144 in 2 0.144 in 2 0.144 in 2 A s 0.128 in 2 0.221 in 2 0.309 in 2 0.280 in 2 0.193 in 2 OneWay Slab Example OneWay Slab Example Compute the moments ( 29 ( 29 ( 29 ( 29 2 u u u s y y 2 0.354 k/ft 11 ft 1.78 kft 24 0.925 2 12 in....
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This note was uploaded on 10/03/2011 for the course CVEN 444 taught by Professor Staff during the Summer '08 term at Texas A&M.
 Summer '08
 Staff

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