Fall_2008_Test_3__Key_Cncepts_from_the_T - CMP 210 Fall...

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CMP 210 Fall, 2008 Key Terms and Concepts from the Text for Test 3 Chapter 20 Types of Elevated concrete floor systems : 1) beam-supported floors 2) beamless floors Beam-supported concrete floors The transfer of loads from a solid slab to the four supporting beams is represented approximately by 45 deg. Lines originating from the slab corners. If the slab panel is a square, each supporting beam receives the same amount of load. If the slab panel is rectangular, one pair of beams carries a greater load than the other pair. - A reinforced-concrete floor slab with beams on all four sides a) one-way (solid) slab -load is effectively transferred along one direction -Primary reinforcement: placed along the short direction -Secondary reinforcement: placed in the perpendicular direction (resist stresses) Long dimesion of slab > 2.0 Short dimension of slab b) two-way (solid) slab Long < 2.0 Short -The ratio of the two dimensions is as close to 1.0 as possible -both directions participate in carrying the load -Primary reinforcement: provided in both directions Band Beam reinforced concrete floor: beams are wide and shallow - more economical formwork , than a beam-and-girder floor -Not completely solid a) one-way joist slabs (ribbed floor) -Constructed with U-shaped pans as formwork placed over a platform deck -gap between pans represents the width of joists (adjustable) - beams should preferably span along the shorter direction -Pans: made of glass fiber-reinforced plastic (GFRP) 1) standard-module: minimum thickness of only 2 in.with 20-in. pans and 2 ½ in. with 30-in. pans 2) wide-module: larger spacing between joists (slab thickness is large) - Pans are available in 53-in. and 66-in. widths b) two-way joist floor (waffle slab) -consists of joists in both directions -yields a stiffer floor -suited for square or almost square column-to-column bays -framework consists of GFRP domes placed on a flat form deck, lips butting each other - dome dimensions produce 3-ft, 4-ft, and 5-ft center-to-center distances between domes Commonly used beamless concrete floors are: 1) Flat Plate: floor consists of a slab of constant thickness 2) Flat Slab: floor consists of a slab with drop panels at each column Posttensioned elevated concrete floor: prestressing tendons are combined with conventional steel reinforcement -Primary reason for use: reduce floor depth Precast concrete: strength is usually 5 to 6 ksi (Type III Concrete) Precast concrete members are classified as: a) Architectural precast concrete - Concrete elements that are used as nonstructural, cladding elements Use: precast concrete curtain walls b) Structural precast concrete
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Hollow core slab -Prestressed concrete slabs that contain voids in their central region
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Fall_2008_Test_3__Key_Cncepts_from_the_T - CMP 210 Fall...

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