Term
What are control joints and isolation joints? Explain the purpose and typical locations for each in a concrete slab.
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Definition
control joints – intentionally weakened sections through concrete slab. Resist tensile forces caused by concrete drying. Allows the concrete not to be disfigured.
Isolation joints – completely separate the slab from adjacent elements. Major reason is to relieve potential stresses. Located where the edge of concrete slab abuts a wall, also columns and load bearing walls
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Term
List the steps that are followed in forming and pouring a concrete wall |
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Definition
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Forming. 1) concrete wall is made like concrete slab. 2) On top of slab, a groove is made for mechanical connection. 3) steel bars installed vertically in footing.
Pouring. 1) 2 concrete bars are poured at an interval in such a way that the axis of the future wall will intersect their midpoint at a right angle 2) trench is dug extending through the bars 3) In the trench, reinforcement is provided with a transverse partition 4) The concrete is poured in the trench between the two transverse partitions.
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Term
Distinguish one way concrete framing systems from two-way systems. Are steel and wood framing systems one way or two way? Is one way construction more efficient structurally than two way construction.
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Definition
An one-way slab rests across parallel line of support furnished by walls or beams. The formwork of one-way slab is erected only after pouring of walls and columns. The forms for girder and beams are built along with the forms of slabs as a single piece.
Two-way concrete framing systems are more economical. Columns can be spaced in bays. Used for heavily loaded floors. Generally used to accommodate the varying stresses in different zones of the slab with in a uniform thickness of concrete.
Steel and wood are one-way systems. One-way systems are more efficient.
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Term
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List the common one way and two way concrete framing systems and indicate the possibilities and limitations of each.
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Definition
one-way - solid slab/ribbed slab
two-way- flat slab/ waffle slab system |
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Term
why posttension a concrete structure rather merely reinforce it? |
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Definition
| Posttension rather than reinforce it. it puts concrete in compression and puts soem steel rods in tension. External tension/bending loads can be applied to structure many times stronger. |
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