CONCRETE STRUCTURES

POSTTENSIONED CONCRETE:
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Applications:
	1.	Shipping considerations
	2.	Curved cable profile
	3.	Tendons to be stressed in stages
	4.	Join precast elements

Requirements:
	1.	Tendons free to elongate
		No bond to concrete
	2.	Ducts grouted afterwards
		corrosion protection
		increase strength
	3.	Wedged or treated connections
	
Designer specifies:
	1.	Position of centerline of tendons
	2.	Magnitude of prestress force

Materials:
	Prestressed Steel:
		1.	Stranded Cable (7 strands)
			tensile strength 250-270 kips/sqin
		2.	High strength bars
			145 - 160 kips/sqin
			3/4" - 1 3/8" (

	Concrete:
		1.	Poured in Place Concrete
			2.5 - 4 kips/sqin
			for short spans 20'-0" max
		2. 	High Strength Concrete
			4 - 10 kips/sqin
			for longer structures
			over 75'-0"
			dead weight = major load
		3..	Reduced weight

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ASSOCIATIONS