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Title: Design of floors with prestressed joists, using redistribution and love load alternancy

Author(s): Lahuerta, J.A.; Modrego, M.

Publication: ACHE

Volume: 44

Issue: 189

Appears on pages(s): 137 - 144



Date: 1/8/1993

The design of building floors with joists of prestressed concrete, according to the spanish norm EF-88, requires two phases: GENERAL PHASE: Writing the Technical Characteristics Card of the floor system, TCC. This includes: Joists: Shape, dimensions and tendons. Fabrication stresses. Long time effects. Design moments. Blocks: Shape, dimensions and weights. Floor types: Heights, joist distances, weights. Service, and cracking bending moments strength. Uncracked and cracked stiffness. In positive and negative bending. Ultimate shear force. The card will be write by the manufacturer, and needs Use Approval of the M.O.P.T.M.A. DESIGH PHASE: Designing the floors of a building. Structural Annex including: The TCC of the floor system with Use Approval. Actions on the floor according Norm AE 88. Cases of live loads alternancy .Action effects, bending moments and shear forces, on every different floor member. The use of allowed redistributio simlpifies the calculus and generaly saves money. Specify the type of joists and reinforcement by means of TCC. Controlling deflections. Drawings: in plans, al the joists and empties for conducts. In elevations, all the different floor members. This is responsability of the design author. The simplified manner of considering the live load alternancy is the object of this communication.

ACI International Partner, ACHE Spain, International Partner Access

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