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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Investigation and Repair of Posttensioned
Concrete Slabs -A Case History
Author(s): Stephen Hom and Garrison Kost
Publication: Concrete International
Appears on pages(s): 44-49
Keywords: beams (supports); concrete slabs; control joints; cracking (fracturing); epoxy resins; parking facilities; post-tensioning; pressure grouting; prestressed
Abstract:Prestressed concrete floor systems that are rigidly restrained against movement have been experiencing severe structural cracking in many buildings that were constructed 10 to 15 years ago. A case history of the investigation of such a floor system in a three-story underground parking garage that was designed and constructed in the late 1960s is presented. The floor system consists of post-tensioned beams and slabs rigidly anchored to the exterior walls. The indications of a distress condition were the excessive amount of movement at an expansion joint separating two portions of the garage and the multiplicity of cracks in the slabs and columns. A finite-element analysis was performed to confirm that concrete shrinkage and creep were the main contributors to cracking. The crack pattern generated for the analysis compared very well with the actual crack pattern of the slab. To insure the structural integrity of the slabs, the cracks were pressure grouted with epoxy adhesive, and a subsequent load test was performed on a portion of the ‘slab. The analysis, repair, and testing of the slab are presented and discussed.
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