Field measured pre-stress Concrete losses versus design code estimates

In Florida, pre-stressed concrete bridges with a hybrid structural configuration, consisting of simply supported girders and continuous deck units providing composite action, are prevalent. In this study, an actual bridge with this configuration is instrumented with embedded vibrating wire strain ga...

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Bibliographic Details
Published in:Experimental mechanics 2003-06, Vol.43 (2), p.201-215
Main Authors: ONYEMELUKWE, O. U, MOUSSA ISSA, P. E, MILLS, C. J
Format: Article
Language:English
Subjects:
Applied sciences
Bridges
Building structure
Buildings. Public works
Concrete structure
Construction (buildings and works)
Exact sciences and technology
Measurements. Technique of testing
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Summary:In Florida, pre-stressed concrete bridges with a hybrid structural configuration, consisting of simply supported girders and continuous deck units providing composite action, are prevalent. In this study, an actual bridge with this configuration is instrumented with embedded vibrating wire strain gages during construction. The axial strain data are utilized to determine the time-dependent pre-stress loss variation and distribution in the pre-tensioned concrete girders used for the bridge. In this paper, however, we discuss the bridge instrumentation and monitoring technique used, and the deduced pre-stress losses obtained from field-measured strains up to 150 days, before placement of the composite slab. A comparison of the measured loss with the estimates of the Precast/Prestressed Concrete Institute (PCI) and the American Association of State Highway and Transportation Officials (AASHTO) indicates that the field-measured pre-stress loss is non-uniform across the girder depth, opposed to a uniform distribution implicitly assumed in most codes. The measured pre-stress variation is used in computing the concrete stress distribution in the girder at different depths within the given cross-section. When compared to the concrete stress from using the PCI and AASHTO suggested losses, the stress distribution resulting from using the field-measured loss is found to be non-linear, and in most cases higher.
ISSN:0014-4851
1741-2765
DOI:10.1007/BF02410501