Prediction and Control of Initial Deflection in Partially Prestressed Post-Tensioned Beams with Unbonded Tendons

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Title: Prediction and Control of Initial Deflection in Partially Prestressed Post-Tensioned Beams with Unbonded Tendons

Author(s): P. R. Chakrabarti

Publication: Special Publication

Volume: 161

Issue:

Appears on pages(s): 197-242

Keywords: beams (supports); cracking (fracturing); deflection; moments of inertia; partial prestressing; post-tensioning; prestressing steels; span-depth ratio; T-beams; unbonded prestressing; Structural Research

Date: 4/1/1996

Abstract:
In this project, an attempt is made to study the instantaneous load- deflection behavior of partially prestressed beams with unbonded post- tensioning tendons. Thirty-three beams with the following variables were tested: different mixes of reinforcing and prestressing steel, T-beams and rectangular beams, normal and high-strength concrete, low and high ratios of span/depth, and different effective stresses in tendons. Cracking was observed and deflections measured at precracking and postcracking stages. A suitable method for deflection calculation at precracking and postcracking stages is proposed. The proposed deflections and the deflections obtained by current ACI 318-89/92 code equations are compared with the measured deflections.