Cracking and Ductility Analysis of Steel Fiber-Reinforced Prestressed Concrete Beams in Flexure


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Title: Cracking and Ductility Analysis of Steel Fiber-Reinforced Prestressed Concrete Beams in Flexure

Author(s): Suhas S. Joshi, Nikesh Thammishetti, S. Suriya Prakash, and Saumitra Jain

Publication: Structural Journal

Volume: 115

Issue: 6

Appears on pages(s): 1575-1588

Keywords: crack bridging; digital image correlation (DIC); ductility; prestressed concrete beams; steel fibers

Date: 11/1/2018

The present study focuses on understanding the effect of steel-fiber dosage on cracking and ductile behavior of prestressed concrete beams (PCBs) under flexure using digital image correlation (DIC). Seven prestressed concrete beams were cast and tested under a shear span-depth ratio (a/d) of 5 to simulate the flexure/flexure-shear dominant behavior. Full field strain measurement with the DIC technique was used to understand the effectiveness of steel fibers on the crack-bridging mechanisms. Three different volumetric fiber reinforcement ratios—0.35%, 0.70%, and 1.0%—were considered. Test results revealed that the strain energy-based ductility increased with an increase in fiber dosage from 0.35% to 1.0%. Post-cracking stiffness improved by 50% due to the addition of 1.0% volume of steel-fiber dosage. DIC measurements of displacements and strains were found to be in good agreement with the conventional linear variable displacement transducer (LVDT) measurements. DIC results clearly established the effect of fibers on crack bridging and strain reduction. Concrete strains and the strain in the prestressing strand reduced due to the better crack bridging of steel fibers.