BEHAVIOR OF HYBRID FIBER REINFORCED PRESTRESSED CONCRETE BEAMS UNDER FLEXURE-SHEA

Joshi, Suhas S and S, Suriya Prakash (2019) BEHAVIOR OF HYBRID FIBER REINFORCED PRESTRESSED CONCRETE BEAMS UNDER FLEXURE-SHEA. Masters thesis, Indian institute of technology Hyderabad.

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Abstract

The present study aims at understanding the effect of hybridization of the steel and synthetic fibers on the flexure-shear behavior of prestressed concrete (PSC) beams. The first phase of the test program consists of evaluating the efficiency of individual fibers viz. steel and structural synthetic fibers on the performance of prestressed concrete (PSC) beams. Later, a hybrid fiber combination consisting of steel and synthetic fibers are introduced to understand the behavior. The effect of different fiber reinforcement on the behavior of prestressed concrete beams are evaluated in two stages. First, fracture tests are conducted to understand the influence of fibers at the material level. Secondly, full-scale prestressed concrete beams are tested for evaluating the effect of fiber addition on the flexure-shear behavior. The test matrix consists of seventeen beams with fiber reinforced concrete, having fiber dosages of 0.35%, 0.70% and 1.0% by volume of concrete. All the beam specimens are tested at a shear span (a) to depth ratio (d) of five under four-point bending configuration. Effect of hybrid fiber addition on the overall load-displacement, load-strain, and strain energy absorption capacity of PSC beams are analyzed. Other parameters such as shear span to depth ratio (a/d), the compressive strength of concrete, prestressing reinforcement ratio are kept constant. Results of hybrid fiber reinforced specimens is compared with the results of steel and Synthetic (polyolefin) fiber reinforced beams. The test results portray that the addition of fibers stiffen the post-cracking response and increases the energy absorption capacity. Additionally, failure mode changed from flexure-shear (brittle) to flexure (ductile) mode with the addition of fibers. Change of failure mode occurred at dosages of 0.35% for steel and hybrid fibers and 0.70% for synthetic (Polyolefin) fibers. The strain energy absorption capacity increased by more than 100% at 1.0% fiber addition for both steel and macro-synthetic fibers. Flexural capacity of the tested vi specimens is verified with the RILEM recommendation for fiber reinforced concrete specimens. RILEM recommendations always underpredicted the actual value, indicating the conservative estimates of design guidelines. Cracking behavior of PSC beams are analyzed viz. crack width and crack spacing parameters using Eurocode, CEB-FIP modal code and Moffatt’s modified formulation. It is observed that, as the fiber dosage is increased, corresponding crack widths are reduced in the post-cracking regime.

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IITH Creators:
IITH CreatorsORCiD
S, Suriya Prakashhttp://orcid.org/0000-0003-0319-1773
Item Type: Thesis (Masters)
Uncontrolled Keywords: Steel Fiber, Polyolefin Fiber, Crack Width
Subjects: Civil Engineering
Divisions: Department of Civil Engineering
Depositing User: Team Library
Date Deposited: 15 Feb 2019 10:47
Last Modified: 15 Feb 2019 10:47
URI: http://raiith.iith.ac.in/id/eprint/4815
Publisher URL:
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