Strengthening Torsion Critical Reinforced Concrete Beam by Externally Bonded Carbon Fiber Reinforced Polymer: Analytical to Experimental Investigation
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Date
2018-03-19
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AAU
Abstract
Although there is an enormous amount of knowledge on behavior, design and detailing of
reinforced concrete (RC) members for torsion, many structural members are found to be torsion
critical. If a structural member becomes torsion critical, the available mitigations are either to
strengthen or to demolish the structural component. Considering its economic implications,
demolishing the structure element might not be feasible; as a result, strengthening becomes the
only option. One method of strengthening a torsion critical member is by using externally
bonded carbon fiber reinforced polymers (CFRP). While there is a great deal of work conducted
on strengthening torsion critical members, most of the studies are limited to the case of pure
torsion. Often, along with torsional moment, most of the torsion critical beams are subjected to
associated shear and flexural moment.
In this study, the effectiveness of the strengthening technique using CFRP is scrutinized by
conducting experimental tests on specimens for the combined action of flexure and torsion.
Furthermore, the thesis presented an analytical modeling of combined action using a proposed
truss model (COMBINED-SMM-FRP).
In the thesis, an additional comprehensive analytical study was conducted using nonlinear finite
element packages DuCOM-COM3 and VecTor3. Additionally, the capability of the proposed
analytical model (COMBINED-SMM-FRP) in predicting the response of fiber wrapped RC
members under the action of combined torsion and flexure was also examined.
The experimental, analytical and the nonlinear finite element studies showed the application of
CFRP can substantially enhance the cracking and ultimate strength of torsion critical members.
In the experimental investigation, an ultimate strength enhancement of more than 60 percent is
observed for the strengthened specimen relative to their control specimens.
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Keywords
Fiber Reinforced Polymer, Bonded Carbon, Torsion, Reinforced Concrete Beam