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February 25-26, 2019 | Paris, France
Materials Science and Engineering
2
nd
International Conference on
Journal of Materials Science and Nanotechnology | Volume 3
F
ibre reinforced polymers (FRP) reinforcement has been used
for flexural strengthening either as an externally bonded
(EB) system in the formof FRP laminate (sheets, plates or strips)
applied to the soffit tension side of the reinforced concrete (RC)
members or as a near-surface mounted (NSM) system in the
formof FRP strips or bars embedded inside a pre-cut groove into
the concrete cover at the tension side of the RC member filled
with epoxy adhesive. Although flexural strengthening using
non-prestressed FRP reinforcement can remarkably increase
the ultimate strength of a member, it does not significantly
change the behaviour of the member under service loads or
substantially increase the stiffness of the member. It should be
notedthatinnon-prestressedFRPstrengtheningapplicationonly
a portion of the strength of the FRP reinforcement is effective
and the system is a passive strengthening technique that
remains inactive until additional loads are applied. To achieve
an increase in the stiffness of the member, the strengthening
system must be active rather than passive. Thus, to improve
the efficiency of the system, the FRP reinforcement should be
prestressed before being bonded to the concrete. Therefore,
by prestressing the FRP, the material is used more efficiently
because a greater portion of its tensile capacity is employed,
and it contributes to the load-bearing capacity under both
service and ultimate conditions. Prestressing the EB and NSM
FRP reinforcement requires a special anchorage system that
should be practical in implementation. In general, prestressing
is used to enhance the flexural behaviour of reinforced concrete
members under service loads especially in bridges and (or)
beams that have large spans and there is a limitation on the
deflection and serviceability conditions. Because of their high
tensile strengthproperties, FRPmaterials have great advantages
for use in prestressing and post-tensioning strengthening
applications. The specialized application of prestressing the
FRP reinforcement for flexural strengthening of structures
combines the noncorrosive and lightweight benefits of the FRP
reinforcement with the advantages associated with external
prestressing. However, the challenging part of the active FRP
strengthening system is the application of the prestressing force
to the FRP material using appropriate practical anchorage and
prestressing system. A comprehensive reviewon the techniques
and anchorage systems developed to prestress the EB and NSM
FRPwith the focus on thepracticality of theprestressing systems
where the FRP is prestressed against the member itself, and the
performance of members strengthened using prestressed FRP
reinforcement are discussed in this presentation.
Speaker Biography
Raafat El-Hacha is a Professor of Structural Engineering at the University of Calgary in the
Department of Civil Engineering. His pioneer research has been recognized as pushing the
boundaryofknowledge inusing innovativeandsmartadvancedmaterialsforstrengthening
existing structures and for new construction, such as fibre reinforced polymers (FRP),
shape memory alloy, and ultra-high performance concrete for hybrid structural systems
in bridge applications and other structures. He published over 220 journal and conference
papers, co-authored 3 refereed design guidelines. Supervised and graduated 42 PhD and
MSc students. Served as guest editor for 3 journals and edited/co-edited 8 conference
proceedings. He is a Fellow of the International Institute for FRP in Construction (IIFC) and
the Canadian Society of Civil Engineers (CSCE). He is the recipient of several awards and
fellowships including the CSCE Casimir Gzowski Gold Medal, CSCE Excellence in Innovation
in Civil Engineering Award, IIFC President’s Award, Killam Professorship Award, Erasmus
Mundus International Fellowship (twice) and many others for his outstanding academic
and professional achievements.
e:
relhacha@ucalgary.caRaafat El-Hacha
University of Calgary, Canada
Flexuralstrengtheningofconcretestructuresusingprestressedfibrereinforcedpolymers