material-science-2019-keynote

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February 25-26, 2019 | Paris, France

Materials Science and Engineering

International Conference on

Journal of Materials Science and Nanotechnology | Volume 3

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.

relhacha@ucalgary.ca

Raafat El-Hacha

University of Calgary, Canada

Flexuralstrengtheningofconcretestructuresusingprestressedfibrereinforcedpolymers