Composite applications in concrete structures

Professor John L Clarke

The Concrete Society

Why use FRP reinforcement?

• Corrosion of steel reinforcement in concrete structures in aggressive environments is a major problem

• Current concrete approaches are often inadequate

• Stainless steel reinforcement is expensive

• FRP should offer a viable alternative

Japanese road bridge

Bridge with FRP prestressing

Japanese foot and cycle bridge

Berlin Footbridge

Oslo Footbridge

Herning Bridge,Denmark

Casting ‘steel-free’ deck

Fender support beam, Qatar

Non-magnetic fencing

Summary - FRP reinforcement

• Correctly specified FRP materials are suitable for use in concrete

• Initial design guidance is now available

• Initial conservative safety factors will be modified as experience grows

• Demonstration structures world-wide show that the material is viable

Reasons for strengthening

• Requirement for increased load capacity (e.g. change of use or regulations)

• Insufficient/incorrectly located reinforcement

• Change of structural form (e.g. cutting holes through slabs or removal of supports)

• Damage (e.g. corrosion or impact)

Types of strengthening

• Beams and slabs– Bending– Shear

• Columns– Axial load– Bending– Shear (impact)– Seismic loading

Types of materials

• Pultruded composite plates

• Fabrics– Sheet materials – Tapes

• Pre-formed shells

• Pre-formed shear straps

Coil of carbon plate

Strengthening concrete with FRP

• Advantages– Cost effective solution - rapid installation and

hence limited possession time– Limited preparation - no bolts required

• Disadvantages– Lack of agreed design approaches– Lack of long term experience– Approach appears to be too easy (!!)

Strengthening canal bridge

Installing FRP strips on bridge deck

Bridge strengthened with FRP

Strengthening Glade Bridge

Applying adhesive to fabric

Fabric impregnation machine

Wrapping column

Wrapping column

Column wrapping machine

Bridge over Bodmin Bypass

Contents of Concrete Society Technical Report 55

• Introduction • Background

• Material types and properties

• Review of applications

• Structural design - flexure, shear, columns

• Detailing

• Workmanship

• Available materials • Quality control