FRP composites in bridge design

1 FRP composites in bridge designBridge Owners Forum 29 Jan 2013 Jon ShaveNetwork Group for composites in ConstructionHead of Specialist Civil Engineering Consultancy Services,Parsons Brinckerhoff12 FRP composites in bridge designIntroductionJon ShaveNetwork Group for composites inConstructionHead of Specialist Civil EngineeringConsultancy Services, Parsons composites in bridge designAgendaWhat is NGCC?What are FRP composites ?Why use them in bridges?What have we learned so far?What challenges remain?Recent developments in design guidanceFuture opportunities4 CompositesindustryConstructionindustryFR P composites in bridge designWhat is NGCC?Encourages effective use of FRPP artnering + collaborationRaise profileProvide informationTraining and events5 FRP composites in bridge designWhat is NGCC?Our members include:clients, designers, architects,contractors, suppliers, manufacturers, : Networking with professionals across industry andacademia Collaboration and research opportunities Technical information in website members area Exhibition opportunities Special rates at events6 FRP composites in bridge designWhat is NGCC?

2 NGCC provides representation on the Europeanworking group to develop eurocodes forFRP composites Has set up a bridge design groupdeveloping design guidance Has set up subgroups to coordinate FRPresearch and development and training7 FRP composites in bridge designAgendaWhat is NGCC?What are FRP composites ?Why use them in bridges?What have we learned so far?What challenges remain?Recent developments in design guidanceFuture opportunities8 FRP composites in bridge designWhat are FRP composites ?FRP CompositesBenefits Non-corroding Do not need painting Light weight Strong Able to resist harsh environments Can be non-conductive and non-magnetic9 FRP composites in bridge designWhat are FRP composites ?FRP CompositesFibres Glass Carbon (standard and high modulus) Aramid BasaltResin matrix Polyesters Vinyl esters Epoxies Phenolics Thermoplastics (eg polyamides)Additives10 FRP composites in bridge designWhat are FRP composites ?

3 FRP CompositesProperties11 FRP composites in bridge designWhat are FRP composites ?FRP CompositesManufacturing processes Pultrusion Variety of moulding processes Open moulding (hand or spraylamination) Vacuum infusion Resin transfer moulding Vacuum bag or press moulding12 FRP composites in bridge designWhat are FRP composites ?FRP CompositesManufacturing processes Pultruded components Prismatic sections Standard profiles (off the shelf) Lower partial factors for design Limited geometries Moulded components / structures Unlimited geometric possibilities Optimised fibre layouts Can reduce need for joints Bespoke tooling13 FRP composites in bridge designAgendaWhat is NGCC?What are FRP composites ?Why use them in bridges?What have we learned so far?What challenges remain?Recent developments in design guidanceFuture opportunities14 FRP composites in bridge designWhy use them in bridges?

4 Why use them in bridges?Non-corrodingNo need to paintLight weight installation advantagesCost?Not always the best solutionParticular situations Difficult access Corrosive environments Need to minimise weight on supporting structure Quick installation over existing road / railway15 FRP composites in bridge designAgendaWhat is NGCC?What are FRP composites ?Why use them in bridges?What have we learned so far?What challenges remain?Recent developments in design guidanceFuture opportunitiesFRP bridge StructuresBridge applications Overview of FRP bridges Case Study: St Austell FootbridgeFRP composites in bridge design Motorway overbridgesusing hybrid systemBridge applicationsFRP composites in bridge designBridge applications Short spanroad bridgesBridge applicationsFRP composites in bridge designBridge applications Lifting bridgesBridge applicationsFRP composites in bridge designBridge applicationsIntroduction Footbridges Case study.

5 St AustellFootbridge DesignSt Austell Footbridge DesignLaser survey of old footbridgeSt Austell Footbridge DesignSt Austell Footbridge DesignSt Austell Footbridge design The first bridge on the UK rail networkto be entirely constructed from FRP Pultruded main elements Moulded exterior skinSt Austell Footbridge design Pultruded panels bonded and secured withadditional mechanical connection design philosophy developedfor robustness Unexpected joint failure wouldcause reduction of stiffness,not collapseSt Austell Footbridge DesignInstalled October 2007 by Edmund NuttallSt Austell Footbridge design bridge is very light (central span is 5 tonnes) Potential for vibration caused by train buffeting Low mass might result in high accelerations uncomfortable for pedestrians? Magnitude of train buffeting loading?Vibration research Goring temporary footbridge A very lively structureVibration research Dynamic testing carried out with Sheffield UniversityVibration research Accelerometers positionedon structureVibration research Determination of modal properties Measurement of structure (s)Acceleration(m/s2)HorizontalVertical 1 Vertical 2 Comparison of theoretical response withactual (seconds)VerticalUDLover20m(kN/m2)EN1991 -2UK NAD DD ENV1991-3:2000 Reduced loading to match peakmeasured accelerationVibration (seconds)VerticalUDLover20m(kN/m2)EN1991 -2UK NAD DD ENV1991-3.

6 2000 Reduced loading to match peakmeasured acceleration Comparison of theoretical response withactual responseVibration research Derivation of revised loading model basedon measurements PB-derived loads used to design St AustellFootbridge Research provides data to allow lightweightfootbridges to be used over railway linesVibration researchTesting and monitoring Before fabricationMaterial testingComponent testing After fabricationStructure load testing After installationDynamic testing & monitoringTesting and monitoring Static load testingWater load - uniformLinear behaviourSmall deflectionsTesting and monitoring Dynamic testing Modal properties Pedestrian-induced vibrations Train buffetingvibrationsTesting and monitoring Ongoing monitoring of structure Philosophy developed for dynamic monitoring ofnatural frequencies and modeshapes42 FRP composites in bridge designAgendaWhat is NGCC?

7 What are FRP composites ?Why use them in bridges?What have we learned so far?What challenges remain?Recent developments in design guidanceFuture opportunities43 FRP composites in bridge designWhat challenges remain?ChallengesGaps in codesClients unfamiliar with materials?Costs need to be competitive at constructionRecyclability of materialsDesign issues eg flexibility, fire, robustness44"Failure is central to every single calculation thatan engineer makes is a engineering is allabout understanding how thingsbreak or fail."Henry Petroski45 Collapse of the (steel) I-35 WHighway bridge , Minnesota,Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 2007I-35W Highway bridge , Minnesota, Aug 200758 Collapse of the (concrete)De la Concorde Overpass, Montreal,200659 Inquiries recommendedimprovements to:robustness indesignandmanagement of vulnerable structures60 How do we apply principles ofrobustness to FRP structures?

8 61 How do we apply principles ofrobustness to FRP structures?Not Plastic!Gaps in (2) A structure shall be designed to have adequate: structural resistance, serviceability, and EN1990 General design (2) A structure shall be designed and executed in away that it will not be damaged by events such as: explosion impact, and the consequences of human errors,to an extent disproportionate to the original cause63BS EN1990 General design principles64 ULSG eneral design principles65 ULSG eneral design principlesIn ductile structures, we often rely on a very usefultheorem that allows us to make simplifications in design principlesIf the load has a magnitude such that it is possible to find astress distribution corresponding to stresses within theyieldsurface and satisfying theequilibriumconditionsand the statical boundary conditions for the actual load,then this load will not be able to cause collapse of design principlesThe Lower Bound Theorem of LimitAnalysisIf the load has a magnitude such that it is possible to find astress distribution corresponding to stresses within theyieldsurface and satisfying theequilibriumconditionsand the statical boundary conditions for the actual load,then this load will not be able to cause collapse of design principlesThe Lower Bound Theorem of LimitAnalysisNot valid without ductility!

9 If the load has a magnitude such that it is possible to find astress distribution corresponding to stresses within theyieldsurface and satisfying theequilibriumconditionsand the statical boundary conditions for the actual load,then this load will not be able to cause collapse of design principlesWe can not rely on the lower bound theorem for FRP design70 ULSG eneral design principlesWe can not rely on the lower bound theorem for FRP designNo shortcuts!Relative stiffness effectsShear flexibilityAnisotropy Cosmetic componentsSelf equilibrating stressesThermal effectsDifferential settlement71 SLSG eneral design principlesBut FRP structure designs are very often governed by SLS criteria72 SLSG eneral design principlesSLS driven design is quite unusual in bridge designIt provides safety and robustness benefits73 SLSG eneral design principlesConsider a simply supported beam, subject to excessive load74 SLSG eneral design principlesConsider a simply supported beam, subject to excessive loadSteel design , governed by ULS - collapse with almost no warning- ULS factor of safetyRk/Ekabout design principlesConsider a simply supported beam, subject to excessive loadSteel design , governed by ULS - collapse with almost no warning- ULS factor of safetyRk/Ekabout design .

10 Governed by SLS - large deflections before collapse- ULS factor of safetyRk/Ekabout 5-107677 Designing for robustnessGeneral design principlesSo how do we design for robustness?What would happen next if there was some local damage / overstress?78 Designing for robustnessGeneral design principlesBS EN for robustnessGeneral design principlesBS EN for robustnessGeneral design principlesThe undamaged structure is designed for SLS and details are identifiedA vulnerable detail is chosen for further investigationThe structure is modelled with this detail removed using thecombination of actions for the accidental design situationThe effects from this analysis are compared with the ULSdesign resistance for short term the damaged structure has insufficient resistance,the design is revised to improve for robustnessGeneral design principlesPhilosophy developed for St Austell Footbridge82 Designing for robustnessGeneral design principlesHybrid joints- Bonded and bolted83 Robustness needs to be considered in ALL designsChallenges are different with FRPHigh strain to failure SLS governsFramework for design proposed at paper at FRP Bridges2012.