FRP composites in bridge design - BridgeForumbridgeforum.org/bof/meetings/bof39/BOF39 - Shave - FRP composites... · 3 FRP Composites in bridge design Agenda What is NGCC? What are

FRP composites in bridge design

Bridge Owners’ Forum 29 Jan 2013

Jon ShaveNetwork Group for Composites in ConstructionHead of Specialist Civil Engineering Consultancy Services,Parsons Brinckerhoff

1

2

FRP Composites in bridge design

Introduction

Jon ShaveNetwork Group for Composites inConstructionHead of Specialist Civil EngineeringConsultancy Services, Parsons [email protected]

3


Agenda

What 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 opportunities

4

Compositesindustry

Constructionindustry

FRP Composites in bridge designWhat is NGCC?

Encourages effective use of FRPPartnering + collaborationRaise profileProvide informationTraining and events

5


Our members include:clients, designers, architects,contractors, suppliers, manufacturers,academics…

Benefits:• Networking with professionals across industry and

academia• Collaboration and research opportunities• Technical information in website members area• Exhibition opportunities• Special rates at events

6


NGCC• provides representation on the European

working 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 training

7


Agenda


8

FRP Composites in bridge designWhat are FRP Composites?

FRP Composites

Benefits• Non-corroding• Do not need painting• Light weight• Strong• Able to resist harsh environments• Can be non-conductive and non-magnetic

9


FRP CompositesFibres

• Glass• Carbon (standard and high modulus)• Aramid• Basalt

Resin matrix• Polyesters• Vinyl esters• Epoxies• Phenolics• Thermoplastics (eg polyamides)

Additives

10


FRP Composites

Properties

11


FRP Composites

Manufacturing processes

• Pultrusion

• Variety of moulding processes– Open moulding (hand or spray

lamination)– Vacuum infusion– Resin transfer moulding– Vacuum bag or press moulding

12


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 tooling

13


Agenda


14

FRP Composites in bridge designWhy use them in bridges?

Why use them in bridges?Non-corrodingNo need to paintLight weight – installation advantages

Cost?Not always the best solution

Particular situations• Difficult access• Corrosive environments• Need to minimise weight on supporting structure• Quick installation over existing road / railway

15


Agenda


FRP Bridge Structures

Bridge applications

• Overview of FRP bridges

• Case Study: St Austell Footbridge


• Motorway overbridgesusing hybrid system

Bridge applicationsFRP Composites in bridge design

Bridge applications

• Short spanroad bridges


Bridge applications

• Lifting bridges


Bridge applications

Introduction

• Footbridges

• Case study: St AustellFootbridge Design

St Austell Footbridge Design

Laser survey of old footbridge




• The first bridge on the UK rail networkto be entirely constructed from FRP

• Pultruded main elements

• Moulded exterior skin


• Pultruded panels bonded and secured withadditional mechanical connection

• Design philosophy developedfor robustness

• Unexpected joint failure wouldcause reduction of stiffness,not collapse


Installed October 2007 by Edmund Nuttall


• 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 structure

Vibration research

• Dynamic testing carried out with Sheffield University

Vibration research

• Accelerometers positionedon structure

Vibration research

• Determination of modal properties• Measurement of structure response

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

873 874 875 876 877 878 879 880 881 882 883

Time (s)

Acc

eler

atio

n(m

/s2 )

HorizontalVertical 1Vertical 2

• Comparison of theoretical response withactual response

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 0.05 0.1 0.15 0.2 0.25

Time (seconds)

Ver

tical

UD

Lov

er20

m(k

N/m

2 )

EN1991-2

UK NAD DD ENV1991-3:2000

Reduced loading to match peakmeasured acceleration

Vibration research

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 0.05 0.1 0.15 0.2 0.25

Time (seconds)

Ver

tical

UD

Lov

er20

m(k

N/m

2 )

EN1991-2

UK NAD DD ENV1991-3:2000

Reduced loading to match peakmeasured acceleration

• Comparison of theoretical response withactual response

Vibration 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 lines

Vibration research

Testing and monitoring

• Before fabricationMaterial testingComponent testing

• After fabricationStructure load testing

• After installationDynamic testing & monitoring


• Static load testing

Water load - uniform

Linear behaviour

Small deflections


• Dynamic testing

• Modal properties• Pedestrian-induced vibrations• Train buffeting

vibrations


• Ongoing monitoring of structure

• Philosophy developed for dynamic monitoring ofnatural frequencies and modeshapes

42


Agenda


43

FRP Composites in bridge designWhat challenges remain?

Challenges

Gaps in codesClients unfamiliar with materials?Costs need to be competitive at constructionRecyclability of materialsDesign issues – eg flexibility, fire, robustness

44

"Failure is central to engineering… every single calculation thatan engineer makes is a failurecalculation.

Successful engineering is allabout understanding how thingsbreak or fail."

Henry Petroski

45

Collapse of the (steel) I-35WHighway Bridge, Minnesota,Aug 2007

I-35W Highway Bridge, Minnesota, Aug 2007












58

Collapse of the (concrete)De la Concorde Overpass, Montreal,2006

59

Inquiries recommendedimprovements to:

robustness indesign

andmanagement of vulnerable structures

60

How do we apply principles ofrobustness to FRP structures?

61

How do we apply principles ofrobustness to FRP structures?

Not Plastic!

Gaps in designstandards

2.1(2) A structure shall be designed to have adequate:• structural resistance,• serviceability, and• durability.

62

BS EN1990General design principles

2.4(2) A structure shall be designed and executed in a

way 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 cause

63

BS EN1990General design principles

64

ULSGeneral design principles

65


In ductile structures, we often rely on a very usefultheorem that allows us to make simplifications in theanalysis…

66


If the load has a magnitude such that it is possible to find astress distribution corresponding to stresses within theyield surface and satisfying the equilibrium conditionsand the statical boundary conditions for the actual load,then this load will not be able to cause collapse of thebody.

67


The Lower Bound Theorem of LimitAnalysis


68


The Lower Bound Theorem of LimitAnalysis

Not valid without ductility!


69


We can not rely on the lower bound theorem for FRP design

70


We can not rely on the lower bound theorem for FRP design

No shortcuts!

Relative stiffness effects

Shear flexibility

Anisotropy

“Cosmetic” components

Self equilibrating stresses

Thermal effects

Differential settlement

71

SLSGeneral design principles

But FRP structure designs are very often governed by SLS criteria

72


SLS – driven design is quite unusual in bridge design

It provides safety and robustness benefits

73


Consider a simply supported beam, subject to excessive load

74



Steel design, governed by ULS - collapse with almost no warning- ULS factor of safety Rk/Ek about 1.6

75



Steel design, governed by ULS - collapse with almost no warning- ULS factor of safety Rk/Ek about 1.6

FRP design, governed by SLS - large deflections before collapse- ULS factor of safety Rk/Ek about 5-10

76

77

Designing for robustnessGeneral design principles

So how do we design for robustness?

What would happen next if there was some local damage / overstress?

78


BS EN 1991-1-7 B.9.1

79


BS EN 1991-1-7 B.9.1

80


The undamaged structure is designed for SLS and ULS.

Vulnerable details are identified

A vulnerable detail is chosen for further investigation

The structure is modelled with this detail removed using thecombination of actions for the accidental design situation

The effects from this analysis are compared with the ULSdesign resistance for short term effects.

If the damaged structure has insufficient resistance,the design is revised to improve robustness.

81


Philosophy developed for St Austell Footbridge

82


Hybrid joints- Bonded and bolted

83

Robustness needs to be considered in ALL designs

Challenges are different with FRP

High strain to failure – SLS governs

Framework for design proposed at paper at FRP Bridges2012.

“Successful engineering is all about understanding howthings break or fail."

Henry Petroski

84


Agenda



Most previous designs carried out using combination of:• (previously) BD37• (now) Eurocodes for loading and basis of design• BD90,• Eurocomp Design Code,• Product design manuals,• Project-specific “aspects not covered” or departures (often developed by

designers).

Currently no Eurocode for FRP design (there are plans for oneeventually).

There is a need for a more coordinated and comprehensive set ofdesign rules and principles.

New developments in design guidance


NGCC has an FRP Bridge Design Group

Producing design guidance on FRP bridge design

-Eurocode aligned

-Aims to plug the gaps in current standards and provide bestpractice guidance

-Focus on principles and failure criteria to be covered.

New developments in design guidance

Strengthening using FRP:new edition of TR55

87

What does TR55 cover?

How has it changed in 3rd edition?

88



89

What does TR55 cover?1 Introduction2 Background3 Material types and properties4 Review of applications5 Structural design of strengthened

members6 Strengthening members in flexure7 Shear strengthening8 Strengthening axially loaded

members9 Emerging technologies10 Workmanship and installation11 Long term inspection and

monitoring90


2 Background

• Advantages• Disadvantages

91


3 Material types and properties

• Fibres• Fabrics• Plates• Rods and strips• Preformed shells• Specials• Adhesives and resins

92

93


5 Structural design of strengthened members

94


95

96

7 Shear strengthening


97

8 Strengthening axially loaded members


98


8 Strengthening axially loaded members

99


8 Strengthening axially loaded membersSquare and rectangular columns:



100

How has it changed in the 3rd edition?

• Eurocode alignment

• Research advances

• Further experience of materials

• Links to CompClass & CSWIP

101


• Fire design

• Improvements and rationalisation ofdesign processes

• Deep embedment bars

• Emerging technologies

102


• Eurocode alignment

• Eurocodes have effectivelyreplaced British Standards fordesign.

• FRP outside scope of Eurocodes

103

TR553rd Ed

BS EN1990

BS EN1991

BS EN1992


• Eurocode alignment• Particular impact on:

• Basis of design• Load models• Concrete

104

TR553rd Ed

BS EN1990

BS EN1991

BS EN1992



• Combinations of actions• Robustness• Initial strain• SLS criteria

105

Characteristic

Frequent

Quasi-permanent



• Fire design• Shear strengthening

106

Conclusion



107

108


Agenda


© Optima Projects

FRP Composites in bridge designFuture opportunities

Mirabella V 75m long hull mould & on sea trials(VT Shipbuilding)

75m long windturbine blade

(Reinforced Plastics /Seimens)



• Most conventional bridgeswould have 2 or moreintermediate piers.

• Piers are complex, expensive &time consuming to build

• FRP design to have 300m clearspan to avoid the need forpiers.


Low laminate stresses(SLS driven design)


© Optima Projects

FRP Composites in bridge designBridge applications

© Optima Projects

115


Agenda


116


Jon ShaveNetwork Group for Composites inConstructionHead of Specialist Civil EngineeringConsultancy Services, Parsons [email protected]

FRP composites in bridge design

Bridge Owners’ Forum 29 Jan 2013

Jon ShaveNetwork Group for Composites in ConstructionHead of Specialist Civil Engineering Consultancy Services,Parsons Brinckerhoff

117

Documents

FRP composites in bridge design - BridgeForumbridgeforum.org/bof/meetings/bof39/BOF39 - Shave - FRP composites... · 3 FRP Composites in bridge design Agenda What is NGCC? What are