BOF39 - Shave - FRP Composites in Bridge Design

7/27/2019 BOF39 - Shave - FRP Composites in Bridge Design

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FRP composites in bridge design

Bridge Owners Forum 29 Jan 2013

Jon ShaveNetwork Group for Composites in Construction

Head of Specialist Civil Engineering Consultancy Services,

Parsons Brinckerhoff

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FRP Composites in bridge design

Introduction

Jon Shave

Network Group for Composites inConstruction

Head of Specialist Civil EngineeringConsultancy Services, Parsons Brinckerhoff

[email protected]


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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 guidance

Future opportunities


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Compositesindustry

Constructionindustry

FRP Composites in bridge designWhat is NGCC?

Encourages effective use of FRP

Partnering + collaboration

Raise profile

Provide information

Training and events


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Our members include:

clients, designers, architects,

contractors, suppliers, manufacturers,academics

Benefits:

Networking with professionals across industry andacademia

Collaboration and research opportunities

Technical information in website members area

Exhibition opportunities

Special rates at events


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NGCC

provides representation on the European

working group to develop eurocodes for

FRP composites

Has set up a bridge design group

developing design guidance

Has set up subgroups to coordinate FRP

research and development and training


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Agenda

What is NGCC?







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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


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FRP Composites

Fibres Glass

Carbon (standard and high modulus)

Aramid

Basalt

Resin matrix Polyesters

Vinyl esters

Epoxies

Phenolics

Thermoplastics (eg polyamides)

Additives


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FRP Composites

Properties


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FRP Composites

Manufacturing processes

Pultrusion

Variety of moulding processes

Open moulding (hand or spraylamination)

Vacuum infusion

Resin transfer moulding Vacuum bag or press moulding


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FRP Composites

Manufacturing 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


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Agenda

What is NGCC?







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FRP Composites in bridge designWhy use them in bridges?

Why use them in bridges?

Non-corroding

No need to paint

Light 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


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Agenda

What is NGCC?







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FRP Bridge Structures


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Bridge applications

Overview of FRP bridges

Case Study: St Austell Footbridge



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Motorway overbridges

using hybrid system

Bridge applications

FRP Composites in bridge designBridge applications


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Short span

road bridges

Bridge applications



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Lifting bridges

Bridge applications



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Introduction

Footbridges


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Case study: St Austell

Footbridge Design


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St Austell Footbridge Design

Laser survey of old footbridge


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The first bridge on the UK rail network

to be entirely constructed from FRP

Pultruded main elements

Moulded exterior skin


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Pultruded panels bonded and secured with

additional mechanical connection

Design philosophy developedfor robustness

Unexpected joint failure would

cause reduction of stiffness,not collapse


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Installed October 2007 by Edmund Nuttall


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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?


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Vibration research

Goring temporary footbridge

A very lively structure


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Vibration research

Dynamic testing carried out with Sheffield University


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Vibration research

Accelerometers positioned

on structure


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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)

Acceleration(m/s2)

Horizontal

Vertical 1

Vertical 2


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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)

Vertica

lUDLover20m

(kN/m

2) EN1991-2

UK NAD DD ENV1991-3:2000

Reduced loading to match peak

measured acceleration

Vibration research


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-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)

Vertica

lUDLover20m

(kN/m

2) EN1991-2

UK NAD DD ENV1991-3:2000

Reduced loading to match peak

measured acceleration

Comparison of theoretical response withactual response

Vibration research


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Derivation of revised loading model basedon measurements

PB-derived loads used to design St Austell

Footbridge

Research provides data to allow lightweight

footbridges to be used over railway lines

Vibration research


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Testing and monitoring

Before fabricationMaterial testing

Component testing

After fabricationStructure load testing

After installation

Dynamic testing & monitoring


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Static load testing

Water load - uniform

Linear behaviour

Small deflections


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Dynamic testing

Modal properties

Pedestrian-induced vibrations

Train buffeting

vibrations


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Ongoing monitoring of structure

Philosophy developed for dynamic monitoring of

natural frequencies and modeshapes


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Agenda

What is NGCC?



What have we learned so far?





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FRP Composites in bridge designWhat challenges remain?

Challenges

Gaps in codes

Clients unfamiliar with materials?

Costs need to be competitive at construction

Recyclability of materials

Design issues eg flexibility, fire, robustness


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"Failure is central to engineering

every single calculation that

an engineer makes is a failure

calculation.

Successful engineering is all

about understanding how things

break or fail."

Henry Petroski


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Collapse of the (steel) I-35W

Highway Bridge, Minnesota,

Aug 2007


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I-35W Highway Bridge, Minnesota, Aug 2007


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

2006


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Inquiries recommended

improvements to:

robustness in

design

and

management of vulnerable structures


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How do we apply principles of

robustness to FRP structures?


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How do we apply principles of

robustness to FRP structures?

Not Plastic!

Gaps in design

standards


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2.1

(2) A structure shall be designed to have adequate:

structural resistance, serviceability, and

durability.

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BS EN1990General design principles


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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

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BS EN1990General design principles


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ULSGeneral design principles


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In ductile structures, we often rely on a very useful

theorem that allows us to make simplifications in the

analysis


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If the load has a magnitude such that it is possible to find a

stress distribution corresponding to stresses within the

yield surface and satisfying the equilibrium conditions

and the statical boundary conditions for the actual load,

then this load will not be able to cause collapse of thebody.


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The Lower Bound Theorem of Limit

Analysis







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The Lower Bound Theorem of Limit

Analysis

Not valid without ductility!







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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


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SLSGeneral design principles

But FRP structure designs are very often governed by SLS criteria


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SLS driven design is quite unusual in bridge design

It provides safety and robustness benefits


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Consider a simply supported beam, subject to excessive load


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Steel design, governed by ULS - collapse with almost no warning

- ULS factor of safety Rk/Ek about 1.6


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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


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Designing for robustnessGeneral design principles

So how do we design for robustness?

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


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BS EN 1991-1-7 B.9.1

G


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BS EN 1991-1-7 B.9.1

G l d i i i l


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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 the

combination of actions for the accidental design situation

The effects from this analysis are compared with the ULS

design resistance for short term effects.

If the damaged structure has insufficient resistance,

the design is revised to improve robustness.

G l d i i i l


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Philosophy developed for St Austell Footbridge

G l d i i i l


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Hybrid joints

- Bonded and bolted


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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 Bridges

2012.

Successful engineering is all about understanding how

things break or fail."

Henry Petroski


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Agenda

What is NGCC?



What have we learned so far?




New developments in design guidance


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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 bydesigners).

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.




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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.



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Strengthening using FRP:

new edition of TR55

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What does TR55 cover?

How has it changed in 3rd edition?

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1 Introduction

2 Background

3 Material types and properties

4 Review of applications

5 Structural design of strengthened

members

6 Strengthening members in flexure

7 Shear strengthening

8 Strengthening axially loaded

members

9 Emerging technologies

10 Workmanship and installation11 Long term inspection and

monitoring

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2 Background

Advantages

Disadvantages

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3 Material types and properties

Fibres

Fabrics

Plates

Rods and strips

Preformed shells

Specials

Adhesives and resins

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5 Structural design of strengthened members


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7 Shear strengthening



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8 Strengthening axially loaded members



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8 Strengthening axially loaded members


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8 Strengthening axially loaded membersSquare and rectangular columns:


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How has it changed in the 3rd edition?

Eurocode alignment

Research advances

Further experience of materials

Links to CompClass & CSWIP

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Fire design

Improvements and rationalisation of

design processes

Deep embedment bars

Emerging technologies

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Eurocode alignment

Particular impact on:

Basis of design

Load models

Concrete

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TR553rd Ed

BS EN1990

BS EN1991

BS EN1992


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Eurocode alignment


Combinations of actions

Robustness

Initial strain

SLS criteria

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Characteristic

Frequent

Quasi-permanent


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Eurocode alignment


Fire design

Shear strengthening

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Conclusion



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Agenda

What is NGCC?



What have we learned so far?What challenges remain?





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Optima Projects




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Mirabella V 75m long hull mould & on sea trials

(VT Shipbuilding)

75m long wind

turbine blade(Reinforced Plastics /

Seimens)




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Most conventional bridgeswould have 2 or more

intermediate piers.

Piers are complex, expensive &

time consuming to build FRP design to have 300m clear

span to avoid the need for

piers.



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Low laminate stresses

(SLS driven design)



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Optima Projects

Bridge applications


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Optima Projects

R C


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Agenda

What is NGCC?



What have we learned so far?What challenges remain?



FRP C it i b id d i


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Jon Shave

Network Group for Composites inConstruction

Head of Specialist Civil EngineeringConsultancy Services, Parsons Brinckerhoff

[email protected]


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FRP composites in bridge design

Bridge Owners Forum 29 Jan 2013

Jon Shave

Network Group for Composites in ConstructionHead of Specialist Civil Engineering Consultancy Services,

Parsons Brinckerhoff

Documents

BOF39 - Shave - FRP Composites in Bridge Design