BCF1: July 2001

Minutes

Minutes of First Bridge Consultants Forum meeting
on 16^th July 2001 at King’s College, Cambridge

 Printable version of these Minutes (134Kb)

Present:

Campbell Middleton (Chair)	CUED
Nigel Beavor	Babtie
Mike Chubb	WS Atkins
Ian Firth	Flint & Neill
Peter Fox	Hyder
Jolyon Gill	Maunsell
Richard Hornby	Cleveland Bridge
Gareth Hughes	WSP
Paul Jackson	Gifford
Vardi Jones	Highpoint Rendel
Darren Kimberley	Scott Wilson Kirkpatrick
Angus Low	Arup
Sam Luke	Mouchel
Simon de Neumann	CUED/Flint & Neill
Graham Nicholson	TGP
Tony Small	Pell Frischmann
Mungo Stacy	CUED/RBA
Malcom Taylor	Mouchel
Godfrey Webster	Owen Williams
Stuart Withycombe	Halcrow
Steve Denton (Tech. Secretary)	Parsons Brinckerhoff

Introductory Presentation by Cambpell Middleton

Campbell Middleton introduced the meeting, setting out the objectives as:

• Identify research needs/topics.
• Disseminate information.
• Recommended research priorities to owners.

Opportunities for cooperation with CUED were described, including:

• Research Partnerships:
  • PhD Studentships
  • Consultancy
  • Offer research seminars.
  • "Blue-skies" research collaboration
• Undergraduate level:
  • 4^th year projects.
  • Special lectures to undergraduates.
  • Slide sets.
  • Student Sponsorship.
  • Vacation work experience.
• Event Sponsorship.
  • Research seminars.
  • Projects/Prizes.

Members of Cambridge University staff working in relevant fields were briefly identified, including Chris Morley, Chris Burgoyne, Janet Lees and Allan McRobie.

Presentation by Simon de Neumann

 Presentation - A Student's Perspective on Employment Opportunities

Simon De Neumann gave a brief presentation discussing how civil engineering consultants can better attract graduate engineers. The need to make companies known to students, to effectively advertise posts and act proactively in recruitment were all highlighted. Specifically, the following issues were identified:

• Difficulties in obtaining vacation employment in first year.
• Limited exposure of civil engineering consultancies to students.

Presentation by Angus Low, Ove Arup & Partners

Recent and Current Research

• Pedestrian excitation of bridges Good understanding has been developed. Future research requirement is the 'peakiness' of excitation.
• Soil pressures on abutments of integral bridges Do soils simply act as part of loading or part of structure? Ove Arup have developed internal guidelines.
• Black top for orthotropic bridge decks
• Guidance on height and forces need for derailment containment (in relation to CTRL).

Further comments:

• Research is in universities and application in industry. However, under current market there is little room for development.
• Encourage research for complete problems, eg bracing for composite structures.
• "Free time donated by Consultant to, for example, Eurocodes, how do we get paid a realistic fee for this work?"
• Delays can occur when seeking to gain a departure from Standard. Thus procurement routes, in particular, programme pressures act to resist research.

Presentation by Ian Firth, Flint & Neill

Recent and Current Research

• Highway Traffic Loading
• Fatigue Life (BD77)
• Wind Loading
• Thermal Actions
• Aerodynamics – Review BD49, wind tunnel tests, comparison of predictions with real data.
• Cable and stay Dynamics – Examination of problems of stay vibrations and development of analytical tools to model 3D non-linear stay vibrations.
• Pedestrian Bridge Vibrations – Development of lateral response criteria, review of provisions of draft EN regarding bridge vibrations. A great deal of work to be done.
• Steel Bridge Assessment - stability provision of BS5400 Part 3 – large displacement NLFE.
• GFRP (new build applications) – Halgavor Bridge, develop design for box girder highway bridge, instrumentation and monitoring systems – optical fibres.

Proposed Research Needs

• Aerodynamic Response of Footbridges
• Pedestrian Bridge Vibrations
• Bridge Cable and Stays (including cable-deck interaction – experiment and theory).
• Polymer Composites (including development of composite GRP formwork – shear connectors).
• Intelligent Bridges

Others

• Bridge Specific Pedestrian Loading.
• Empirical Parapet Impact Loading Criteria
• Surfacing Systems for Steel Orthotropic Bridge Decks

Presentation by Vardi Jones, Highpoint Rendel

Recent Research and Future Research Needs

• Pedestrian Loading. - Lack of 'pooling' of expert knowledge on pedestrian loading in recent years. Site Specific pedestrian loading.
• Use of additives in concrete. (experience in Middle East), including calcium nitrate, Stainless and epoxy coated reinforcement - what are long-term properties.
• Seismic and Dynamic Isolation. Highpoint Rendel has investigated dynamic isolator devices (following Turkey earthquake). Comparative studies would be beneficial together with further work on computational.
• Eurocodes - work required to understand the implications of their adoption. Specific reference made to ship impact criteria.
• Soil pressure and integral bridges – more work is required. Can information be disseminated more widely?

Campbell Middleton suggested that research reports should be submitted electronically to be held on BOF website.  This was a popular suggestion, and received support.

Presentation by Graham Nicholson, Tony Gee

 Handout

Recent and Current Research

• New materials and strengthening. In particular, strengthening of metallic structures, working with CIRIA, Railtrack and material manufacturers.
• Fatigue (working with Cambridge University).

Proposed Research Needs.

• Bracing rules for composite structures – need for validation of rules.
• FRP strengthening – need for further data on preloaded beams then strengthened and tested to failure.
• Integral bridges – soil behaviour under thermal loading

Presentation by Jolyon Gill, Maunsell

Recent and Current Research

• FRP Composite road bridge - working with TRL on road panels.
• 'Spaces concept' – Trusses use material very effectively although approach gives rise to maintenance issues. Wrapping in FRP composite sleeve may overcome these issues.  Work is ongoing.  Nodes are expensive. Robotic welding may be advantageous

It was suggested that bridge owners should think longer term (40-50 years) and cost in maintenance and reliability, in which case the spaces concept may be resurrected. 

Discussion

Ian Firth remarked that whole-life-costing needs to be accepted by Bridge Owners. Angus Low asked what the current way of evaluating this is and observed that it is dependent on the discount rate. Ian Firth added that PFI schemes place particular pressures on the lowest cost at day one.

Presenation by Richard Hornby, Cleveland Bridge

Recent and Current Research

• Weld procedures
• Painting systems
• Steel houses (system solutions)

Proposed Research Needs

• Protection to suspension cables
• Surfacing for orthotropic decks – in relation to providing composite action.
• Feedback on failures (database).
• Research targeted to where conservatism actually lies in codes

Discussion

Paul Jackson mentioned that Eurocodes have been criticised for requiring designers to address fundamentals.

Jolyon Gill commented that real life failures are often due to a combination of factors, and Campbell Middleton raised the question of whether we need a database of failures.

Jolyon Gill and Tony Small both felt that monitoring structures is beneficial. Steve Denton commented that the benfits of monitoring can be limited particularly if the primary interest is ULS.

It was noted that the organisation of the Highway Agency is changing and losing aspects of its expertise.   This process leads to issues in relation to reviewing departures. 

Godfrey Webster observed that client’s interest in failures tends to focused on financial implications, and technical aspects can become sub-judicy.   Therefore the information is not disseminated.

Paul Jackson asked whether the checker should be charged with identifying potential savings.

Presentation by Malcolm Taylor, Mouchel

Recent and Current Research.

• FRP Composites – numerous including: Robust project (FRP Strengthening), CFRP Prestressing Technology, Eurocomp, New build using composites (Asset system).
• Sign Gantries
• Parapets
• Aluminium Bridges
• Silane
• Compressive Membrane Action

Proposed Research Needs.

• Better identification of customer needs.
• Single framework for bridge research - a need for better coordination.
• Whole Life Costing

Presenation by Stuart Withycombe, Halcrow

Recent and Current Research.

• Thaumosite attack - stemming from Gloucester structures.
• Strengtheing of composite bridge decks – fatigue life of shear connectors.  Use of spring-pin connectors,  undertook recent work with TWI.
• Investigation of aerodynamic response of bridge decks, with Glasgow University. Numerical/computer modelling and calibration – with tests.

Proposed Research Needs.

• Cable stays and suspension cables - dynamic response, inspection and monitoring.
• Integral bridges – onerous conditions for   loading.
• Cable stayed bridges – tower design.
• Shear capacity of voided slabs
• Parapets – assessment of masonry brick parapets.

Discussion

Angus Low commented that design for impact is often based on load, but highlighted that mass is important and relevant.  Masonry parapets have mass but limited strength.

Noted by Tony Small that work in the field has been done at Newcastle.

Paul Jackson remarked that it is difficult to show that whether parapet remains on bridge.

Ian Firth has proposed an IABSE study on bridge parapet strength (although Highways Agency have shown little interest).

Presentation by Gareth Hughs, WSP

Recent and Current Research

• Deterioration of structures, particularly prestressed structures.
• Tests to investigate deterioration of RC Viaduct in London – noted that half-cell measurements changed.

Proposed Research Needs

• Modelling of deterioration.   Collect all available data on deterioration; perhaps modify g factors to account for deterioration (g_o = 1.2 g₁₂₀ = 1.0 at end of life).

Discussion

Mike Chubb commented that during the Midland links project a deterioration model was developed, although monitoring was halted at a crucial time.

Campbell Middleton raised some concerns over the accuracy/validity of existing deterioration models.

Presenation by Nigel Beavor, Babtie

 Handout

Recent and Current Research

• Reliability analysis - co-sponsors with Railtrack and HA of three PhDs.  Need for greater practical engineering input into reliability work.
• Coping/edge units on reinforcement earth walls - (for Scottish Office) – impact considerations, testing undertaken.

Proposed Research Needs

• Assimilation and co-ordination – with real, practical need.
• Geotechnical issues: integral bridge – back of abutment issues;  CFA piles;   Durability of steel ‘H’ piles; Run-on-slabs.
• Shear strengthening of prestressed concrete structures using CFRP
• Instrumentation and intelligent bridges Practical advice.

Presenation by Peter Fox, Hyder

Recent and Current Research

• Vibration of viaducts with external prestressing
• Segmental viaducts – Ultimate capacity of externally stressed bridges.
• Track/ballast structure interaction, seismic forces, vehicle structure dynamics, impact factors (considered on Taiwan highspeed raillink)
• Soil structure interaction for seismic loading.

Proposed Research Needs

• Shear, punching shear in pile caps   Allowing for shear enhancement.   Use of shear-friction concept.
• Shear behaviour of joints in segmental construction – effects of shear key size.
• Ultimate capacity of segmental structures
• Corrosion of steel piles
• Diaphragm design - Avoidance of cracking.
• Integral bridges

Presentation by Godfrey Webster, Owen Williams

Recent and Current Research

• Strengthening of steel composite structures (Tinsley Viaduct) – shortage of shear connectors. Research into spiral pins or bolt anchors.   Some static and fatigue tests have been undertaken.  Problems with spiral pins if thin sections.
• Wind shielding of viaducts

Proposed Research Needs:

• Aerodynamic behaviour of thin deck footbridges
• Pedestrian excitation of footbridges
• Behaviour of welds under complex stress states, principally fatigue behaviour.
• BS5400 Part 3 - new rules for effective length - is it possible to develop simplified rules for common situations
• Shear connection in steel-concrete composite structures – ignores bond between steel flange and concrete – can make allowance for splice bolts.
• Determining existing stresses in metallic and prestressed concrete structures

Presentation by Tony Small, Pell Frischmann

 Handout
 Bridge Summary Table

Recent and Current Research

• Arch bridges
• Half-through girders
• Composite action
• Rivet shear

Proposed Research Needs

• Arch bridges: mechanism methods, treatment of skewed arches, distribution of loading.
• Half-Through Girders: Eigenvalue extraction, NLFE analysis, treatment of imperfections.
• Composite action: Incidental composite action, SLS and ULS treatment, Partial composite action.
• Rivet shear: Group action, rivet head losses.

Presentation by Darren Kimberley, Scott Wilson Kirkpatrick

Recent and Current Research

• Chloride extraction/desalination trial - risk of generating ASR.
• Trial on two types of embedded sacrificial anode (CP).
• Deterioration model - for programming refurbishment and replacement of number of piers on long span viaduct.
• Bond test on plain bars - in regions where cover is delaminated.

Proposed Research Needs

• Patch repairs – allowing for contribution of reinforcement to allow greater areas of concrete breakout.
• Corrosion of steel piles
• Integral abutments - lateral earth pressures.

Presentation by Mike Chubb, WS Atkins

 Presentation

Recent and Current Research

• Behaviour/strength of deteriorated structures   Design rules have been developed.
• NDT – review of different techniques, measurement of stresses, corrosion.
• Real strength of structures -   Including testing of distribution of shear in slabs.
Eurocodes – advice to HA on implementation.
• Cathodic protection
• Precast deck panels for composite bridges
• Casting of concrete on live structures -   Vibration issues.
• Risk assessments/reliability analysis
• Prioritisation and condition indicators for bridges.

Proposed Research Needs

• Integral bridges
• HA research targeted at HA bridges.   Need to take account of CSS/LA structures
• Pedestrian loading - Discomfort criteria
• Target reliability - (definition)
• CP:  There is a requirement to remove concrete to behind reinforcement – alternative approaches?

Presentation by Paul Jackson, Gifford & Partners

Recent and Current Research

• Impact in UK codes - BD37 based on "wheel hop" analysis at frequency of 10Hz.   Work for BD21 looks at body bounce.   Dynamic response different at SLS and ULS.
• Arches -  Use of discrete element analysis, use of design strengthening.

Presentation by Steve Denton, Parsons Brinckerhoff

Recent and Current Research

• Strength of concrete structures:   Extensive work in following areas:
  • Ductility, NLFE analysis, plasticity theory
  • Compressive Membrane action
  • Anchorage/shear near supports with short anchorage lengths.
• Buried structures – distribution of load effects and impact factors.
• Applications of FRP: Extensive work in following areas:
  • Development of design guidelines for strengthening, bond behaviour, anchorage, sensitivity to cracking
  • Thermal effects and strengthening of metallic structures
  • FRP for new construction
• Durability and deterioration - Including large, internally funded research project into Sulfate attack of concrete structures.
• Preventative maintenance strategies for bridges - Deterioration modelling, reliability analysis.

Proposed Research Needs

• Strengthening applications using FRP: Fundamental work required to better understand basic mechanics.
• Deterioration behaviour and modelling for concrete structures