Bridge Engineering Research at The University of Sheffield

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Bridge Engineering ResearchatThe University of
Sheffield

• Dr Paul Reynolds
• Vibration Engineering Section
• http//vibration.shef.ac.uk/

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The Department of Civil and Structural Engineering

• 27 academics 11 in structures
• Particular research strengths in
• structures (dynamics, NFR, fire, computational
  mechanics)
• concrete materials (durability, sustainability)
• groundwater protection and restoration
• Areas of interest specific to bridge engineering
• use of FRP composites in bridges
• masonry arch bridges and parapets
• vibration serviceability of footbridges

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The Centre for Cement and Concrete (CCC)

• Established 1993
• Director Professor Peter Waldron
• Academic Members 17
• Researchers 48
• Manager Dr Kypros Pilakoutas

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Vibration Engineering Section

• VES was established by Prof. Peter Waldron in
  1993
• Currently managed by Drs Paul Reynolds and
  Aleksandar Pavic
• Expertise in vibration serviceability of civil
  engineering structures, including
• floors
• sports stadia
• footbridges

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London Millennium Bridge
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Vibration Serviceability of Footbridges

• VES has been engaged in footbridge VS research
  since 1993
• London Millennium Bridge raised awareness of the
  problems
• SLE is a relatively uncommon particular problem
  that needs to be fully understood
• there are much more common issues that require
  further research

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Areas of Current Uncertainty
Synchronous Lateral Excitation (SLE)
Source
Path
Receiver

• Pedestrian Excitation
• individual pedestrians
• small groups
• large crowds
• Vandal Loading
• Non-Pedestrian Excitation

• Modelling
• inclusion of non- structural components
• boundary conditions
• simplified methods?
• Designing in Damping
• the future?

• Acceptable Levels of
• Vibration
• stationary vs. moving
• Levels of Vibration to
• cause lock-in
• horizontal
• vertical

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VES Approach to VS
Analytical Modelling
Dynamic Testing

• Finite Element Analysis
• (usually ANSYS)
• MATLAB simulations
• time domain simulations using convolution
  methods
• Monte-Carlo simulations to examine
  statistical models of human excitation

• Modal Testing
• using shaker excitation
• using natural/ambient excitation
• Vibration Response
• Measurements
• controlled pedestrians
• vandal loading
• Remote Monitoring

• FE model correlation
• MAC/COMAC etc.
• FE model updating
• FEMtools software

LEARNING HOW TO MODEL BETTER FOOTBRIDGEDYNAMICS
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Shaker Modal Testing

• Aberfeldy Footbridge Scotland

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Shaker Modal Testing
Input
LinearSystem
Output
controlled shaker excitation
acceleration response measurement
natural frequencies mode shapes modal damping
ratios modal masses
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Shaker Modal Testing

• Lateral Modes

f 0.98 Hz ? 1.0
f 2.73 Hz ? 1.2
f 5.72 Hz ? 1.7
f 8.50 Hz ? 2.7
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Shaker Modal Testing

• Vertical Modes

f 1.52 Hz ? 0.4
f 1.86 Hz ? 0.70
f 2.49 Hz ? 0.7
f 3.01 Hz ? 0.8
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Shaker Modal Testing

• Torsional Modes

f 3.48 Hz ? 5.5
f 4.29 Hz ? 3.2
f 5.10 Hz ? 4.2
f 6.05 Hz ? 3.3
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Shaker Modal Testing of London Millennium Bridge
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Ambient Vibration Testing

• Royal Victoria Dock Bridge London

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Ambient Vibration Testing
f 0.39 Hz ? 1.7
f 1.27 Hz ? 0.8
f 2.58 Hz ? 0.4
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Pedestrian Response Tests
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Areas of Current Uncertainty
Areas for Future Research
Synchronous Lateral Excitation (SLE)
Source
Path
Receiver

• Pedestrian Excitation
• individual pedestrians
• small groups
• large crowds
• Vandal Loading
• Non-Pedestrian Excitation

• Modelling
• inclusion of non- structural components
• boundary conditions
• simplified methods?
• Designing in Damping
• the future?

• Acceptable Levels of
• Vibration
• stationary vs. moving
• Levels of Vibration to
• cause lock-in
• horizontal
• vertical

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Driving Interests for FRP
High strength
Durability
Low weight
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Eurocrete Case Studies
ChalgroveFootbridge(1995/96)
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Eurocrete Case Studies
Oslo Footbridge(1996/97)
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US Department of Transportation
Sierrita de la Cruz Creek Bridge(2000)
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Research on FRP at Sheffield
Bond
Column Confinement
EBR
Flexure and Cracking
RC
Design Philosophy
Plate Bonding
Punching Shear
Shear Strengthening
Shear
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Sheffield Involvement in FRP Research
fib Task Group 9.3http//allserv.rug.ac.be/smatt
hys/fibTG9.3
Eurocrete Project (94-97)
CurvedNFRCRAFT Eureka (03-05)http//www.curvednf
r.com
EU TMR ConFibreCreteNetwork (97-02)http//www.sh
ef.ac.uk/tmrnet
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Required Bridge Research on FRP

• Demonstration/monitoring projects
• Design Guidelines
• Whole-life costing studies

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Permanent Formwork

• Permanent Formwork Systems

Steel decking Corrosion Fire protection Constant
thickness One way spanning Need additional
finishes
Pre-cast concrete Heavy
GRC Low stiffness (tensile stress?) Small (12 m
span) panels
Omni-plank type Crack in tension zone during
casting
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GRC Permanent Formwork
Drainage
Architectural

• Light self-weight
• Easy to create complicatedshapes
• Good Durability of the cover
• Fast to install
• Corrosion protection to thesteel reinforcement

Bridges
Tunnels
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Bridge Permanent Formwork

• Combination of new materials
• Development of integrated permanent formwork
  solutions
• Solve the problem of formwork connections
• Case studies
• Design guidelines

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Steel Fibres Recycled from Waste Tyres
Tyre Recycling
Research Work
Shredded
Bending Tests
Bond Tests
Cube Tests
Design Rules
Pyrolysed

• Bridge Applications
• Foundations
• Decks

http//www.shef.ac.uk/tyre-recycling
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Masonry parapet research

• EPSRC project (also involving Universities of
  Liverpool Teesside) recently completed
• Concerned with (i) fundamental behaviour (ii)
  developing reinforcement strategies
• Key findings
• Typically failure via large-panel formation
  (resistance then due to inertia base friction)
• But very weakly mortared walls fail in loose
  block failure modes
• Diagonal reinforcement effective (even when
  mortar bond v. weak)
• Analysis tools now developed which can simulate
  behaviour in many cases

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Masonry parapet researchpotential follow-on work

• Do bridge owners wish to support follow-on
  developments?
• Transformation of mechanism analysis research
  software into usable tool for practitioners
• Update CSS guidance note and BS6779-4 to reflect
  our much improved understanding of how masonry
  parapet walls resist vehicle impacts

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Masonry parapet researchmechanism analysis
software

• Method (published in Int. J. Impact Eng, 2002)
  identifies critical mechanism from a library of
  possible ones
• Quick easy to investigate the influence of
  different parameters

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Masonry parapet research update to design codes

• Original numerical modelling work which
  underpinned CSS document and BS6779-4 has now
  been significantly improved upon
• Also potential for inclusion of more guidance on
  reinforcement strategies

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RING1 Masonry arch bridge analysis software

• Sophisticated masonry block modelling capability
• Simple uncoupled backfill interaction model

1funded to date by Network Rail
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Current backfill interaction models
Lateral earth pressures based on modified Rankine
theory
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Key Project Aims

• Development of RING to include fully coupled
  modelling of soil and masonry elements
• Develop optimised field investigation techniques
  for backfill characterisation
• Calibrate on field, model and laboratory tests
  load and kinematic data

Work sponsored by Essex County Council in
collaboration with Mouchel Essex
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Image analysis provides soil displacement vectors
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Additional aims

• Incorporate current geotechnical design code
  principles into assessment methodology
• Develop soil and masonry reinforcement modelling
  capability in RING with automatic optimisation
  (sponsored by EPSRC)

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For more information

• Dr Paul Reynolds
• Tel [phone]
• p.reynolds_at_sheffield.ac.uk
• Web sites
• http//vibration.shef.ac.uk/
• http//www.shef.ac.uk/civil/
• This presentation will be posted at
• http//vibration.shef.ac.uk/presentations/bridgefo
  rum/