AN INNOVATIVE APPROACH TO SMALL BRIDGE REHABILITATION Peter Marchant ITS Pipetech Pty Ltd, NSW Australia
Introduction
Summary Since first construction our principle infrastructure we are witnessing Increasing traffic frequency Heavier loading Requirement for a longer working life Increasing demands on Design Ever changing Design Codes Less opportunity for infrastructure closures Need for a different approach to maintain serviceability Keep the infrastructure open
Alternative to New Build Planned Inspections Maintenance & Remediation Think out of the Box Understand the Demands on the Structure Simple information provision can save significant cost
Conditions leading to failure Deteriorating Arch ring material Loss of Arch thickness Foundation movement Loss of Arch support Foundation scour Impact damage Weak or uncompacted or over compacted fill Water ingress and erosion Poor design
Simple Testing Hammer Testing Acoustic Emission Radar Thermal Imaging Ultrasonic Testing
Loading
Considerations & Assumptions Consider the original methodology of construction Potential loss of bedding and support at the side zones and deteriorated condition Full or partial rehabilitation In the absence of physical data assume the worst and design as a stand alone element
Modelling Modeling using the FE analysis program i.e. Strand 7, Plaxis etc. Two dimensional Beam model to represent the point load test as AS/NZ3725 Three Dimensional Modelling Outputs determine the Concrete and Reinforcement requirements
Design
Philosophy & Parameters Designed as a Buried pipe to Australian Standard AS/NZ3725 Loading to AS/NZ5100 Road & rail Deflection and point load tests to AS/NZ 4058 Concrete design in accordance with AS 3600 Design life requirement - 100 years
Design Considerations Soil cover Deformation Extent of Corrosion Rail & Road loading Soil Modulus Support Zone Compaction probing
Concrete Mix Design Need to ensure Quality in consistent concrete is fundamental Designs to AS3600 Test and trial mixings Computer controlled batching for mix traceability Mix blending is critical QA testing and site checks fundamental
Concrete & Rebar design Reinforcement Specifications Single or Twin Cage Reo Elliptical cages Deformed bar- N12 to N20 Distribution bar N12 to N16 Steel Dramix fibre Concrete Specifications 40, 50 & 60 Mpa special design mix - 10mm aggregate with super plasticizer Fly Ash or GGBS replacement
Temporary Works Super strong light weight modular panel system Each Panel weighing less than 60 Kg Smooth external surface Design checked using FE modelling Design sign off to Australian Standards
Profiles
Using Tunneline for Rehabilitation on Bridges Full profile Rehab Top Arch Abutments Parabolic Arches Jack Arches Box Bridges
Applications Arch Bridges Flat deck bridges Circular Culverts Elliptical Bridge Culverts Box Bridge Culverts Pedestrian Underpass
Installation
Installation Initially set the invert Followed by sides Finally crown panel Stop End Concrete Strike and move forward
Site Quality Control Reinforcement Accuracy in placement Stability of the cage during erection Quality Procedures to ensure standards are met Final sign off pre formwork erection
Quality Control Site Procedures Developed ITP with hold & verification points Concrete Testing pre start Design verification by third party Pre shutter build check sheet Pre pour check sheet Concrete Slump and Cylinder tests Final visual inspection Pre Pour Inspection Quality Management ITS-FM-QA-069 [1] DETAILS OF POUR Shutter (to Erection be completed Tolerance Checklist and approved prior to pour) Quality Management ITS-FM-QA-077 [1] CONTRACT/SITE NAME: DATE: ITS ENGINEER: CONTRACT NAME: CONTRACT No: DATE: DAY: ENGINEER: ITS SUPERVISOR: CONTRACT No: DAY: SUPERVISOR: CONTRACTOR: CONTRACTOR: WEATHER: SHUTTER SIZE: DRAWING SHAPE: NO: SUPPLIER: AMBIENT CHAIN TEMP: WIDTH LEVEL INSTALLATION DATE CHAIN METHOD: WIDTH DATE HEIGHT HEIGHT LEVEL 52 2 TESTING REQUIREMENTS: 4 54 SHUTTER SIZE: SHAPE: CLEANLINESS 56 REINFORCEMENT 58 WITHIN TOLERANCES PERMIT TO LOAD 6 8 10 CHAIN YES NO YES 60 NO YES NO YES NO 12 62 36 86 Tolerances Height :- Plus or Minus 15mm 38 88 Width :- Plus or Minus 15mm 40 90 SITE Level Q.A :- FILE Plus or Minus 5mm DISTRIBUTION 42 92 48 98 SIGNED FOR ITS DATE & TIME SIGNED FOR VicRoads DATE & TIME 50 100 DISTRIBUTION SITE Q.A FILE CLIENT OTHERS 14 64 16 66 18 68 20 70 22 72 Tolerances Height :- Plus or Minus 15mm 24 74 Width :- Plus or Minus 15mm 26 76 Level :- Plus or Minus 5mm 28 78 30 80 32 82 34 84 CLIENT 44 94 OTHERS 46 96
Benefits 100 Year Design Life No disruption to the operational infrastructure above Flood Immunity is not compromised No Road or Track Closures Uses time tested materials Designed to Australian Standards Low carbon footprint Quick Program times
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