BridgeInspectionManual (QLD)

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Bridge Inspection

Manual

Prepared byBridge Asset ManagementStructures DivisionRoad Systems & Engineering


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DC1 June 2004

BridgeInspectionManual

Second Edition, June 2004

Registration Number 80.640

Issued by theQueensland Department of Main RoadsRoad System and Engineering

For document content enquiries:- Principal EngineerBridge Asset ManagementPhone: (07) 3834 2556Facsimile: (07) 3834 2065

For document distribution enquiries:- Road System & EngineeringTechnical Reference Centre

Phone: (07) 3834 5488Facsimile: (07) 3834 2612


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DC1 June 2004

Bridge Inspection Manual

First Published 2000Second Published 2004

COPYRIGHT

State of Queensland (Department of Main Roads) 2004

Copyright protects this publication. Except for the purposes permitted by and subject tothe conditions prescribed under the Copyright Act, reproduction by any means (includingelectronic, mechanical, photocopying, microcopying or otherwise) is prohibited without theprior written permission of the Queensland Department of Main Roads. Enquiriesregarding such permission should be directed to the Road Network Management Division,Queensland Departmentof Main Roads.

DISCLAIMER

This publication has been created for use in the design, construction, maintenance andoperation of road transport infrastructure in Queensland by or on behalf of the State ofQueensland.

The State of Queensland and the Department of Main Roads give no warranties as to thecompleteness, accuracy or adequacy of the publication or any parts of it and accepts noresponsibility or liability upon any basis whatever for anything contained in or omitted fromthe publication or for the consequences of the use or misuse of the publication or any partsof it.

If the publication or any part of it forms part of a written contract between the State ofQueensland and a contractor, this disclaimer applies subject to the express terms of thatcontract.


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CONDITIONS OF USE

This manual is intended for use by Main Roads under the following conditions :-

1. Staff using the manual have appropriate training, experience and, where necessary,supervision by a competent engineer

2. Decisions effecting the overall safety of the bridge or critical elements are made orimmediately reviewed by a senior structural engineer from Structures Division.

This manual may be used by Local Government for a similar purpose. They must ensuretheir staff are also appropriately trained and experienced, and seek advice from competentbridge engineers when decisions regarding public safety have to be made.


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BRIDGE INSPECTION MANUAL

The economy of Queensland is based on the free movement of heavy loads. Bridges are a

key element in the road network, and it is essential that their condition is monitored and

essential repairs planned and completed to an appropriate timescale. This manual sets out the

process for ensuring that bridges have adequate strength for the safe movement of heavy

loads across our 2500 bridges and many thousands of major culverts.

This document establishes a statewide policy, systematic inspection and reporting procedures

and data management requirements for bridge inspections. It also identifies those

accountable for implementing the policy and the inspector's accreditation requirements for

the various levels of inspection.

It is intended that this manual will be improved over time with use and, to that end, it is

requested that users refer suggested improvements to Principal Engineer (Bridge Asset

Management) of Structures Division using the BAMANDSRS Advice Notes system.

J M Fenwick

Executive Director (Structures Division)


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Project Sponsor

John Fenwick, Executive Director (Structures Division)

Project Manager

Peter Graham, Principal Engineer (Bridge Asset Management)(Tel: (07) 3834 2556, Fax: (07) 3834 2065)(E-mail: [email protected])

Project Team

John Best, Principal Engineer (Bridge Services)Alan Carse, Principal Engineer (Concrete Technology)David Cole, Computer Systems Officer (Design Systems)

Julie Keene, Typist

Acknowledgments

This manual is based on the "VicRoads - Bridge Inspection Manual" which has been modifiedto reflect the bridge stock and operational requirements of the Department of Main Roads,Queensland. Acknowledgment is hereby made of the use of that document and the generousassistance provided by VicRoads in general and Mr Ken McGregor in particular.

Reproductions

Reproduction of extracts from this publication may be made subject to due acknowledgment ofthe source.

Revision History

Version Date Prepared by Comments

1 May 1998 Bridge Asset Management

(Transport Technology Division)

Draft

(for trial use)1 January 2000 Bridge Asset Management(Transport Technology Division)

Release

1 September 2000 Bridge Asset Management(Structures Division)

Amendment No. 1

2 June 2004 Bridge Asset Management(Structures Division)


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TABLE OF CONTENTS

Part One: Policy Page Nos

1.0 Bridge Management System........................................................................1.2

1.1 Background and Objectives.........................................................................1.2

1.2 Scope...............................................................................................................1.3

1.3 Accountabilities.............................................................................................1.4

1.4 Bridge Information.......................................................................................1.5

1.5 Inspection Requirements..............................................................................1.5

1.5.1 - Level 1 - Routine Maintenance Inspection......................................1.61.5.2 - Level 2 - Bridge Condition Inspection.............................................1.81.5.3 - Level 3 - Detailed Structural Engineering Inspection..................1.11

Part Two: Deterioration Mechanisms

1.0 Material Defects............................................................................................2.5

1.1 General...........................................................................................................2.5

1.2 Concrete.........................................................................................................2.5

1.2.1 Corrosion of reinforcement..............................................................2.51.2.2 Carbonation.......................................................................................2.61.2.3 Alkali - Silica Reaction (ASR).........................................................2.61.2.4 Cracking.............................................................................................2.61.2.5 Spalling...............................................................................................2.81.2.6 Surface Defects..................................................................................2.91.2.7 Delamination...................................................................................2.10

1.3 Steel ...........................................................................................................2.11

1.3.1 Corrosion.........................................................................................2.111.3.2 Permanent Deformations...............................................................2.111.3.3 Cracking...........................................................................................2.121.3.4 Loose Connections..........................................................................2.13

1.4 Timber..........................................................................................................2.14

1.4.1 Fungi.................................................................................................2.141.4.2 Termites...........................................................................................2.15

1.4.3 Marine Organisms..........................................................................2.161.4.4 Corrosion of Fasteners...................................................................2.17


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1.4.5 Shrinkage and Splitting..................................................................2.171.4.6 Fire...................................................................................................2.181.4.7 Weathering......................................................................................2.19

1.5 Masonry.......................................................................................................2.20

1.5.1 Cracking...........................................................................................2.201.5.2 Splitting, Spalling and Disintegration...........................................2.201.5.3 Loss of Mortar and Stones.............................................................2.20

1.6 Protective Coatings.....................................................................................2.21

2.0 Common Causes of Older Bridge Deterioration......................................2.22

2.1 Concrete Bridges.........................................................................................2.22

2.1.1 Monolithic and simply supported T-beams..................................2.222.1.2 Precast I beams...............................................................................2.232.1.3 Precast prestressed inverted "T" beams......................................2.232.1.4 Box Girder Bridges.........................................................................2.232.1.5 Prestressed Voided Flat Slab Bridges...........................................2.242.1.6 Reinforced Concrete Flat Slabs.....................................................2.242.1.7 Precast Prestressed Deck Units......................................................2.242.1.8 Precast Prestressed Voided "T" Slabs..........................................2.252.1.9 Decks and Overlays.........................................................................2.252.1.10 Diaphragms.....................................................................................2.262.1.11 Kerbs, Footways, Posts and Railing..............................................2.262.1.12 Abutments........................................................................................2.272.1.13 Piers..................................................................................................2.28

2.2 Steel Bridges................................................................................................2.29

2.3 Timber Bridges............................................................................................2.30

2.3.1 Timber Girders...............................................................................2.302.3.2 Corbels.............................................................................................2.312.3.3 Decking (timber and steel trough).................................................2.31

2.3.4 Kerbs, Posts and Railing................................................................2.332.3.5 Piles...................................................................................................2.332.3.6 Walings and Crossbraces...............................................................2.342.3.7 Headstocks.......................................................................................2.352.3.8 Abutments........................................................................................2.35

2.4 Deck J oints...................................................................................................2.37

2.5 Bearings.......................................................................................................2.39

2.6 Other Structure Types................................................................................2.40

2.6.1 Box Culverts....................................................................................2.40


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2.6.2 Pipe Culverts...................................................................................2.40

2.7 Causes of deterioration not related to bridge materials..........................2.41

2.7.1 Damage due to Accidents...............................................................2.41

2.7.2 Drainage...........................................................................................2.412.7.3 Debris...............................................................................................2.422.7.4 Vegetation........................................................................................2.422.7.5 Scouring of Foundations.................................................................2.422.7.6 Movement of the Structure............................................................2.422.7.7 Condition of Approaches................................................................2.43

3.0 References....................................................................................................2.45

Part Three: Procedures

1.0 General..........................................................................................................3.31.1 Levels of Inspection..........................................................................3.31.2 Safety.................................................................................................3.31.3 Bridge Component Designation......................................................3.41.4 Advice Notes.....................................................................................3.5

2.0 Level 1 - Routine Maintenance Inspections...............................................3.62.1 Purpose..............................................................................................3.62.2 Scope..................................................................................................3.62.3 Frequency of Inspections.................................................................3.5

2.4 Extent of Inspections........................................................................3.62.5 Inspector Accreditation...................................................................3.72.6 Inspection Procedure.......................................................................3.7

2.6.1 Preparation for Inspection..................................................3.72.6.2 Inspection..............................................................................3.7

2.7 Data Recording...............................................................................3.10

3.0 Level 2 - Bridge Condition Inspections....................................................3.123.1 Purpose............................................................................................3.123.2 Scope of the Inspection..................................................................3.123.3 Inspector Accreditation.................................................................3.13

3.4 Extent of Inspection.......................................................................3.133.5 Inspection Procedure.....................................................................3.14

3.5.1 Preparation for Inspection................................................3.143.5.2 Inspection............................................................................3.15

3.6 Data Recording...............................................................................3.163.7 Data Transfer .................................................................................3.163.8 Condition Rating............................................................................3.17

3.8.1 General................................................................................3.173.8.2 Compilation of the Component Inventory.......................3.173.8.3 Condition State Criteria....................................................3.193.8.4 Component Condition Assessment...................................3.19

3.8.5 Measurement......................................................................3.203.8.6 Structure Condition Assessment ......................................3.22


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3.8.7 Exposure Classifications....................................................3.223.9 Inventory Data...............................................................................3.233.10 Timber Drilling Survey.................................................................3.243.11 Measurement of Scour...................................................................3.25

4.0 Level 3 - Detailed Structural Engineering Inspection............................3.264.1 Purpose............................................................................................3.264.2 Scope................................................................................................3.264.3 Inspector Accreditation.................................................................3.274.4 Frequency.......................................................................................3.274.5 Extent of Inspection.......................................................................3.274.6 Inspection Procedure.....................................................................3.284.7 Data Recording in the Field..........................................................3.284.8 Reporting........................................................................................3.284.9 Load Capacity................................................................................3.29

Appendix A: Inspection Report Forms - Proforms and Samples

Appendix B: Standard Component Schedule

Appendix C: Standard Component Identification Guidelines

Appendix D: Standard Component Condition State Guidelines

Appendix E: Inspector Accreditation Appraisal Procedure

Appendix F: Guidelines for the Management of Sub-Standard andDefective Bridges

Appendix G: Breakdown of Complex and Non-Standard Structures

Appendix H: Advice Notes

LIST OF FIGURESPart One: Policy

Figure 1.1 - Bridge Asset Management System Framework

Figure 1.2 - Bridge Asset Management Mechanisms

Figure 1.3 - Bridge Information System Overview

Table 1.5 - Summary of Structure Inspection Frequencies

Part Two: Deterioration Mechanisms


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Figure 1.2.1 (a) - Corrosion of Headstock Reinforcement due to Chloride IonPenetration in a Marine Environment

Figure 1.2.1 (b) - Corrosion of Reinforcement in the Soffit of a Cast Insitu

Culvert due to Carbonation

Figure 1.2.1 (c) - Calcium Chloride Induced Corrosion of Suspended SlabSoffit in an RCBC

Figure 1.2.1 (d) - Spalling due to Calcium Chloride Distress in an RCBC

Figure 1.2.1 (e) - Corrosion Of Reinforcement And Spalling Of Cantilever SoffitDue To Poor Cover And Chloride Penetration

Figure 1.2.1 (f) - Corrosion Of Reinforcement And Spalling Of Deck Slab

Surface Due To Poor Cover And Chloride Attack

Figure 1.2.2 (a) - Carbonation Testing of a Freshly Broken Concrete Core

Figure 1.2.2 (b) - Carbonation Induced Corrosion

Figure 1.2.3 (a) - General View of Longitudinal Cracking due to ASRin Prestressed Deck Units

Figure 1.2.3 (b) - View of Deck Unit Soffit Cracking due to ASR

Figure 1.2.3 (c) - View of Vertical Crack due to ASR in a Prestressed Pile

Figure 1.2.3 (d) - View of ASR Gel Exudations

Figure 1.2.4 (a) - Cracking of Structures

Figure 1.2.4 (b) - Severity of Cracking

Figure 1.2.4 (c) - Plastic Settlement/Shrinkage Cracking in a Bridge Deck

Figure 1.2.4 (d) - Plastic Cracking Passing Completely Through a Bridge Deck

Figure 1.2.4 (e) - Shear Crack In R.C. Headstock

Figure 1.2.4 (f) - Bursting Cracks In Anchorage Zone Of Post-Tensioned Girder

Figure 1.2.4 (g) - Accurate Measurement of Crack Widths

Figure 1.2.8 (a) - General View of Prestressed Pile

Figure 1.2.8 (b) - Water Wash Including Aggregate Particles Causing

Abrasion of Pile Surface


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Figure 1.3.3 - Common Crack Locations of Steel 1Common Crack Locations of Steel 2

Figure 1.4.1 (a) - Fungal Fruiting Body and Decay of Girder

Figure 1.4.1 (b) - Rot Pocket in Girder

Figure 1.4.2 (a) - Termite damage in Deck Planks

Figure 1.4.2 (b) - Section of Pile Showing Termite Nest in Internal Pipe

Figure 1.4.2 (c) - Termite Galleries On Pile And Headstock

Figure 1.4.5 (a) - Splitting in Timber Girder

Figure 1.4.5 (b) - Splitting in Timber Pile

Figure 1.4.7 (a) - Weathered and Rotted Timber Deck Planks

Figure 1.4.7 (b) - Rotted Ends of Deck Planks

Figure 2.3.3 (a) - Corrosion of J oints Between Trough Sections

Figure 2.3.3 (b) - Cracking and Perforating of Steel Troughing

Figure 2.3.5 - Rotting of Abutment Pile Below Ground Level

Figure 2.4.1 (a) - Scour of Stream Bed and Significant Loss of Material AroundPier Pilecaps and Piles

Figure 2.4.1 (b) - Localised Scour of Stream Bed and Debris Build-Up AroundPier Piles

Figure 2.6.2 (a) - General View of Masonry Pipe Culvert, Showing Efflorescenceand Spalling of Base Brickwork

Figure 2.6.2 (b) - View of Efflorescence and Staining due to Chemical Leaching

of Mortar

Part Three: Procedures

Figure 1.0 - Standard Component Matrix

Figure 1.3 - Bridge Component Designation

Figure 1.4 - Culvert Component Designation

Figure 1.5 - General Terminology for Bridges

Figure 1.6 - General Terminology for Timber Bridges


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Figure 1.7 - General Terminology for Masonry Bridges

Figure 1.8 - Terminology for Precast Crown Culverts

Figure 1.9 - Terminology for Slab Deck Culverts

Figure 1.10 - Terminology for Modular Culverts


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PART ONEPolicy


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Bridge Asset Management BRIDGE INSPECTION MANUAL 1.1Structures Division PART ONE POLICY J une 2004

TABLE OF CONTENTS

Part One: Policy

Page Nos

1.0 Bridge Management System........................................................................1.2

1.1 Background and Objectives.........................................................................1.2

1.2 Scope...............................................................................................................1.3

1.3 Accountabilities.............................................................................................1.4

1.4 Bridge Information.......................................................................................1.5

1.5 Inspection Requirements..............................................................................1.6

1.5.1 - Level 1 - Routine Maintenance Inspection......................................1.6

1.5.2 - Level 2 - Bridge Condition Inspection.............................................1.8

1.5.3 - Level 3 - Detailed Structural Engineering Inspection..................1.11

LIST OF FIGURES

Figure 1.1 - Bridge Asset Management System Framework

Figure 1.2 - Bridge Asset Management Mechanisms

Figure 1.3 - Bridge Information System Overview

Table 1.5 - Summary of Structure Inspection Frequencies


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PART ONE - BRIDGE INSPECTION POLICY

1.0 Bridge Asset Management System (BAMS)

The BAMS has been developed to ensure that the bridge assets of the DMR aremanaged effectively and efficiently. Bridge inspection and condition rating is an

integral component of the BAMS and its relationship with other principal componentsof the system is shown in the system framework diagram (Figure 1.1) and in themechanisms used to deliver desired outcomes (Figure 1.2).

The primary objective of the BAMS is to establish an integrated and accessibleinformation system for bridge inventory, condition, load capacity and inspection andworks history. The Bridge Information System (BIS) has been developed for thispurpose, as detailed in the BIS overview (Figure 1.3).

1.1 Background and Objectives

Inspection regimes had traditionally been established and managed independently bythe various District offices within the constraints of other demands on limitedresources. As a consequence there had been a large variation in the extent andfrequency of bridge inspections and the format and consistency of the inspectionresults and records.

In order that the network may be managed effectively a systematic statewideinspection and condition rating and monitoring system is required to enable managersto identify maintenance needs, assess the effectiveness of treatments, model patternsof deterioration and forecast future maintenance, rehabilitation and replacement

budget needs. This document establishes statewide procedures for inspection andcondition rating and includes requirements for inspection scope and frequency,documentation, data management and accreditation levels. It also identifies thoseresponsible for implementing the policy.

The purpose of this policy is to ensure that the condition of all structures issystematically monitored to ensure that conditions which may lead to severestructural damage or collapse are identified as soon as possible in order that theappropriate intervention or remedial action may be undertaken.

In addition, the data collected from the inspections may be used to:

Develop inspection and maintenance programmes. Carry out load capacity assessments. Provide feedback to the design process. Monitor the health of the bridge assets and effectiveness of maintenance

treatments on a local or statewide basis.


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1.2 Scope

This policy applies to the following structures:

All bridges. All culverts that have an opening span, height or diameter greater than 1.8

metres and a waterway area in excess of 3.0 square metres.

These structures have an opening large enough to:

walk through and are therefore capable of being inspected relatively easily. close the road and create a significant safety hazard in the event of structural

failure.

All structures complying with these criteria will be allocated a unique number in the

Bridge Information System (BIS) and in addition will be physically numbered topermit ready identification in the field. However an additional, optional module hasbeen included in the BIS which will permit Districts to record data on "other"structures if desired. In this event the Districts can adopt a local numbering system tolocally manage these assets. It is anticipated that these smaller structures shall bemanaged through the RMPC system.

The policy also identifies accountabilities for bridge management and establishes therequirements for data management and a systematic inspection and condition ratingprogramme. The latter is achieved through a three level hierarchy of inspectionscomprising:

Level 1 - Routine Maintenance Inspections Level 2 - Bridge Condition Inspections and Level 3 - Detailed Structural Engineering Inspections


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1.3 Accountabilities

District Directors are accountable for the management of all bridges on the Statecontrolled road network. These management responsibilities include:

Development of uniform, consistent and cost effective inspectionprogrammes; including quality assurance systems, accreditation of inspectorsand the co-ordination of joint services among districts.

Monitoring the delivery of the bridge inspection programme. Ensuring that Routine Maintenance Inspections are carried out at least once

every twelve months, inspection data is monitored and recorded andrecommendations are actioned.

Ensuring that Bridge Condition Inspections are carried out at the requiredfrequencies, inspection data is monitored and recorded and recommendationsare actioned.

Ensuring that the required "Maintenance Activities" are recorded, entered inthe BIS and managed effectively.

Commissioning Detailed Engineering Inspections, investigations and analysiswhen required, and ensuring that recommendations are actioned.

Ensuring that all inspection data is transferred to the Bridge InformationSystem within 30 days of its collection. However, in the event that a defectivestructure is detected, all inspection data shall be entered into the BIS as soonas is practicably possible.

Development of "Structure Management Plans" in accordance with theguidelines in Appendix F. Plans are to be developed in conjunction withStructures Division, for all defective structures.

Executive Director (Structures) through Principal Engineer (Bridge AssetManagement) is accountable for:

Promulgating and monitoring the implementation of this policy. Developing, implementing and maintaining the Bridge Information System

and providing the necessary access and reporting mechanisms for all DMRpersonnel involved in bridge management.

Ensuring the technical adequacy of the specified inspection processes. Developing and supporting the technical procedures; including the preparation

of the supporting manuals and the training and accreditation programmes

necessary to implement this policy.


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Monitoring the delivery of the bridge inspection programme through a dataand physical auditing programme.

Supplying the specialist resources to enable PE (BAM) to develop, implementand support the Bridge Inspection Manual and attendant procedures andprocesses. This includes Bridge Asset Management Section arranging orcarrying out detailed structural engineering inspections for the Districts.

Executive Director (Road Network Management) through Director (RoadsInformation) is accountable for:

Providing resources to maintain and audit data that is held in the BIS. Providing resources to develop and maintain the BIS IT system through the

ARMIS service request (ASR) system.

Providing resources to train and support BIS and mobile-BIS users. Ensuring that current bridge inspection forms are available on the BIS. Maintaining an accredited bridge inspectors register. Supporting the BIS Functional Manager Principal Engineer (Bridge Asset

Management).

1.4 Bridge Information

Comprehensive bridge inventory and condition data will be recorded in the BridgeInformation System (BIS), which is maintained by the Executive Director (RoadNetwork Management). This system provides accessible and timely information toall DMR personnel involved in bridge management and is integrated with ARMIS.This connects all related bridge and road data through a common location referencesystem. Refer to Figure 1.3 for an overview of the system.

The District Director will act as an agent for Executive Director (Road NetworkManagement) and is responsible for entering and managing the inventory, inspection,condition and maintenance data at the local level in accordance with the documentedguidelines for the BIS and this manual.

Details of the data recording requirements for the various inspection levels aredefined in the inspection requirements section.

In the past it has not been possible to compare past bridge maintenance expenditureand condition trends. The adoption of the unique numbering system for structuralassets will permit the tracking of all expenditure on the asset through the FinancialInformation Management System (FIMS).

The development of standard bridge maintenance activity costing procedures within

the RMPC and special maintenance and rehabilitation/strengthening programmeswould greatly assist this objective.


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1.5 Inspection Requirements

The safety and condition of bridges on the state road network is monitored through athree level hierarchical bridge inspection regime that was introduced in March 1998.The overall requirements are summarised in the Table 1.5 and the detailed

requirements for each category of inspection are listed independently. The frequencyof inspections is related to the structure type, age and condition depending on theassessed risk of deterioration or damage.

Where annual inspections are specified, they shall be undertaken not less than10 months nor greater than 14 months after the previous inspection.

In the case of biennial inspections, the range is 20-28 months after theprevious inspection.

If the inspection frequency is three years or greater then the tolerance is plusor minus six months.

1.5.1 Level 1 - Routine Maintenance Inspections

Purpose

A visual inspection to check the general serviceability of the structure, particularly forthe safety of road users, and identify any emerging problems.

Level 1 inspections may be carried out in conjunction with routine maintenance of the

structure and the adjacent pavement as part of the Road Maintenance PerformanceContract. (RMPC)

Scope

The scope of a Routine Maintenance Inspection will include:

Inspection of approaches, waterway, deck/footway, substructure,superstructure and attached services to assess and report any significantvisible signs of distress or unusual behaviour, including active scours or deckjoint movements.

Check of miscellaneous inventory items, including the type, extent andthickness of the bridge surfacing as well as details of existing services.

Recommendation of a Bridge Condition Inspection if warranted by observeddistress or unusual behaviour of the structure.

Identify maintenance work requirements, and record on the StructureMaintenance Scheduleform (M1).


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Verification of the Structural Inventory data held in the BIS as part of theinitial inspection and as required thereafter (standard forms can be producedfrom the BIS for this purpose)

Procedures and Inspector Accreditation

Routine Inspections shall be carried out in accordance with the Bridge InspectionProcedures - Level 1 (Refer to part 3 of the Bridge Inspection Manual) by anaccredited Bridge Inspector.

Frequency

Minimum frequency is generally one inspection per year for all structures, howeverfrequencies may be increased for defective structures as tabulated below or asstipulated in a specific "Structure Management Plan" as per the guidelines in

Appendix F. In addition, Routine Maintenance Inspections will also be carried outimmediately after flooding, fire or accident damage events. Level 1 inspections aregenerally not required in the same year as a Level 2 or 3 inspection.

Structure Type Condition State of Structure Inspection Frequency(years)

Timber structuresand steel culverts inwet environments

1-23-4

1*1**

Other structures1-234

1*1*1**

* Generally not required in same year as Level 2 or 3 inspection** Level 1 and Level 2 inspection cycles to be staggered by six months to ensure that

the structure is inspected every six months

Data Recording

The inspection is conducted using the "Routine Maintenance Inspection Report" formincluded in Appendix A.

The inspector shall forward a completed Routine Maintenance Inspection Report and,if applicable, a completed Structure Maintenance Schedule form, to the District

Office and the District data control officer shall record inspection data and anyrelevant actions, including the need for a condition or detailed engineering inspectionor maintenance requirements, in the Bridge Information System within 30 days of theinspection.

In addition the inspector shall forward a completed Structural Inventory VerificationForm in order that the current BIS data may be positively verified or amended within30 working days of the first Level 1 inspection


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1.5.2 Level 2 - Bridge Condition Inspections

Purpose

An inspection to assess and rate the condition of a structure (as a basis for assessing

the effectiveness of past maintenance treatments, identifying current maintenanceneeds, modelling and forecasting future changes in condition and estimating futurebudget requirements).

Scope

The scope of the Bridge Condition Inspection will include:

Compiling, verifying and updating inspection inventory element items asappropriate.

Visual inspection of the principal bridge components (including measurementof crack widths, etc.) and an assessment of condition using a standardcondition rating system as defined in the inspection procedures.

The inspection of timber bridges will be supplemented by a drillinginvestigation, and will also include the identification and reporting ofundersized timber members.

Soundings to determine the presence of active scour. Reporting the condition of the principal bridge components and determining

an aggregate rating of the structure as a whole.

Identifying and programming preventative maintenance requirements andrecording on theStructure Maintenance Scheduleform (M1). If accessequipment is required to conduct the inspection, then routine / preventativemaintenance may also be completed in conjunction with the inspection.

Requesting a detailed bridge inspection by a bridge engineer if warranted byapparent rapid changes in structural condition and/or apparent deterioration tocondition state 4.

Development of "Structure Management Plans" in conjunction with StructuresDivision for all defective structures. Refer to Appendix F for plan guidelines.

Underwater inspections of those elements in permanent standing water at thespecified frequency.

Recommending requirements for the next inspection and nominatingcomponents for closer monitoring as appropriate.

Recommending supplementary testing as appropriate.


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Completion of the Design Inventory data held in the BIS as part of theinitial inspection and as required thereafter (standard forms can be producedfrom the BIS for this purpose)

As these inspections may be carried out with the use of an Under Bridge InspectionUnit (UBIU), it is recommended that on such occasions District personnel takeadvantage of the availability of the UBIU and conduct routine maintenance on thosecomponents not normally accessible, such as bearings.

Condition Rating

The condition rating system shall reflect the performance, integrity and durability ofthe structure and its principal components. The assessment of the nature and extent ofdefects shall be detailed in the procedures as appropriate to each component type.The overall structure condition rating is based on the condition of its principal load

bearing components as described in Section 3.8.6 of Part Three. The condition ratingshave been developed to represent the easily discernible stages of deterioration astabulated below.

ConditionState

SubjectiveRating

Description

1 Good Free of defects

2 Fair Free of defects affecting structuralperformance, integrity and durability

3 Poor Defects affecting the durability which requiremonitoring, detailed structural engineeringinspection or maintenance.

4 Very Poor Defects affecting the performance and

structural integrity of the structure whichrequire urgent action as determined by adetailed structural engineering inspection.

5(whole structure

rating only)

Unsafe Bridge must be closed.

Procedures and Accreditation

Bridge Condition Inspections shall be carried out in accordance with BridgeInspection Procedures - Level 2 (Refer to Part Three of the Bridge InspectionManual) by an experienced Bridge Inspector or Bridge Engineer who has attended aLevel 2 training course and who has fulfilled the accreditation requirements stipulatedin Appendix E.


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Frequency

All new structures shall be given a Level 2 inspection prior to the end of the DefectsLiability period for the construction contract, and thereafter generally in accordancewith the frequencies tabulated below. The frequency of inspecting defective structures

may be increased as stipulated in a specific "Structures Management Plan"

Structure Type Condition State ofStructure

Inspection Frequency(years)

Timber or steelculverts in

wet environments

1-23

21**

Other 1-23

53

Components UnderWater

1-23

81

All 41** with "Structures

Management Plan"** Level 1 and Level 2 inspection cycles to be staggered by six months to ensure that

the structure is inspected every six months

These standard frequencies may be modified as a result of recommendations in aDetailed Engineering Inspection Report, and as agreed in the "Structure ManagementPlan" (refer Appendix F). Additional Level 2 inspections will be required when:

Recommended in a Level 1 - Routine Maintenance Inspection Report;

Major maintenance, rehabilitations or other modifications have been carriedout; and

Detailed Engineering Inspections are carried out.Data Recording

The inspector shall provide a report of the condition of the principal components ofthe structure, by defect and extent, in accordance with the standard components andreport proforma defined in Part 3 - Procedures - Level 2. The completed report shallbe downloaded from the data capture tool or entered manually in the Bridge

Information System within 30 working days of the inspections. However, in the eventthat a defective structure is detected, all inspection data should be entered as soon asis practicably possible.

The District data control officer shall ensure that the inventory and condition data arein the correct format and compatible with existing entries. This data and anyrecommended actions including inspection inventory amendments and the need for aDetailed Engineering Inspection or maintenance requirements shall be entered in theBIS.

In addition, the inspector shall forward a completed Design Inventory Verification

Form in order that the current BIS data may be positively verified or amended within30 working days of the first Level 2 bridge inspection.


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1.5.3 Level 3 - Detailed Structural Engineering Inspections

Purpose

An extensive inspection which may include physical testing and structural analysis to

assess the structural condition and behaviour of a structure, to identify and quantifythe current and projected deterioration of the structure, and to assess appropriatemanagement options.

Scope

The scope of a detailed Engineering Inspection and analysis will include:

Auditing the performance of the Districts Inspection Regime with respect tothe structure.

Detailed inspection of all relevant bridge components, including testing andanalyses as necessary to supplement visual inspection.

Reporting the condition, structural adequacy, evidence of distress, mode ofdeterioration and projected deterioration. A Level 2 - Bridge ConditionInspection Report shall generally be completed, by the Engineer as part of thisinspection.

Development of "Structure Management Plans" in conjunction with theDistricts as required. Refer to Appendix F for plan guidelines.

Recommendations of management actions and/or maintenance/rehabilitationtreatment options.

Procedures and Inspector Accreditation

Detailed Structural Engineering Inspections shall be carried out in accordance withBridge Inspection Procedures - Level 3, (Refer to Part 3 of the Bridge InspectionManual) by an experienced bridge engineer. Inspections must be arranged throughthe Principal Engineer (Bridge Asset Management) of Structures Division. StructuresDivision is the preferred supplier of inspection services.

Frequency

A detailed Engineering Inspection will be carried out in one of the followingcircumstances:

As the result of recommendations in a Level 2 Bridge Condition InspectionReport which has rated the structure condition as poor or a principalcomponent in Condition State 3 or 4.

In order to assess the condition of a structure prior to carrying outprogrammed works such as rehabilitation, strengthening or widening.


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To provide a Load Rating for the structure.Data Recording

The inspecting engineer shall provide a written report to the District Director with acopy to the Principal Engineer (Bridge Asset Management) Structures Division,within 60 days of the inspection. This detailed engineering report shall include:

Assessments of load capacity and condition (including a Level 2 report, whereapplicable)

Recommendations for further investigation and testing, remedial action andfuture inspection and monitoring regime as required.

A "Structure Management Plan" if required (refer Appendix F).The District Director shall consider the recommendations of the report and initiate thenecessary actions. If the District Director does not agree with the recommendations aresponse to that effect shall be made in writing to the inspecting engineer and copiedto the Principal Engineer (Bridge Asset Management) within 30 days of receipt of theinspection report.

A copy of the final report shall be forwarded to the Principal Engineer (Bridge AssetManagement) who shall be responsible for entering the Level 3 inspection into theBridge Information System (BIS) within 30 days of completion of the report.


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FIGURE1.1-BRIDGEASSETMANAGEMENTSYSTEMF

RAMEWORK

``

INSPEC

TION

SYSTEM

BridgeInspectionManual

Inspectionfrequencies

Policy

andaccountabilities

Inspectora

ccreditation&auditing

N.D.T.research

Maintenan

cerequirements

Level3inspections

Competen

cytraining

InspectorHandbook

FINANCIALMA

NAGEMENTSYSTEM

Valuation(Brid

gesandCulverts)

InspectionCosts

MaintenanceE

xpenditure

ConstructionC

osts

Pre-Constructi

onCosts

RoadUserCosts

BRIDGEINFORMATION

SYSTEM

StructuralInventory(

Location,Geometry,etc.)

DesignInventory(De

signData,EquivaenceRatings,etc.)

InspectionInventory(ElementInventory,Condition,etc.)

MaintenanceActivities

WhichbridgeInterface

StandardReports

MobileB.I.S.

IncorporationofWhichbridge

BridgeSufficiencyA

nalysis

MAINTENAN

CESYSTEM

Whichbridge

Maintenance

Prioritisationtool

TimberBridgeMaintenance

Manual

MRS11.87

TimberBridge

Materials

Specification

Repairtechniques

BridgeMain

tenanceManual

Managemen

tofDefectiveand

Sub-Standar

dBridges

WholeofLi

feAssessments

STRUC

TURECAPACITIES

StructureEquivalenceRating

me

thodology

Specificbridgeassessmentsfor

Ex

cessMassVehiclepermits

AssessedDesignClasses

48tC

raneAccessMaps

VulnerableAssetMaps

Timberbridgecapacityresearch

QuickbridgeRapidAnalysis

To

ol

TechnicalinputforVehicle

LimitsManual

Districtguidelinesforassessing

struc

turesforpermits

80tC

raneAccessMaps

HLP

AccessMaps

Popu

lationofEquivalence

RatingsandDesignCapacity

ADVICENOTESDATABASE

OperationalSupport

KEY

Currentlyoperational

Tobe

implemented


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Design inventory

Inspection inventory

This area of BIS records thestructures construction details, itssuperstructure, substructure, designdetails, component details andservices. An advanced feature of thismodule is its ability to store and

retrieve an image of the plans.

BAMS requires that all structuresundergo periodic inspection. Detailsof the inspections are managed by theinspection inventory module. It catersfor:

!

!

!

In addition to the diary functionsand standard reports that areavailable to aid the inspection

scheduling process, the systemmaintains a full history of inspectionsand their results. These may includephotographs and/or sketches.

recording and reporting of threelevels of inspection,printing of pre-printed or blankinspection forms,recording of special inspectionrequirements.

The accredited inspector register isheld and managed in the BIS.

Maintenance activities

Mobile BIS

This module

The core system is based on theARMIS (A Road ManagementInformation System) architecture andservers and requires connection tothe departments data network.Another version has been developedwhich complements the core system.Known as mobile BIS, it allows datato be replicated onto a laptop PC for

update in the field. The main database

provides a mechanismfor creating a backlog of maintenanceactivities to address defects identifiedin the inspections and to compile adetailed estimate for the works. The"maintain jobs" feature allows

stewards to approve activities andcreate maintenance jobs at a bridge orgroup of bridges level. Actual costscan be recorded to generate a workshistory for the structure andestimate/costs comparisons. Severalreports are available to assist networkmanagers maintain the bridge stock.

Bridge Information System

What is a structure?!

!

!

In Queensland, this currently comprises some2,700 bridges and over 10,000 major culvertsthat have a current replacement value in excessof two billion dollars.

All Main Roads owned bridges or culvertswith a diameter of more than 1.8m and awaterway area in excess of 3m.Minor structures including pipes and culvertsof smaller size.

Obstructions, i.e. any other feature over aState-owned road, e.g. overhead signs,gantries etc.

BAMS

Introducing BIS

Structure inventory

The system developed to managestructures within Main Roads is theBridge Asset Management System(BAMS). It comprises a number ofintegrated processes covering:

!

!

!

!

!

!

!

The Bridge Information System orBIS is the computer system whererecords that support BAMS arestored, maintained and analysed. Itsmain modules are:

! Structure Inventory! Design Inventory! Inspection Inventory! Maintenance Activities! Load Capacity Inventory.

Further development of the systemwill provide for heavy vehiclerouting and network performanceanalysis.

The inventory is the heart of BIS. Itrecords the key features of thestructure, including its unique ID, itsconstruction type, material, locationand hydraulic data.

PolicyInspection methodologyInspection manualBridge Information SystemHeavy vehicle assessment/managementAsset management reportingMaintenance prioritisation.

TA

IS

H

...

W

FIGURE 1.3 - BRIDGE INFORMATION SYSTEM OVERVIEW


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BIS

Business defined Integrated with BAMS Inspections Maintenance Sketches and photographs Standardreports Decision support Investment priorities MobileBIS

can be synchronised with the updateswhen staff return to the office.

The number of standard reportsavailable from the system is indicatedby the following list:

BIS reports! Structure Listing! Structure Details (overview,

location, geometry, environment,hydraulics, deficiencies,photographs)

! Design Detail! Modified Structure! Inspection Summary! Condition Rating! Next Inspection! No Inspection Data! Components in Poor Condition! Completed Inspections! Maintenance Activities Detail

Listing (bridge or job)

TheMobile BIS allows inspectors tocapture bridge inspection data,identify defects and compile themaintenance backlog and estimate inthe field.

Standard outputs

Inspection reports! Structure Condition Inspection

Report! Defective Components Report! Standard Procedure Exceptions

Report! Photographic and Sketches

Record! Timber Drilling Survey Reports.

A number of additional reports areprepared by the Bridge AssetManagement section of the RoadSystems and Engineering Division ofQueensland Main Roads, based ondata extracted from the BIS using thedata browser query tool or theprioritisation extract file.

! Progress Report! Trends in Inspection! Outstanding Inspections! Progress of the Bridge and

Culvert Inspection Programme! Trends in Bridge condition

! Bridge and Culvert InspectionStatus

! Defective bridges by severity andtrend thereof

! Mapping of the bridge data.

Asset management reports

Heavy vehicle management

Prioritisiation

! Vulnerable Asset maps! 48t Mobile Crane bridge crossing

restrictions maps.

! The "Whichbridge" software

uses a data file extracted fromBIS to calculate bridge and bridgegroup risk scores.

! Road Reference/Road Inventory(RR/RI) for location informationas well as other information suchas date of last reseal.

! Road Maintenance PerformanceContracts (RMPC) formaintenance activity details

!

BIS data sources

SummaryBIS is an integrated suite ofmodules and provides a completeview of the structures maintainedby Main Roads. The systemarchitecture gives a solid

foundation for current andanticipated needs

CONTACTBridge Asset Management BranchFloor 8 Spring Hill Office Complex477 Boundary Street, Spring Hill Q 4000

Peter Graham

Functional ManagerPhone: (07) 3834 2556Fax: (07) 3834 2065Email: [email protected]

!

!

!

!

!

!

!

It supports enhanced decision making by providingtimely and up to date information on the status ofstructure assetsPlanning tools assist the districts in planningstructure maintenanceThe system gives detailed insights into the capacityof the State-controlled road network (SCRN)

BIS includes a comprehensive reporting facility thatassists operational and head office staff manage thebridge assetsData extracted from the BIS allows detailedassessment and strategic analysis of the State-controlled structures and assists the Department inthe further development of the Road NetworkStrategy, the Roads Implementation Plan and AssetValuation.Heavy vehicle management makes significant use ofinformation in BIS. Development of effectivemanagement systems to ensure the safety of roadusers, and to maximise the performance of thebridge asset, are dependent on the quality andaccuracy of the data in BIS.The information is also used for a variety of externalreporting requirements.


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PART TWODeterioration

Mechanisms


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Bridge Asset Management BRIDGE INSPECTION MANUAL 2.1Structures Division PART TWO J une 2004

DETERIORATION MECHANISMS

TABLE OF CONTENTS

Part Two: Deterioration MechanismsPage Nos

1.0 Material Defects............................................................................................2.5

1.1 General...........................................................................................................2.5

1.2 Concrete.........................................................................................................2.5

1.2.1 Corrosion of reinforcement..............................................................2.51.2.2 Carbonation.......................................................................................2.61.2.3 Alkali - Silica Reaction (ASR).........................................................2.61.2.4 Cracking.............................................................................................2.61.2.5 Spalling...............................................................................................2.81.2.6 Surface Defects..................................................................................2.91.2.7 Delamination...................................................................................2.10

1.3 Steel ...........................................................................................................2.11

1.3.1 Corrosion.........................................................................................2.111.3.2 Permanent Deformations...............................................................2.111.3.3 Cracking...........................................................................................2.121.3.4 Loose Connections..........................................................................2.13

1.4 Timber..........................................................................................................2.141.4.1 Fungi.................................................................................................2.141.4.2 Termites...........................................................................................2.151.4.3 Marine Organisms..........................................................................2.161.4.4 Corrosion of Fasteners...................................................................2.171.4.5 Shrinkage and Splitting..................................................................2.171.4.6 Fire...................................................................................................2.181.4.7 Weathering......................................................................................2.19

1.5 Masonry.......................................................................................................2.20

1.5.1 Cracking...........................................................................................2.201.5.2 Splitting, Spalling and Disintegration...........................................2.201.5.3 Loss of Mortar and Stones.............................................................2.20

1.6 Protective Coatings.....................................................................................2.21

2.0 Common Causes of Older Bridge Deterioration......................................2.22

2.1 Concrete Bridges.........................................................................................2.222.1.1 Monolithic and simply supported T-beams..................................2.222.1.2 Precast I beams...............................................................................2.23


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2.1.3 Precast prestressed inverted "T" beams......................................2.232.1.4 Box Girder Bridges.........................................................................2.232.1.5 Prestressed Voided Flat Slab Bridges...........................................2.242.1.6 Reinforced Concrete Flat Slabs.....................................................2.24

2.1.7 Precast Prestressed Deck Units......................................................2.242.1.8 Precast Prestressed Voided "T" Slabs..........................................2.252.1.9 Decks and Overlays.........................................................................2.252.1.10 Diaphragms.....................................................................................2.262.1.11 Kerbs, Footways, Posts and Railing..............................................2.262.1.12 Abutments........................................................................................2.272.1.13 Piers..................................................................................................2.28

2.2 Steel Bridges................................................................................................2.29

2.3 Timber Bridges............................................................................................2.30

2.3.1 Timber Girders...............................................................................2.302.3.2 Corbels.............................................................................................2.312.3.3 Decking (timber and steel trough).................................................2.312.3.4 Kerbs, Posts and Railing................................................................2.332.3.5 Piles...................................................................................................2.332.3.6 Walings and Crossbraces...............................................................2.342.3.7 Headstocks.......................................................................................2.352.3.8 Abutments........................................................................................2.35

2.4 Deck J oints...................................................................................................2.37

2.5 Bearings.......................................................................................................2.39

2.6 Other Structure Types................................................................................2.40

2.6.1 Box Culverts....................................................................................2.402.6.2 Pipe Culverts...................................................................................2.40

2.7 Causes of deterioration not related to bridge materials..........................2.41

2.7.1 Damage due to Accidents...............................................................2.412.7.2 Drainage...........................................................................................2.412.7.3 Debris...............................................................................................2.422.7.4 Vegetation........................................................................................2.422.7.5 Scouring of Foundations.................................................................2.422.7.6 Movement of the Structure............................................................2.422.7.7 Condition of Approaches................................................................2.43

3.0 References....................................................................................................2.45


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LIST OF FIGURES

Figure 1.2.1 (a) - Corrosion of Headstock Reinforcement due to Chloride IonPenetration in a Marine Environment

Figure 1.2.1 (b) - Corrosion of Reinforcement in the Soffit of a Cast Insitu Culvertdue to Carbonation

Figure 1.2.1 (c) - Calcium Chloride Induced Corrosion of Suspended SlabSoffit in an RCBC

Figure 1.2.1 (d) - Spalling due to Calcium Chloride Distress in an RCBC

Figure 1.2.1 (e) - Corrosion Of Reinforcement And Spalling Of Cantilever Soffit DueTo Poor Cover And Chloride Penetration

Figure 1.2.1 (f) - Corrosion Of Reinforcement And Spalling Of Deck Slab Surface DueTo Poor Cover And Chloride Attack

Figure 1.2.2 (a) - Carbonation Testing of a Freshly Broken Concrete Core

Figure 1.2.2 (b) - Carbonation Induced Corrosion

Figure 1.2.3 (a) - General View of L ongitudinal Cracking due to ASRin Prestressed Deck Units

Figure 1.2.3 (b) - View of Deck Unit Soffit Cracking due to ASR

Figure 1.2.3 (c) - View of Vertical Crack due to ASR in a Prestressed Pile

Figure 1.2.3 (d) - View of ASR Gel Exudations

Figure 1.2.4 (a) - Cracking of Structures

Figure 1.2.4 (b) - Severity of Cracking

Figure 1.2.4 (c) - Plastic Settlement/Shrinkage Cracking in a Bridge Deck

Figure 1.2.4 (d) - Plastic Cracking Passing Completely Through a Bridge Deck

Figure 1.2.4 (e) - Shear Crack In R.C. Headstock

Figure 1.2.4 (f) - Bursting Cracks In Anchorage Zone Of Post-Tensioned Girder

Figure 1.2.4 (g) - Accurate Measurement of Crack Widths

Figure 1.2.8 (a) - General View of Prestressed Pile

Figure 1.2.8 (b) - Water Wash Including Aggregate Particles CausingAbrasion of Pile Surface


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Figure 1.3.3 - Common Crack L ocations of Steel 1 and Common Crack Locations ofSteel 2

Figure 1.4.1 (a) - Fungal Fruiting Body and Decay of Girder

Figure 1.4.1 (b) - Rot Pocket in Girder

Figure 1.4.2 (a) - Termite damage in Deck Planks

Figure 1.4.2 (b) - Section of Pile Showing Termite Nest in Internal Pipe

Figure 1.4.2 (c) - Termite Galleries On Pile And Headstock

Figure 1.4.5 (a) - Splitting in Timber Girder

Figure 1.4.5 (b) - Splitting in Timber Pile

Figure 1.4.7 (a) - Weathered and Rotted Timber Deck Planks

Figure 1.4.7 (b) - Rotted Ends of Deck Planks

Figure 2.3.3 (a) - Corrosion of J oints Between Trough Sections

Figure 2.3.3 (b) - Cracking and Perforating of Steel Troughing

Figure 2.3.5 - Rotting of Abutment Pile Below Ground Level

Figure 2.4.1 (a) - Scour of Stream Bed and Significant Loss of Material Around PierPilecaps and Piles

Figure 2.4.1 (b) - Localised Scour of Stream Bed and Debris Build-Up Around Pier Piles

Figure 2.6.2 (a) - General View of Masonry Pipe Culvert, Showing Efflorescence andSpalling of Base Brickwork

Figure 2.6.2 (b) - View of Efflorescence and Staining due to Chemical Leaching ofMortar


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1.0 MATERIAL DEFECTS

1.1 General

This section describes the defects that are normally found in concrete, steel, timber,

masonry and coatings. Each defect is briefly described and the causes producing itare identified.

1.2 Concrete

Based on concrete defects described in Ontario Ministry of Transportation, OntarioStructure Inspection Manual (Ref. 1) and adjusted for Queensland conditions.

Concrete is used in structures as plain concrete, such as tremie and mass concrete; or,it is combined with conventional steel reinforcement as reinforced concrete, or withprestressing steel reinforcement as prestressed concrete.

Defects in concrete can often be related to the lack of durability of the concrete,resulting from the composition of the concrete, poor placement practices, poor qualitycontrol or the aggressive environment in which it is placed.

The following defects which have occurred in the Queensland road infrastructure aredescribed. They have been listed in order of occurrence from most common to leastas found in our concrete road bridges to date:

(i) Corrosion of Reinforcement (v) Spalling(ii) Carbonation (vi) Surface Defects

(iii) Alkali-Silica Reaction (ASR) (vii) Delamination(iv) Cracking

1.2.1 Corrosion of Reinforcement

Corrosion is effected by the deterioration of reinforcement by electrolysis. The alkalicontent in concrete protects the reinforcement from corrosion but when moisture,oxygen and/or chloride ions above a certain concentration are dissolved in water andpenetrate through the concrete to reinforcement, this protection breaks down andcorrosion starts. In the initial stages, corrosion may appear as rust staining on theconcrete surface. In the advanced stages, the surface concrete above thereinforcement cracks, delaminates and spalls off exposing heavily rustedreinforcement. This process is illustrated in Figure 1.2.1 (a), (b), (e) and (f).

In Queensland, the most common example of reinforcement corrosion is found in thesquare section reinforced concrete piles which were used extensively until theintroduction of prestressed octagonal piles.


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Cracking typically follows the line of the corner reinforcement where the density ofthe concrete is compromised by limited access for compaction. The severity of thecracking increases until the cover concrete delaminates and ultimately spalls offexposing the corroded reinforcement. In addition horizontal cracking caused by

driving stresses is often found in this type of pile.

1.2.2 Carbonation

Carbon dioxide in the atmosphere can dissolve in moisture within the concrete poresand react with calcium hydroxide in the cement paste to form a neutral calciumcarbonate. Over a long period of time this gradually lowers the alkalinity of theconcrete cover to the steel reinforcement, thus reducing the passive oxide layeraround the steel and placing it in a more acidic environment whereby it is susceptibleto corrosion.

The depth of carbonation from the exterior surface can be estimated by using a pHindicator, eg phenolphthalein dissolved in water. The carbonated zone remains clearwhile the uncarbonated area turns pink when the solution is applied to a freshlybroken surface (see Figure 1.2.2 (a)). Carbonation induced corrosion is shown inFigure 1.2.2 (b).

1.2.3 Alkali - Silica Reaction (ASR)

Some aggregates react adversely with the alkalies in cement to produce a highlyexpansive alkali-silica gel. The expansion of the gel under moist conditions leads tocracking and deterioration of the concrete. The cracking occurs through the entire

mass of the concrete. Alkali-Silica reactions are generally slow by nature, and theresults may not be apparent for 5-10 years. The appearance of prestressed concreteaffected by alkali-silica reaction is shown in Figures 1.2.3 (a), (b), (c) and (d).

1.2.4 Cracking

A crack is a linear fracture in concrete which extends partly or completely through themember. Cracks in concrete occur as a result of tensile stresses introduced in theconcrete. Tensile stresses are initially carried by the concrete and reinforcement untilthe level of the tensile stresses exceeds the tensile capacity of the concrete. After thispoint the concrete cracks and the tensile force is transferred completely to the steelreinforcement. The crack widths and distribution are controlled by the reinforcementin reinforced and prestressed concrete, whereas in plain concrete there is no suchcontrol.


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The buildup of tensile stresses and, therefore, cracks in the concrete may be due toexternally applied loads, external restraint forces, internal restraint forces, differentialsettlements, differential temperature or shrinkage or corrosion of the reinforcement.Externally applied loads generate a system of internal compressive and tensile

stresses, in the members and components of the structure, as required to maintainstatic equilibrium. For example, prestressing generates bursting effects at anchoragezones which will cause tensile cracks if the member is inadequately reinforced as inFigure 1.2.4(f). Cracks resulting from externally applied loads initially appear ashairline cracks and are harmless. However as the reinforcement is further stressed theinitial cracks open up and progressively spread into wider cracks. Of particularconcern is the development of shear cracks in structural members adjacent to supportswhich may be indicative of incipient brittle failure as in Figure 1.2.4(e).

External restraint forces are generated if the free movement of the concrete inresponse to the effects of temperature, creep and shrinkage is prevented from

occurring due to restraint at the member supports. The restraint may consist offriction at the bearings, bonding to already hardened concrete, or by attachment toother components of the structure. Cracks resulting from the actions of externalrestraint forces develop in a similar manner as those due to externally applied loads.

Internal restraint forces are caused by the differential expansion or contraction of theexterior surface of concrete relative to the interior mass of the concrete, as in plasticshrinkage. The resulting surface cracks are normally shallow and appear as patterncracks. However, if a slab is significantly affected by plastic shrinkage cracking thecracks may continue through the depth of the slab as in Figure 1.2.4 (d).

Differential movements or settlements result in the redistribution of external reactionsand internal forces in the structure. This may in turn result in the introduction ofadditional tensile stresses and, therefore, cracking in the concrete components of thestructure. Movement cracks may be of any orientation and width, ranging from finecracks above the reinforcement due to formwork settlement, to wide cracks due tofoundation or support settlement.

The types and location of cracking that are the most likely to be observed are shownin Figure 1.2.4 (a)

The severity of cracking is shown in Figure 1.2.4 (b) and is defined as:

Hairline up to 0.1mmMinor 0.1 to 0.3mmModerate 0.3 to 0.6mmSevere Greater than 0.6mm

Over time, the concrete surface deteriorates and spalling of the crack edges willoccur. When measuring crack widths, it is important to ensure that is it the actualwidth of the crack that is measured, and not the width of the spalled area. Thedifference between crack width and spalled width is illustrated in Figure 1.2.4 (g)


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Figures 1.2.4 (c) and (d) show an example of severe plastic settlement/shrinkagecracking in a reinforced concrete bridge deck. ASR cracking most commonly occursin prestressed deck units in Queensland (see Figures 1.2.3 (a) to (d)). In thoseelements ASR is characterised by longitudinal cracking on the soffits and exposed

side faces. Vertical cracking has also been detected in some prestressed octagonalpiles which is the result of Alkali-Silica Reaction (ASR). The risk of this type ofcracking has been minimised in new piles by the use of an approved mass of fly ashin the approved mix designs. In addition, the alkali-silica gel formed by the reactionmay often be seen in, or exuding from the cracks. This gel is a clear or translucentviscous substance. Usually the gel absorbs calcium as it exudes through the paste anddeposits on the soffit of deck units as a white substance. It should be noted thatcalcium carbonate is often found in and around cracks and usually forms whitestalactites on the soffit of deck units.

1.2.5 Spalling

A spall is a fragment, which has been detached from a larger concrete mass. Spallingmay be a continuation of the corrosion process whereby the actions of external loadsor pressure exerted by the corrosion of reinforcement and attendant expansion resultsin the breaking off of the delaminated concrete. The spalled area left behind ischaracterised by sharp edges.

Vehicular or other impact forces on exposed concrete edges, deck joints orconstruction joints, may also result in the spalling or breaking off of pieces ofconcrete locally.

Spalling may also be caused by overloading of the concrete in compression. Thisresults in the breaking off of the concrete cover to the depth of the outer layer ofreinforcement. Spalling may also occur in areas of localised high compressive loadconcentrations, such as at structure supports, or at anchorage zones in prestressedconcrete.

The imposition of external loads may also cause spalling. Restraint forces generatedby seized bearings often cause spalling of the bearing support area on the front face ofthe bearing shelf.

Spalling of concrete is shown in Figure 1.2.1 (b).


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1.2.6 Surface Defects

The following surface defects in concrete are described herein:

- Segregation- Cold Joints- Deposits - efflorescence, exudation, encrustation, stalactite- Honeycombing- Abrasion- Slippery Surface

Surface defects are not necessarily serious in themselves; however, they areindicative of a potential weakness in concrete.

Segregation is the differential concentration of the components of mixed concrete

resulting in non-uniform proportions in the mass. Segregation is caused by concretefalling from a height, with coarse aggregates settling to the bottom and the fines ontop. Another form of segregation occurs where reinforcing bars prevent the uniformflow of concrete between them. Segregation is more likely to occur in higher slumpconcrete.

Cold Joints are produced if there is a delay between the placement of successivepours of concrete, and if an incomplete bond develops at the joint due to the partialsetting of concrete in the first pour.

Deposits are often left behind where water percolates through the concrete and

dissolves or leaches chemicals from it and deposits them on the surface.

Deposits may appear as the following:

efflorescence: A deposit of salts, usually white and powdery. exudation: A liquid or gel-like discharge through pores or cracks in

the surface.

encrustation: A hard crust or coating formed on the concrete surface. stalactite: A downward pointing formation hanging from the

concrete surface, usually shaped like an icicle.

Honeycombing is produced due to the improper or incomplete vibration of theconcrete which results in voids being left in the concrete where the mortar failed tocompletely fill the spaces between the coarse aggregate particles.


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Abrasion is the deterioration of concrete brought about by vehicles scraping againstconcrete surfaces, such as decks, kerbs, barrier walls or piers or the result of dynamicand/or frictional forces generated by vehicular traffic, coupled with abrasive influx ofsand, dirt and debris. It can also result from friction of waterborne particles against

partly or completely submerged members (see Figures 1.2.8 (a) and (b)). The surfaceof the concrete appears polished.

A slippery surface may result from the polishing of the concrete deck surface by theaction of repetitive vehicular traffic where inadequate materials and processes havebeen used.

1.2.7 Delamination

Delamination is defined as a discontinuity in the surface concrete which issubstantially separated but not completely detached from concrete below or above it.

Visibly, it may appear as a solid surface but can be identified as a hollow sound bytapping. Delamination begins with the corrosion of reinforcement and subsequentcracking of the concrete. However, in the case of closely spaced bars, the crackingextends in the plane of the reinforcement parallel to the exterior surface of theconcrete.


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1.3 Steel

Based on Ontario Ministry of Transportation, Ontario Structure Inspection Manual(Ref. 1)

The use of steel has progressed from cast iron, wrought iron, rivet steel and plaincarbon steel to notch tough low temperature steel.

The following defects commonly occurring in steel are described:

Corrosion Permanent Deformations Cracking Loose Connections

1.3.1 Corrosion

Corrosion is the deterioration of steel by chemical or electro-chemical reactionresulting from exposure to air, moisture, industrial fumes and other chemicals andcontainments in the environment in which it is placed. The terms rust and corrosionare used inter-changeably in this sense. Corrosion, or rusting, will only occur if thesteel is not protected or if the protective coating wears or breaks off.

Rust on carbon steel is initially fine grained, but as rusting progresses it becomesflaky and delaminates exposing a pitted surface. The process thus continues with

progressive loss of section.

1.3.2 Permanent Deformations

Permanent deformation of steel members can take the form of bending, buckling,twisting or elongation, or any combination of these. Permanent deformations may becaused by overloading, vehicular collision, or inadequate or damaged intermediatelateral supports or bracing.

Permanent bending deformation may occur in the direction of the applied loads andare usually associated with flexural members; however, vehicular impact may

produce permanent deformations in bending in any other member.

Permanent buckling deformations normally occur in a direction perpendicular to theapplied load and are usually associated with compression members. Buckling mayalso produce local permanent deformations of webs and flanges of beams, plategirders and box girders.

Permanent twisting deformations appear as a rotation of the member about itslongitudinal axis and are usually the result of eccentric transverse loads on themember.


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Permanent axial deformations occur along the length of the member and are normallyassociated with applied tension loads.

1.3.3 Cracking

Crack is a linear fracture of the steel. Cracks are mainly produced due to fatigue andcan, under certain conditions, lead to brittle fracture.

Brittle fracture is a crack completely through the component that usually occurswithout prior warning or plastic deformation. Brittle fracture may result at fatigueprone details after initial fatigue cracking.

The primary factors leading to fatigue cracking are: the number of applied stresscycles, which is a function of the volume of traffic; the magnitude of the stress range,which depends on the applied live load; and the fatigue strength in the connection

detail. Cracks caused by fatigue usually occur at points of tensile stressconcentrations, at welded attachments or at termination points of welds. Cracks mayalso be caused or aggravated by overloading, vehicular collision or loss of sectionresistance due to corrosion. In addition, stress concentrations due to the poor qualityof the fabricated details and the fracture toughness of materials used are contributingfactors. Material fracture toughness will determine the size of the crack that can betolerated before fracture occurs.

Welded details are more prone to cracking than bolted or riveted details. Grinding offthe weld reinforcement to be smooth or flush with the joined metal surfaces improvesfatigue resistance. Once the cracking occurs in a welded connection, it can extend into

other components due to a continuous path provided at the welded connection, andpossibly lead to a brittle fracture.

Bolted or riveted connections may also develop fatigue cracking, but a crack in onecomponent will generally not pass through into the others. Bolted and rivetedconnections are also susceptible to cracking or tearing resulting from prying action,and by a build-up of corrosion forces between parts of the connection.

Common locations susceptible to cracking are illustrated in Figure 1.3.3. As cracksmay be concealed by rust, dirt or debris, the suspect surfaces should be cleaned priorto inspection.

Cracks that are perpendicular to the direction of stress are very serious, with thoseparallel to the direction of stress less so. In either case, cracks in steel shouldgenerally be considered serious, as parallel crack may for a number of reasons turninto a perpendicular crack. Any crack should be carefully noted and recorded as to itsspecific location in the member, and member structure. The length, width (ifpossible) and direction of crack should also be recorded.


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1.3.4 Loose Connections

Loose connections can occur in bolted or riveted connections; and, may be caused bycorrosion of the connector plates or fasteners, excessive vibration, overstressing,

cracking or the failure of individual fasteners.

Loose connections may sometimes not be detectable by visual inspection. Crackingor excessive corrosion of the connector plates or fasteners, or permanent deformationof the connection or members framing into it, may be indications of a looseconnection. Tapping the connection with a hammer is one method of determining ifthe connection is loose.


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1.4 Timber

Based on Austroads 1991 "Bridge Managemen

BridgeInspectionManual (QLD)

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Transcript of BridgeInspectionManual (QLD)