THROUGH-LIFE CARE AND MANAGEMENT OF CONCRETE STRUCTURES - ASSESSMENT, PROTECTION, REPAIR AND STRENGTHENING...

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1 Contents Editor's remarks... iii Preface... iv 9 THROUGH-LIFE CARE AND MANAGEMENT OF CONCRETE STRUCTURES - ASSESSMENT, PROTECTION, REPAIR AND STRENGTHENING Introduction Background Concrete - A family of materials Service life design and through-life management aspects Reactive and proactive approaches to structure management Management systems for populations of structures Assessment of existing buildings and structures The condition of infrastructure The challenge for assessment, management and repair Brief overview of the development and history of concrete construction Introduction Early forms of concrete and concrete construction th century development of reinforced concrete Early 20 th century development of reinforced concrete Overview of historical developments in concrete construction and design guidance Evolution in the properties of concrete Change in the strength of steel reinforcement Early prestressing systems Overview of historical design requirements and approaches to concrete structure design Guidance, standards and sources of information for the assessment of existing concrete structures Introduction CEB Bulletin CONTECVET project ISO 13822: Bases for design of structures- Assessment of existing structures JCSS report: Probabilistic assessment of existing structures fib Bulletin LIFECON project REHABCON project NORECON project Management of highway structures CONREPNET project fib Bulletin 62: Structural Concrete Textbook on behaviour, design and performance, vol. 5 xi

2 CBDG guidance on the assessment of concrete bridges Sustainable Bridges project fib Bulletin Management of deteriorating concrete structures Institution of Structural Engineers: Appraisal of existing structures - 3 rd Edition fib Model Code Swiss codes for the conservation of existing structures BRE handbook on the assessment of large panel system dwelling blocks for accidental loading fib Bulletin 59: Condition control and assessment of reinforced concrete structures exposed to corrosive environments (carbonation / chlorides) Through-life management of existing structures Introduction Performance requirements and owner obligations Reliability and functionality requirements Responsibilities and liabilities Societal and sustainability perspectives Value judgements, decision criteria and probabilistic concepts Asset management systems Conservation strategies Hazard and risk issues Reasons for assessment (owner s brief or other requirements) Conservation of historical structures - attitudes and influences Previous experience - In-service performance of concrete structures and remedial interventions Introduction Durability of concrete structures in Denmark (Idorn) Lessons to be learnt from European failures (Hauser) Errors associated with USA concrete structures (Fraczek / ACI) In-service performance of 200 UK concrete bridges (Wallbank) Quality of UK concrete construction (Clark et al) In-service performance inadequacies and the premature deterioration of concrete structures (Jones et al) Performance of 40 UK concrete bridges (Tajalli and Rigden) Durability of post-tensioning tendons (fib Bulletin 15) Stress corrosion cracking and associated failures in prestressed concrete construction in Germany (fib Task Group 9.5) Effectiveness of concrete repairs (Baldwin and King) Strategic improvements to the concrete repair industry in the USA (Emmons) xii fib Bulletin 62: Structural Concrete Textbook on behaviour, design and performance, vol. 5

3 Remedial interventions on concrete structures (CONREPNET) Chloride penetration into high strength and high performance concretes (Helland et al) Overview of recommendations for improving the durability and through-life performance SCOSS and CROSS Conservation management - Overview of philosophy and process steps Introduction Proactive conservation measures (Strategy A) Reactive conservation measures (Strategy B) Situations where conservation measures are not feasible (Strategy C) Conservation management processes Condition survey and monitoring activities Condition assessment Condition evaluation and decision-making Interventions - Preventive, maintenance, remedial and strengthening works Selection of interventions Recording of life cycle information, reporting of assessment outcomes and recommendations Deterioration and damage mechanisms Introduction Deterioration mechanisms Classification of environmental aggressivity Corrosion induced deterioration of structural concrete Accidental damage mechanisms fire, impact, etc Extreme events Progressive collapse, disproportionate structural damage and related issues Influence of deterioration upon through-life performance Gathering of information, condition survey, inspection, monitoring and associated activities Introduction Review of available technical information Gathering data for condition control purposes Condition survey, testing and inspection activities Locations for survey, testing and other information gathering activities Other survey / inspection tasks and activities Structural monitoring Condition survey - Testing and investigations Introduction fib Bulletin 62: Structural Concrete Textbook on behaviour, design and performance, vol. 5 xiii

4 9.9.2 General observations upon testing Simple on-site testing Non-destructive testing techniques Laboratory testing of material samples Static load testing Dynamic response measurements and testing Advantages and limitations of selected testing and inspection techniques Criteria for the interpretation of the results of some non-destructive tests Structural condition assessment Introduction General approach Overview of structural condition assessment activities Structural condition assessment process steps Safety concepts in general Material influences Re-calculation Modelling of deteriorated concrete and corroded reinforcement Hidden strengths Reliability updating and estimating residual service life Condition evaluation and decision-making Introduction Verification against performance criteria for safety and other parameters Formats for verification of safety and other parameters Target reliability levels Partial safety factors for use in the assessment of existing structures Relevance of guidance in earlier codes of practice Safety concepts in codes of practice for design Evaluation and selection of a structure management or intervention option Assessment and treatment of historical and heritage concrete structures and associated architectural concrete surfaces Interventions and through-life management activities and measures General Types of intervention Maintenance interventions Preventive interventions Remedial interventions Rebuild, reconstruction and replacement Strengthening or upgrading interventions xiv fib Bulletin 62: Structural Concrete Textbook on behaviour, design and performance, vol. 5

5 Other through-life management activities and measures Execution of interventions Recording Standards for the protection, repair and strengthening of concrete structures Introduction European Standards Japanese Standards Australian Standards USA Standards ISO Standards The protection, repair and strengthening of concrete structures using the EN 1504 standards Introduction Durability investigation and assessment procedure Selection of an intervention method for concrete protection, repair or strengthening EN 1504 series: Overview of principles and methods related to protection and repair of concrete structures Supplementary information and guidance Structural assessment and repair after a fire Introduction Effects of heating and subsequent cooling Investigation and structural assessment procedure Assessment of damage Procedures for structural repair after a fire Recording and reporting Recording Types and purpose of report General requirements for a report Report structure and content Process of preparing a report Application example Introduction Steps for making an assessment and a subsequent intervention on a structure Illustration of process - Intervention works upon a bridge Proactive durability management - Example from practice of the protection and repair of a concrete structure fib Bulletin 62: Structural Concrete Textbook on behaviour, design and performance, vol. 5 xv

6 9.19 Case study Reliability assessment of a bridge subject to chloride induced corrosion and associated structural deterioration Synopsis Introduction The Neumarkt Bridge Inspection Performance assessment activities Bridge management Some possible scenarios Concluding comments Future look Overview Potential implications of climate change Work of fib Special Activity Group 7 (SAG7): Assessment and interventions upon existing structures Future reduction in CO 2 emissions and the work of fib Special Activity Group 8 (SAG8): Sustainability Acknowledgements References and bibliography References and bibliography Useful conference proceedings and other texts Abbreviations and short form names of projects Glossary: Definitions and terminology xvi fib Bulletin 62: Structural Concrete Textbook on behaviour, design and performance, vol. 5