DOCTORAL DISSERTATION - Fakulta stavební - VŠB- ?· DOCTORAL DISSERTATION ... Simulation-Based Reliability…

  • Published on
    06-Jul-2018

  • View
    212

  • Download
    0

Embed Size (px)

Transcript

  • VB TECHNICAL UNIVERSITY OF OSTRAVA

    FACULTY OF CIVIL ENGINEERING

    DOCTORAL DISSERTATION

    RELIABILITY OF REINFORCED CONCRETE BRIDGE DECKS WITH RESPECT TO INGRESS OF CHLORIDES

    POSUZOVAN SPOLEHLIVOSTI ELEZOBETONOV MOSTOVKY S OHLEDEM K PSOBEN CHLORID

    by

    Ing. Petr Konen

    Supervisor: Prof. Ing. Pavel Marek, DrSc. Ostrava, 2007

  • - 2 -

    Petr Konen, 2007 Department of Structural Mechanics Faculty of Civil Engineering VB Technical University of Ostrava Czech Republic

  • - 3 -

    Annotation The aim of the submitted work is to make a probabilistic durability assessment of concrete bridges

    affected by deicing agents applied to melt snow. The potential of the application simulation tools,

    see SBRA (Based Reliability Assessment method), is studied with respect to chloride ingress

    induced corrosion of bridge decks with epoxy-coated steel reinforcement. Representative slabs of

    this type are e.g. bridge decks in some parts of the U.S.

    The durability of the investigated decks is severely threatened by the risk of corrosion because the

    concrete surface is directly exposed to deicing salts. It is necessary to study the effect of cracks in

    the reinforced bridge deck which are the most likely gate for chloride ions to enter flaws in

    epoxy-coating.

    The stochastic approach is applied in the evaluation of the corrosion process in order to respect the

    inherent randomness of pertinent random input variables. The Monte Carlo simulation tool is

    applied with random variables described by bounded distributions.

    Response to the considered loading by chlorides is computed using Ficks second Law of

    diffusion. It is expressed by the concentration of chlorides in the most exposed location of the

    reinforcement (especially in the epoxy-coating defect). This concentration is compared in the

    assessment with the chloride threshold (amount of chlorides sufficient to start corrosion). The

    likelihood of corrosion initiation is statistically evaluated and compared with the target probability.

    The stochastic model based on the SBRA method utilizes FEM as a transformation model and can

    significantly facilitate the study of the significance of input variables with respect to corrosion

    initiation. The results indicate that the variation in input parameters substantially affect durability of

    bridge deck. The most important variable is diffusion constant. The effect of epoxy-coated

    reinforcement improves durability under proper handling and construction practices.

  • - 4 -

    Anotace Pedloena prce je zamena na pravdpodobnostn posudek trvanlivosti elezobetonovch most

    vystavench psoben chlorid. Jsou hledny monosti vyuit simulanch nstroj viz. SBRA

    (Simulation-Based Reliability Assessment) pi rozboru trvanlivosti z hlediska vzniku koroze

    u mostovky s vztu chrnnou epoxidovm povlakem. Typickm pkladem takovch desek jsou

    mostovky realizovan v nkterch oblastech U.S.A.

    Trvanlivost sledovanch mostovek je vn ohroena rizikem koroze ocelov vztue vzhledem

    k vystaven povrchu betonu pmmu psoben posypovch sol. Je nutn sledovat efekt trhliny

    v elezobetonov mostovce usnadujc prnik chlorid k vztui pokozenou epoxidovou

    ochranou ocelov vztue.

    Pi rozboru koroznho procesu je uplatnno stochastick modelovn zohledujc vstupn nahodile

    promnn veliiny. Je uita simulan metoda Monte Carlo a nhodn promnn jsou vyjdeny

    useknutmi rozdlenmi.

    Jako transforman model k uren odezvy na uvaovan zaten chloridy slou druh Fickv

    zkon difuze. Odezva je vyjdena koncentrac chlorid v nejexponovanjch mstech vztue

    (zejmna v mstech poruchy epoxidovho povlaku), kter je v posudku porovnna

    s tzv. chloridovm prahem, co je koncentrace nutn pro zapoet koroze. Statisticky je

    vyhodnocena pravdpodobnost vzniku koroze, kter je porovnna s nvrhovou pravdpodobnost.

    Stochastick model na bzi metody SBRA vyuvajc jako transforman model MKP me

    vznamn poslouit ke studiu vlivu jednotlivch vstupnch promnnch na trvanlivost z hlediska

    rizika vzniku koroze. Z vsledk prce vyplv, e rozptyl vstupnch parametr vznamn

    ovlivuje trvanlivost mostovky. Nejzvanj uvaovanou veliinou je difuzn souinitel. Dle se

    ukazuje, e kvalitn proveden epoxidov ochrana vztue pozitivn ovlivuje trvanlivost

    elezobetnov desky.

  • - 5 -

    Acknowledgments I would like to take this opportunity to express my gratitude to the many people whose support,

    guidance, and assistance made the completion of this thesis possible. First, I owe my greatest

    gratitude to my wife Nika, my mother and my family for their continuous support and patience

    during my graduate studies.

    I would also like to thank professor Pavel Marek, my supervisor. I learned a lot through

    collaboration with him and he was always ready to not only discuss research topics but also to share

    his experience gained throughout the years. His broad support to young engineers allowed me to

    spread the idea of Simulation-Based Reliability Assessment throughout presentations at national as

    well as foreign conferences, and allowed me to meet interesting people. He facilitated a bridge

    between myself and professor Paul J. Tikalsky, who had invited me to Penn State University.

    Professor Tikalsky, who hosted my research visit at Penn State, inspired me to write a thesis on the

    topic of stochastic bridge deck performance assessment. Professor Tikalsky originated the idea of

    Simulation-Based Reliability Assessment of reinforced concrete structures with respect to cracks

    and their interaction with epoxy-coated reinforcement. He gave me helpful advice throughout

    interesting consultations. It was also at PSU where I assisted Dave Tepke, Dr. Tikalskys grad

    student. He also helped a great deal with my introduction to the field of durability of concrete with

    respect to corrosion through long lasting discussions.

    In addition, I would like to acknowledge the support of this work that has been provided by

    VB - Technical University of Ostrava, Czech Science Foundation (Project No. 103/04/1451 and

    No. 103/07/0557), Pennsylvania Department of Transportation, Ministry of Transportation and

    Ministry of Education of the Czech Republic (Project MOSTDYN - part SBRA), and Pennsylvania

    State University.

  • - 6 -

    Content Notation............................................................................................................................................... 8

    Greek Symbols ................................................................................................................................ 9 Other Symbols................................................................................................................................. 9 Model Variations............................................................................................................................. 9

    1. Introduction.................................................................................................................................. 10 1.1 Bridge Decks from Reinforced Concrete ................................................................................ 11 1.2 Effect of Cracks and Epoxy-Coating ...................................................................................... 13 1.3 Reliability Assessment of Bridge Deck .................................................................................. 14

    2. Objectives of Thesis ..................................................................................................................... 24 2.1 Scope of Thesis ....................................................................................................................... 24

    3. Road Map to Performance-Based Design of Concrete Bridge Decks ..................................... 26 3.1 Random Input Variables.......................................................................................................... 26 3.3 SBRA Analysis ....................................................................................................................... 29 3.4 Reliability Assessment ............................................................................................................ 32 3.5 Durability Assessment............................................................................................................. 33 3.6 Results ..................................................................................................................................... 34 3.7 Summary ................................................................................................................................. 34

    4. SBRA Model of Bridge Deck with Crack and Epoxy-coated Reinforcement ........................ 35 4.1 Input Parameters of the Model ................................................................................................ 35 4.2 Transformation Model............................................................................................................. 46 4.3 Monte Carlo Simulation .......................................................................................................... 53 4.4 SBRA Analysis ....................................................................................................................... 54 4.5 Summary ................................................................................................................................. 65

    5. Parametric Study .........................

Recommended

View more >