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Deterioration Models and Service Life Planning (Part 1) Rak-43.3301 Repair Methods of Structures I (4 cr) Esko Sistonen.

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Presentation on theme: "Deterioration Models and Service Life Planning (Part 1) Rak-43.3301 Repair Methods of Structures I (4 cr) Esko Sistonen."— Presentation transcript:

1 Deterioration Models and Service Life Planning (Part 1) Rak Repair Methods of Structures I (4 cr) Esko Sistonen

2 MICRO-LEVEL DURABILITY AND LOADING FACTORS pore size distribution of the cement paste in sandwich- element concrete facade total air content and protective pore ratio in cement paste water-cement ratio tensile strength of cementpaste, especially in tranzition layer near aggregate stones micro-cracking of concrete due to chemical reactions and crystallizations of materials carbonation rate of different concrete mixtures corrosion rate of reinforcement in carbonated and cracked concrete critical moisture content of concrete for reinforcement corrosion

3 MICRO-LEVEL DAMAGE MECHANISMS correlation between air pore amount, moisture content and freeze-thaw cycle resistance of concrete salt crystallization and its effect on concrete damages chemical reactions in concrete under Finnish climate stresses and cracks due to temperature changes and gradients in conrete changes of pore structure of concrete mathematical evaluation methods of the durability of concrete under Finnish climate

4 MACRO-LEVEL DURABILITY AND LOADING FACTORS moisture distribution of impregnated or coated sandwich-element concrete facade compared with plain concrete facades (due to rain water or heat and moisture transfer) temperature distribution in outer panel of sandwich-facades during the year carbonation rates of impregnated or coated concrete facade chloride content in concrete facades

5 MACRO LEVEL DAMAGE MECHANISMS frost damage mechanisms of concrete in sandwich- facades corrosion mechanisms of reinforcement in sandwich- facades cracking of concrete and stresses between inner and outer panel due to temperature variation and shrinkage strains in facade elements due to temperature gradients chemical and salt problems in Finnish concrete facades effect of different impregnations and coatings to moisture content, carbonation and damages in sandwich-facades service life calculation methods and formulas for sandwich-facades

6 Agents aggressive to inorganic materials

7 Common defects in facades due to the different causes

8 MICRO-LEVEL REPAIR METHODS methods to decrease moisture content and carbonation in concrete (effect on decrease in frost damages and reinforcement corrosion) impregnation of concrete coatings for concrete surface cathodic protection of reinforcements realkalisation of concrete critical chloride content

9 Random-Variable Degradation Model in case of a single inspection. J.M. van Noortwijk, M.D. Pandey, A stochastic deterioration process for time-dependent reliability analysis

10 Service life of concrete structures – a two-phase modeling deterioration FIB (CEB-FIP), Bulletin 3 – Structural Concrete – Textbook on behaviour, Design and Performance (Updated knowledge of the CEB/FIP Model Code 1990), Vol. 3, December 1999.

11 Relationship between durability and performance CEB-FIP: Durable of Concrete Structures, Design Guide, T. Thelford, London, 1992.

12 Transport mechanisms for aggressive substances influence on concrete and reinforcement, and importance of the protective concrete layer – to protect the structure against deterioration FIB (CEB-FIP), Bulletin 3 – Structural Concrete – Textbook on behaviour, Design and Performance (Updated knowledge of the CEB/FIP Model Code 1990), Vol. 3, December 1999.

13 t d = γ t t g t d = the design service life, γ t = the lifetime safety factor, and t d = the target service life.

14 Service life predicted with only mean values and mean values and scatters of the parameters in the prediction models. R(t) and S(t) are expressed with both mean values and scatters. DuraCrete (1999)

15 Increase of failure probability the resistance R of a structure, and of the load effect S FAILURE = R < S; the probability of failure defined as: Pf (t) = P{R(t) < S(t)}

16 The meaning of lifetime safety factor in a performance problem Durability Design of Concrete Structures- RILEM Report 14:(Ed. A. Sarja and E. Vesikari), Spon, London, p.155.

17 The meaning of lifetime safety factor in degradation problem Durability Design of Concrete Structures- RILEM Report 14:(Ed. A. Sarja and E. Vesikari), Spon, London, p.155.

18 Probability density function for strength (f R ) and action - load (f S ) and failure probability (shaded area)

19 Calculation of failure probability (Thoft- Christensen &Baker 1982).

20 Full-probabilistic performance concept. Ferreira, R.M. (2004), PROBABILITY-BASED DURABILITY ANALYSIS OF CONCRETE STRUCTURES IN MARINE ENVIRONMENTS

21 Reliability index  Relationship of failure probability p f and reliability index β for a normal distributed reliability function. Ferreira, R.M. (2004), PROBABILITY-BASED DURABILITY ANALYSIS OF CONCRETE STRUCTURES IN MARINE ENVIRONMENTS

22 Exposure Classes for concrete structures according to EN 206-1:2000

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24 Classification of concrete facade structure into carbonation and frost exposure classes.


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