scholarly journals Applicability of Existing Crack Controlling Criteria for Structures with Large Concrete Cover Thickness

2021 ◽  
Vol 64 (1) ◽  
pp. 69-91
Author(s):  
Chavin Nilanga Naotunna ◽  
S.M Samindi M.K Samarakoon ◽  
Kjell Tore Fosså
Keyword(s):  
Crack Width ◽  
Concrete Cover ◽  
Future Research ◽  
Model Code ◽  
Long Term Study ◽  
Model Code 2010 ◽  
The Aesthetic ◽  
Cover Thickness ◽  
Crack Widths ◽  
Calculation Models

Abstract Widely used crack width calculation models and allowable crack width limits have changed from time to time and differ from region to region. It can be identified that some crack width calculation models consist with limitations for parameters like cover thickness. The current Norwegian requirement for cover thickness is larger than these limitations. The applicability of existing crack width calculation models and the allowable crack width limits must be verified for structures with large cover thickness. The background of crack width calculation models in Eurocode, Model Code 2010, Japanese code, American code and British code have been examined. By comparing the experimental crack widths with the predictions of the aforementioned models, the existing codes can be identified as requiring modification. Considering the durability aspect, it can be identified a long-term study proving that the allowable crack width can be increased with the increase in cover thickness. When considering the aesthetic aspect, the authors suggest categorizing the structures based on their prestige level and deciding the allowable crack widths accordingly. The paper proposes potential solutions for future research on how to improve both crack width calculation methods and allowable crack width limits to be used effectively in structures with large cover thickness.

scholarly journals Applicability of existing crack controlling criteria for structures with large concrete cover thickness: Review.

2020 ◽  
Author(s):  
Chavin Naotunna ◽  
S.M Samindi M.K Samarakoon ◽  
Kjell Fosså
Keyword(s):  
Crack Width ◽  
Concrete Cover ◽  
Design Stage ◽  
Rc Structures ◽  
Model Code ◽  
Design Life ◽  
Service Load ◽  
Model Code 2010 ◽  
Cover Thickness ◽  
Calculation Models

Adverse effects from the cracks in Reinforced Concrete (RC) structures are controlled at the structural design stage. Cracks due to service load are controlled by limiting the ‘calculated crack width’ to a ‘maximum allowable crack width’. With the understanding of social and economic advantages of long design life structures, there is a trend of constructing structures up to 300 years of design life. To enhance durability, such structures require relatively large concrete cover thickness. The existing ‘crack width calculation models’, have to be validated before using on such large cover structures. The predictions of crack width calculation models in Eurocode 2, Model Code 2010, Japanese Code, American Code and British code were compared with the results of recent experiments with large cover specimens. It could identify that the aforementioned models have to be improved to predict the crack widths of large cover structures. The necessary improvements of each model have been identified. Next, a literature survey was conducted to check the applicability of the existing ‘allowable crack width limits’, for the structures with large concrete covers. To effectively use the existing allowable limits on such structures, the necessary improvements and future works have been identified considering the durability, aesthetic and tightness criteria.

scholarly journals Uncertainty in Crack width Estimates According to Fib Model Code 2010

2017 ◽  
Vol 17 (1) ◽  
pp. 155-158
Author(s):  
Jan Mlčoch ◽  
Jana Marková ◽  
Miroslav Sýkora
Keyword(s):  
Reinforced Concrete ◽  
Model Uncertainty ◽  
Crack Width ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Shear Reinforcement ◽  
Model Code ◽  
Model Code 2010

Abstract The contribution is focused on quantifying model uncertainty of crack width estimates for reinforced concrete beams. Predictions obtained by the model provided by the fib Model Code 2010 are compared with results of tests of beams having different longitudinal and shear reinforcement ratios and concrete cover. Trends of model uncertainty with basic variables are investigated.

Experimental Measurement, Modeling and Calculation of Volume Changes of Cement Concrete

2020 ◽  
Vol 832 ◽  
pp. 51-62
Author(s):  
Michal Kropáček ◽  
Radim Čajka
Keyword(s):  
Experimental Measurement ◽  
Outdoor Environment ◽  
Strain Gauges ◽  
Cement Concrete ◽  
Volume Changes ◽  
Entire Process ◽  
Model Code ◽  
Model Code 2010 ◽  
Calculation Models

The paper describes experimental measurement of volume changes of cement concrete. Volume changes include swelling and shrinkage of cement concrete specimens measured by string strain gauges both internal and external. Parallel to this measurement, the volume changes will be measured by means of shrinkage drains. The measurement of volume changes by the shrinkage drains is allowing continuous volume changes to be measured from the beginning of the setting of the concrete. It is possible to capture the entire process of hydration of concrete. The specimens are in the laboratory and in the outdoor environment, so it’s possible to compare values from different environments. The measured results are compared with the calculation models of shrinkage (Model B4 from Bažant [4]; Model Code 2010 [16] and ČSN EN 1992-1-1 [9]).

Thickness of Concrete Cover for Corrosion Protection of Steel Reinforcement and Crack Control

2010 ◽  
Vol 95 ◽  
pp. 61-68 ◽  
Author(s):  
Rina Farhat
Keyword(s):  
Corrosion Protection ◽  
Crack Width ◽  
Limit State ◽  
Concrete Cover ◽  
Steel Reinforcement ◽  
Strain Diagram ◽  
Stress Strain ◽  
Crack Control ◽  
Strain Relationship ◽  
Cover Thickness

Thickness of concrete cover positively affects both the protection of the steel against corrosion and the safe transmission of bond forces. On the other hand it affects Crack control inversely, larger concrete cover causes larger crack width, and as a result it yields reduction in the protection of the steel against corrosion. The influence of the distance between the centroid of the longitudinal reinforcement to the neutral axis, and the stress in the tension steel, on the crack width and Crack control, will be examined. Computations will be done using personal computer program developed for nonlinear analysis of rectangular reinforced concrete sections in flexure. The analysis is performed using Stress-strain relationship for confined concrete: parabola – rectangle with decending branch to 0.3 fc at Ecu, followed by horizontal branch. Stress-strain diagram for reinforcing steel, with an inclined top branch with a strain limit of E su . Beams and slabs elements sections will be examined for the flexural moments from the external loads acting at serviceability limit state. This paper will introduce by computing the concrete fibers stresses and strains over the height of the section, for different element thickness, the influence of tension steel stresses and concrete cover thickness on crack control and corrosion protection of steel reinforcement.

fib Bulletin 65. Model code 2010 Volume 1

2012 ◽  
Author(s):  
Walraven ◽  
Bigaj-van Vliet ◽  
Balazs ◽  
Cairns ◽  
Cervenka ◽  
...  
Keyword(s):  
Model Code ◽  
Model Code 2010

scholarly journals Long-Term Concrete Shrinkage Influence on the Performance of Reinforced Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 254
Author(s):  
Alinda Dey ◽  
Akshay Vijay Vastrad ◽  
Mattia Francesco Bado ◽  
Aleksandr Sokolov ◽  
Gintaris Kaklauskas
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Structures ◽  
Tension Stiffening ◽  
Model Code ◽  
Concrete Shrinkage ◽  
Time Period ◽  
Governing Factor ◽  
Model Code 2010 ◽  
Mathematical Process

The contribution of concrete to the tensile stiffness (tension stiffening) of a reinforced concrete (RC) member is a key governing factor for structural serviceability analyses. However, among the current tension stiffening models, few consider the effect brought forth by concrete shrinkage, and none studies take account of the effect for very long-term shrinkage. The present work intends to tackle this exact issue by testing multiple RC tensile elements (with different bar diameters and reinforcement ratios) after a five-year shrinking time period. The experimental deformative and tension stiffening responses were subjected to a mathematical process of shrinkage removal aimed at assessing its effect on the former. The results showed shrinkage distinctly lowered the cracking load of the RC members and caused an apparent tension stiffening reduction. Furthermore, both of these effects were exacerbated in the members with higher reinforcement ratios. The experimental and shrinkage-free behaviors of the RC elements were finally compared to the values predicted by the CEB-fib Model Code 2010 and the Euro Code 2. Interestingly, as a consequence of the long-term shrinkage, the codes expressed a smaller relative error when compared to the shrinkage-free curves versus the experimental ones.

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