scholarly journals A Numerical Model for the Freeze-Thaw Damages in Concrete Structures

2005 ◽  
Vol 17 (5) ◽  
pp. 857-868 ◽  
Author(s):  
Tae-Jun Cho
Keyword(s):  
Numerical Model ◽  
Concrete Structures ◽  
Freeze Thaw

scholarly journals Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1251
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Xiangtian Xu ◽  
Yanjun Shen ◽  
Hailiang Jia ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Concrete Structures ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Steel Bar ◽  
Concrete Interface

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

scholarly journals Diagnosis of concrete structures distress due to alkali-aggregate reaction

2015 ◽  
Vol 63 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Z. Owsiak ◽  
J. Zapała-Sławeta ◽  
P. Czapik
Keyword(s):  
Concrete Structures ◽  
Chemical Exposure ◽  
Alkali Silica Reaction ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Alkali Aggregate Reaction ◽  
Freeze Thaw Cycle ◽  
Concrete Elements ◽  
Reaction Attack

Abstract Damage and defects observed in concrete elements, such as a network of microcracks, popouts and eflorrescence can be caused by a variety of deleterious processes. The causes can include mechanical (overloading), physical (freeze-thaw cycle) or chemical exposure (sulphate corrosion, alkali-aggregate reaction). This paper analyses distress due to alkali-silica reaction, detected in selected concrete structures. The analysed concrete elements exhibited cracking, exudations and surface popouts. Identification of the presence of hydrated sodium-potassiumcalcium silicate gel can be considered the primary symptom suggestive of an alkali-silica reaction attack. Other damage-causing mechanisms can occur simultaneously.

Influence of Silane Treatment on the Freeze-Thaw Resistance of Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 565-568 ◽  
Author(s):  
Xiao Jian Gao ◽  
Hong Wei Deng ◽  
Ying Zi Yang
Keyword(s):  
Surface Treatment ◽  
Water Adsorption ◽  
Concrete Structures ◽  
Air Entrainment ◽  
Concrete Surface ◽  
Silane Treatment ◽  
Cold Regions ◽  
Bonding Force ◽  
Freeze Thaw ◽  
Surface Impregnation

The influences of silane impregnation on water adsorption, bonding force between ice and concrete surface and resistance to freeze-thaw of concretes were studied. Two strength grades (C30 and C50) and the air entrainment were considered for concrete preparation. The results show that surface impregnation with silane reduces the final water adsorption of concrete by more than 90% when compared with the untreated specimen. The silane treatment significantly decreases the bonding force between ice and concrete surface. The resistance to freeze-thaw of both new and old concretes can be improved by the silane treatment. Therefore, the surface treatment with silane is suggested as an effective method to improve the durability of concrete structures in cold regions.

Research on resistance degradation and reliability of pre-stressed concrete structures in freeze-thaw zone

2018 ◽  
Vol 9 (4) ◽  
pp. 442-454
Author(s):  
Jinliang Liu ◽  
Yanmin Jia ◽  
Guanhua Zhang ◽  
Jiawei Wang
Keyword(s):  
Service Life ◽  
Structural Reliability ◽  
Concrete Structures ◽  
Calculation Model ◽  
Time Dependent ◽  
Content Type ◽  
Freeze Thaw ◽  
Remaining Service Life ◽  
Resistance Degradation ◽  
Thaw Zone

Purpose In the freeze-thaw zone, the pre-stressed concrete of bridge structure will be damaged by freezing-thawing, the bearing capacity of structure will decrease and the safety will be affected. The purpose of this paper is to establish the time-dependent resistance degradation model of structure in the freeze-thaw zone, and analysis the structural reliability and remaining service life in different freeze-thaw zones. Design/methodology/approach First, according to the theory of structural design, a calculation model of the resistance of pre-stressed concrete structures in f freeze-thaw zone is established. Second, the time-dependent resistance model was verified by the test beam bending failure test results done by the research group, which has been in service for 20 years in freeze-thaw zone. Third, using JC algorithm in MATLAB to calculate the index on the reliability of pre-stressed concrete structure in frozen thawed zones, forecasting the s remaining service life of structure. Findings First, the calculation model of the resistance of pre-stressed concrete structures in freeze-thaw zone is accurate and it has excellent applicability. Second, the structural resistance deterioration time in Wet-Warm-Frozen Zone is the earliest. Third, once the pre-stressed reinforcement rusts, the structural reliability index will reach limit value quickly. Finally, the remaining service life of structure meets the designed expectation value only in a few of freeze-thaw zones in China. Originality/value The research will provide a reference for the design on the durability of a pre-stressed concrete structure in the freeze-thaw zone. In order to verify the security of pre-stressed concrete structures in the freeze-thaw zone, engineers can use the model presented in this paper for durability checking, it has an important significance.

scholarly journals A 3D finite element model for reinforced concrete structures analysis

2011 ◽  
Vol 4 (4) ◽  
pp. 548-560 ◽  
Author(s):  
G. F. F. Bono ◽  
A. Campos Filho ◽  
A. R. Pacheco
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Numerical Model ◽  
Concrete Structures ◽  
Strain Curve ◽  
Uniaxial Stress ◽  
Element Model ◽  
Reinforced Concrete Structures ◽  
Principal Stresses ◽  
Stress Strain

This work presents a numerical model for 3D analyses through the finite element method of reinforced concrete structures subjected to monotonic loads. The proposed model for concrete is orthotropic and uses the equivalent uniaxial strain concept. The equivalent uniaxial stress-strain relation is generalized to take into account the triaxial stress conditions. The parameters used in the equivalent uniaxial stress-strain curve are determined from the failure surface defined in the principal stress space. The implementation in finite elements is based on the consideration of smeared cracks with cracks rotating according to the directions of the principal stresses. Also, an embedded reinforcement model was implemented to represent existent reinforcing bars. Finally, some results are compared with experimental data from the literature to demonstrate the validity of the numerical model developed.

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