scholarly journals Insight into Thermal Stress Distribution and Required Reinforcement Reducing Early-Age Cracking in Mass Foundation Slabs

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 477
Author(s):  
Barbara Klemczak ◽  
Aneta Żmij
Keyword(s):  
Stress Distribution ◽  
Thermal Stresses ◽  
Concrete Structures ◽  
Early Age ◽  
Correct Calculation ◽  
Thermal Origin ◽  
Standards And Guidelines ◽  
Heat Released ◽  
Different Levels ◽  
Insight Into

The heat released during cement hydration results in temperature-induced non-uniform volume changes in concrete structures. As a consequence, tensile thermal stresses of significant values may occur. The level of these stresses can be lowered by using various technological measures during the construction process and a proper concrete mix composition. Nevertheless, the application of an appropriate reinforcement is a reliable method for controlling the width and spacing of possible cracks. The rules for calculating this reinforcement are not precisely detailed in the standards devoted to concrete structures. Additionally, the correct calculation of the reinforcement requires the identification of the tensile stress distribution in a mass slab. The presented study provides insight into stress distribution and relevant reinforcement for controlling early-age cracks of thermal origin. The existing standards and guidelines are discussed and clarified. The possible paths for calculating the reinforcement are proposed through the example of mass foundation slabs with different levels of external restraints. The results indicate a significant impact of the calculation method as well as the restraint conditions of the slab on the area of required reinforcement.

scholarly journals Control of Early-Age Cracking in Watertight Concrete Structures

2018 ◽  
Vol 26 (3) ◽  
pp. 16-21
Author(s):  
Lýdia Matiašková ◽  
Juraj Bilčík ◽  
Július Šoltész
Keyword(s):  
Risk Assessment ◽  
Thermal Stresses ◽  
Concrete Structures ◽  
Mitigation Strategies ◽  
Early Age ◽  
Concrete Members ◽  
Mat Foundations

Abstract Considering the importance of leaking cracks in terms of serviceability and durability of watertight concrete structures, emphasis is placed on thermal movements and their effect on foundation slabs and walls. Both members are usually restrained to some degree externally and/or internally. The results indicate that restrained thermal stresses are the primary cause of early-age cracks in concrete members. This paper offers a discussion of mitigation strategies to prevent the formation and propagation of early-age separating cracks. A FEM-based analysis was used to determine the development of stresses in walls on mat foundations in relation to the crack risk assessment.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

Thermal stresses in multilevel interconnections: Aluminum lines at different levels

1997 ◽  
Vol 12 (9) ◽  
pp. 2219-2222 ◽  
Author(s):  
Y-L. Shen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
Future Studies ◽  
Level Lines ◽  
The Finite Element Analysis ◽  
Staggered Arrangement ◽  
Upper Level ◽  
Different Levels

Numerical results on the evolution of thermal stresses in multilevel interconnects are presented. Two levels of aluminum lines with an aspect ratio of unity, aligned vertically or arranged in a staggered manner, are considered by recourse to the finite element analysis. The stresses are found to be significantly higher in the lower-level lines than in the upper-level lines, for both the aligned and staggered arrangements. The stress magnitudes are generally smaller in lines of staggered arrangement, compared to the case of aligned lines. Implications of the present findings are discussed, with directions of future studies highlighted.

scholarly journals Early-Age Cracking in Concrete: Causes, Consequences, Remedial Measures, and Recommendations

2018 ◽  
Vol 8 (10) ◽  
pp. 1730 ◽  
Author(s):  
Md. Safiuddin ◽  
A. Kaish ◽  
Chin-Ong Woon ◽  
Sudharshan Raman
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Real Life ◽  
Early Age ◽  
Structural Elements ◽  
Remedial Measures ◽  
Curing Conditions ◽  
Factors Affecting ◽  
Different Types ◽  
Service Conditions

Cracking is a common problem in concrete structures in real-life service conditions. In fact, crack-free concrete structures are very rare to find in real world. Concrete can undergo early-age cracking depending on the mix composition, exposure environment, hydration rate, and curing conditions. Understanding the causes and consequences of cracking thoroughly is essential for selecting proper measures to resolve the early-age cracking problem in concrete. This paper will help to identify the major causes and consequences of the early-age cracking in concrete. Also, this paper will be useful to adopt effective remedial measures for reducing or eliminating the early-age cracking problem in concrete. Different types of early-age crack, the factors affecting the initiation and growth of early-age cracks, the causes of early-age cracking, and the modeling of early-age cracking are discussed in this paper. A number of examples for various early-age cracking problems of concrete found in different structural elements are also shown. Above all, some recommendations are given for minimizing the early-age cracking in concrete. It is hoped that the information conveyed in this paper will be beneficial to improve the service life of concrete structures. Concrete researchers and practitioners may benefit from the contents of this paper.

scholarly journals Evaluation of Stress Distribution Among Two Different Preangled Abutments of Implants in Two Different Densities of Bone at Different Levels Along the Implant–In Vitro Study

2018 ◽  
Vol 19 (11) ◽  
pp. 1370-1375
Author(s):  
Nibha K Singh ◽  
Suma B Chalapathy ◽  
Roger P Thota ◽  
Kiran Chakravarthula ◽  
Ramesh Tirnati ◽  
...  
Keyword(s):  
Stress Distribution ◽  
In Vitro Study ◽  
Vitro Study ◽  
Different Levels

scholarly journals Transcendental Philosophy as a Research Programme

2021 ◽  
Vol 40 (3) ◽  
pp. 93-126
Author(s):  
Michael Lewin
Keyword(s):  
Research Programme ◽  
Transcendental Philosophy ◽  
Pure Reason ◽  
Critique Of Pure Reason ◽  
The Third ◽  
Definite Form ◽  
Historical Investigation ◽  
Clear Idea ◽  
Different Levels ◽  
Insight Into

Transcendental philosophy was not born like Athena out of Zeus’s head, mature and in full armour from the very beginning. That is why in both prefaces to the Critique of Pure Reason (1781 and 1787) Kant introduces the concept of transcendental philosophy as an “idea.” The idea understood architectonically develops slowly and only gradually acquires a definite form. As witnessed by the works of Kant himself and of his predecessors and followers, the idea of transcendental philosophy has undergone a series of changes and adjustments compared to the initial plan. In this context, my goal is not simply exegesis and historical investigation of transcendental philosophy, but also to look at it from a systematic and methodological perspective. I examine the concept of transcendental philosophy from the viewpoint of programmatic metaphilosophy. The first part discusses programmatics as a distinct subsection of metaphilosophy. I argue that Kant’s architectonic methodology and the methodology of Lakatos can be used to understand the inception, development and degradation of philosophical systems. In the second part I look at the project of transcendental philosophy and the stages of its development from the standpoint of architectonics. The third part shows that Lakatos’s methodology can provide a detailed insight into the elements of transcendental philosophy, a clear idea of its logic and identify the component parts that can be improved and developed. In spite of the different levels of detailing and epistemological prerequisites, the methodologies of Kant and Lakatos can be combined to achieve a metaphilosophically informed and progressive understanding of philosophical projects.

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