scholarly journals Cracks analysis in the reinforced concrete pipes

2017 ◽  
Vol 12 (2) ◽  
pp. 88-93 ◽  
Author(s):  
Lidia Buda-Ozog ◽  
Izabela Skrzypczak ◽  
Joanna Kujda
Keyword(s):  
Reinforced Concrete ◽  
Load Capacity ◽  
Experimental Studies ◽  
Concrete Pipes ◽  
Current State ◽  
Concrete Pipe ◽  
Basic Parameters ◽  
Numerical Research ◽  
State Of Research ◽  
Geometrical Dimensions

In this paper, the analysis of cracking due to tensile stress in a reinforced concrete pipe is presented. The tensile strength of concrete in case of the member of a high relative curvature is significantly different from the strength of uncurved elements. The current state of research indicates that only methods of nonlinear fracture mechanics lead to a satisfactory agreement between the results of calculations and experimental studies, and allow for compiling correctly the influence of basic parameters of stretched concrete and geometrical dimensions on the load capacity of crush pipes made from concrete. Obtaining consistent results of experimental and numerical research is still a very complicated issue. This paper presents the results of the experimental investigation performed on three pipes and the numerical model of the analysed element of the pipes made using the ATENA (Advanced Tool for Engineering Nonlinear Analysis) program. The numerical analyses of cracks were compared with the results of experimental studies.

A new test method for evaluating the long-term performance of fiber-reinforced concrete pipes

2019 ◽  
Vol 23 (7) ◽  
pp. 1336-1349 ◽  
Author(s):  
Fouad T Al Rikabi ◽  
Shad M Sargand ◽  
Issam Khoury ◽  
John Kurdziel
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Steel Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Synthetic Fiber ◽  
Concrete Pipes ◽  
Concrete Pipe ◽  
Long Term Performance ◽  
Term Performance

Synthetic fibers have been used recently to minimize the need for steel reinforcement in the concrete pipe to enhance their ductility. However, synthetic fiber has properties that may change over time due to its viscoelastic behavior. The objective of this study is to investigate the long-term performance of fiber-reinforced concrete pipes using a new test frame. A three-dimensional finite element model was created for the long-term testing frame to ensure its compliance with the American Society for Testing and Materials requirement. The finite element results showed that the testing frame successfully transferred the load to the concrete as the pipe cracked at the location where high flexural stresses are expected. Concrete pipe reinforced with synthetic fiber dosage of 9 kg/m3 along the steel reinforcement area of 5.7 cm2/m was tested to evaluate the concrete pipe system performance. The pipe was tested under two load stages for 120 days each. Load stages 1 and 2 included applying 40% and 70% of the ultimate load obtained by the authors in a previous study, respectively. The strain and deflection increased linearly within 5 days of applying the load and then leveled off. The pipe showed a slight increase in the crack width and deflection, indicating that fiber creep did not have a significant impact on the long-term performance of the concrete pipe. Also, it was observed that strain values surpassed those for plain concrete material, suggesting that including synthetic fiber in the concrete pipe mix enhanced the pipe ductility.

The Determination of Prestress for Reinforced Concrete Pipes Based on Elasticity

2011 ◽  
Vol 213 ◽  
pp. 510-514
Author(s):  
Rong He ◽  
Wei He ◽  
Heng Xiang Zheng
Keyword(s):  
Reinforced Concrete ◽  
Critical Conditions ◽  
Elastic Model ◽  
Concrete Pipes ◽  
Inner Pressure ◽  
Concrete Pipe ◽  
Stress Boundary Condition ◽  
Theory Result ◽  
Stress Boundary

Based on elasticity, an elastic model was used to derivate the stress function and the stress expressions. According to the stress boundary condition and the geometry dimension of a cylinder-cross-section pipe, the constants are determined. First supposed the pipe were empty and the inner pressure were zero, the maximum prestress for the reinforced concrete pipe was determinate. Second, supposed the liquid pressure was the maximum, the model was used to determinate the minimum prestress. Combined the two critical conditions, the reasonable range of prestress for reinforced concrete pipe was got. In designing, the prestress must be consistent with it to prevent the concrete from crushing or bursting. At last, some differences between the theory result and the fact were pointed out to guide the application of the model.

A Review of Issues in Gamified Surveys

2016 ◽  
Vol 35 (2) ◽  
pp. 147-166 ◽  
Author(s):  
Florian Keusch ◽  
Chan Zhang
Keyword(s):  
Behavioral Outcomes ◽  
Experimental Studies ◽  
Research Literature ◽  
Future Research ◽  
Web Surveys ◽  
Survey Quality ◽  
Current State ◽  
Unpublished Studies ◽  
State Of Research ◽  
Game Elements

The term “gamification” is used for a wide variety of techniques aimed to increase respondent engagement while filling out web surveys. Suggested approaches range from rephrasing questions to sound more game-like to embedding the entire survey into a game where respondent avatars adventure through a fantasy land while answering survey questions. So far, only a few experimental studies regarding the influence of gamification on survey responding have been published in peer-reviewed journals. This article systematically reviews the current research literature on gamification in surveys by first answering the question as to what gamification entails in the context of web surveys by identifying relevant gamification elements. Next, the article discusses how these elements could influence survey data quality using the Total Survey Error framework. Finally, a systematic review of empirical evidence on gamified surveys from published and unpublished studies is provided. While most studies found in our literature review reported a positive effect of using game elements, such as challenges, story/narrative, rewards, goals/objectives, and badges, on psychological outcomes among survey respondents (e.g., fun, interest, satisfaction), the influence of these elements on behavioral outcomes (e.g., completion and break-offs, item omission, satisficing, responses) and, therefore, survey quality is more unclear. This article informs survey researchers and practitioners of the current state of research on survey gamification and identifies potential areas for future research.

scholarly journals TO THE STUDY OF THE MECHANISM OF TRIGGERING THE PLACEBO EFFECT: PLACEBO AND AUTO-SUGGESTION

2021 ◽  
Vol 9 (3) ◽  
pp. 221-228
Author(s):  
A.V. Khaikin ◽  
Keyword(s):  
Placebo Effect ◽  
Experimental Studies ◽  
Linear Structure ◽  
The Unconscious ◽  
Ethical Problems ◽  
Positive Expectation ◽  
Current State ◽  
The Subject ◽  
State Of Research

The current state of research on the placebo effect is considered. The task is set to develop the idea of the role of positive expectation in the mechanism of placebo implementation. A number of assumptions concerning the nature of placebo and approaches to its study are put forward. Consideration of the effect in its linear structure can contribute to the study of the nature of the placebo. It is useful to understand this phenomenon as consisting of a stage of psychological triggering and a stage of psychosomatic and physiological implementation. In turn, it is useful to consider the first of them as consisting of a preliminary stage of forming a positive (or negative – with nocebo) expectation, confidence in a certain effect of a placebo agent, and the stage of actually triggering a placebo. When implementing the placebo effect, the active expectation of a certain internal process and its result activates the mechanism of auto-suggestion, within which the expected is realized. The placebo is triggered by the implementation of one of the types of autosuggestion process, which does not presuppose any purposeful actions of the subject, for example, orders addressed to the unconscious. A significant part of the studies of the placebo effect nature can be carried out within the framework of the study of the mechanisms and patterns of this way of autosuggestion, which is triggered by the confident active expectation of the subject in the onset of certain internal changes. It is clear that such studies can be carried out in contexts other than those of placebo and nocebo implementation, for example, neutral in relation to the physical and emotional state and make their conduct not burdened with ethical problems. Which, of course, can significantly contribute to the intensification of the study of the placebo nature. It is concluded that the proposed concept develops the thesis about the necessary role of positive expectation in the implementation of the placebo effect, explaining the role of expectation in the mechanism of its launch. Understanding the mechanism of the placebo effect as a mechanism for self-suggestion will significantly simplify the conditions for experimental studies of placebo patterns and creates a context for further research.

scholarly journals Post-strengthening of reinforced concrete beams with prestressed CFRP strips. Part 1: analysis under static loading

2012 ◽  
Vol 5 (3) ◽  
pp. 343-361
Author(s):  
M. R. Garcez ◽  
G. L. C. P. Silva Filho ◽  
Urs Meier
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Existing Structures ◽  
Flexural Tests ◽  
Strengthening Technique ◽  
Epoxy Matrices

Different FPR post-strengthening techniques have been developed and applied in existing structures aiming to increase their load capacity. Most of the FRP systems used nowadays consist of carbon fibers embedded in epoxy matrices (CFRP). Regardless of the advantages and the good results shown by the CFRP post-strengthen technique, experimental studies show that, in most cases, the failure of post-strengthened structures is premature. Aiming to better use the tensile strength of the carbon fiber strips used as post-strengthening material, the application of prestressed CFRP strips started to be investigated. The main purpose of this paper is to analyze the effects of the composite prestressing in the performance of the CFRP post strengthening technique. The experimental program was based on flexural tests on post-strengthened reinforced concrete beams subjected to static - part 1 and cyclic - part 2 loading. Experimental results allowed the analysis of the quality and shortcomings of post-strengthen system studied, which resulted in valuable considerations about the analyzed post-strengthened beams.

Measured load capacity of buried reinforced concrete pipes

2016 ◽  
Vol 113 (1) ◽  
Author(s):  
Katrina MacDougall ◽  
Neil A. Hoult ◽  
Ian D. Moore
Keyword(s):  
Reinforced Concrete ◽  
Load Capacity ◽  
Concrete Pipes ◽  
Measured Load

Field Performance of Instrumented Concrete Pipe Under Deep Burial

1997 ◽  
Vol 1594 (1) ◽  
pp. 224-234 ◽  
Author(s):  
Glenn A. Hazen ◽  
Shad M. Sargand ◽  
Mohammed Haque ◽  
John O. Hurd
Keyword(s):  
Reinforced Concrete ◽  
Computer Program ◽  
Field Performance ◽  
Concrete Pipes ◽  
Deep Burial ◽  
Direct Design ◽  
Concrete Pipe ◽  
Design Calculations ◽  
Buried Concrete ◽  
Contact Pressures

Two 1.524-m-diameter, reinforced concrete pipes were instrumented to compare field results with design calculations. A computer program, Standard Installation Direct Design, developed by the American Concrete Pipe Association was used to design the pipe. Instrumented pipes were completely monitored until 11.9 m of cover had been placed. Measurements of soil contact pressures and vertical and horizontal deflections continued for 6 months. The computer-simulated and observed responses of the buried concrete pipe installations were compared. Pipe contact pressures measured at the invert were much smaller than those assumed from calculations of thrust and moment. Design moments were conservative compared with the experimentally measured values. Thrusts are difficult to calculate accurately and show large experimental variations.

Experimental Study of Corroded RC Beams Strengthened with CFRP under Fatigue and Monotonic Loads

2011 ◽  
Vol 243-249 ◽  
pp. 142-148
Author(s):  
Lei Wang ◽  
Jin Xiu Liang
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Composite Laminates ◽  
Load Capacity ◽  
Experimental Studies ◽  
Corrosion Damage ◽  
Fatigue Loading ◽  
Reinforced Concrete Beams ◽  
Ultimate Load Capacity ◽  
Cfrp Composite

This paper summarizes the results and discussion of experimental studies on corroded, reinforced concrete 4 point beam test specimens (120 mm x 200 mm x 1700 mm) repaired by external bonding of carbon fiber reinforced polymer (CFRP) composite laminates to the tensile face of the beam. The primary parameters investigated in this experimental study were distortion, stress distribution, and ultimate load capacity of the corroded reinforced concrete beams. The results indicate that the load capacity and the rigidity of repaired corroded beams by CFRP were significantly higher than the un-repaired, corroded beams. Beams with a low degree of corrosion damage, repaired by CFRP, were still able to demonstrate good mechanical properties after a short-term fatigue loading.

scholarly journals Mechanical homeostasis in tissue equivalents: a review

2021 ◽  
Author(s):  
Jonas F. Eichinger ◽  
Lea J. Haeusel ◽  
Daniel Paukner ◽  
Roland C. Aydin ◽  
Jay D. Humphrey ◽  
...  
Keyword(s):  
Multiple Scales ◽  
Experimental Studies ◽  
Biological Tissues ◽  
Future Research ◽  
Collagen Gels ◽  
Tissue Equivalents ◽  
Current State ◽  
Open Questions ◽  
Mechanical Homeostasis ◽  
State Of Research

AbstractThere is substantial evidence that growth and remodeling of load bearing soft biological tissues is to a large extent controlled by mechanical factors. Mechanical homeostasis, which describes the natural tendency of such tissues to establish, maintain, or restore a preferred mechanical state, is thought to be one mechanism by which such control is achieved across multiple scales. Yet, many questions remain regarding what promotes or prevents homeostasis. Tissue equivalents, such as collagen gels seeded with living cells, have become an important tool to address these open questions under well-defined, though limited, conditions. This article briefly reviews the current state of research in this area. It summarizes, categorizes, and compares experimental observations from the literature that focus on the development of tension in tissue equivalents. It focuses primarily on uniaxial and biaxial experimental studies, which are well-suited for quantifying interactions between mechanics and biology. The article concludes with a brief discussion of key questions for future research in this field.

scholarly journals Post-strengthening of reinforced concrete beams with prestressed CFRP strips: part 2: analysis under cyclic loading

2012 ◽  
Vol 5 (4) ◽  
pp. 420-439
Author(s):  
M. R. Garcez ◽  
L. C. P. Silva Filho ◽  
Urs Meier
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Existing Structures ◽  
Flexural Tests ◽  
Strengthening Technique ◽  
Epoxy Matrices

Different FPR post-strengthening techniques have been developed and applied in existing structures aiming to increase their load capacity. Most of the FRP systems used nowadays consist of carbon fibers embedded in epoxy matrices (CFRP). Regardless of the advantages and the good results shown by the CFRP post-strengthen technique, experimental studies show that, in most cases, the failure of post-strengthened structures is premature. Aiming to better use the tensile strength of the carbon fiber strips used as post-strengthening material, the application of prestressed CFRP strips started to be investigated. The main purpose of this paper is to analyze the effects of the composite prestressing in the performance of the CFRP post strengthening technique. The experimental program was based on flexural tests on post-strengthened reinforced concrete beams subjected to static - part 1 and cyclic - part 2 loading. Experimental results allowed the analysis of the quality and shortcomings of post-strengthen system studied, which resulted in valuable considerations about the analyzed post-strengthened beams.

Sign in / Sign up

Export Citation Format

Share Document