scholarly journals Crack Detection and Localisation in Steel-Fibre-Reinforced Self-Compacting Concrete Using Triaxial Accelerometers

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2044
Author(s):  
Jeffri Ramli ◽  
James Coulson ◽  
James Martin ◽  
Brabha Nagaratnam ◽  
Keerthan Poologanathan ◽  
...  
Keyword(s):  
Crack Detection ◽  
Structural Integrity ◽  
Steel Fibre ◽  
Warning System ◽  
Sensor Technology ◽  
Structural Elements ◽  
Structural Failure ◽  
Self Compacting Concrete ◽  
Three Point Bending ◽  
Large Structures

Cracking in concrete structures can significantly affect their structural integrity and eventually lead to catastrophic failure if undetected. Recent advances in sensor technology for structural health monitoring techniques have led to the development of new and improved sensors for real-time detection and monitoring of cracks in various applications, from laboratory tests to large structures. In this study, triaxial accelerometers have been employed to detect and locate micro- and macrocrack formation in plain self-compacting concrete (SCC) and steel-fibre-reinforced SCC (SFRSCC) beams under three-point bending. Experiments were carried out with triaxial accelerometers mounted on the surface of the beams. The experimental results revealed that triaxial accelerometers could be used to identify the locations of cracks and provide a greater quantity of useful data for more accurate measurement and interpretation. The study sheds light on the structural monitoring capability of triaxial acceleration measurements for SFRSCC structural elements that can act as an early warning system for structural failure.

Preliminary Investigation on the Flexural Behaviour of Steel Fibre Reinforced Self-Compacting Concrete Ribbed Slab

2018 ◽  
Vol 15 (1) ◽  
pp. 31
Author(s):  
Nur Aiman Suparlan ◽  
Muhammad Azrul Ku Ayob ◽  
Hazrina Ahmad ◽  
Siti Hawa Hamzah ◽  
Mohd Hisbany Mohd Hashim
Keyword(s):  
Ultimate Load ◽  
Steel Fibre ◽  
Preliminary Investigation ◽  
Bending Test ◽  
Flexural Behaviour ◽  
Self Compacting Concrete ◽  
Two Samples ◽  
Simple Support ◽  
Set Up ◽  
Ultimate Load Carrying Capacity

A ribbed slab structure has the advantage in the reduction of concrete volume in between the ribs resulting in a lower structural self-weight. In order to overcome the drawbacks in the construction process, the application of steel fibre self-compacting concrete (SCFRC) is seen as an alternative material to be used in the slab. This preliminary investigation was carried out to investigate the flexural behaviour of steel fibre self-compacting concrete (SCFRC) as the main material in ribbed slab omitting the conventional reinforcements. Two samples of ribbed slab were prepared for this preliminary study; 2-ribbed and 3-ribbed in 1 m width to identify the effect of the geometry to the slab’s flexural behaviour. The dimension of both samples is 2.5 m x 1 m with 150 mm thickness. The compressive strength of the mix is 48.6 MPa based on the cubes tested at 28 days. Load was applied to failure by using the four point bending test set-up with simple support condition. The result of the experiment recorded ultimate load carrying capacity at 30.68 kN for the 2-ribbed slab and 25.52 kN for 3-ribbed slab. From the results, the ultimate load of the 2-ribbed sample exceeds 3-ribbed by approximately 20%. This proved that even with lower concrete volume, the sample can still withstand an almost similar ultimate load. Cracks was also observed and recorded with the maximum crack width of 2 mm. It can be concluded that the steel fibres do have the potential to withstand flexural loadings. Steel fibre reduces macro-crack forming into micro-cracks and improves concrete ductility, as well as improvement in deflection. This shows that steel fibre reinforced self-compacting concrete is practical as it offers good concrete properties as well as it can be mixed, placed easier without compaction. 

Vibration-Based Crack Detection in L-Frames

2014 ◽  
Vol 658 ◽  
pp. 261-268
Author(s):  
Jean Louis Ntakpe ◽  
Gilbert Rainer Gillich ◽  
Florian Muntean ◽  
Zeno Iosif Praisach ◽  
Peter Lorenz
Keyword(s):  
Strain Energy ◽  
Crack Detection ◽  
Natural Frequencies ◽  
Vibration Modes ◽  
Structural Elements ◽  
Element Analysis ◽  
Accurate Localization ◽  
Mathematical Expressions ◽  
Measurement Results ◽  
Non Destructive

This paper presents a novel non-destructive method to locate and size damages in frame structures, performed by examining and interpreting changes in measured vibration response. The method bases on a relation, prior contrived by the authors, between the strain energy distribution in the structure for the transversal vibration modes and the modal changes (in terms of natural frequencies) due to damage. Using this relation a damage location indicator DLI was derived, which permits to locate cracks in spatial structures. In this paper an L-frame is considered for proving the applicability of this method. First the mathematical expressions for the modes shapes and their derivatives were determined and simulation result compared with that obtained by finite element analysis. Afterwards patterns characterizing damage locations were derived and compared with measurement results on the real structure; the DLI permitted accurate localization of any crack placed in the two structural elements.

scholarly journals Frost durability of steel fiber self-compacting concrete for pavements

2016 ◽  
Vol 11 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Jerzy Wawrzeńczyk ◽  
Agnieszka Molendowska ◽  
Adam Kłak
Keyword(s):  
Steel Fibre ◽  
Air Entrainment ◽  
Hardened Concrete ◽  
Polymer Microspheres ◽  
Self Compacting Concrete ◽  
Freeze Thaw ◽  
Concrete Mix ◽  
Finished Surface ◽  
Frost Durability ◽  
Scaling Resistance

The paper presents the results from the research on self-compacting concrete with different steel fibre type addition. The reference self-compacting concrete mix with water/binder = 0.33 was prepared, then modified with steel fibres in the amounts of 0–60 kg/m3 and air entrained with polymer microspheres (40 μm diameter). The major objective of the research was to determine the effect of steel fibre and air content on the self-compacting concrete mix properties and hardened concrete frost durability. The tests also included internal cracking and scaling resistance evaluation for concrete specimens subjected to cyclic freeze-thaw process − two beams were frozen in air and two beams were partially submerged in water and then frozen. The scaling resistance was tested using the slab method on the specimens with sawn surface and on the specimens with natural finished surface. Non-air entrained steel fibrereinforced concretes, despite their high strength class (C55/67–C60/75) and medium absorption (4.34–5.11%), showed unsatisfactory resistance to internal cracking and scaling tests. The beams partially submerged in water failed after 100 freeze-thaw cycles, which confirms a significant influence of water uptake from moist environment during freeze-thaw cycles and the acceleration of the damage process. Test results indicate that air entrainment with polymer microspheres is a very effective method and allows obtaining very good air pore structure parameters and frost resistance results. The specimens with top − finished surface exhibited less damage in the scaling resistance tests in relation to the specimens with sawn surface.

Chopinian Particularities in Piano’s Sonata op. 58

2021 ◽  
Vol 13 (62) (SI) ◽  
pp. 69-78
Author(s):  
Lioara FRĂȚILĂ
Keyword(s):  
Structural Integrity ◽  
Classical Type ◽  
Late Period ◽  
Structural Elements ◽  
Piano Sonata ◽  
Strong Connection ◽  
Sonata Cycle ◽  
Aesthetic Results ◽  
The Postponement

The paper herein highlights those aspects of Chopin’s Piano Sonata Op.58 that demonstrate the strong connection with the classical-type sonata, its significance and the evolution of expression. Chopin’s Third Piano Sonata, Op.58 is the largest solo work of his late period. Chopin’s successful combination of the Classical and the Romantic aesthetic, results in an effective balancing of structural integrity and emotional fulfilment. Every moment of Op.58 possesses qualities of movements in a traditional sonata cycle; however, the tendency to blend structural elements, the expansion of thematic material and the postponement of climaxes contribute to Chopin’s distinctive treatment of the sonata genre style include blurring of genres, complex use of chromaticism, intricacy of counterpoint, textural and thematic variety

Use of Finite-Element Stress Analysis in the Design of a Tank-Cannon-Launched Training Projectile

1994 ◽  
Author(s):  
Michael S. L. Hollis
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Structural Integrity ◽  
Compressive Loading ◽  
Structural Failure ◽  
Finite Element Stress Analysis ◽  
Von Mises ◽  
Current Kinetic ◽  
A Current ◽  
Stress Analyses

Abstract The U.S. Army Armament Research. Development, and Engineering Center (ARDEC) recently expressed a need for a tank-cannon-launched training projectile with reduced penetration capability. The expressed primary design goals for this projectile were to minimize the probability of personnel injury and materiel loss in the event of an accidental impact during a training exercise. In order to meet these design goals, the solid-steel flight body of a current kinetic energy (KE) training projectile, the M865IP, was replaced with a hollow aluminum configuration. Because of the incorporation of aluminum, the structural integrity of the entire projectile during launch was put in question. Thus, a thorough stress analysis of the new design was conducted to alleviate concerns about its structural integrity. Two-dimensional, axisymmetric, quasi-static stress analyses were performed on two new KE training projectile designs. The first analysis indicated that structural failure was possible in the aft portion of the projectile due to compressive loading by the gun gases. Structural failure in this case would be circumferential yielding of the hollow flight body. The aft portion of the round was redesigned, and subsequent stress analysis showed the possibility of structural failure to be resolved. The finite-element modeling approach, the applied boundary conditions, and the results of the stress analyses conducted, based on use of the von Mises failure criterion, will be discussed in detail.

Development of a Pedestrian Collision Warning System Integrated Into Windscreen Pillars

2018 ◽  
Author(s):  
D. V. Zeziulin ◽  
D. Y. Tyugin ◽  
A. V. Tumasov ◽  
A. M. Groshev ◽  
D. M. Porubov
Keyword(s):  
Commercial Vehicle ◽  
Warning System ◽  
Recognition System ◽  
Traffic Situation ◽  
Structural Elements ◽  
Commercial Vehicles ◽  
Warning Signals ◽  
Collision Warning ◽  
Video Cameras ◽  
Experimental Researches

In Russia, 36% [1] of all accidents are a collision with a pedestrian. Vehicle structural elements limit visibility to drivers and do not allow fully assessing the traffic situation, forming blind zones. It especially applies to commercial vehicles with large dimensions. The system allowing to expand visibility of the car due to use of displays in windscreen pillars is presented in this article. It is proposed to use the pedestrian recognition system integrated into the windscreen pillars based on neural networks. The system allows to detect and estimate distance to the objects and to give warning signals about possible collision. It consists of an on-board computer, video cameras and output devices. Interior elements of a commercial vehicle were developed and installed. External side mirrors were replaced with video cameras. The exterior elements were designed and installed. Further there were carried out experimental researches of the system.

Sign in / Sign up

Export Citation Format

Share Document