scholarly journals Non-Destructive Diagnostics of Concrete Beams Strengthened with Steel Plates Using Modal Analysis and Wavelet Transform

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3014
Author(s):  
Magdalena Knak ◽  
Erwin Wojtczak ◽  
Magdalena Rucka
Keyword(s):  
Wavelet Transform ◽  
Modal Analysis ◽  
Adhesive Bonding ◽  
Concrete Beams ◽  
Load Capacity ◽  
Adhesive Joints ◽  
Steel Plates ◽  
Vanishing Moments ◽  
Term Operation ◽  
Non Destructive

Externally bonded reinforcements are commonly and widely used in civil engineering objects made of concrete to increase the structure load capacity or to minimize the negative effects of long-term operation and possible defects. The quality of adhesive bonding between a strengthened structure and steel or composite elements is essential for effective reinforcement; therefore, there is a need for non-destructive diagnostics of adhesive joints. The aim of this paper is the detection of debonding defects in adhesive joints between concrete beams and steel plates using the modal analysis approach. The inspection was based on modal shapes and their further processing with the use of continuous wavelet transform (CWT) for precise debonding localization and imaging. The influence of the number of wavelet vanishing moments and the mode shape interpolation on damage imaging maps was studied. The results showed that the integrated modal analysis and wavelet transform could be successfully applied to determine the exact shape and position of the debonding in the adhesive joints of composite beams.

scholarly journals Detection and Imaging of Debonding in Adhesive Joints of Concrete Beams Strengthened with Steel Plates Using Guided Waves and Weighted Root Mean Square

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2167 ◽  
Author(s):  
Erwin Wojtczak ◽  
Magdalena Rucka ◽  
Magdalena Knak
Keyword(s):  
Root Mean Square ◽  
Guided Waves ◽  
Concrete Beams ◽  
Adhesive Joints ◽  
Steel Plates ◽  
Mean Square ◽  
Engineering Structures ◽  
Adhesive Film ◽  
External Reinforcement ◽  
Non Destructive

Strengthening of engineering structures is an important issue, especially for elements subjected to variable loads. In the case of concrete beams or slabs, one of the most popular approaches assumes mounting an external reinforcement in the form of steel or composite elements by structural adhesives. A significant disadvantage of adhesive joints is the lack of access to the adhesive film for visual condition assessment, thus, there is a need for non-destructive diagnostics of these kinds of connections. The aim of this paper was the identification and visualization of defects in adhesive joints between concrete beams and steel plates using the guided wave propagation technique. The initial theoretical and numerical analyses were performed. The experimental wave field was excited and measured by the scanning laser Doppler vibrometry. The collected signals were processed by the weighted root mean square (WRMS) calculation. As a result, 2-D damage maps were obtained. The numerical simulations were performed to corroborate the experimental results. The results showed that the guided waves could be successfully applied in non-destructive diagnostics of adhesive joints between concrete and steel elements. However, the quality of damage visualizations strongly depended on the location of excitation.

scholarly journals Flexural Behavior of Reinforced Concrete Beams Retrofitted with Modularized Steel Plates

2021 ◽  
Vol 11 (5) ◽  
pp. 2348
Author(s):  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Maximum Load ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Flexural Behavior ◽  
Element Analysis ◽  
Flexural Performance ◽  
Structural Capacity

Many structural retrofitting methods tend to only focus on how to improve the strength and ductility of structural members. It is necessary for developing retrofitting strategy to consider not only upgrading the capacity but also achieving rapid and economical construction. In this paper, a new retrofitting details and technique is proposed to improve structural capacity and constructability for retrofitting reinforced concrete beams. The components of retrofitting are prefabricated, and the components are quickly assembled using bolts and chemical anchors on site. The details of modularized steel plates for retrofitting have been chosen based on the finite element analysis. To evaluate the structural performance of concrete beams retrofitted with the proposed details, five concrete beams with and without retrofitting were tested. The proposed retrofitting method significantly increased both the maximum load capacity and ductility of reinforced concrete beams. The test results showed that the flexural performance of the existing reinforced concrete beams increased by 3 times, the ductility by 2.5 times, and the energy dissipation capacity by 7 times.

scholarly journals Análisis experimental de distintas configuraciones de chapa metálica en el refuerzo a flexión de vigas de concreto armado

2016 ◽  
Vol 6 (2) ◽  
pp. 188-199
Author(s):  
C. C. Deghenhard ◽  
T. Teixeira ◽  
A. Vargas ◽  
M. Vito ◽  
Â. C. Piccinini ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Cast Steel ◽  
Epoxy Adhesive ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Steel Sheets ◽  
Structural Reinforcement ◽  
Vertical Displacements

Análisis experimental de distintas configuraciones de chapa metálica en el refuerzo a flexión de vigas de concreto armadoRESUMENEl acero de refuerzo estructural externo a través de chapas de acero pegadas con adhesivo epóxico es una opción para incrementar la capacidad de carga de elementos de concreto reforzado. En este estudio se evaluaron vigas de concreto reforzadas con chapas de acero SAE 1020 de diferentes espesores (0.75, 1.50 y 2.25 mm), longitudes (80 and 150 cm) y configuración (en forma de U o plana) con el propósito de revisar y comparar las mejores prácticas con chapas pegadas al refuerzo estructural. Se elaboraron 21 vigas construídas con una sección trasversal de 12 x 20 cm y una longitud de 200 cm, con concreto C25 y armadura de flexión con 2 Ø10 mm. Las vigas fueron sometidas a ensayos de flexión en 4 puntos, lo que permitió analizar las cargas últimas y desplazamientos verticales. Como resultado, se presenta una comparación relativa al desempeño de las vigas.Palabras clave: refuerzo estructural; placas de acero coladas, vigas de concreto reforzado. Experimental analysis of various configurations of metal sheets in the reinforcement of flexion of reinforced concrete beamsABSTRACT The external structural reinforcing steel in the way of steel sheets attached with epoxy adhesive is an option to increase the load capacity of reinforced concrete elements. This study evaluated concrete beams reinforced with steel sheets SAE 1020 of different thicknesses (0.75, 1.50, and 2.25 mm), longitudes (80 and 150 cm), and configurations (U-shape or flat) with the purpose of reviewing and comparing the best practices with sheets adhered to the structural reinforcement. Twenty-one beams were built with a cross-section of 12 x 20 cm and a longitude of 200 cm, with C25 concrete, and flexion frame with 2 Ø10 mm. The beams where subject to a four-point flexural test, which allowed analyzing the optimal loads and vertical displacements. Thus, a comparison relative to the performance of the beams is presented.Keywords: structural reinforcement; cast steel plates; reinforced concrete beams. Análise experimental de distintas configurações de chapa metálica no reforço à flexão em vigas de concreto armadoRESUMO O reforço estrutural externo com chapa metálica colada com adesivo epóxi é uma opção que possibilita aumentar a capacidade de carga em elementos de concreto armado. Este trabalho avaliou experimentalmente vigas de concreto armado com reforço de chapas de aço SAE 1020 de diferentes espessuras (0,75; 1,50 e 2,25 mm), comprimentos (80 e 150 cm) e configurações (perfil U ou simplesmente plana) com intuito de revisar e comparar as melhores práticas de reforço estrutural com chapa colada. Foram fabricadas 21 vigas com seções transversais de 12x20 cm e comprimento de 200 cm, utilizando concreto C25 e armadura de flexão com 2 Ø10 mm. As vigas foram submetidas a ensaios de flexão em 4 pontos, o que permitiu analisar as cargas últimas e deslocamentos verticais. Como resultado, apresenta-se um comparativo de desempenho das vigas.Palavras-chave: Reforço estrutural; chapa de aço colada; vigas de concreto armado.

scholarly journals Finite element analysis of reinforced concrete deep beam with large opening

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elsayed Ismail ◽  
Mohamed S. Issa ◽  
Khaled Elbadry
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
The Other ◽  
Deep Beam ◽  
Web Openings ◽  
Design Load ◽  
Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

NON-DESTRUCTIVE EVALUATION OF MECHANICAL DAMAGE OF ADHESIVES USING MAGNETO-ELECTRIC NANOPARTICLES

2021 ◽  
Author(s):  
GONZALO SEISDEDOS ◽  
BRIAN HERNANDEZ ◽  
JULIETTE DUBON ◽  
MARIANA ONTIVEROS ◽  
BENJAMIN BOESL ◽  
...  
Keyword(s):  
Adhesive Joint ◽  
Adhesive Bonding ◽  
Mechanical Damage ◽  
Adhesive Bond ◽  
Tensile Tests ◽  
Adhesive Joints ◽  
Adhesive Bonds ◽  
Magnetic Signatures ◽  
Looper System ◽  
Lock In

Adhesive bonding has been shown to successfully address some of the main problems with traditional fasteners, such as the reduction of the overall weight and a more uniformly distributed stress state. However, due to the unpredictability of failure of adhesive bonds, their use is not widely accepted in the aerospace industry. Unlike traditional fastening methods, it is difficult to inspect the health of an adhesive joint once it has been cured. For adhesive bonding to be widely accepted and implemented, there must be a better understanding of the fracture mechanism of the adhesive joints, as well as a way to monitor the health of the bonds nondestructively. Therefore, in-field structural health monitoring is an important tool to ensure optimal condition of the bond is present during its lifetime. This project focuses on the advancement of a non-invasive field instrument for evaluation of the health of the adhesive joints. The tool developed is based on a B-H looper system where coils are arranged into a noise-cancellation configuration to measure the magnetic susceptibility of the samples with a lock-in amplifier. The B-H looper system can evaluate the state of damage in an adhesive bond by detecting changes in surface charge density at the molecular level of an epoxy-based adhesive doped with magneto-electric nanoparticles (MENs). Epoxy-based adhesive samples were doped with MENs and then scanned using the B-H looper system. To evaluate the health of the adhesive joint, microindentation and tensile tests were performed on MENs-doped adhesive samples to understand the relationship between mechanical damage and magnetic signal. Correlations between magnetic signatures and mechanical damage were minimally observed, thus future studies will focus on refining the procedure and damaging methodology.

scholarly journals Discrete and Dual Tree Wavelet Features for Real-Time Speech/Music Discrimination

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Timur Düzenli ◽  
Nalan Özkurt
Keyword(s):  
Wavelet Transform ◽  
Real Time ◽  
Wavelet Transforms ◽  
Principal Component ◽  
Discrete Wavelet ◽  
Vanishing Moments ◽  
Zero Crossings ◽  
Time Frequency ◽  
Common Time ◽  
Classification Tool

The performance of wavelet transform-based features for the speech/music discrimination task has been investigated. In order to extract wavelet domain features, discrete and complex orthogonal wavelet transforms have been used. The performance of the proposed feature set has been compared with a feature set constructed from the most common time, frequency and cepstral domain features such as number of zero crossings, spectral centroid, spectral flux, and Mel cepstral coefficients. The artificial neural networks have been used as classification tool. The principal component analysis has been applied to eliminate the correlated features before the classification stage. For discrete wavelet transform, considering the number of vanishing moments and orthogonality, the best performance is obtained with Daubechies8 wavelet among the other members of the Daubechies family. The dual tree wavelet transform has also demonstrated a successful performance both in terms of accuracy and time consumption. Finally, a real-time discrimination system has been implemented using the Daubhecies8 wavelet which has the best accuracy.

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