scholarly journals Application of Rotation Rate Sensors in Modal and Vibration Analyses of Reinforced Concrete Beams

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4711 ◽  
Author(s):  
Piotr Adam Bońkowski ◽  
Piotr Bobra ◽  
Zbigniew Zembaty ◽  
Bronisław Jędraszak
Keyword(s):  
Reinforced Concrete ◽  
Rotation Rate ◽  
Civil Engineering ◽  
Concrete Beams ◽  
Full Scale ◽  
Reinforced Concrete Beams ◽  
Mode Shapes ◽  
Dynamic Strain ◽  
Difference Approximation ◽  
Derivatives Of

The recent rapid development of rotation rate sensor technology opens new opportunities for their application in more and more fields. In this paper, the potential of rotational sensors for the modal analysis of full-scale civil engineering structural elements is experimentally examined. For this purpose, vibrations of two 6-m long beams made of ultra-high performance concrete (UHPC) were measured using microelectromechanical system (MEMS) rotation rate sensors. The beams were excited to vibrations using an impact hammer and a dynamic vibration exciter. The results of the experiment show that by using rotation rate sensors, one can directly obtain derivatives of mode shapes and deflection shapes. These derivatives of mode shapes, often called “rotational modes”, bring more information regarding possible local stiffness variations than the traditional transversal and deflection mode shapes, so their extraction during structural health monitoring is particularly useful. Previously, the rotational modes could only be obtained indirectly (e.g., by central difference approximation). Here, with the application of rotation rate sensors, one can obtain rotational modes and deflection shapes with a higher precision. Furthermore, the average strain rate and dynamic strain were acquired using the rotation rate sensors. The laboratory experiments demonstrated that rotation rate sensors were matured enough to be used in the monitoring and modal analyses of full-scale civil engineering elements (e.g., reinforced concrete beams).

Role of Dynamic Testing in Assessment of Bridges

1997 ◽  
Vol 1594 (1) ◽  
pp. 115-124 ◽  
Author(s):  
P. C. Das ◽  
J. S. Owen ◽  
B. J. Eccles ◽  
M. A. Woodings ◽  
B. S. Choo
Keyword(s):  
Reinforced Concrete ◽  
Natural Frequencies ◽  
Concrete Beams ◽  
Dynamic Testing ◽  
Reinforced Concrete Beams ◽  
Mode Shapes ◽  
Ambient Conditions ◽  
Frequency Changes ◽  
Frequency Ratios

Six reinforced concrete beams were loaded incrementally up to failure. After each increment the load was removed and measurements of the modal properties of the beams were made by impulse testing. The variation of the natural frequencies, frequency ratios, mode shapes, and the level of damage were investigated. It was found that on completion of the tests the natural frequencies of the beams had been reduced by an average of 25 percent in each mode. However, changes in mode shape were very small, and appreciable differences were only observed when the damage was highly localized. Modeling of the beam by using finite elements predicted trends that compared well with experimental observations. It is concluded that if dynamic testing were used in monitoring reinforced concrete structures, then the changes in frequency due to initial concrete cracking or yield of the reinforcement could be detected. More useful information associated with the spread and type of cracking through a structure may be detectable, although the level of the frequency changes is of the same order as those due to changes in ambient conditions.

scholarly journals FE Models of GFRP and CFRP Strengthening of Reinforced Concrete Beams

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
Kasidit Chansawat ◽  
Tanarat Potisuk ◽  
Thomas H. Miller ◽  
Solomon C. Yim ◽  
Damian I. Kachlakev
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Three Dimensional ◽  
Full Scale ◽  
Reinforced Concrete Beams ◽  
Flexural Strengthening ◽  
Frp Composites ◽  
Strengthened Beam ◽  
Three Dimensional Finite Element

Three-dimensional finite element (FE) models are developed to simulate the behavior of full-scale reinforced concrete beams strengthened with glass and carbon fiber-reinforced polymer sheets (an unstrengthened control beam, a flexural-strengthened beam, a shear-strengthened beam, and a beam with both shear and flexural strengthening). FE models use eight-node isoparametric elements with a smeared cracking approach for the concrete and three-dimensional layered elements to model the FRP composites. Analysis results are compared with data obtained from full-scale beam tests through the linear and nonlinear ranges up to failure. It was found that the FE models could identify qualitatively trends observed in the structural behavior of the full-scale beams. Predicted crack initiation patterns resemble the failure modes observed for the full-scale beam tests.

scholarly journals Experimental Validation of Finite Element Models for Reinforced Concrete Beams with Discontinuities That Form Dowel-Type Joints

Vibration ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 537-550
Author(s):  
Marios Filippoupolitis ◽  
Carl Hopkins
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Modal Assurance Criterion ◽  
Fem Model ◽  
Beam Elements ◽  
Concrete Elements

Earthquakes have the highest rate of mortality among the natural disasters and regularly lead to collapsed structures with people trapped inside them. When a reinforced concrete building collapses due to an earthquake, many of the concrete elements (i.e., beams and columns) are damaged and there are large sections where the concrete is missing and the steel reinforcement is exposed (i.e., concrete discontinuities). The prediction of vibration transmission in collapsed and severely damaged reinforced-concrete buildings could help decisions when trying to detect trapped survivors; hence there is need for experimentally validated finite element models of damaged concrete elements. This paper investigates the dynamic behaviour of damaged reinforced concrete beams using Experimental Modal Analysis (EMA) and Finite Element Methods (FEM). FEM models are assessed using two beams with one or more concrete discontinuities that form dowel-type joints. These models used either beam or spring elements for the exposed steel bars and were experimentally validated against EMA in terms of eigenfrequencies and mode shapes. Improved agreement was achieved when using springs instead of beam elements in the FEM model. The comparison of mode shapes used the Partial Modal Vector Ratio (PMVR) as a supplement to the Modal Assurance Criterion (MAC) to confirm that spring elements provide a more accurate representation of the response on all concrete parts of the beams.

scholarly journals Tratado Prático Sobre Funções de Singularidade: Modelamento de Cargas em Vigas de Concreto Armado

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Nilo Serpa
Keyword(s):  
Reinforced Concrete ◽  
Key Words ◽  
Civil Engineering ◽  
Concrete Beams ◽  
Exhaustive Search ◽  
Reinforced Concrete Beams ◽  
Broad Perspective ◽  
Elastic Curve ◽  
Class 1 ◽  
The Subject

<p>Present treatise deals with applications of singularity functions from a broad perspective in civil engineering, extending its use to hyperstatics, and deepening mathematical questions little explored before. The content is presented through examples discussed in detail, giving to the reader a clear and objective reading. Original mathematical formulations are developed, such as the Macaulay-Serpa series. The treatise is extended to the calculation of hyperstatic porticoes and to the modeling of triangular loads. In this context, the theory appears as an important instrument for the analysis of ruptures in reinforced concrete beams. For the accomplishment of this treatise, an exhaustive search of bibliographical references was made, showing that the existent literature on the subject, mostly of foreign origin, is quite limited.</p><p class="-1"><strong>Key words: </strong>Singularity functions, reinforced concrete, hyperstatics, discontinuous loading, elastic curve.</p><p class="-1">==================================================================================== </p><p>O presente tratado versa sobre aplicações das funções de singularidade numa ampla perspectiva da engenharia civil, estendendo seu uso à hiperestática e aprofundando questões matemáticas pouco exploradas anteriormente. O conteúdo é apresentado através de exemplos discutidos em detalhes, proporcionando ao leitor uma leitura clara e objetiva. Formulações matemáticas originais são desenvolvidas, como a série Macaulay-Serpa. O tratado é estendido ao cálculo de pórticos hiperestáticos e à modelagem de cargas triangulares. Nesse contexto, a teoria aparece como um instrumento importante para a análise de rupturas em vigas de concreto armado. Para a realização deste tratado, foi feita uma busca exaustiva das referências bibliográficas, mostrando que a literatura existente sobre o assunto, principalmente de origem estrangeira, é bastante limitada.</p><p class="-1"><strong>Palavras-Chave: </strong>Funções de singularidade, concreto armado, hiperestática, carga descontínua, curva elástica. </p>

scholarly journals Experimental investigation of cracking behaviour of concrete beams reinforced with steel fibres produced in Lithuania

2017 ◽  
Vol 12 (2) ◽  
pp. 82-87 ◽  
Author(s):  
Adas Meškėnas ◽  
Viktor Gribniak ◽  
Gintaris Kaklauskas ◽  
Aleksandr Sokolov ◽  
Eugenijus Gudonis ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Residual Strength ◽  
Steel Fibre ◽  
Concrete Beams ◽  
Full Scale ◽  
Reinforced Concrete Beams ◽  
Fibre Reinforced Concrete ◽  
Structural Behaviour ◽  
Steel Fibre Reinforced Concrete ◽  
Straightforward Application

Concrete is the most widely used material for bridge structures in Lithuania. A case study performed by the authors revealed that application of fibres might improve serviceability of such structures. However, adequacy of prediction of the post-cracking behaviour of steel fibre reinforced concrete might be insufficient. The latter issue is closely related to the assessment of the residual strength of steel fibre reinforced concrete. The residual strength, in most cases, is considered as a material property of the cracked concrete. However, in the prediction of the structural behaviour of the concrete members with bar reinforcement, a straightforward application of the residual strength values assessed by using standard techniques might lead to incorrect results. The present study deals with the post-cracking behaviour of structural elements made of concrete with aggregates and fibres provided by Lithuanian companies. Test results of three full-scale and sixteen standard steel fibre reinforced concrete beams with two different content of fibres (23.6 kg/m3 and 47.1 kg/m3) are presented. The full-scale beams were reinforced with high-grade steel bars. Effectiveness of the application of the minimum content of the fibres in combination with bar reinforcement was revealed experimentally.

scholarly journals Lublin University of Technology, Faculty of Civil Engineering and Architecture, Department of Construction Management

2013 ◽  
Vol 12 (4) ◽  
pp. 219-224
Author(s):  
Tadeusz Ciężak
Keyword(s):  
Reinforced Concrete ◽  
Construction Management ◽  
Maximum Degree ◽  
Civil Engineering ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Compression Zone ◽  
University Of Technology ◽  
Limiting Value ◽  
Concrete Reinforcement

This paper presents a methodology of dimensioning of double reinforced concrete beams which are reinforced in the light of the requirements of the EC2 [1] in two variants. In the first variant, the limiting value of the compression zone was determined on the basis of limiting strains of concrete and steel. The maximum degree of concrete reinforcement of bending elements are assumed in the second case. The considered problem is illustrated by computational examples in relation to the concrete classes C30/37 and C70/85. Results of the calculations cannot be the basis for generalizations, however, differences in the section of the reinforcement determined in both cases are small and do not exceed 6%.

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