scholarly journals Estimation of damage severity using sparse static measurement

2015 ◽  
Vol 23 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Ivana ŠTIMAC GRANDIĆ ◽  
Davor GRANDIĆ
Keyword(s):  
Structural Damage ◽  
Structural Response ◽  
Estimation Procedure ◽  
Simple Arithmetic ◽  
Damage Scenarios ◽  
Severity Estimation ◽  
Influence Line ◽  
Single Sensor ◽  
Grey Relation Coefficient

A new structural damage estimation procedure using grey relation coefficient and curvature of displacement influence line in beams using sparse measurement is proposed in this paper. The method is based on static structural response which can be obtained using single sensor. Determination of damage location as well as determination of corre­sponding damage severity can be easily calculated with simple arithmetic operations, which is the main advantage of the proposed method. Conducted numerical simulation for different damage scenarios and various measurement sparseness and experimental validation confirm the effectiveness of proposed damage severity estimation procedure.

scholarly journals Multivariate empirical mode decomposition–based structural damage localization using limited sensors

2021 ◽  
pp. 107754632110069
Author(s):  
Sandeep Sony ◽  
Ayan Sadhu
Keyword(s):  
Empirical Mode Decomposition ◽  
Structural Damage ◽  
Cost Effective ◽  
Threshold Value ◽  
Damage Localization ◽  
Time Frequency ◽  
Multivariate Empirical Mode Decomposition ◽  
Percentage Difference ◽  
Mode Decomposition

In this article, multivariate empirical mode decomposition is proposed for damage localization in structures using limited measurements. Multivariate empirical mode decomposition is first used to decompose the acceleration responses into their mono-component modal responses. The major contributing modal responses are then used to evaluate the modal energy for the respective modes. A damage localization feature is proposed by calculating the percentage difference in the modal energies of damaged and undamaged structures, followed by the determination of the threshold value of the feature. The feature of the specific sensor location exceeding the threshold value is finally used to identify the location of structural damage. The proposed method is validated using a suite of numerical and full-scale studies. The validation is further explored using various limited measurement cases for evaluating the feasibility of using a fewer number of sensors to enable cost-effective structural health monitoring. The results show the capability of the proposed method in identifying as minimal as 2% change in global modal parameters of structures, outperforming the existing time–frequency methods to delineate such minor global damage.

Full-Scale Experimental Evaluation of the Flood Resiliency of Thin Concrete Overlay on Asphalt Pavements

2021 ◽  
pp. 036119812110615
Author(s):  
Angel Mateos ◽  
John Harvey ◽  
Miguel Millan ◽  
Rongzong Wu ◽  
Fabian Paniagua ◽  
...  
Keyword(s):  
Structural Damage ◽  
Water Saturation ◽  
Critical Time ◽  
Structural Response ◽  
Extreme Weather Events ◽  
Pavement Materials ◽  
Structural Capacity ◽  
Weather Events ◽  
Pavement Structure ◽  
Falling Weight

The capacity to resist flooding is one of the critical challenges of pavement resiliency in locations subject to inundation. Flooding increases moisture contents, which weakens most pavement materials. Although the effect of moisture on the mechanical properties of most pavement materials is reversible, the structural damage caused by trafficking applied on the weakened pavement structure is not. The critical time for structural damage is typically after the flood and before “life-line” pavements have dried back when trucks are bringing in relief supplies and hauling out demolition. This fact, together with the increased occurrence of extreme weather events and sea level rise resulting from climate change, emphasizes the need to better understand the impacts of flooding on identified life-line pavements. This paper evaluates the flooding resiliency of thin concrete overlay on asphalt (COA) pavements by studying the effects that water saturation produces on the pavement structure. The research is based on the structural response and distresses measured in five thin COA sections that were instrumented with sensors and tested with a heavy vehicle simulator (HVS) under flooded conditions. The research shows that the flooding did not produce a noticeable change in the structural capacity of the COA, based on the structural response measured under the loading of the HVS wheel and the falling weight deflectometer, but did result in some structural damage to the asphalt base in some of the sections.

scholarly journals Structural Assessment of the Hull Response of an FPSO Unit to Dropped Objects: A Case Study

2019 ◽  
Vol 26 (4) ◽  
pp. 39-46 ◽  
Author(s):  
Ozgur Ozguc
Keyword(s):  
Structural Damage ◽  
Local Buckling ◽  
Structural Response ◽  
Offshore Structures ◽  
Mechanical Equipment ◽  
Structural Members ◽  
Impact Area ◽  
Explicit Dynamic ◽  
The Impact

Abstract Offshore structures are exposed to the risk of damage caused by various types of extreme and accidental events, such as fire, explosion, collision, and dropped objects. These events cause structural damage in the impact area, including yielding of materials, local buckling, and in some cases local failure and penetration. The structural response of an FPSO hull subjected to events involving dropped objects is investigated in this study, and non-linear finite element analyses are carried out using an explicit dynamic code written LS-DYNA software. The scenarios involving dropped objects are based on the impact from the fall of a container and rigid mechanical equipment. Impact analyses of the dropped objects demonstrated that even though some structural members were permanently deformed by drop loads, no failure took place in accordance with the plastic strain criteria, as per NORSOK standards. The findings and insights derived from the present study may be informative in the safe design of floating offshore structures.

scholarly journals Identification of Structural Damage in Bridges Using High-Frequency Vibrational Responses

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Ivana Mekjavić
Keyword(s):  
High Frequency ◽  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Damage Model ◽  
Reinforced Concrete Beam ◽  
Computational Technique ◽  
Damage Scenarios ◽  
Identification Approach ◽  
Girder Bridge

The present research aims to develop an effective and applicable structural damage detection method. A damage identification approach using only the changes of measured natural frequencies is presented. The structural damage model is assumed to be associated with a reduction of a contribution to the element stiffness matrix equivalent to a scalar reduction of the material modulus. The computational technique used to identify the damage from the measured data is described. The performance of the proposed technique on numerically simulated real concrete girder bridge is evaluated using imposed damage scenarios. To demonstrate the applicability of the proposed method by employing experimental measured natural frequencies this technique is applied for the first time to a simply supported reinforced concrete beam statically loaded incrementally to failure. The results of the damage identification procedure show that the proposed method can accurately locate the damage and predict the extent of the damage using high-frequency (here beyond the 4th order) vibrational responses.

Structural interrogation using phase space topology of the wind-induced responses

2017 ◽  
Vol 24 (14) ◽  
pp. 3148-3172
Author(s):  
Riya C George ◽  
Sudib K Mishra
Keyword(s):  
Phase Space ◽  
Structural Damage ◽  
Model Building ◽  
Chaotic Signal ◽  
Experimental Investigations ◽  
Damage Scenarios ◽  
Space Topology ◽  
Frame Building ◽  
Low Dimensional ◽  
Phase Space Topology

The applicability of the phase space interrogation (PSI) methodology for structural health monitoring (SHM) is limited on account of the fact that the structure needs to be excited by a low dimensional chaotic signal. The present study demonstrates that the phase space interrogation can still be applied to structures subjected to ambient/moderate wind excitations. Key to this extension is the relative low dimensionality of the wind-induced structural responses, amenable to phase space embedding by virtue of Takens’ embedding theorem. The so-formed pseudo-attractor is shown to sufficiently reflect the changes in system dynamics induced by structural damage(s). A widely employed damage feature, namely, the changes in phase space topology (CPST) is subsequently employed to the reconstructed attractor to link it with the presence, severity, as well as localization of damage(s). The CPST is established as a legitimate damage-sensitive feature by studying its variability with alternative damage scenarios in a multistoried frame building subjected to wind excitations. The performance of the methodology is demonstrated under different degrees of noise contamination in the measured responses as well as varying intensity of wind speed. The statistical robustness of the procedure is also assessed. The numerical findings are supported by the evidence from a limited number of experimental investigations carried out on a model building with inflicted damage scenarios. The wind loadings for the tests are simulated using a wind tunnel testing facility. Finally, a simple analysis is presented that establish the viability of the phase space analysis analytically.

scholarly journals Field Deployment of a Portable Optical Spectrometer for Methane Fugitive Emissions Monitoring on Oil and Gas Well Pads

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2707 ◽  
Author(s):  
Eric J. Zhang ◽  
Chu C. Teng ◽  
Theodore G. van Kessel ◽  
Levente Klein ◽  
Ramachandran Muralidhar ◽  
...  
Keyword(s):  
Near Infrared ◽  
Oil And Gas ◽  
Tunable Diode Laser ◽  
Angle Of Arrival ◽  
Good Correspondence ◽  
Laser Absorption ◽  
Deviation Analysis ◽  
Single Sensor ◽  
Field Deployment

We present field deployment results of a portable optical absorption spectrometer for localization and quantification of fugitive methane (CH4) emissions. Our near-infrared sensor targets the 2ν3 R(4) CH4 transition at 6057.1 cm−1 (1651 nm) via line-scanned tunable diode-laser absorption spectroscopy (TDLAS), with Allan deviation analysis yielding a normalized 2.0 ppmv∙Hz−1/2 sensitivity (4.5 × 10−6 Hz−1/2 noise-equivalent absorption) over 5 cm open-path length. Controlled CH4 leak experiments are performed at the METEC CSU engineering facility, where concurrent deployment of our TDLAS and a customized volatile organic compound (VOC) sensor demonstrates good linear correlation (R2 = 0.74) over high-flow (>60 SCFH) CH4 releases spanning 4.4 h. In conjunction with simultaneous wind velocity measurements, the leak angle-of-arrival (AOA) is ascertained via correlation of CH4 concentration and wind angle, demonstrating the efficacy of single-sensor line-of-sight (LOS) determination of leak sources. Source magnitude estimation based on a Gaussian plume model is demonstrated, with good correspondence (R2 = 0.74) between calculated and measured release rates.

scholarly journals Determination Of Gas Mixture Components Using Fluctuation Enhanced Sensing And The LS-SVM Regression Algorithm

2015 ◽  
Vol 22 (3) ◽  
pp. 341-350 ◽  
Author(s):  
Łukasz Lentka ◽  
Janusz M. Smulko ◽  
Radu Ionescu ◽  
Claes G. Granqvist ◽  
Laszlo B. Kish
Keyword(s):  
Support Vector Machine ◽  
Least Squares ◽  
Temperature Change ◽  
Nonlinear Regression ◽  
Ultraviolet Irradiation ◽  
Support Vector ◽  
Gas Mixture ◽  
Gas Concentration ◽  
Single Sensor

Abstract This paper analyses the effectiveness of determining gas concentrations by using a prototype WO3 resistive gas sensor together with fluctuation enhanced sensing. We have earlier demonstrated that this method can determine the composition of a gas mixture by using only a single sensor. In the present study, we apply Least-Squares Support-Vector-Machine-based (LS-SVM-based) nonlinear regression to determine the gas concentration of each constituent in a mixture. We confirmed that the accuracy of the estimated gas concentration could be significantly improved by applying temperature change and ultraviolet irradiation of the WO3 layer. Fluctuation-enhanced sensing allowed us to predict the concentration of both component gases.

scholarly journals Amino acid availability: aspects of chemical analysis and bioassay methodology

2003 ◽  
Vol 16 (2) ◽  
pp. 127-141 ◽  
Author(s):  
Paul J. Moughan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chemical Analysis ◽  
Structural Damage ◽  
Human Subjects ◽  
Scientific Evidence ◽  
Hydrolysis Time ◽  
Amino Acid Availability

AbstractIt is important to be able to characterise foods and feedstuffs according to their available amino acid contents. This involves being able to determine amino acids chemically and the conduct of bioassays to determine amino acid digestibility and availability. The chemical analysis of amino acids is not straightforward and meticulousness is required to achieve consistent results. In particular and for accuracy, the effect of hydrolysis time needs to be accounted for. Some amino acids (for example, lysine) can undergo chemical modification during the processing and storage of foods, which interferes with amino acid analysis. Furthermore, the modified amino acids may also interfere with the determination of digestibility. A new approach to the determination of available lysine using a modifiedin vivodigestibility assay is discussed. Research is required into other amino acids susceptible to structural damage. There is recent compelling scientific evidence that bacterial activity in the small intestine of animals and man leads to the synthesis and uptake of dietary essential amino acids. This has implications for the accuracy of the ileal-based amino acid digestibility assay and further research is required to determine the extent of this synthesis, the source of nitrogenous material used for the synthesis and the degree of synthesis net of amino acid catabolism. Although there may be potential shortcomings in digestibility assays based on the determination of amino acids remaining undigested at the terminal ileum, there is abundant evidence in simple-stomached animals and growing evidence in human subjects that faecal-based amino acid digestibility coefficients are misleading. Hindgut microbial metabolism significantly alters the undigested dietary amino acid profile. The ileal amino acid digestibility bioassay is expected to be more accurate than its faecal-based counterpart, but correction of the ileal amino acid flow for amino acids of endogenous origin is necessary. Approaches to correcting for the endogenous component are discussed.

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