Dataset Information

Feasibility Study of Digital Image Correlation in Determining Strains in Concrete Exposed to Fire.

ABSTRACT: Concrete is prone to spalling when exposed to fire. During fire tests, the strains of concrete elements are hard to identify, both from the fire-exposed face and the non-exposed face. This paper presents a field experiment which employed the original CivEng digital image correlation (DIC) method developed at the Cracow University of Technology to measure the strain fields of elements exposed to heating by a pin-point gas burner. The paper presents experimental proof that it is possible to analyze the deformation of both unheated and fire-exposed sides of heated concrete by the DIC method. The strain fields, crack patterns and modes of crack development are presented. The study shows the encouraging results of employing the DIC method to test concrete behavior under fire attack.

SUBMITTER: Mroz K

PROVIDER: S-EPMC7321450 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Feasibility Study of Digital Image Correlation in Determining Strains in Concrete Exposed to Fire.

Mróz Katarzyna K Tekieli Marcin M Hager Izabela I

Materials (Basel, Switzerland) 20200531 11

Concrete is prone to spalling when exposed to fire. During fire tests, the strains of concrete elements are hard to identify, both from the fire-exposed face and the non-exposed face. This paper presents a field experiment which employed the original CivEng digital image correlation (DIC) method developed at the Cracow University of Technology to measure the strain fields of elements exposed to heating by a pin-point gas burner. The paper presents experimental proof that it is possible to analyz ...[more]

PMID: 32486464

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Project description:The infrastructure is in many countries aging and continuous maintenance is required to ensure the safety of the structures. For concrete structures, cracks are a part of the structure's life cycle. However, assessing the structural impact of cracks in reinforced concrete is a complex task. The purpose of this paper is to present a dataset that can be used to verify and compare the results of the measured crack propagation in concrete with the well-known Digital Image Correlation (DIC) technique and with Crack Monitoring from Motion (CMfM), a novel photogrammetric algorithm that enables high accurate measurements with a non-fixed camera. Moreover, the data can be used to investigate how existing cracks in reinforced concrete could be implemented in a numerical model. Therefore, the first potential area to use this dataset is within image processing techniques with a focus on DIC. Until recently, DIC suffered from one major disadvantage; the camera must be fixed during the entire period of data collection. Naturally, this decreases the flexibility and potential of using DIC outside the laboratory. In a recently published paper (Belloni et al., 2023), an innovative photogrammetric algorithm (CMfM) that enables the use of a moving camera, i.e. a camera that is not fixed during data acquisition, was presented. The imagery of this dataset (Sjölander et al., 2023) was used to verify the potential of this algorithm and could be used to validate other approaches for non-fixed cameras. The second potential area is structural engineering. The data can be used to verify non-linear material models used in finite element (FE) software to simulate the structural response of reinforced concrete. In particular, the data can be used to investigate how existing cracks should be modelled in a FE model. The dataset presented in this paper includes data collected from a three-point bending test performed in a laboratory environment on uncracked and pre-cracked reinforced concrete beams. Structural testing was performed using a displacement-controlled set-up, which continuously recorded the force and the vertical displacement of a centric placed loading piston. First, the response of three uncracked beams was recorded. Thereafter, photos of the resulting cracks were taken, and a detailed mapping was presented. Material properties for the concrete, e.g., compressive strength, are presented together with testing of the tensile capacity of the reinforcement and a compressive test of the soft fiber boards used at the support to ensure good contact between steel and concrete. Then, the structural response of the pre-cracked beams was tested. During this test, four fixed cameras were used to monitor the crack propagation at different locations on the beam. Images are presented at the start of the load sequences and at pre-defined load stops during the testing. Hence, the crack opening captured in the images can be correlated to the force-displacement data. Moreover, a non-fixed camera was used to capture additional imagery at the location of each fixed camera.

Project description:ObjectiveThis study aimed at investigating the feasibility of using the spatiotemporal image correlation (STIC) technology for prenatal cardiac screening, finding factors that influence the offline evaluation of reconstructed fetal heart, and establishing an optimal acquisition scheme.MethodsThe study included 452 gravidae presenting for routine screening at 3 maternity centers at 20-38 gestational weeks. The factors influencing the quality of STIC volume data were evaluated using t test, chi-square test, and logistic regression analysis. The predictive power was evaluated using the receiver operating characteristic (ROC) curve.ResultsAmong the 452 fetuses enrolled, 353 (78.1%) were identified as successful and 99 (21.9%) as failure of evaluation of the reconstructed fetal heart. The total success rate of qualified STIC images was 78.1%. The display rates of reconstructed cardiac views were 86.5% (four-chamber view), 92.5% (left ventricular outflow tract view), 92.7% (right ventricular outflow tract view), 89.9% (three-vessel trachea view), 63.9% (aortic arch view), 81.4% (ductal arch view), 81% (short-axis view of great vessels), 80.1% (long-cava view), and 86.9% (abdominal view). A logistic regression analysis showed that more than 28 gestational weeks [OR = 0.39 (CI 95% 0.16, 0.19), P = 0.035], frequent fetal movements [OR = 0.37 (CI 95% 0.16, 0.87), P = 0.022], shadowing [OR = 0.36 (CI 95% 0.19, 0.72), P = 0.004], spine location at 10-2 o'clock [OR = 0.08 (CI 95% 0.02, 0.27), P = 0.0], and original cardiac view [OR = 0.51 (0.25, 0.89), P = 0.019] had a significant impact on the quality of STIC. The area under the ROC curve was 0.775.ConclusionsFetal cardiac-STIC seems a feasible tool for prenatal screening of congenital heart diseases. The influence factors on the quality of STIC images included the intensity of training, gestational age, fetal conditions and parameter settings. The optimal acquisition scheme may improve the application and widespread use of cardiac STIC.

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Feasibility Study of Digital Image Correlation in Determining Strains in Concrete Exposed to Fire.

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Feasibility Study of Digital Image Correlation in Determining Strains in Concrete Exposed to Fire.

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