scholarly journals Non-Destructive Testing of the Longest Span Soil-Steel Bridge in Europe—Field Measurements and FEM Calculations

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3652 ◽  
Author(s):  
Mikołaj Miśkiewicz ◽  
Bartosz Sobczyk ◽  
Pawel Tysiac
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
Field Measurements ◽  
Load Test ◽  
Steel Bridge ◽  
Good Correspondence ◽  
Total Station ◽  
Non Destructive ◽  
Inductive Sensors

The article describes interdisciplinary and comprehensive non-destructive diagnostic tests of final bridge inspection and acceptance proposed for a soil-steel bridge made of corrugated sheets, being the European span length record holder (25.74 m). As an effect of an original concept a detailed and precise information about the structure short-term response was collected. Periodic diagnostics of bridge deformations was done one year after it was built. Load test design was based on numerical simulations performed by means of finite element method (FEM). In situ measurements were done with the aid of: inductive sensors, optical total station, and terrestrial laser scanner. The results produced by terrestrial laser scanning were used to build a precise image of structure deformation in 3D space during the tests. The accuracy of laser mapping was significantly increased using the information coming from total station and inductive sensors. These have higher accuracy and therefore can be used as reference. Thus, new quality in measurements is introduced. Good correspondence between in situ values and FEM estimations was achieved. Therefore, such a combination of testing methods can be used in non-destructive diagnostics of structures and is an interesting alternative for the standard approach, in which the measurements are done in limited number of points.

CHARACTERIZING ANOMALIES IN DISTRIBUTED STRAIN MEASUREMENTS OF CAST-IN-SITU BORED PILES

2016 ◽  
Vol 78 (8-5) ◽  
Author(s):  
Hisham Mohamad ◽  
Bun Pin Tee ◽  
Koh An Ang ◽  
Mun Fai Chong
Keyword(s):  
Load Transfer ◽  
Load Test ◽  
Strain Sensing ◽  
Strain Profile ◽  
A New Technique ◽  
Optical Time ◽  
Distributed Optical Fiber ◽  
Non Destructive ◽  
Distributed Strain

This paper describes the method of identifying typical defects of bored cast-in-situ piles when instrumenting using Distributed Optical Fiber Strain Sensing (DOFSS). The DOFSS technology is based on Brillouin Optical Time Domain Analyses (BOTDA), which has the advantage of recording continuous strain profile as opposed to the conventional discrete based sensors such as Vibrating Wire strain gauges. In pile instrumentation particularly, obtaining distributed strain profile is important when analysing the load-transfer and shaft friction of a pile, as well as detecting any anomalies in the strain regime. Features such as defective pile shaft necking, discontinuity of concrete, intrusion of foreign matter and improper toe formation due to contamination of concrete at base with soil particles, among others, may cause the pile to fail. In this study, a new technique of detecting such defects is proposed using DOFSS technology which can potentially supplement the existing non-destructive test (NDT) methods. Discussion on the performance of instrumented piles by means of maintained load test are also presented

scholarly journals Terrestrial Laser Scanning and Settled Techniques: A Support to Detect Pathologies and Safety Conditions of Timber Structures

2013 ◽  
Vol 778 ◽  
pp. 350-357 ◽  
Author(s):  
Clara Bertolini-Cestari ◽  
Filiberto Chiabrando ◽  
Stefano Invernizzi ◽  
Tanja Marzi ◽  
Antonia Spanò
Keyword(s):  
Laser Scanning ◽  
Planning Process ◽  
Laser Scanner ◽  
Texture Mapping ◽  
Surface Model ◽  
Resolution Model ◽  
Close Range ◽  
High Resolution Model ◽  
Increasing Demand ◽  
Non Destructive

Nowadays, there is an increasing demand for detailed geometrical representation of the existing cultural heritage, in particular to improve the comprehension of interactions between different phenomena and to allow a better decisional and planning process. The LiDAR technology (Light Detection and Ranging) can be adopted in different fields, ranging from aerial applications to mobile and terrestrial mapping systems. One of the main target of this study is to propose an integration of innovative and settled inquiring techniques, ranging from the reading of the technological system, to non-destructive tools for diagnosis and 3D metric modeling of buildings heritage. Many inquiring techniques, including Terrestrial Laser Scanner (TLS) method, have been exploited to study the main room of the Valentino Castle in Torino. The so-called “Salone delle Feste”, conceived in the XVIIth century under the guidance of Carlo di Castellamonte, has been selected as a test area. The beautiful frescos and stuccoes of the domical vault are sustained by a typical Delorme carpentry, whose span is among the largest of their kind. The dome suffered from degradation during the years, and a series of interventions were put into place. A survey has revealed that the suspender cables above the vault in the region close to the abutments have lost their tension. This may indicate an increase of the vault deformation; therefore a structural assessment of the dome is mandatory. The high detailed metric survey, carried out with integrated laser scanning and digital close range photogrammetry, reinforced the structural hypothesis of damages and revealed the deformation effects. In addition, the correlation between the survey-model of the intrados and of the extrados allowed a non-destructive and extensive determination of the dome thickness. The photogram-metrical survey of frescos, with the re-projection of images on vault surface model (texture mapping), is purposed to exactly localize formers restoration and their signs on frescos continuity. The present paper illustrates the generation of the 3D high-resolution model and its relations with the results of the structural survey; both of them support the Finite Element numerical simulation of the dome.

scholarly journals Characterization of Adobe Blocks: Point-Load Assessment as a Complementary Study of Damaged Buildings and Samples

Heritage ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 864-888
Author(s):  
Adria Sanchez-Calvillo ◽  
Elia M. Alonso-Guzman ◽  
Wilfrido Martinez-Molina ◽  
Marco A. Navarrete-Seras ◽  
Jose L. Ruvalcaba-Sil ◽  
...  
Keyword(s):  
Rural Communities ◽  
Formal Analysis ◽  
Complete Characterization ◽  
Point Load ◽  
Load Test ◽  
Construction Technique ◽  
Load Tests ◽  
Non Destructive

Adobe masonry is one of the oldest construction systems still in use today, Mexico has an enormous cultural heritage with traditional adobe houses being very representative of the rural communities and their culture. The 2017 Puebla Earthquake on September 19th struck the country causing the loss, destruction, and damage of historic buildings in several Mexican states, with the traditional earthen dwellings being the most vulnerable structures to these events. The fast abandonment of the local materials and techniques entails further research regarding the characterization of these construction systems, therefore, reconstruction efforts first require the recovery of the construction technique. After the seismic events, adobe samples of the remaining adobe structures of Jojutla de Juarez were collected. This population was one of the most affected in all the country, and, because of the major losses suffered, the study was conducted to determine the material properties of the dwellings’ adobe shards and natural quarry clays of the region. The characterization included destructive and non-destructive tests, mineralogical and granulometry analyses, and composition of the adobe samples of the buildings, as well as the aggregates. As a novelty, the compressive strength of the pieces was tested by two methods: the traditional compression strength test and the point-load test, in order to obtain the indicative values and the correlation equations between both tests. From the formal analysis and the laboratory, it was observed that the adobes from Jojutla presented different compositions which combined with the building malpractices and alterations to the traditional systems caused unpredictable behavior during the earthquake. The conduction of point-load tests in situ, as a part of a complete characterization methodology, could be an alternative to study the mechanical properties of patrimonial or damaged building samples before its disappearance.

scholarly journals Applicability and Analysis of the Results of Non-Contact Methods in Determining the Vertical Displacements of Timber Beams

2021 ◽  
Vol 11 (19) ◽  
pp. 8936
Author(s):  
Boštjan Kovačič ◽  
Luka Štraus ◽  
Mateja Držečnik ◽  
Zoran Pučko
Keyword(s):  
Construction Projects ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Meteorological Conditions ◽  
Total Station ◽  
Engineering Geodesy ◽  
Vertical Displacements ◽  
Robotic Total Station ◽  
Timber Beams

Determining the displacements and consequent deformations of structures is a demanding branch of engineering. Displacements are most often determined by geodetic methods, among which high-precision non-contact methods have recently taken the lead. Engineering geodesy is an indispensable part of construction projects. In the desire for efficient and fast measurements, the technology of terrestrial laser scanning (TLS) and the use of robotic total station (RTS) and other geodetic methods are becoming more and more useful for engineers. In the presented study, we focused on the measurement and comparison of vertical displacements with various mentioned equipment and the determination of the influence of meteorological conditions on the displacements of timber beams that we used to perform the experiment. Measurements were performed both in the laboratory and outdoors. A novelty in the work was the use of a TLS scanner to determine the evaluation of small value displacements and the analysis of the usability of geodetic measuring equipment. In the Materials and Methods section, we describe the equipment used and the characteristics of the beams. The Results section describes the experimental outcomes, which include the performance of experimental analysis of vertical displacements of timber beams under different meteorological conditions. Altogether, the results consist of geodetic measurements and the processing of measured data. The results of measurements of vertical displacements with a terrestrial laser scanner were compared with the results obtained with a robotic total station were evaluated and compared with the displacements calculated from static analysis and the results of other methods used.

scholarly journals Divergence of apparent and intrinsic snow albedo over a season at a sub-alpine site with implications for remote sensing

2021 ◽  
Author(s):  
Edward Hamilton Bair ◽  
Jeff Dozier ◽  
Charles Stern ◽  
Adam LeWinter ◽  
Karl Rittger ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Surface Topography ◽  
Near Infrared ◽  
Laser Scanner ◽  
Field Measurements ◽  
Spectral Unmixing ◽  
Snow Albedo ◽  
The Difference ◽  
Multispectral Sensors

Abstract. Intrinsic albedo is the bihemispherical reflectance of a substance with a smooth surface. Conversely, the apparent albedo is the bihemispherical reflectance of the same substance with a rough surface. For snow, the surface is often rough, and these two optical quantities have different uses: intrinsic albedo is used in scattering equations whereas apparent albedo should be used in energy balance models. Complementing numerous studies devoted to surface roughness and its effect on snow reflectance, this work analyzes a timeseries of intrinsic and apparent snow albedos over a season at a sub-alpine site using an automated terrestrial laser scanner to map the snow surface topography. An updated albedo model accounts for shade, and in situ albedo measurements from a field spectrometer are compared to those from a spaceborne multispectral sensor. A spectral unmixing approach using a shade endmember (to address the common problem of unknown surface topography) produces grain size and impurity solutions; the modeled shade fraction is compared to the intrinsic and apparent albedo difference. As expected and consistent with other studies, the results show that intrinsic albedo is consistently greater than apparent albedo. Both albedos decrease rapidly as ablation hollows form during melt, combining effects of impurities on the surface and increasing roughness. Intrinsic broadband albedos average 7 % greater than apparent albedos, with the difference being about 6 % in the near-infrared or 3–4 % if the average (planar) topography is known and corrected. Field measurements of spectral surface reflectance confirm that multispectral sensors see the apparent albedo but lack the spectral resolution to distinguish between darkening from ablation hollows versus low concentrations of impurities. In contrast, measurements from the field spectrometer have sufficient resolution to discern darkening from the two sources. Based on these results, conclusions are: 1) impurity estimates from multispectral sensors are only reliable for relatively dirty snow with high snow fraction; 2) a shade endmember must be used in spectral mixture models, even for in situ spectroscopic measurements; and 3) snow albedo models should produce apparent albedos by accounting for the shade fraction. The conclusion re-iterates that albedo is the most practical snow reflectance quantity for remote sensing.

HISTOLOGICAL ASSESSMENT OF THE CHONDRAL AND CONNECTIVE TISSUES OF THE KNEE BY CONFOCAL ARTHROSCOPE

2004 ◽  
Vol 08 (02n03) ◽  
pp. 75-86 ◽  
Author(s):  
C. W. Jones ◽  
A. Keogh ◽  
D. Smolinski ◽  
J. P. Wu ◽  
T. B. Kirk ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Knee Joints ◽  
Connective Tissues ◽  
Histological Assessment ◽  
Merino Sheep ◽  
Histological Characteristics ◽  
Orthopedic Diseases ◽  
Non Destructive ◽  
Repair Techniques

Conventional histological assessment of tissue requires the removal of tissue from its physiological environment for pathological processing. In this study we report on the development and application of a laser scanning confocal arthroscope (LSCA) capable of in situ histological assessment by confocal microscopy. The knee joints of three euthanasied adult Merino sheep were imaged using the LSCA and a combination of fluorescent contrasting agents. LSCA images of various tissues were examined for common histological characteristics. The confocal histology images from the ovine knee acquired during the course of our study illustrated some of the major histological features of chondral and connective tissues. Our study demonstrates the efficacy of the LSCA for the histological assessment of the chondral and connective tissues of the ovine knee. The LSCA provides an easy and rapid method for assessing the in situ structure of cartilage, muscle, tendon, ligament, meniscus and synovium in their native and unaltered physiological environment. By obviating the need for mechanical biopsy, the LSCA provides a method for the non-destructive assessment of the chondral and connective tissues of the knee, and may be of great benefit in the investigation of orthopedic diseases or in the assessment of newly emerging cartilage repair techniques.

scholarly journals Retrieval of Forest Structural Parameters From Terrestrial Laser Scanning: A Romanian Case Study

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 392
Author(s):  
Ionuț-Silviu Pascu ◽  
Alexandru-Claudiu Dobre ◽  
Ovidiu Badea ◽  
Mihai Andrei Tanase
Keyword(s):  
Correlation Coefficient ◽  
Laser Scanning ◽  
Structural Parameters ◽  
Laser Scanner ◽  
Field Measurements ◽  
Point Clouds ◽  
Field Work ◽  
Major Influence ◽  
Natural Forests ◽  
Biophysical Parameters

Research Highlights: The present study case investigates the differences occurring when tree’s biophysical parameters are extracted through single and multiple scans. Scan sessions covered mountainous and hill regions of the Carpathian forests. Background and Objectives: We focused on analyzing stems, as a function of diameter at breast height (DBH) and the total height (H), at sample plot level for natural forests, with the purpose of assessing the potential for transitioning available methodology to field work in Romania. Materials and Methods: We performed single and multiple scans using a FARO Focus 3D X130 phase shift terrestrial laser scanner at 122kpts and 0.3:0.15 mm noise compression ratio, resulting in an average point density of 6pts at 10m. The point cloud we obtained underpinned the DBH and heights analysis. In order to reach values similar to those measured in the field, we used both the original and the segmented point clouds, postprocessed in subsamples of different radii. Results: Pearson’s correlation coefficient above 0.8 for diameters showed high correlation with the field measurements. Diameter averages displayed differences within tolerances (0.02m) for 10 out of 12 plots. Height analysis led to poorer results. For both acquisition methods, the values of the correlation coefficient peaked at 0.6. The initial hypothesis that trees positioned at a distance equivalent to their height can be measured more precise, was not valid; no increase in correlation strength was visible for either heights or diameters as the distance from scanner varied (r = 0.52). Conclusions: With regard to tree biophysical parameters extraction, the acquisition method has no major influence upon visible trees. We emphasize the term “visible”, as an increase in the number of acquisitions led to an increased number of detected trees (16% in old stands and 29% in young stands).

scholarly journals EVALUATION OF FOREST CANOPY AND UNDERSTORY GAP FRACTION DERIVED FROM TERRESTRIAL LASER SCANNING

2016 ◽  
Vol XLI-B8 ◽  
pp. 589-591 ◽  
Author(s):  
K. C. Chen ◽  
C. K. Wang
Keyword(s):  
Carbon Sequestration ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Laser Scanner ◽  
Forest Carbon ◽  
Area Index ◽  
The Earth ◽  
Gap Fraction ◽  
Forest Carbon Sequestration ◽  
Non Destructive

The quantification of forest carbon sequestration is helpful to understand the carbon storage on the Earth. The estimation of forest carbon sequestration can be achieved by the use of leaf area index (LAI), which is derived from forest gap fraction. The hemispherical image-based technique is the most popular non-destructive means for obtaining such information. However, only the gap fraction of the top canopy is derived due to the limitation of imaging technique. The gap fraction information of understory is thus neglected. In this study, we evaluate the use of a terrestrial laser scanner (TLS) to obtain the forest canopy and understory gap fraction. The forest TLS data were manually classified as the top canopy and understory layers to facilitate the estimation of top canopy and understory gap fraction, respectively.

3D Laser Scanner Techniques

2011 ◽  
pp. 500-527
Author(s):  
Mercedes Farjas ◽  
Jesús Martinez-Frias ◽  
Jose María Hierro
Keyword(s):  
Morphological Study ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanner ◽  
3D Laser Scanning ◽  
The Subject ◽  
First Time ◽  
Non Destructive ◽  
Arbitrary Objects ◽  
Scanning Systems

The use of 3D scanning systems for acquiring and analyzing the external shape features of arbitrary objects has different applications in different cultural, scientific, and technological fields. In this work, 3D laser scanning techniques are used, for the first time, to our knowledge, as a novel and non-destructive application for the morphological study of meteorite impact rocks. The subject of the study was a rock displaying impact textures and associated with the Karikkoselkä impact crater (Finland) (Lehtinen et al. 1996). This methodology permitted: (1) a computerized three-dimensional modelling to be carried out on the bulk impact-related rock; (2) other more specific characterizations to be performed, such as detailed topographic studies of its surface impact features; (3) some physical properties of the rock to be determined (volume); (4) the shatter cone impact texture to be completed with a realistic estimation of its convergence angle; and (5) a broad demonstration of the significance and effectiveness of 3D laser scanning techniques as a complementary tool for the study of this type of meteoritic impact-related rocks.

scholarly journals Use of an ultra-long-range terrestrial laser scanner to monitor the mass balance of very small glaciers in the Swiss Alps

2016 ◽  
Author(s):  
Mauro Fischer ◽  
Matthias Huss ◽  
Mario Kummert ◽  
Martin Hoelzle
Keyword(s):  
Mass Balance ◽  
Long Range ◽  
Laser Scanning ◽  
Near Infrared ◽  
Laser Scanner ◽  
Field Measurements ◽  
Swiss Alps ◽  
Infrared Range ◽  
Mass Balances ◽  
Digital Elevation

Abstract. Due to the relative lack of empirical field data, the response of very small glaciers (< 0.5 km2) to current atmospheric warming is not fully understood yet. Investigating their mass balance is a prerequisite to fill this knowledge gap. Application of the direct glaciological method is one option. Since most recently, terrestrial laser scanning (TLS) techniques operating in the near infrared range are successfully applied for the creation of repeated high-resolution digital elevation models and consecutive derivation of annual geodetic mass balances of very small glaciers. This method is promising, as laborious and potentially dangerous field measurements as well as the inter- and extrapolation of point measurements can be circumvented. However, it still owes to be validated. Here, we present TLS-derived annual surface elevation and geodetic mass changes for five very small glaciers in Switzerland (Glacier de Prapio, Glacier du Sex Rouge, St. Annafirn, Schwarzbachfirn, and Pizolgletscher) and two consecutive years (2013/14–2014/15). The scans were acquired with an ultra-long-range Riegl VZ-6000 especially designed for surveying snow- and ice-covered terrain. Zonally variable conversion factors for firn and bare ice surfaces were applied to convert geodetic volume to mass changes. We compare the geodetic results to direct glaciological mass balance measurements coinciding with the TLS surveys and carefully assess the uncertainties and errors included in both methods. Average glacier-wide mass balances were negative in both years, showing remarkably stronger mass losses in 2014/15 (−1.65 m w.e.) compared to 2013/14 (−0.59 m w.e.). Geodetic mass balances were slightly less negative but in close agreement with the direct glaciological ones (R2 = 0.91). Due to the very dense in-situ measurements, the uncertainties in the direct glaciological mass balances were small compared to the majority of measured glaciers worldwide (&amp;pm;0.09 m w.e. yr−1 on average), and similar to uncertainties in the TLS-derived geodetic mass balances (&amp;pm;0.13 m w.e. yr−1).

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