1. Processing of signals produced by strain gauges in testing measurements of the bridgesBoštjan Kovačič, Rok Kamnik, Andrej Štrukelj, Nikolai Ivanovich Vatin, 2015, objavljeni znanstveni prispevek na konferenci Opis: Practical example of signal processing from strain gauge, inductive transducer and total station measurements are used to illustrate the features of the bridge load testing measurements. FFT provides accurate representation of physical behavior for static and dynamic signals obtained when loading the bridge. As a reference measurement the signal from inductive transducer was taken. A static part of the load test was also geodetically measured and theoretically calculated. The results are comparable.
Ključne besede: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Objavljeno v DKUM: 12.07.2023; Ogledov: 445; Prenosov: 33
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2. Measurement and interpretation of the small strain stifness of Boštanj silty sandGregor Vilhar, Vojkan Jovičić, 2009, izvirni znanstveni članek Opis: This paper presents measurements, and an interpretation of these measurements, based on the use of bender-element probes for Boštanj silty sand. The samples were prepared at different initial void ratios and isotropically compressed up to 5 MPa. The bender-element technique was used to determine the dynamic shear modulus ($G_0$) of the soils at very small strains. The multiple bender-element probes were shot at different excitation frequencies in order to increase the reliability of the measurements. The $G_0$ stiffness was determined by using three different techniques: a) the first-time arrival, b) the phase-change method and c) the cross-correlation method. The systematic differences observed between the $G_0$ values, calculated using the three techniques, are discussed. The variation of $G_0$ in the log$G_0$ - log$p'$ plane was evaluated for the Boštanj silty sand and compared with other sands.
Ključne besede: silty sand, triaxial testing, small strain stiffness, bender elements, time-domain and frequency-domain, measurements
Objavljeno v DKUM: 06.06.2018; Ogledov: 1194; Prenosov: 170
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3. The assesment of pile shaft resistance based on axial strain measurements during the loading testAndrej Štrukelj, Stanislav Škrabl, Ksenija Štern, Janko Logar, 2005, izvirni znanstveni članek Opis: Near Maribor, a new bridge over the Drava river is being under construction. Before the main works actually started, static and dynamic loading tests of piles were performed. The goal of the static loading test was to determine the bearing capacitiy of the test pile. It was also interesting to determine the share of the axial load distributed on the shaft and pile toe. In order to measure the distribution of the axial force along the pile, a specially made steel canal was built in the pile before concreting. Inside this canal the strain gauges were distributed evenly at the distance of one meter. The strains were measured for each loading phase in all measuring points. The distribution of the axial force was assessed from the obtained results and based on the distribution of the axial force the shaft resistance could be determined. The unexpectedly high bearing capacity of the pile shaft made the obtained results highly interesting. In this paper, measuring methods and measuring results are discussed. Behaviour of the pile and the soil during the loading test were also modelled by axial symmetric and three dimensional models. The calculated and measured results show a very good agreement.
Ključne besede: civil engineering, bridges, soil mechanics, pile shaft resistance, loading test, strain measurements, elastoplastic soil modelling, finite element method
Objavljeno v DKUM: 16.05.2018; Ogledov: 1430; Prenosov: 85
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4. The different methods of displacement monitoring at loading tests of bridges or different structuresBoštjan Kovačič, Rok Kamnik, Andrii Bieliatynskyi, 2016, objavljeni znanstveni prispevek na konferenci Opis: By measuring the displacements and deformations at different structures we deal in the Faculty of Civil Engineering, transportation Engineering and Architecture in University of Maribor for about 20 years. At that time we measured over 600 structures. Most loading tests of bridges and Viaducts were made. The measurements of movements needed to be as precise and accurate as possible. To do that laboratory test of instruments were made to see which instrument gives us reliable results. Displacements can be determined by geodetic and physical methods, depends of the construction. The use of geodetic methods are still preferable. In the paper the measurements with the total station, the level and rotation level, photogrammetry and solutions on the field by physical methods with inductive transducers are presented. We need to measure displacements as quick as possible but efficiently because we can not repeat the measurements under the same conditions. Also the surveying on the bridge and in the lab with the comparison of methods is presented under the different hard terrain conditions - water beneath the construction, big height of the structure, unapproachability, large span structures.
Ključne besede: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Objavljeno v DKUM: 02.08.2017; Ogledov: 1262; Prenosov: 354
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5. Vertical displacements measuring methods during bridge load testsBoštjan Kovačič, Ante Marendić, Rok Kamnik, Mikhail Volkov, Vera Roy, 2016, objavljeni znanstveni prispevek na konferenci Opis: This article introduces the use of the GNSS method for the load testings of bridge structures. We know that there area lot of methods by which you can determine vertical displacement. However, as new bridge constructions are constructed over almost impossible and inaccessible gorges and valleys, the classic measurements method do not allow us to determine vertical displacement so reliably any more or they are very time-consuming. The GNSS method is well known but there are difficulties when determining the altitude component of this method, which is rather questionable. For this purpose, the methods were tested as practical examples in which some difficulties were encountered, so subsequently another test recording was performed of altitude changes using this method.
Ključne besede: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Objavljeno v DKUM: 29.08.2016; Ogledov: 2014; Prenosov: 466
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