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The effect of the backfill on the integrity of a buried pipeline upon heavy-duty vehicle crossings
Gajdoš, Lubomír ; Šperl, Martin ; Slížková, Zuzana ; Drdlová, M.
The aim of this work was to determine stresses in the wall of a buried empty gas pipeline caused by the weight of backfill as well as by heavy-duty vehicles crossing the pipeline, and, on their basis to assess the applicability of protective sleeves. A buried pipeline with zero internal pressure of transported medium (empty pipeline) differs from an unburied pipeline by the vertical load due to the weight of the backfill which causes an ovalness of the circular cross section of the pipeline. This leads to the rise of through-wall bending stresses with the tensile stress at the outside surface at the 3 and 9 o´clock positions and compressive stress at the inside surface. At the 6 and 12 o´clock positions the stresses are tensile at the inside surface and compressive at the outside surface. The current depth of soil cover above gas pipelines is 0.5 m. For pipes DN500, t ~ 6.5 mm the through-wall bending stress is found to be σb ≈ ±10 MPa. In comparison with the yield stress of pipeline material, this stress is negligible. The situation is changed when heavy-duty vehicles cross the pipeline. For example, when a MAN truck with the mass load 3270 kg acting on a single wheel of the front axle crosses this pipeline, the pressure transmitted to the pipe will cause the through-wall bending stress σb ≈ ±76 MPa. This stress is superimposed to that of the backfill to give the total value ±86 MPa. When dead loads, imposed by backfill cover, together with live loads, caused by truck-wheel loads, are excessive a crushing of side walls of the pipeline and/or ring buckling of the pipe cross section can happen.
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Chemical and microstructural analysis of brick samples from the object of Zákupy castle horse stables
Frankeová, Dita ; Bauerová, Pavla ; Náhunková, Pavla ; Ševčík, Radek ; Mácová, Petra ; Slížková, Zuzana ; Vondráčková, Michaela
As part of the construction-technical survey, historical brick samples were characterized using thermal analysis (TGA), scanning electron microscopy (SEM/EDS), ion chromatography (IC), infrared spectrometry (FTIR) and physical tests. The results of the tests testify to the good production quality of the masonry elements used. Based on the analyzes carried out, it can be assumed that the observed damage to the bricks is caused by high wetting of the masonry in combination with frost cycles, as well as crystallization cycles of water-soluble salts present in the surface layer of some bricks.
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Book of Abstracts. 18th Youth Symposium on Experimental Solid Mechanics
Kytýř, Daniel ; Doktor, Tomáš ; Zlámal, Petr
The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all areas of experimental research and its application in solid and fluid mechanics. The topic will particularly concern to: Conventional and Advanced Experimental Methods in Solid and Fluid Mechanics; Non-Destructive Testing and Inspection, Measurements in Material Science, Computer Assisted Testing and Simulation, Engineering Design Simulation, Hybrid Methods, Experimental Techniques – Numerical Simulation, Optical Methods and Image Processing, Measurements in Biomechanics, Sensor Techniques for Micro- and Nano-Applications, Measurement Methods for Forensic Engineering.
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Research of the ruin of Štamberk Castle in the context of the region
Novotný, Jakub ; Ramešová, Michaela
The paper provides an overview of the research results of the Štamberk castle carried out according to newly defined principles for the research, management and presentation of historical ruins, the aim of which is to support new solutions to increase the usability of the castle for tourism and to integrate the monument into the regional structures of localities with tourism potential. The castle was an important place within the territory of today's Highlands. The subject of the project, on which ITAM CAS has been collaborating with the Telčsko Microregion since 2020, is research into the history of the castle with a focus on the technological aspects of its construction, structural changes and demise. It includes the creation of a 3D model of the ruins in a landscape context. The project focuses on the history of lime production and the related inventory of geological sites. This research brings new information important not only for learning about the history of the castle or for studying analogous situations, but also for increasing the attractiveness of the monument for tourism. The paper first presents the current standards of research and management of ruins, then it deals with an outline of the research potential of Štamberk for the field of tourism with an emphasis on the history of the castle, mapping the landscape framework and identifying links to the regional environment. At the end, it summarizes the results so far that can be used to present the historical, cultural and natural wealth of the region with a specific link to tourism.
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"Breathing" of longitudinally stiffened steel webs subject to repeated partial edge loading
Kutmanová, I. ; Škaloud, Miroslav ; Januš, K.
The aim of the first part of the Prague experimental research on web "breathing" was to look into the effect of the repeated\ncharacter of patch loading on the ultimate limit state of steel plate girder webs fitted with longitudinal ribs. 80 experimental panels were tested to date, the flange size and the position and dimensions of the longitudinal ribs being varied. During the tests, the "breathing" of the girder webs under the action of a cyclic patch load, the initiation and propagation of cracks in the most heavily stressed areas of the webs, and their influence on the "erosion" of the plastic failure mechanisms of the test girders were carefully studied. Final analysis of the data obtained made it possible for the authors to establish the limit fatigue loads, longitudinally stiffened steel plate girders whose thin webs are subject to a repeated partial edge load.
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Ultimate load behaviour of longitudinally stiffened steel webs subject to partial edge loading
Kutmanová, I. ; Škaloud, Miroslav ; Januš, K. ; Löwitová, O.
The objective of the contribution is to describe the main results and conclusions of a several years' experimental investigation into the ultimate limit state of steel plate girders whose thin webs were loaded by a partial edge load. Altogether 184 experimental girders were tested, with the following geometrical characteristics of the test girders being varied from girder to girder: (i) the depth-to-thickness ratio of the webs, (ii) the flange size, (iii) the position of\nthe longitudinal rib, (iv) its dimensions and (v) the length of load. Special care was given to a study of (a) the\nstiffeners location and size and (b) the dimensions of the loaded flange upon the progression of plastification, the failure mechanisms and ultimate strengths of the girders tested.
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Nonstationary vibrations of rectangular plate excited by concentrated force with linearly variable frequency
Náprstek, Jiří ; Fischer, Ondřej
Many physical and technical problems can be modelled as a rectangular plate with certain edge-supports, loaded by forces with variable frequency (e.g. machines in industrial buildings, electrodynamic systems). Such systems can be solved numerically using finite element method, i. e. solving the system of ordinary differnetial equations in time. In some practical cases of frequency-variation this problem can be solved analytically - the advantage of such a procedure is the objectivity and the possibility of parametric analyses of the problem.
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