Instytut Podstawowych Problemów Techniki

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This paper presents the effects of changes in temperature and moisture content on the dynamic properties of semi-circular arches made of clay brick and gypsum mortar constructed and tested in the laboratory. First, the mechanical properties of the materials used were determined by experimental tests. Operational Modal Analysis was then performed for each condition to measure natural frequencies, mode shapes, and modal damping ratios. An empirical equation for estimating the natural frequencies of the studied arch at different material moisture contents was proposed using the obtained results from experimental tests. Finally, the Finite Element Model Updating Method (FEMU) was applied to calibrate some of the material mechanical properties in modelled arches. In contrast to the effect of moisture, temperature changes showed a difficulty to interpret effect on the dynamic properties of the arch. On the other hand, Poisson's ratio did not affect the dynamic behaviour of the specimen.

Słowa kluczowe:

Operational Modal Analysis, Brick Masonry Semi-Circular Arch, Temperature, Moisture, Dynamic Parameters

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In this paper, several parametric studies were performed on the dynamic behaviour of seven types of Persian brick masonry arches using the finite element method. The studied parameters included the arch types, arch thickness, arch scale, support conditions, and brick arrangement. The finite element models were calibrated using experimental results obtained from operational modal analysis of an arch constructed in the laboratory. The parametric studies have shown that the type of arch significantly affects the natural frequencies. The increasing of arch thickness leads to increase of the natural frequencies. Simply supported arches exhibit reduced natural frequencies, compared to those fixed at their supports. Brick arrangement has little effect on the natural frequency. Finally, an empirical equation for estimating the fundamental frequency of the studied arches was proposed using the obtained results from finite element models. The high accuracy of the empirical equation was tested through measurements on a real full-scale arch.

Słowa kluczowe:

Geometric Parameters, Natural Frequencies, Brick Arrangement, Support Conditions, Persian Brick Masonry Arches

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In this paper, the dynamic properties of three types of Persian brick masonry arches, semi-circular, ordinary pointed and ordinary four-centred have been studied. These arches were constructed with clay brick, and gypsum mortar in the laboratory and experimental tests were conducted. First, the mechanical properties of the used materials were determined. Then, operational modal analysis was used to measure the dynamic properties of the constructed arches. Afterwards, a horizontal displacement was applied to the arch support to create a crack. The arches were repaired then, and dynamic identification was performed for each case. Several damage detection methods were used to evaluate their ability to detect damage in brick masonry arches. Finite element model updating was used to track changes in the material properties of arches and to match numerical results with dynamic laboratory results. The study showed that damage has a significant effect on the dynamic properties of arches. Repairing the damage partially restores the dynamic parameters to the undamaged condition, but it cannot completely transform the arch into an arch without damage. Damage detection methods were able to identify the occurrence of damage to the arches, but there are limitations in the use of these methods. Diagrams were generated to estimate the static moduli of brick and of gypsum mortar from the dynamic modulus of elasticity of the assemblage of brick and gypsum mortar.

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Through an analysis of TAWS/FMS data collected and registered during the last minute of TU-154M aircraft flight fromWarsaw to Smolensk, we show the value and existence of space for undertaking research works on enhancing standard functionality of TAWS/FMS systems to enable their effective use in examination of the course and causes of air accidents. The flight ended up in the total destruction of the aircraft and the death of all passengers and crew on board. The TAWS/FMS flight altitudes and spatio-temporal data, i.e. geographical location and speed of the aircraft motion, were inspected for their internal and external consistency with the data from the ATM QAR service recorder. Using the data from ATM QAR, records from the cockpit voice recorder (CVR), jointly with data from the TAWS/FMS systems, it was possible to reconstruct the most probable horizontal and vertical trajectory of the TU-154M aircraft during the last minute of flight before its complete destruction, as well as the likely scenario of accompanying events. The data available from recorders enabled the authors to gain information on the preliminary stage of the course of accident, and the first phase of the aircraft’s destruction, resulting in serious damage of the left wing of the aircraft. Enhanced standard functionality of TAWS/FMS systems, incorporating use of their data in the post-accident situations examination, would have improved results and simplified the present analysis considerably.

Słowa kluczowe:

TAWS system, aircraft accident examination, Polish TU-154M, Smolensk, abductive analysis, aircraft safety engineering, Q codes altitudes corrective formulas, ICAO atmosphere

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Paper discusses a concept and conservation methodology of the XVII. century curvilinear canvas painting „Adoration of the Magi” from the Saint-Aubain Cathedral church in Namur (Belgium). Atypical form of the painting bowed in the horizontal plane, adapted to a, wall and its enormous size (3.70 x 4.50 m) required using some innovative technologies and materials. Restoration work required access to both the face and the back of the picture. But how to overturn the painting? How to strengthen its support? How to tight. it? Such problems can be solved only by the interdisciplinary collaboration of a team of professionals. In this way decisions about the conservation were discussed in the group of experts from various disciplines. The article focuses o! n the problem of curvilinear canvas stretching, which is presented fro m different points of view. In the council participated restorers, scientist and engineers. Finally, we agreed that the basic premise of the conservation process was a detailed analysis of the canvas shape and its preservation on each step of the conservation works. The concept required construction of two curved platforms: concave and convex. The new system of the canvas overturning was also designed. An innovating method of strengthening of the canvas vertical direction during lining process by using Kevlar fibres was applied. The XVII. century stretcher frame was preserved as an example of historical construction. The new stretching system was built out of the original stretcher frame. The conservation works were finished in 2014, the painting was put in the frame and fixed on the wall. The optical analysis of its shape achieved one year after showed that its state is stable.

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Paper discusses a concept and conservation methodology of the XVIIIth century curvilinear canvas painting ‘Adoration of the Magi’ from the Saint–Aubain Cathedral church in Namur (Belgium). Atypical form of the painting bowed in the horizontal plane, adapted to the apse wall and its very large size (3.70 x 4.50 m) required using some innovative technologies and materials. The basic premise of the conservation process was a detailed analysis of the canvas shape and its preservation on each step of the conservation works. The concept required construction of two curved platforms: concave and convex. The new system of the canvas overturning was also designed. An innovative method of strengthening of the canvas during lining process in vertical direction by using Kevlar fibres was applied. Required strengthening and modification of the stretching frame is also discussed.

Słowa kluczowe:

curvilinear, large-size, lining, stretching, Kevlar fibres

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This paper presents a newly developed acoustic tracing method for a non-invasive survey of detachment defects of rendered masonry. The method analyses acoustic signals generated by tapping the surface in densely located points, which are registered together with the geometrical coordinates by means of a video camera. FFT analysis enabled a comparison to be made between the audible wall response and formalized parameters of the sound samples, i.e. the excitation band and the dominant frequency of the spectrum. It was concluded that the audible spectrum for non-detached parts includes several narrow band components, whilst the detached areas respond in a wider frequency band.

Słowa kluczowe:

Acoustic excitation, Plaster detachment defects, Frequency response, Inspection systems, Signal processing

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Paper discusses large size canvas paintings stretching methods and deformations and damages specific for large canvas resulting from an incorrect stretching. Analysis of the preservation state of a wooden stretcher construction and its functionality was an important step in development of the program of conservation work. The case study of M. H Loders painting „Adoration of the Magi” (XVIII c.) from the cathedral Saint - Aubain in Namur (Belgium) is presented. The painting is exhibited 5,5 m above the floor and has a unique shape, as the wooden stretcher frame is adjusted to the round apse walls. Thus usual direct inspection was difficult due to poor access to the reverse side of the painting. Preliminary conclusions on the construction and preservation state of the stretcher frame were drawn on the basis of a thorough inspection of the painting surface. Actual shape of the painting and precise stretchers dimensions were measured with a laser scanner. More information concerning the stretcher frame construction was obtained from a simple micro-camera system combined with LED lighting introduced from the canvas reverse side.

Słowa kluczowe:

3D Laser Scanner, Deformation, Large - Size Painting, Wooden Stretcher Frame

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Methodology of measurements of critical stress intensity factor KIc as given in ASTM E 399 for metals is compared with that suggested by the Commission on Testing Methods ISRM for rocks. Standard geometries of specimens are shown. Specjal attention is drawn to the differences in the methodology of measurements, important for the interpretation of experimental results and evaluation of their correctness.

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Measurements of the state of stress in rocks are of vital importance in mining operations. These stresses are very difficult to measure. The reason for this is the necessity of making measurements inside the rock mass, usually at a distance of several meters from the rock face. Moreover, working conditions in mines are often arduous, which makes the application of more sophisticated measuring techniques difficult.

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A circular disk specimen with specjal cut-outs is proposed for testing brittle materials under plane stress conditions.Results obtained for gypsum show general disagreement with the assumption of the constant strength of brittle materials. The results are compared with the known failure criteria and an extended Mises criterion is found to be the most suitable one.

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The paper presents the application of various 3D imagining methods to study the state of the mural painting in the dome of Blessed Ladislaus' Chapel of St. Anne's Church in Warsaw. The temple was built on the embankment of the Vistula river in the XV-th century. The chapel was added to the nave in the XVII-th century. From the beginning this location of the church caused a lot of structural problems. The church stability was disturbed due to digging an underground tunnel nearby in the years 1947-49. The Ladislaus' Chapel, situated close to the tunnel on the side of the escarpment was the most endangered. The current rescue work of the mural painting of the chapel dome required an accurate measurement and inventory of the architectural structure. The dome was measured using various methods: laser scanning and photogrammetry. As a result, we obtained 4 models of the chapel dome, which could be combined and compared.

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Environmental and mechanical quantities need to be measured and registered in order to provide engineers and researchers with data required for diagnostics of heritage structures' condition. Analysis of the needs of diagnostic measurements and monitoring of historic structures shows that a large number of structures should be supervised. However hardware costs and resources needed to implement existing technologies constitute a barrier for a wide usage of modern sensors. The presented research shows that everyday usage of smartphones can be extended into a technology suitable for technical diagnostic purposes. Smartphone has many intrinsic sensors factory installed so it is already a sensing device. By calibrating the sensors the smartphone can be upgraded from being a sensing device to become the real measuring equipment. This emerging technology called Smartphone Aided Structural Monitoring and Measurements (SASMM) is not limited to the examples presented in this paper.

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Znaczny rozwój inwestycji wielkogabarytowych obiektów sportowych stworzył potrzebę równoległego rozwoju metod monitorowania bezpieczeństwa stadionów mogących pomieścić dziesiątki tysięcy ludzi. Powszechną cechą eksploatacji wielkich stadionów jest ich wykorzystanie zarówno do organizacji imprez sportowych jak i masowych imprez kulturalnych np. koncertów. Specyfika takich dużych imprez sportowych i kulturalnych niesie w sobie zagrożenia dla konstrukcji na skutek nieprzewidywalnych na etapie projektowania zmian obciążeń wywołanych drganiami i montażem na elementach konstrukcji dodatkowego ciężkiego sprzętu.
Mając na uwadze powyższe uwarunkowania jako cel badań przyjęto opracowanie, wdrożenie i przetestowanie w praktyce światłowodowego systemu monitorowania deformacji konstrukcji stadionu mieszczącego się w Warszawie przy ulicy Łazienkowskiej 3, należącego do WOSiR, a obecnie użytkowanego przez Klub Piłkarski

Słowa kluczowe:

monitorowanie konstrukcji, systemy FBG, monitorowanie deformacji konstrukcji stadionu

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Wśród europejskiego dziedzictwa obrazów wielkoformatowych można wyróżnić szczególną grupę płócien nieplanarnych. W trakcie prowadzonych prac badawczych i konserwatorskich należy odpowiedzieć na pytania o pierwotny kształt aktualnie zdeformowanego obrazu, stopień zniekształcenia płótna, wpływ pełzania na deformację oraz bezpieczny sposób przywrócenia właściwego kształtu i zabezpieczenia przed jego zmianą w przyszłości. Wielkoformatowe obrazy na płótnie podlegają znaczącym deformacjom wynikającym z procesów reologicznych aktywowanych zmianami wilgotności i temperatury. Deformacje te narastają wraz z upływem czasu pod wpływem sił wynikających z ciężaru własnego i napięcia na krośnie. Efekty te mają tym większe znaczenie im większa jest powierzchnia obrazu. Ich konserwacja i prawidłowe napięcie stanowią szczególnie trudne wyzwanie konserwatorskie. Wszystkie te problemy pojawiły się w trakcie konserwacji obrazu „Pokłon Trzech Króli” H.M. Lodera, który znajduje się w katedrze w Namur (Belgia). Obraz o wymiarach 3.70m x 4.50m zawieszony był w prezbiterium kościoła i miał wygiętą formę, zbliżoną do łuku ściany absydy. Strzałka łuku krosna wynosiła 37cm. Do najpoważniejszych problemów należały katastrofalne w skutkach deformacje osłabionego mechanicznie podobrazia. Płótno pod wpływem własnego ciężaru i zachodzących procesów reologicznych wyciągnęło się i zaczęło obwisać, tak że jego nadmiar zebrał się w części centralnej u dołu malowidła. W trakcie prowadzonych prac opracowana została metodyka pomiaru, korekcji kształtu i napinania obrazów wielkoformatowych. Po wykonaniu zdalnych pomiarów optycznych zawieszonego na ścianie obrazu (globalny i lokalny skaning laserowy, fotogrametria) dokonano identyfikacji zdeformowanego i pierwotnego kształtu płótna. Następnie zaproponowano nowatorski sposób wzmocnienia i napinania płótna polegający na wprowadzeniu w warstwie dublażowej układu nici aramidowych poprowadzonych wzdłuż tworzących zidentyfikowanej powierzchni prostokreślnej płótna. Wielokrotnie większy moduł sprężystości nici aramidowych niż płótna dublażowego umożliwia przeniesienie dominującej części naprężeń wynikających z napięcia płótna i ciężaru własnego obrazu. W połączeniu ze znacznie mniejszą wrażliwością aramidu na zmiany wilgotności i temperatury znacząco zmniejsza się także intensywność procesów reologicznych ograniczając pełzanie, obwisanie i utrwalając krzywoliniowy kształt obrazu.

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Religious art objects preserved in the form of curved canvas paintings present a very interesting subject for the research, both from technical and conservation points of view. The work concentrates on theoretical and experimental analysis of mechanically correct stretching of curvilinear canvas to avoid folding and buckling of paintings. It is shown that treating curvilinear canvas as a ruled surface might be a very promising solution. Reverse engineering can help to discover the ruled surface shape adequate to the individual curved painting.

Słowa kluczowe:

canvas, stretching, ruled surface, religious paintings

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Streszczenie:

Paper discusses a concept and conservation methodology of the XVIIIth century curvilinear canvas painting “Adoration of the Magi” from the Saint – Aubain Cathedral church in Namur (Belgium). Atypical form of the painting bowed in the horizontal plane, adapted to the apse wall and its very large size (3.70 x 4.50 m) required using some innovative technologies and materials. The basic premise of the conservation process was a detailed analysis of the canvas shape and its preservation on each step of the conservation works. The concept required construction of two curved platforms: concave and convex. The new system of the canvas overturning was also designed. An innovative method of strengthening of the canvas during lining process in vertical direction by using Kevlar fibres was applied. Required strengthening and modification of the stretching frame is also discussed.

Słowa kluczowe:

curvilinear, large-size canvas painting, lining, stretching, Kevlar fibres

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Nowadays large stadium structures are designed for assumed static loads and it is difficult to calculate important influence of real stresses resulting from dynamic loads caused by moving crowds. The paper presents Structural Health Monitoring System, based on multiplexed Fiber Bragg Grating sensors. They are used to measure strains and temperature of structural elements and allow us to measure dynamic deformations to observe changes in structural behaviour of the stadium during cheering on a football competition and calculate instantaneous anthropogenic loads.

Słowa kluczowe:

Structural Health Monitoring, FBG sensors, monitoring of concrete structures

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