Modelling of single degree of freedom SMA oscillators by using rheological schemes

The article describes the approach to modelling of single degree of freedom SMA oscillators by using rheological schemes. Certain sets of rheological components are presented and their influence on the oscillator response is examined. Regarding the field of civil engineering, the devices incorporating SMA elements mostly find applications in mitigation of natural disaster hazards, such as earthquakes. The promising results of applications are possible due to unique properties of SMA, such as shape memory effect (recovering of relatively high strains while material is heated) and superelasticity (recovering of strains upon load removal). The most common approach to the formulation of SMAs constitutive relations is a thermomechanical modelling, in which constitutive equations are dependent on internal state variables. One of the advantages of the phenomenological modelling approach presented in the article is a possibility of formulation of constitutive relationships as a set of explicit differential equations. Such system of equations can be easily implemented in mathematical software or in the commercial FEM codes as a user's subroutines. As an example of numerical application of presented approach, the simple one-dimensional oscillator is used in order to solve the case of forced vibrations of a cantilever with embedded SMA reinforcement

Modelling of single degree of freedom SMA oscillators by using rheological schemes

The article describes the approach to modelling of single degree of freedom SMA oscillators by using rheological schemes. Certain sets of rheological components are presented and their influence on the oscillator response is examined. Regarding the field of civil engineering, the devices incorporating SMA elements mostly find applications in mitigation of natural disaster hazards, such as earthquakes. The promising results of applications are possible due to unique properties of SMA, such as shape memory effect (recovering of relatively high strains while material is heated) and superelasticity (recovering of strains upon load removal). The most common approach to the formulation of SMAs constitutive relations is a thermomechanical modelling, in which constitutive equations are dependent on internal state variables. One of the advantages of the phenomenological modelling approach presented in the article is a possibility of formulation of constitutive relationships as a set of explicit differential equations. Such system of equations can be easily implemented in mathematical software or in the commercial FEM codes as a user's subroutines. As an example of numerical application of presented approach, the simple one-dimensional oscillator is used in order to solve the case of forced vibrations of a cantilever with embedded SMA reinforcement

Numeryczna weryfikacja drewnianych zabudowań grodu z wczesnej epoki żelaza w Biskupinie

Biskupin is one of the most recognizable archaeological site in Poland and Central Europe. The origins of the excavations dates back to year 1934 and had lasted almost continuously until 1974. In the framework of the grant from the Ministry of Culture and National Heritage interdisciplinary team of scientists from Archaeological Museum in Biskupin and Warsaw University of Technology performed multi-dimensional analysis of the settlement. Based on the integrated vector documentation, resulting from the photographic documentation, numerical models of structural systems of main types of buildings and defensive rampart were prepared. The aim of the analysis was a verification of the earlier findings of archaeological and architectural researches. The analysis allowed to verify both the arrangement of individual parts of structure of buildings, their work and the interconnection, as well as the possible dimensions of the individual components.Jednym z najbardziej spektakularnych osiągnięć przedwojennej polskiej archeologii było odkrycie grodu z przełomu epoki brązu i wczesnej epoki żelaza w Biskupinie, stanowisko 4. Podstawowymi drewnianymi konstrukcjami kształtującymi zabudowę tego terenu były zewnętrzne ulice, falochrony, mury obronne, ulice wewnętrzne i budynki gospodarcze. Gród został zniszczony i odbudowany dwukrotnie podczas swojego istnienia. Badania dendrochronologiczne dowodzą, że większość materiału drewnianego użytego do budowy budynków ze starszej fazy osady została wycięta w latach 739-736 p.n.e. W ramach grantu Ministra Kultury i Dziedzictwa Narodowego interdyscyplinarny zespół naukowców z Muzeum Archeologicznego w Biskupinie i Politechniki Warszawskiej przeprowadził wielowymiarową analizę zabudowy. Na podstawie zintegrowanej dokumentacji wektorowej, powstałej w oparciu o dokumentację fotograficzną, opracowano modele numeryczne układów konstrukcyjnych głównych typów budynków zarówno z etapu starszego, jak i młodszego oraz wału obronnego. Celem badań była identyfikacja i weryfikacja układów i rozwiązań konstrukcyjnych, określenie parametrów geometrycznych elementów tworzących układ konstrukcyjny wykorzystywany w budynkach kultury łużyckiej w Biskupinie jak i konstrukcji wału obronnego. Kolejnym celem była ocena wpływu warunków gruntowych na pracę konstrukcji nośnej analizowanych budynków. Ponadto oceniano wpływ niektórych rozwiązań konstrukcyjnych, takich jak wpływ sumików na sztywność przestrzenną budynku, wpływ ciągłości zabudowy i wpływ półpiętra na nośność wyboczeniową słupa wewnętrznego. Analizy przeprowadzono na modelu budynku przedstawionym w literaturze(Rys. 2), a także zrekonstruowanym na podstawie zachowanej dokumentacji

Approach to conservation of irregular stone masonry based on archaeological excavations in the Black Sea basin

The article presents and describes the methodology of conservation of masonry structures that are architectural monuments discovered as part of the work carried out during archaeological excavations. The authors' experiences presented in the article result from many years of cooperation between the Faculty of Civil Engineering at Warsaw University of Technology, the National Museum in Warsaw and the Antiquity of Southeastern Europe Research Center at the University of Warsaw. Examples of preserved masonry structures come from excavations located in the Black Sea area - from the archaeological site in Tyritake in Kerch on the Crimean Peninsula and Tanais near Rostov-on-Don in Russia. Works on masonry structures located in the area of archaeological excavations are characterized by a unique specificity covering both formal issues, resulting from international standards and agreements regulating the conservation of historic buildings, as well as technical and environmental issues. The basic technical issues include ensuring the safety of further excavation works, protection of masonry structures against the destructive effects of atmospheric conditions and preparing the structure for possible exhibition in archaeological parks organized on the site of excavations. Environmental issues relate to local, social and economic conditions. The article presents the procedures that should be used in the conservation of these types of structures and presents the specific technological and material solutions used in the presented objects

Zalety zastosowania skaningu laserowego w badaniach zabytków architektonicznych na przykładzie stanowisk archeologicznych w Egipcie i Rosji

Every conservation works related to an ancient masonry structures should be preceded by an appropriate diagnostic. This should be understood as geometrical survey and various tests, which results with a proper analysis of the structure, identification of materials, technologies and techniques used during construction. The effective tool which could be used in this field is 3-D laser scanning. The digital image obtained as a result of scanning could be a proper base for a preservation programme, as well as help for creation of a precise digital models for a structural analysis. The examples of 3-D laser scanning application presented in the article are diagnostic works carried by the Division of Fundamentals of Building, Warsaw University of Technology, with the cooperation of Warsaw University, at the archaeological sites in Alexandria, Egypt and in Tanais, Rostov, Russia. Based on this works some most important advantages of laser scanning in identification, diagnostics and preservation of ancient architectural monuments was stated.Wszelkie działania konserwatorskie dotyczące starożytnych konstrukcji murowych powinny być poprzedzone dokładną diagnostyką. Można tutaj wyróżnić działania pomiarowe i różnorodne badania, mające na celu dokładną inwentaryzację analizowanej struktury oraz identyfikację materiałów, technologii i technik użytych w procesie wykonania, które często są współcześnie zapomniane, niestosowane lub zupełnie nieznane. Właściwa interpretacja otrzymanych wyników może przyczynić się do opracowania skutecznego programu konserwatorskiego, mogącego zawierać nie tylko działania zabezpieczające i wzmacniające, ale również rekonstrukcje, zarówno rzeczywiste jak i wirtualne. Efektem tych działań może być również stworzenie wirtualnego obrazu zabytku, zawierającego wszystkie dane o nim. Może to przyczynić się do zachowania zagrożonych obiektów światowego dziedzictwa kulturowego w rzeczywistości wirtualnej. Skutecznym narzędziem do tego typu diagnostyki jest skaning laserowy. Obraz numeryczny uzyskany ze skaningu, z wielością danych, które zawiera, jest podstawa stworzenia skutecznego programu konserwatorskiego, a także daje możliwość wykonania dokładnych, numerycznych modeli badanych konstrukcji, wykorzystywanych w obliczeniach statyczno-wytrzymałościowych. Może być również podstawą dokładnych wizualizacji i rekonstrukcji wirtualnych obiektu. [1]. Przykładem zastosowania skaningu są działania diagnostyczne prowadzone przez Zespół Budownictwa Ogólnego i Zrównoważonego Rozwoju Politechniki Warszawskiej, we współpracy z Uniwersytetem Warszawskim, na wykopaliskach w Aleksandrii w Egipcie i w Tanais pod Rostowem w Rosji

Laboratory Tests and Analyses of the Level of Vibration Suppression of Prototype under Ballast Mats (UBM) in the Ballasted Track Systems

The present paper is aimed at the analysis of under ballast mats (UBM) which are used in ballasted track structures as vibration isolators and to protect the ballast layer against fast degradation. The mats were tested in the laboratory and afterwards a novel 4-DoF mechanical model of the track structure with UBM was developed. The novelty of this study consists in the comparison of two testing procedures: a procedure based on the popular German standard DIN 45673-5 and a new European standard EN 17282, released in October 2020. Major discrepancies were demonstrated in the determined values of the static and dynamic characteristics using both approaches—especially in reference to the mats with higher stiffness

Conservation of irregular stone masonry in Tanais in Russia

The article presents and describes the conservation of masonry structures at archaeological site in Tanais near Rostov-on-Don in Russia. The authors' experiences presented in the article result from many years of cooperation between the Faculty of Civil Engineering at the Warsaw University of Technology and the Centre for Research on the Antiquity of Southeastern Europe at the University of Warsaw. Works on masonry structures located in the area of archaeological excavations are characterized by a unique specificity covering both formal issues, resulting from international standards and agreements regulating the conservation of historic buildings, as well as technical and environmental issues. The basic technical issues include ensuring the safety of further excavation works, protection of masonry structures against the destructive effects of atmospheric condition and preparing the structure for possible presentation in archaeological parks organized on the site of trenches. Environmental issues relate to local, social and economic conditions. The article presents the procedures that should be used in the maintenance of antique irregular masonry and presents the specific technological and material solutions used in the example objects

Materiały polimerowe wykorzystywane do konserwacji zabytkowych konstrukcji kamiennych

In this review, authors discuss the pre-requisites to be fulfilled for the preservation of stone monuments, referring both to the selection of appropriate materials (compatibility principle) as well as to the repair process itself. Since ancient times, a wide range of natural and synthetic polymers has been employed for stone recovery purposes. The paper presents the examples of most commonly used polymeric materials along with recent trends in conservation of stone materials.W artykule o charakterze przeglądowym przedstawiono zasady obowiązujące przy konserwacji zabytków z kamienia, odnoszące się zarówno do doboru odpowiednich materiałów (zasada kompatybilności), jak również samego procesu naprawczego. Opisano szeroką gamę polimerów naturalnych i syntetycznych stosowanych w celach rekonstrukcyjnych oraz główne trendy w konserwacji zabytków kamiennych. zabytkowe konstrukcje kamienne, konserwacja, polimery naturalne, polimery syntetyczne

Conservation of irregular stone masonry in Tanais in Russia

The article presents and describes the conservation of masonry structures at archaeological site in Tanais near Rostov-on-Don in Russia. The authors' experiences presented in the article result from many years of cooperation between the Faculty of Civil Engineering at the Warsaw University of Technology and the Centre for Research on the Antiquity of Southeastern Europe at the University of Warsaw. Works on masonry structures located in the area of archaeological excavations are characterized by a unique specificity covering both formal issues, resulting from international standards and agreements regulating the conservation of historic buildings, as well as technical and environmental issues. The basic technical issues include ensuring the safety of further excavation works, protection of masonry structures against the destructive effects of atmospheric condition and preparing the structure for possible presentation in archaeological parks organized on the site of trenches. Environmental issues relate to local, social and economic conditions. The article presents the procedures that should be used in the maintenance of antique irregular masonry and presents the specific technological and material solutions used in the example objects