Wyniki wyszukiwania - BazTech

1

Modele numeryczne uwzględniające tarczową pracę pokrycia dachowego z blach trapezowych

Korcz N.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

|

2017

|

z. 64, nr 4/I

213--228

PL

W artykule porównano wybrane sposoby uwzględniania w modelowaniu numerycznym tarczowej pracy pokrycia dachowego z blachy trapezowej, możliwe do zrealizowania w programie Autodesk Robot Structural Analysis Professional 2015, w celu oceny słuszności stosowania ich do obliczeń konstrukcji nośnej współpracującej z poszyciem z blachy trapezowej. Analizy przeprowadzono dla pojedynczej przepony. Za pomocą powłokowych elementów skończonych zbudowano dwa typy modeli blachy trapezowej. Uwzględniono podatność połączeń występujących w konstrukcji, wykorzystując pomocnicze belkowe elementy skończone. Wartości podatności na ścinanie paneli uzyskane numerycznie odniesiono do wyników otrzymanych na podstawie znanych procedur analitycznych. Miarą trafności modelu poszycia był poziom zgodności ww. wartości podatności na ścinanie. Zgodnie z tym kryterium wskazano model, który poprawniej odzwierciedla współpracę pokrycia z blachy trapezowej z konstrukcją nośną.

EN

The paper presents the comparison of selected numerical models of trapezoidal cladding acting as a diaphragm which can be used in computer program called Autodesk Robot Structural Analysis Professional 2015. The aim of the analyses was to evaluate the validity of using these models in calculations of the structure including the stressed skin effect. The analyses were carried out for the cantilevered diaphragm as a part of the roof of the single storey steel building. Corrugated sheets were replaced by two types of equivalent orthotropic shell models and the influence of the choice of the model on the stiffness of the diaphragm was observed. Fasteners and connections were substituted by equivalent beam finite elements and their flexibility was included in the calculations. 230 N. Korcz The evaluation of numerical models of trapezoidal sheeting was contingent upon the degree of the agreement between numerical and analytical results of the shear flexibility of analyzed diaphragms, calculated according to [2]. In compliance with this criterion, more accurate numerical model of trapezoidal cladding acting as a diaphragm was pointed.

2

Nest site preference of forest dormouse Dryomys nitedula (Pallas) in the north-western corner of the distribution range

Juškaitis R., Balčiauskas L., Šiožinytė V.

Polish Journal of Ecology

|

2012

|

Vol. 60, nr 4

815--826

EN

Lithuania is situated in the very north-western corner of the large distribution range of the forest dormouse Dryomys nitedula and it might be considered that dormouse habitats should be both different and sub-optimal in this area in comparison to central parts of the range. The aims of the present study were to analyse which vegetation parameters determine nest site preference of D. nitedula and to compare these with nest site preferences of other dormouse species. The population of D. nitedula was studied from 2001 to 2011 using nestboxes set up in a grid system, with regular control of the nestboxes and ringing of dormice captured. During entire study period, 97 individuals were marked with rings and the total number of dormouse captures was 440. Vegetation parameters (the composition of the overstorey and understorey, the numbers and cover of different tree and shrub species, absence of vegetation etc.) were evaluated quantitatively in areas of 2500 m2 around 58 nestboxes at this study site. During the period 2001–2002, the abundance of D. nitedula was relatively high, with the dormice using the entire area of the study site, showing a preference for nest sites with a more diverse overstorey and understorey. However, no significant correlations were found between indices of nestbox use and other vegetation parameters in this period. During the period 2003–2011, when the dormouse abundance was lower but stable, dormice used only part of the study site area, in this preferring nest sites with a better developed and diverse understorey (especially with young rowan, lime and aspen trees), with more abundant mature oak, lime and black alder trees and a higher percentage of raspberry and bramble cover, as well as overgrown clearings. D. nitedula avoided nest sites with higher total number of mature trees (especially Scotch pine and Norway spruce), as well as areas with higher percentage of bilberry cover and open areas (rides, presence of stumps). In general, a well-developed and diverse understorey was the main habitat component which determined nest site preference of D. nitedula in the very northwestern corner of its range. Thus, D. nitedula retains its main habitat requirement which is characteristic also for other parts of its large range. Vegetation parameters determining nest site preference of D. nitedula are rather similar to nest site preference of the common dormouse Muscardinus avellanarius. However, D. nitedula may live in less rich habitats probably because their diet includes more food of animal origin.

3

Light transmission through decorative knitted fabrics in correlation with their fabric cover

Szmyt J., Mikołajczyk Z.

Autex Research Journal

|

2010

|

Vol. 10, no. 2

44--48

EN

The cover factor of Jacquard decorative knitted fabrics determines the quantity of light going through the knitted material. By changing the fabric cover of the knitted material it is possible to influence both the aesthetic and functional features of the product. The intensity of light transmission, determined on the basis of an instrumental method of measuring the light-barrier properties of knitted decorative products, was correlated with values of the fabric cover determined on the basis of both theoretical analysis and experiments.

4

Discrete analytical models of the wood-framed with sheathing building structures and selected experimental test results

Malesza M., Miedziałkowski C.

Archives of Civil Engineering

|

2003

|

Vol. 49, nr 2

213-240

EN

The objective of this paper is to present some problems of mechanics of the wood-framed with sheathing building structural elements. Selected works from significant number of papers published in the world referring to the wood-framed structure are presented. These works are dealing with analytical and experimental investigations. The paper emphasizes the prefabricated large-panelled version of the wood-framed building structural elements. Formation of analytical three-dimensional model of separate diaphragm and complete building structure remains still the basic problem examined lately in the published papers. The analytical model shall predict evaluation of real stressing and its distribution in the structure and shall assess the tracing of redistribution of external loading to each part of diaphragm. Analysis shall be based on real geometry and material characteristic of the structure. The sheathing to framing fastener has strongly nonlinear behaviour under loading and becomes the weakest link in structure. The analytical model has been created applying the finite element method. Finite elements were applied in description of wooden framing, sheathing and connectors. Parameters of fastener nonlinearity and description of different structural details are included in the analytical model. Presented model has been identified in experimental tests conducted on full scale wall diaphragms.

PL

Praca dotyczy problemów statyki szkieletowych budynków drewnianych z poszyciem. Na początku podano wybrane publikacje z dużej liczby opracowań w świecie nt. tego typu budownictwa. Publikacje dotyczą zarówno badań doświadczalnych jak i teoretycznych. Ponadto zwrócono uwagę, że obecnie najczęściej realizowane są drewniane budynki szkieletowe w wersji prefabrykowanej. Podano podstawowe problemy analizowane ostatnio w publikacjach, z których na pierwszy plan wysuwa się zagadnienie budowy modelu obliczeniowego poszczególnych przegród i budynków w schemacie przestrzennym. Pozwoli to na uwzględnienie redystrybucji obciążeń zewnętrznych na poszczególne elementy konstrukcyjne oraz ocenę rozkładu rzeczywistych wytężeń w konstrukcji. Ważne jest więc wtedy uwzględnienie rzeczywistych wymiarów i położenia elementów konstrukcyjnych oraz ich właściwości materiałowych. Jest to ważne tym bardziej, iż najsłabszym ogniwem tych konstrukcji są łączniki, a ich praca pod obciążeniem charakteryzuje się dużą nieliniowością. W artykule przedstawiono taki model obliczeniowy zbudowany z wykorzystaniem metody elementów skończonych. Podano sposób budowy modelu oraz opis elementami skończonymi szkieletu drewnianego, poszycia i łączników. Następnie przedstawiono zagadnienie uwzględniania parametrów nieliniowych i opisu w modelu różnych szczegółów konstrukcyjnych. Model został zweryfikowany badaniami doświadczalnymi w skali naturalnej przegród ściennych.