The new directives and standards about rational and efficient energy use strictly regulate that thermal bridges have to be avoided, and that the thermal insulation (TI) layer should run without interruptions all around the building – even under it or its foundations. For the applications of a TI layer beneath a building’s foundations an appropriate TI material has to be used. Beside its thermal insulation characteristics, the selected TI material has to demonstrate sufficient compressive strength and water resistance, minimal long-term creep, and good durability. One of the most commonly used thermal isolative materials in practice is extruded polystyrene foam (XPS). In general, rather limited research has been performed up until now into the behaviour of XPS foam. As far as is known to the authors, the cyclic compressive and shear stress–strain behaviour of XPS foam, which is essential for its seismic response in earthquake engineering applications, has not yet been researched. The paper summarizes the results of laboratory tests performed in the testing Laboratory of Civil and Geodetic Engineering Faculty at the University of Ljubljana. The aim of the investigation was to determine the mechanical characteristics of XPS foam which are essential for the seismic analysis of modern low-energy building structures, where XPS boards are used as a TI layer beneath the building’s foundations. First, the compressive and shear behaviour of XPS under monotonic and cyclic loading conditions was evaluated. The tests were determined according to the standards SIST EN 826: 1997 (behaviour in compression) and SIST EN 12090: 1999 (behaviour in shear). The test specimens were blocks cut out from the XPS boards of two different quality (400-L and 700-L) and thickness (120 mm and 100 mm). For the tests a servo-hydraulic testing machine was used while the deformations of the XPS specimen were monitored by means of LVDTs. The test specimen for the shear tests consisted of two XPS blocks glued on the system of 3 parallel steel plates where the middle one was movable and the outer plates were fixed. In the second stage of the laboratory tests a non-standardised test was carried out in order to estimate the coefficient of friction between the different constituent elements in the composite structure of a thermally insulated foundation (i.e. a TI foundation set) at different pre-compression levels (from 50 to 300 kPa). Various TI foundation sets were analysed – composed of one or two XPS boards, concrete slab, with/without a waterproofing insulation (HI) or a polyethylene (PE) sheet. For HI different types were applied: without/with adhesive on one/both sides and a HI with sand. The investigated thickness of the XPS boards was 200 mm (one-layered TI), while in the case of two-layered sets 2 boards of thickness equal to 120 mm (400-L) and 100 mm (700-L) were applied. At selected level of pre-compression in the vertical direction of the tested set horizontal displacements were induced by means of a servo-hydraulic actuator. For each tested TI foundation set the response and the coefficients of friction were assessed. The results showed that, in general, XPS material with higher compressive strength also possesses higher shear strength. The measured compressive strengths are similar to the declared values from the producers’ catalogues, while the obtained values of elastic moduli are slightly lower. Comparison of the stress – strain response of the XPS in compression and in shear shows that the obtained shear ductility capacity is smaller, and the strength degradation is evident in the deep nonlinear range of behaviour. Sliding between individual components of TI foundation set was revealed to be a likely failure mechanism in the case of low-rise, light-weight and slender building structures with high strength founded on a TI layer and subjected to strong earthquake loadings. The type and location of the inserted intermediate sheet play an importan
COBISS.SI-ID: 6747233
With an extensive parametric study the most common energy-efficient buildings founded on a layer of XPS were analysed. The purpose of the research was to determine the limits of such buildings on seismic areas and to calculate seismic demand values for thermal insulation material XPS. Material XPS is mainly used in under foundation applications due to its high compressive strength and water resistance. To discover limitations of buildings founded on a layer of XPS, incremental dynamic analyses (IDA) were performed. For input seismic ground motions a set of actual earthquakes from the European database was assumed. A set of buildings for the analysis has been defined on the basis of the fundamental period of vibration, which is a dynamic characteristic depending on the structure’s weight and stiffness. In the study various models with different fundamental period of vibration were analysed, where the main variations were the number of storeys, floor plan dimensions, material of the superstructure and structural system. At the same time also the equivalent models of buildings without the layer of XPS were analysed. With both models compared, also the response amplifications could be presented. The results of the nonlinear dynamic analyses showed some amplification of seismic forces for extremely rigid buildings due to the increase of the fundamental period of vibration. In addition, for higher seismic intensities, the allowed top horizontal displacement of the building could be exceeded. The latter is especially notable for tall and slender buildings, where the phenomenon of rocking is greatest. In such cases, also the compressive strength limit of the XPS could be reached. The phenomenon of rocking appeared to be critical already for buildings higher than 3 storeys. Furthermore, in certain cases, the event of uncontrolled horizontal sliding on the contact surface between the foundation slab and XPS could emerge. It was shown, that horizontal sliding could occur for seismic intensities greater than approximately 0.15 g (multiple layers of XPS with intermediate waterproofing foil) or 0.25 g (only one layer of XPS). Since 0.15 g is regarded as a relatively low seismic intensity, special attention is needed for the design of foundation slab details with XPS also from the point of view of sliding resistance. The event of sliding proved to be more critical for low-rise buildings. On the Slovenian seismic map for design earthquake intensities a large area is covered with seismic intensities larger than 0.15 g, which indicates that special precaution is needed for design of foundation system with a layer of thermal insulation. Building designers should be aware that such foundation system could be exposed to sliding in the case of design earthquake in Slovenia. To conclude, the transfer of energy-efficient buildings to seismic areas, therefore, requires a certain degree of attention and it must be individually considered. The events of sliding and rocking on a layer of XPS could be critical especially for boundary examples, such as higher, slender, heavier, or height-wise irregular and asymmetric buildings.
COBISS.SI-ID: 37627909
Our behaviour towards the environment depends on our beliefs about the environment. Beliefs, however, are a subject of change, particularly during important life transitions such as the transition to adolescence, because this is a period when an individual develops the ability of complex and abstract reasoning. Understanding this transition is therefore crucial for understanding and predicting the attitudes and courses of action in terms of sustainable development later in life. Due to many methodological constraints, the number of empirical studies examining these issues is very limited; the current study aimed to collect empirical data to explore the origins of our beliefs about the environment-related issues. We devised a picture association test and used it to compare childrens and adolescents beliefs about our environment in the context of the means of transportation. A large sample of 2264 participants aged 6-18 years took part in the study. The data supported the claim that childrens beliefs about environment share egocentric properties. The findings represent an important puzzle into the whole picture of childrens thinking and offer us great insight into the origins of beliefs about environment-related questions in adults. Educational implications are addressed.
COBISS.SI-ID: 6793057
With society turning increasingly to sustainable development, sharper demands are being made concerning energy efficiency and other properties that mean reductions in the negative effects of the building on the environment and people. This means that architects must have a suitably adapted solution already in the early design phase, as this has the greatest influence on the final result. Current tools and methods used for this are either focused only on individual topics or are too complex and not adapted for independent use by architects. The paper presents a simplified method for evaluating building sustainability (SMEBS) which addresses these needs. It is intended as a tool to aid architects in the early project planning phases as it allows a quick evaluation of the extent to which the demands of sustainable building are fulfilled. The method was developed on the basis of a study of international building sustainability assessment methods (BSAM) and standards in this field. Experts in sustainable construction were invited to determine weights for assessment parameters using the analytical hierarchy process (AHP). Their judgements reflect the specific characteristics of the local environment.
COBISS.SI-ID: 2336137
Mega-slums are dynamic laboratories for urban pattern making. Instead of surveying about stable urban symbols represented by formal orders and regular geometries, this study explores the semantic meaning of informal urbanism associated with chaos or randomness and often ignored by critique and conventions. Slums are forms of ‘instant urbanity’ that underscore alternative ways of self-organisation, which include bottom-up strategies, autonomous urban dynamics and spatial activation by remaking. Slum making is a form of subsistence urbanity that constructs transitory, elusive or spontaneous geometries. They differ in sizes, magnitudes and geometries regarding cultural, climatic and topographic factors. Slums are unstable systems in continuous transformation. This essay questions the stigmatisation of informalised urban patterns as ‘other’ unclassified codes by analysing a selection of twenty mega-slums in the Americas, Africa and Asia regarding semantics, urban and geometrical values. Their urban tissues contain various symbols that activate the every-day production of spaces. They can be visible or invisible; passive or active; and formal or informal. A taxonomic tree of slums was developed to compare and map slum regions to describe similarities and differences among the selected case studies. From this analysis, a profound discourse appeared between informal settlements: tissue-patterns at macro level and cell-patterns in micro urbanisation. Does the macro pattern inform the micro or vice versa? This current research is based on observational fieldwork, and morphological ‘readings’ of slum-space making and its characteristics. In order to understand, describe, interpret and explain the problematique of “slumness” in different geomorphological, social, economical, demographic and political situations, the ‘reading’ allowed us to understand the changing of urban everyday transformations. With all contradictions, which are taking place on a micro scale regarding sensorial features such as textures, colors, shading, noise, aromas, and scarcity driven by precarious infrastructure such as lack of sanitation systems (sewerage or safe water supply) and drainage; water, soil and air pollutants; brownfields; and natural or manned hazards at local scale, we can experience a complex layering in this ‘place of indeterminacy’. Each loci represents a peculiar every-day urban scene almost intolerable to conventional life standards, with a relegated image of rich urban symbols and organizational patterns that obeys to specific subaltern cultures. Pattern Recognition (PR) can be a method for understanding both morphological common features and organisational dynamics. Patterns are structures that our minds easily signify, identify, organise and connect in terms of scale, geometrical templates and abstract forms at macro and micro levels. In doing so, they are the amalgamation established between dwellers, dwellings and the communication networks within the built environment. The study of slums patterns can re-evaluate the importance of randomised urban structures in nowadays cities. When it comes with complex geometry, scalability arises between territorial, urban and local levels. In fact, a branching pattern can interpret intense connections within its formal structure, which is gradually transformed into slower communications by embedding the human scale and claiming primal meanings between dwellers and habitats. Can cities dignify contemporary urban structures like squatter settlements or slums? According to the Global report on Human Settlements (United Nations Human Settlements Programme, UN-Habitat 2003), “almost 1 billion people, or 32 per cent of the world’s urban population, live in slums” (Annan 2003). It is mandatory to consider all slums as part of the city with its social and spatial potentialities to consolidate flexible urban tissues within its life cycle. It is not simple, but through the proactive involvement of inclusi
COBISS.SI-ID: 3131524