Roof Elements Research Articles

ОПТИМИЗАЦИЯ КОНСТРУКТИВНОГО ИСПОЛНЕНИЯ ПЕРЕКРЫТИЯ НАДРЕАКТОРНОГО ПО РЕЗУЛЬТАТАМ ЧИСЛЕННОГО ИССЛЕДОВАНИЯ НА СТАДИИ ПРОЕКТИРОВАНИЯ

The paper presents basic results of analysis of deformation process and estimation of pipe mockup falling on a reactor roof (RR). Reactor protection against possible falling of various pieces of equipment is provided by keeping RR integrity and no unallowable deformation on it. Full-scale representative testing of RR under dynamic impacts is rather difficult because of a large cost. To decrease costs, at the design stage representative analytical studies were performed, and the design was optimized considering the shock resistance requirements to mitigate consequences of troubles in operation in course of transportation and handling operations at the reactor plant. Computation analysis of falling is performed using dynamics computation module LS-DYNA of program complex ANSYS certified by Rostekhnadzor. The LS-DYNA module is intended for computation analysis of high-linear dynamic processes by an explicit scheme of integration of dynamics equations. Mathematical analysis was made using a verified model of the behavior of a structural material used in the reactor roof, which was built based on the results of experimental studies under compression and tension conditions at various deformation rates and temperatures. The obtained results permitted to analyze collision process, determine values of plastic defor-mations occurred in reactor roof elements. Application of an integrated approach implemented in this computation analysis permitted to solve, with a moderate percentage of conservatism, a problem associated with safe reactor plant operation.

Compact wooden roofs with smart vapour barriers – effect of wooden joists on drying of built-in moisture

The application of a smart vapour barrier in compact wood frame roofs has been investigated. The study was performed using a laboratory setup for small roof elements, exposed to a typical Nordic summer climate and a high level of built-in moisture. The concept of this study was to investigate how various types of wooden joists and their hygroscopic properties influenced the inward drying and moisture distribution within the elements. The results were compared to previous studies with similar roof elements without wooden joists. The results showed that the type and size of wooden joist influenced both the drying speed and the moisture level and distribution within the elements.

Using a feed forward ANN to model the inelastic behaviour of confined sandwich panels

The analysis and design of complex structures like sandwich-panel elements are difficult; the use of finite element method for the analysis is complicated and time consuming when non-linear effects are considered. On the other hand, artificial neural network (ANN) models can capture the non-linear effects and its application requires lesser computational demand. Two ANN models were trained, tested and validated to compute the force for a given displacement of a sandwich-type roof element; 2555 force and element deformation pairs were used for training the ANN models. For the models trained without considering the damping effect, there were two values in the input layer: maximum displacement and current displacement, and for the model considering damping, displacement from the previous step was used as an additional input. Totally, 400 ANN models were trained. Results show that there is a good agreement between the experimental and simulated data, and the models showed a good performance with a mean square error value of 4548.85. Both the ANN models could simulate the inelastic behaviour, loss of rigidity, and evolution of permanent displacements. The models could also interpolate and extrapolate, which enables them to be used as an analysis and design tool for such complex elements.

Constructive Variants for Personalised Formwork

Abstract The aim of this paper is to explore the possibility of working with a personalized reusable composite formwork in order to obtain architectural shapes for roof and wall elements without material loss. Starting with the analysis of the market needs, the definition of the functions and continuing with the conceptual and technical solution proposals, we created a formwork variant that can be reused for different complex shapes. The researches set on sight different variations of the material used, their thickness and the contact surface given by the support elements.

Cranial ornamentation of a large Brachydectes newberryi (Recumbirostra: Lysorophia) from Linton, Ohio.

Although the cranial anatomy of the lysorophian tetrapod Brachydectes has been reported in detail recently, many attributes of the group are inadequately known, and lysorophian systematics remain unclear. One under-described aspect of the genus is the development and variation of cranial ornamentation. Whereas the smallest skulls (< 5 mm in length) lack sculpturing, ornamentation increases in progressively larger specimens and is conspicuous in the largest (> 30 mm skull length) individuals. It includes rugose ornament on the anterior cranial roof elements (frontals and anterior parietals) and pustular ornament on the posterior elements (posterior parietals and postparietals). Such ornamentation is unique within recumbirostrans and is identified as an ontogenetic feature.

Križno lamelirani les – lastnosti in zahteve

Cross-laminated timber (CLT or X-Lam) is a modern building material used for load-bearing construction purposes in residential and non-residential buildings. CLT production has been increasing rapidly in recent years. CLT is suitable for wall, floor, ceiling and roof elements in the construction of houses, multi-family apartment buildings, industrial and storage halls and other buildings and bridges. Manufacturers demonstrate compliance with the essential requirements of the European Construction Products Regulation (CPR) on the basis of an initial type testing and the findings of a factory production control examination. In 2015, a harmonized European standard for CLT was adopted, which defines the requirements for built-in materials, the production and demonstration of constancy of performance, and the CE marking. The article presents the production technology and basic characteristics of CLT and the content of standard EN 16351.

Efficacy of roof-to-beam mechanical connections on the diaphragm behaviour of precast decks with spaced roof elements

The diaphragm action of slab/roof decks ensures the collaboration of different parts of the lateral load resisting system of a building. In reinforced concrete precast buildings for industrial/commercial halls, not seldom the deck is not provided with a cast-in-situ topping: this results into diaphragm action to rely upon the floor mechanical connections alone. In this study, the efficacy of three different typical floor-beam connections, namely hot-rolled angle brackets, cold-formed angle brackets and dowel bars, on the diaphragm action of the deck has been investigated. To this purpose, simplified macroscopic “behaviour models” have been proposed, based on the results of monotonic and cyclic tests carried out within the framework of the research project Safecast (FP7-SME-2007-2; GA 218417/2009). A numerical model of a dry-assembled precast structure with mechanical floor-to-beam connections has been checked against the results of cyclic and pseudo-dynamic tests carried out on a full-scale prototype within the framework of the Precast Structures EC8 project (GA G6RD-CT-2002-70002). Non-linear dynamic analyses have then been performed to investigate the diaphragm action effectiveness of the three different technological solutions to connect slab and beams considering a seismic action orthogonal to the roof elements. Different stiffness distributions of the lateral load resisting system have been considered, investigating the possible bracing effect induced by an integrated connection system of the external cladding panels. A simplified “design-wise” analytical interpretation of the phenomenon is also formulated and checked against the numerical results.

Element geochemical characteristics and formation environment for the roof, floor and gangue of coal seams in the Gujiao mining area, Xishan coalfield, China

The roof, floor and gangue samples of coal seams were collected from a borehole in the Gujiao mining area. The vertical distribution of major elements, trace elements and rare earth elements (REEs) was tested through X-ray fluorescence spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS). The formation environment and material source of the strata were analysed. The results showed that the major elements of the coal seam roof, floor and gangue are Si and Al, followed by Fe, K, and Ti. In the Shanxi Formation, Sn, B, Ta, Bi, Th, U, Li, Be, Nb, In, Cs and Hf are enriched. In the Taiyuan Formation, B, Bi, U, Li, Sr, Mo and Sb are enriched. Sn, B, Th, U, and Be of the Shanxi Formation and B, U, Mo, and Sb of Taiyuan Formation are enriched hazardous elements. The ratios of Sr/Ba, U/Th, Ni/Co and V/Cr could indicate the paleosalinity and redox conditions. The Shanxi Formation was mainly formed in an oxic environment. The roof and floor of the No. 7 coal and the roof of the No. 8 coal are limestone, indicating anoxic and suboxic to dysoxic environments. The lithology of the Shanxi Formation and Taiyuan Formation material source is complex, including sedimentary rocks, granite and alkaline basalt. Most samples are distributed at the intersection of the granite and alkaline basalt, indicating dual sourcing from the granite and alkaline basalt.

Effective polyurethane compositions filled with industrial wastes

Formulations are developed and optimized for of rigid polyurethane foams filled with converter slag. The optimum content of the filler is 30%. Polyurethane compositions have the following characteristics: average density – 42.59 kg/m3, compressive strength at 10% deformation – 0.293 MPa, water absorption by volume 1.71%, coefficient of thermal conductivity – 0.028 W/m·0C. Polyurethane foams are applied in sandwich panels, multi-layer roof constructions and for the manufacture of fixing systems for metal rolled.Sandwich panels with polyurethane foam insulation and sheathing of specialized panels are designed for the construction of pre-fabricated residential buildings. The forecasting of polyurethane durability in building structures as thermal insulation in sandwich panels the foam lifespan is about 75 years, which is approximately two times greater than that of the unreinforced foam.Layered roof structures with modified rigid polyurethane foam are used for buildings and structures for various purposes. Their use makes it possible to solve several tasks: creating a complete architectural image, ensuring high strength and deformation characteristics with good noise and heat insulation, minimization when mounting. The use of lightweight, transportable and technologically advanced roofing elements in conditions of mass production creates significant opportunities for industrial construction. The proposed foam fixing systems during shipping rolled metal in containers makes it possible to exclude the possibility of the longitudinal and transverse shift of pallets with rolls, to protect metal from damage, to simplify the design of the foxing elements, reduce the production cost, and minimize the amount of time for fixing metal rolls in the container.

Corner failure in masonry buildings: An updated macro-modeling approach with frictional resistances

Abstract The failure mode of a free corner in masonry buildings , still poorly investigated, is one of the most common failure mechanisms occurring and clearly recognizable in the aftermath of a seismic event. It is characterized by the formation of a masonry wedge, mainly due to the thrust of roof elements in addition to inertial forces , and it generally involves rocking-sliding motions along the cracks on the interlocked orthogonal walls. The onset of this failure mode is herein analyzed by means of an upgraded macro-block model, based on the kinematic approach of limit analysis and accounting for the influence of frictional resistances on the collapse load multiplier and the related crack pattern. An original criterion weighting the role of rocking vs. sliding motion on the collapse load factor is developed and a formulation with general applicability is obtained. Several parametric analyses are performed in order to highlight the influence of geometrical, mechanical and loading parameters on the seismic capacity of the corner. The reliability of the proposed model and solution procedure is confirmed through the comparison with the results provided by other macro-block models existing in the literature. The final perspective is the next implementation of the proposed model in FaMIVE (Failure Mechanism Identification and Vulnerability Evaluation) applicative.

Spatial and economic conditions of the solar energy use in single-family houses - a case study

The provisions in the European and Polish law oblige to increase the use of energy obtained from renewable energy sources. In order to meet these demands, it is necessary to take into account the singlefamily housing sector that has a significant energy potential. Among the unconventional heat sources that have gained the highest popularity, it is worthy to note installations using solar energy for instance to prepare DHW (domestic hot water) or be used in buildings’ heating. It is also worth mentioning that this type of technical solutions can be successfully used as well in new as modernized old residential buildings. Our paper discusses the problems associated with planning of solar installations with flat and vacuum solar collectors mounted on the roofs of the single-family buildings. During the analysis we used GIS&T technology, multi-criteria decision support as well as detailed spatial data obtained by modern remote sensing techniques including airborne laser scanning. The proposed methodology and tools were used on the example of the selected part of a single-family housing estate located in Bialystok. The research focused on issues of the multi-criteria assessment of the assembly of use of roofs for solar collectors, including data on a solar potential, exposure, slope, surface and roofs’ shape. Additionally, we took into account roof zones on being in a shadow caused by roof elements, roof infrastructure and high vegetation. Based on the simulation results we analyzed possibility of plate and tube solar collectors’ application that would provide warm water for 1-4 habitants of houses. The results of our research showed high utility of the proposed methods in the field of spatial and economic assessment of the use of solar collectors in the single-family housing sector.

Design automation of load-bearing arched structures of roofs of tall buildings

The article considers aspects of the possible use of arched roofs in the construction of skyscrapers. Tall buildings experience large load from various environmental factors. Skyscrapers are subject to various and complex types of deformation of its structural elements. The paper discusses issues related to the aerodynamics of various structural elements of tall buildings. The technique of solving systems of equations state method of Simpson. The article describes the optimization of geometric parameters of bearing elements of the arched roofs of skyscrapers.

Problems of tank roofs resistance to corrosive attacks

Nowadays, there are many types of roofing designed for steel vertical tanks. Their working properties are also quite different. The paper considers technical solutions of tank roofs constructed for storage of liquid aggressive liquids of oil type and the like. It describes a new technology which is being actively introduced at Russian enterprises at the moment. According to this new method, load-bearing structures are installed above roof flashing sheets, thus protecting them from direct contact with an aggressive environment. It ensures corrosion resistance and, consequently, durability of the tank stationary roof. To reduce the risk of corrosion damage it is necessary to increase metal thickness. The researchers suggest using stainless steel instead of regular carbon steel. In this case, steel sheets thickness can also be lessened thus making it possible to reduce loads on underlying constructions. The proposed solution of the units fastening the tank roof elements also simplifies construction inspection activities.

Evaluation of fire damage to the steel structure of an industrial shed

The study concerns an analysis of fire damage to the steel structure of an industrial shed. The shed was used as storage for woodchips, which are an easily inflammable material. Despite the fact that the fire did not affect the entire structure, it resulted in an excessive deformation of the roof elements, damage to curtain walls, and the conveyer. The state of safety of the remaining structure was evaluated based on the performed investigation, study of the archive documentation and static calculations. The critical temperature for steel structural elements was estimated. The structure elements requiring replacement were identified.

INVESTIGATION OF ENERGY EFFICIENCY OF POLYCRYSTALLINE SILICON SOLAR MODULES IN RELATION TO THEIR GEOGRAPHICAL ORIENTATION AND TILT ANGLE

Investigation of the polycrystalline solar modules energy efficiency in relation to their tilt angle and geographical orientation in the real meteorological conditions are presented in this paper. The experimental system comprises five polycrystalline silicon modules, with single power 50 Wp, three of which are placed vertically and oriented towards the East, South and West, respectively, the fourth is horizontal, while the fifth is oriented toward the South at the angle of 33o (optimally inclined solar module). The measurement period was from 01 August to 01 December, 2014. The optimally inclined solar module generated the most of total monthly energy for all four months. The most of total monthly energy was generated in August, by the optimally inclined solar module (6.07 kWh), horizontal solar module (5.69 kWh), the vertical solar module oriented toward the East (2.42 kWh) and the vertical solar module oriented toward the West (2.52 kWh), respectively. Energy efficiency of optimally inclined solar module for the entire measurement period was 14.27%, 11.41% for the horizontal, 10.37% for the South, 5.79% for the East and 5.23% for the West module. The obtained results can be used in modern architecture, for the application of the solar modules as roof and facade elements.

Energy saving concept development for the MORE-CONNECT pilot energy renovation of apartment blocks in Denmark

The European Horizon2020 project MORE-CONNECT on prefabricated deep energy renovation of residential dwellings also covers pilot demonstration projects, which are to be carried out in six of the participating countries. For each country a unique, climate specific concept development analysis is carried out. The concept development follows the MORE-CONNECT methodology and thus aims towards a Zero Energy Building (ZEB) level or if cost limitations require nearly Zero Energy Building (nZEB). For the Danish situation, this means that the energy requirement for heating purpose is to be brought down from around 100 kWh/m² to below 20 kWh/m². As the pilot project has not yet been identified, concept development calculations has been conducted for a generic building. The technologies to be considered for this energy renovation are: Insulation of the façade, insulation of the roof, low-energy windows, heat-recovery ventilation, solar domestic hot water and a PV-system. Within the MORE-CONNECT two technologies are under development in Denmark. The first is a new PV-roof solution in which the PV-cells are fully integrated in the roofing elements. This PV-roof can be fitted into any roof surface shape. It can also be constructed as a PVT-roof connected to a heat pump for heating purposes. The second technology under development is 3-D finishing of a new layer of façade insulation by an industry robot. When an insulation layer has been placed on any given façade a finishing layer of plaster can be added and finished with any desired patterns or painting.The paper presents the present stage of the concept development work and is a continuation of the first concept development analysis presented at the SBE conference in Tallinn in 2016.

Life cycle assessment of product- and construction stage of prefabricated timber houses: a sector representative approach for Germany according to EN 15804, EN 15978 and EN 16485

Energy savings in the use phase of a building’s life cycle increased the relative importance of environmental impacts of the product-, construction- and end-of-life stages of a building. The European Committee for Standardization (CEN) thus developed horizontal standards to enable the sustainability assessment of construction works over their entire life cycle. Consistent with the European standards EN 15804, EN 15978 and EN 16485, a life cycle assessment (LCA) was carried out to determine the environmental impacts of the production and construction stages of an average prefabricated timber house produced in Germany as well as its particular building elements (1 m² inner/outer wall, 1 m² roof element, 1 m² ceiling element). The life cycle inventories (LCIs) were compiled on the basis of annual data of 12 participating manufacturers of prefabricated timber houses. A specific LCA model was developed for the calculation of the input- and output flows referring to the functional units on factory level. Furthermore, one focus was laid on the application of the modular principle according to EN 15804/15978 to construction systems with a high level of prefabrication. The normalization to the overall German impacts shows that the contributions to the environmental categories global warming potential (GWP), acidification (AP) and to the abiotic depletion potential (ADPe) are most important. The highest impacts originate from the manufacturing of the building materials. However, for the categories GWP and AP, around 30% of the impacts originate from the prefabrication of the building elements, their transport and the processes at the construction site.

Smart cool mortar for passive cooling of historical and existing buildings: experimental analysis and dynamic simulation

In order to mitigate Urban Heat Island Effect and global warming, both governments and scientific community are working to reduce energy consumptions. In particular, the construction sector has a high potential in reducing energy demand, by means of both active and passive solutions. The European building stock is mainly composed by existing buildings as well as historical ones, which happens to be the less energy efficient ones. Moreover, retrofit operations are more complex on historical buildings, due to strict regulations for the preservation of such historical and cultural heritage. Considering this challenge, in this work we described and in lab analyzed possible passive solutions specifically designed for historical and existing buildings. In particular, we developed innovative cool colored mortars and tested them in lab, as well as investigated cool colored mortars, cool clay tiles and cool natural gravels performance when applied as envelope and roof elements, by means of dynamic simulation.

NZEB Renovation of Multi-Storey Building with Prefabricated Modular Panels

Reduction of energy use in buildings in EU is expected to be reached with help of fulfilling of requirements of low and nearly-zero energy buildings (nZEB) policy. The efficient way to accomplish the purpose of the nZEB is to apply the integrated design process, considering the long-term sustainability and building costs as a one setup. The multi-storey large concrete element building is renovated to nZEB as a Horizon2020 MORE-CONNECT project pilot in Tallinn. The study of that project includes complex of measures: hygrothermal measurements and analysis, highly insulated facade and roof elements, the full modernisation of heating and ventilation systems. Ventilation ducts are installed into the modular panels to minimize supply ductworks in apartments. Roof panels include solar panels and collectors for renewable energy production. All technical systems will be equipped with monitoring systems and data will be logged periodically. The designed thermal transmittance is U≤0.11W/m2K for walls, U≤0.10W/m2K for roof and U≤0.80W/m2K for windows and external doors. The analyse, design and renovation process of the integrated nZEB design method gave us a unique experience, showing weak links in the chain and helping to prevent faults in the whole process in the future.

Potential of Progressive Construction Systems in Slovakia

Construction industry is a sector with rapid development. Progressive technologies of construction and new construction materials also called modern methods of construction (MMC) are developed constantly. MMC represent the adoption of construction industrialisation and the use of prefabrication of components in building construction. One of these modern methods is also system Varianthaus, which is based on, insulated concrete forms principle and provides complete production plant for wall, ceiling and roof elements for a high thermal insulation house construction. Another progressive construction system is EcoB, which represents an insulated precast concrete panel based on combination of two layers, insulation and concrete, produced in a factory as a whole. Both modern methods of construction are not yet known and wide-spread in the Slovak construction market. The aim of this paper is focused on demonstration of MMC using potential in Slovakia. MMC potential is proved based on comparison of the selected parameters of construction process – construction costs and construction time. The subject of this study is family house modelled in three material variants – masonry construction (as a representative of traditional methods of construction), Varianthaus and EcoB (as the representatives of modern methods of construction). The results of this study provide the useful information in decision-making process for potential investors of construction.