Roof Elements Research Articles

Reinterpreting local wisdom of Rumah Kaki Seribu as sustainable architecture

Awareness of the increasing global issues regarding global warming and climate change has encouraged building designers to look back on knowledge of traditional architecture as energy-efficient and sustainable solutions. This study focuses on the traditional architecture of Rumah Kaki Seribu as sustainable architecture. Rumah Kaki Seribu is a traditional architecture located in the Arfak Mountains, West Papua, inhabited by the Arfak Tribe. Each architectural element of Rumah Kaki Seribu has a different sustainability value. The sustainability value of Rumah Kaki Seribu discussed is the concentration on the fireplace element and the roof element. The fireplace and roof elements were analyzed using the eco-cultural concept of the six competing logics of sustainable architecture by Simon Guy and Graham Farmer. Eco-cultural logic is a logic that is closely related to traditional architecture. The characteristics of sustainable buildings that use eco-cultural logic can be determined by looking at several parameters, namely the image of space, the source of environmental knowledge, the building image, technologies, and the idealized concept of place. The study aims to learn traditional architecture as a design approach to understand and respect the environmental context for solutions to global issues that occur.

Numerical Models of the Connection of Thin-Walled Z-Profile Roof Purlins

High thin-walled purlins of Z cross-section are important elements in steel wide-span structures. Their behaviour is influenced by many variables that need to be examined for every specific case. Their practical design thus requires extended knowledge of their behaviour for the possible configurations and dimensions. Numerical analysis verified by experimental investigation can thus enrich such knowledge. Numerical models have the advantage of repeatability and the ability to offer parametric changes. The parametric study presented shows a detailed description of a finite element model of thin-walled cross-sectional roof purlins connected to other roof elements. Models include various approaches to modelling bolt connection. Two schemes of purlins, with and without cleats, are presented. The results of different approaches in numerical modelling are compared with the results of a physical test on a real structure. The article shows a significant agreement in the case of specific approaches and points out the differences with others. The results can be helpful in terms of how to approach the modelling of thin-walled structures and the effective approach to experimental preparation.

Investigation of the effectiveness of strengthening with FRP applied in metal elements of suspension roof: an analytical approach

The building patrimony of Ukraine includes various examples of metallic structures, especially applied for industrial purposes and in large-span structures. The use of metal structures in construction is due primarily to their mechanical properties. They are frost-resistant and able to withstand temperatures down to -65 degrees as well as they are hard, durable, strong and reliable. They can also be used in areas with high seismic activity. However, as in the case of other types of structures, there is a need to restore or strengthen metal structures due to structural defects, wear of load-bearing elements, as well as to increase the load-bearing capacity. In several situations, strengthening with Fiber Reinforced Polymer composites (FRP) gives better results. The current article deals specifically with this strengthening technique. The main cultural reason to restore the old metallic structures and provide a structural functionality, is based on the need to preserve not only their historical origins but also the scenery value of the places in which they are located. That is why the strengthening should be carried out with the aim of maintaining the original design idea.
 Due to the long-term operation without timely maintenance and major repair, unique and metal large-span structures require strengthening of the load-bearing structures. It is especially important to choose the most efficient method, both in terms of reliability and cost effectiveness. This can lead to the long term interruption of the structure operation and production process, or the inability to use the adjacent territory due to the reconstruction work. At the same time, it is necessary to preserve not only the structure as a whole, but also the external architectural appearance.
 Traditional methods of strengthening are effective, but in some cases not effective or not applicable for use. An example is the increase of the load-bearing structures of the buildings, preserving the external appearance of which is the determining factor. In this case, the use of the discussed methods can be justified alternative. Disadvantages of steel panels and rods for strengthening are possible corrosion, considerable weight, need for high labor content of the work, and consequently the high cost of labor required to perform the work that need large area.
 Nowadays, one of the most dynamic types of large-span structures in architectural and structural view are suspension roofs. The aim of the research is the evaluation of the bearing capacity of the suspended rigid threads strengthened with CFRP (carbon fiber reinforced polymer) laminates and provision the general recommendations to implement reconstruction and strengthening with this type of material. Therefore it was considered variant of strengthening suspended bending-rigid fibers by composite materials. Computations are performed in software ABAQUS, as a result of which the percentage reduction in vertical deformation was 26.6% for bending-rigid fibers strengthened with CFRP laminates. The value of tensile stresses reduced by about 14 %.
 The obtained results of the study confirm the need for further studies and research.

Experimental study on mitigating extreme roof suctions by passive vortex generators

High wind suction always occurs at the edges and corners of large-span low-rise flat roofs, which can lead to severe damage to roof elements and even to the overall destruction of the roof. The passive vortex generator (PVG), a new device which can generate streamwise vortices, is proposed to mitigate the extreme wind suction on a low-rise large-span flat roof. Wind tunnel tests were conducted to investigate the control effect of PVGs, and parametric analysis was performed, with parameters including the height, length, opening angle, tilt angle and interval of PVGs. The maximum reduction of peak wind pressure under the worst wind incident angle with PVGs reaches 74%, and they show excellent control effects at all wind incident angles. The recommended parameters of PVGs are also provided for engineering practice. Spectrum analysis and the structure of the conical vortices show that the streamwise vortices generated by PVGs which mixed into the conical vortices and can distort or destroy the conical vortices, and then alter the position of conical vortices axis and reduce the reattachment range. Meanwhile, the high frequency fluctuation is increased and the low frequency fluctuation is reduced accordingly.

Ferro-geopolymer composites for roofing – A sustainable approach for infrastructures

Ferro-geopolymer is an upcoming building material that replaces the need for cement in construction practices and thereby reducing its carbon footprint. It is a composite consisting of geopolymer mortar matrix and wire meshes as reinforcement. The present study pioneers in the research of a prototype trapezoidal ferro-geopolymer roofing element under flexure. A total of nine specimens were cast, steam cured and subjected to third point loading. Three different spans of 2.5 m, 3.0 m and 3.4 m, and three different mesh types, (i) square welded mesh, (ii) square woven wire mesh, and (iii) hexagonal wire mesh, were the parameters considered for the study. Specimens reinforced with square welded wire mesh exhibited higher flexural strength compared with others, consequent to the additional strength imparted through the rigidity of welded connections. Maximum reduction in flexural strength of 20% and 32%, for specimens reinforced with square woven wire mesh and combination of hexagonal and square welded mesh, with respect to square welded wire mesh was observed for 3.0 m span beam elements. In addition, two analytical methods have been proposed to determine the ultimate flexural strength of ferro-geopolymer specimen and both methods were found to be in good agreement with the experimental results. The coefficient of variation of the predicted value of ultimate strength from the experimental value was obtained to be 9% for Method-I and 6% for Method-II.

Acculturation of local and non-local architecture on the scoping elements of the Merah Panjunan Mosque building in Cirebon

Architectural acculturation has a significant and uniform impact on modern architecture. However, the misunderstanding of this phenomenon tends to occur due to its inability to match its context's function and meaning. Therefore, this study aims to examine the acculturation of local and non-local architecture in mosque buildings. Previous research only focuses on mosque buildings as a syncretic factor, with none on the attributed topic. The research object is the Merah Panjunan Mosque in Cirebon City. This object was chosen based on the building age, the acculturation phenomenon that occurs, and because it is one of the cultural heritage in Cirebon City. The research method includes redrawing the Merah Panjunan Mosque's entire mass in three and two dimensions, making it easy to parse based on architectural anatomy. The study object's decomposition is intended to facilitate analysis in each unit of architectural elements, which is read based on the elaboration of the balance and orientation principles. The analysis results are interpreted in the conclusion section with the Merah Panjunan Mosque capable of displaying local and non-local architecture characterized by Javanese and Chinese architectures as well as a Hindu temple. The dominant composition of the Merah Panjunan Mosque acculturation is shown in the roof elements. Therefore, this research implies that Merah Panjunan acts as a reference for architectural design with the acculturation concept.

On the “cartilaginous rider” in the endocasts of turtle brain cavities

Abstract In recent years, paleoneurology became a very popular research field and hundreds of brain-endocasts were described. The interpretation of a dorsal protuberance of the brain-endocast puzzled researchers for a long time, the so-called (cartilaginous) rider. This is mainly because of technical limitations in the past and due to non-accessibility of comparative material. Using turtles as a case-study, we conducted a literature review and studied embryological data in addition to fossil and extant species’ endocasts. We assessed three hypotheses on the origin of the rider as relating to 1) the pineal gland, to 2) the blood vessel system, and to 3) skull roof elements. Based on our integrated anatomical observations, we refute the pineal gland hypothesis (1) and an exclusive blood vessel explanation (2). However, we show that, in most cases, the cartilaginous origin applies (3). The related cartilages, mainly the anterior process of the chondrocranial tectum synoticum, can persist until adulthood. Its diversity is interpreted in regard to the mechanical support for the temporal skull region, the shape of which has been shown to be in turn related to neck retraction and jaw mechanics. Finally, we highlight the value of embryological data to provide profound hypotheses for evolutionary research despite its low quantitative evaluability. We argue that it should be studied in conjunction with modern computer-aided data acquisition whenever possible.

A Novel Lightweight Phase-changing Cooling Roof Tile

Roof tiles are the most common roof coverings in Indian buildings, especially in traditional residential buildings. Given the important role of roofing characteristics in building energy efficiency and indoor thermal comfort conditions, innovative solutions to improve the thermal energy performance of this diffused roofing element have become a key research issue. In this perspective, cool roofing applications represent an effective solution to this objective. The present work deals with the analysis of innovative cooling roof tile manufactured using a combination of Metakaolin with different percentages, EPS, sodium silicate and coating material. The experimental work was carried out during day and night. The thermal performance of cool roof tiles were assessed in terms of the open-air temperature compared to the thermal performance of ordinary roofing tile. The report discovered that using revolutionary cool roofs greatly increased thermal comfort during the daytime, and preserved thermal comfort during the night. The innovative cool roof tile is cheaper, easier to implement, and less expensive compared to other roofing technologies. The study revealed that the roof's exterior and interior surface temperature reduced about 8°C and 12°C, respectively during day time, while roof's exterior and interior surface temperature maintain atmospheric temperature during night time. The compressive and transverse breaking strength was increasing about 9.1% and 39.6%.

Analysis and comparison of thermal conductance and indoor air temperature on industrial slag with conventional bricks

Wastes from industries and agriculture are on the increase, while the availability of natural resources is getting depleted worldwide the maximum being from the construction industry. Causes of heat gain through the building envelope are exposed wall and roof element, thermal conductivity and temperature difference between interior and exterior of the building. Hence, an alternative building material having less U-value helps in doubling up its potential as an efficient building material. In this research, two model rooms were constructed: one with industrial slag, phosphogypsum and fly ash (spaash) bricks and the other with conventional bricks (CB), and various parameters of the rooms for about six months were analysed. Spaash bricks performed better than CB with an average indoor temperature difference varying between 1.8°C and 2.1°C, a time lag of one hour and also reduced heat flow energy into the building interior by 50% through wall and 32.71% through roof.

Embodied carbon in commercial office buildings: Lessons learned from Sri Lanka

Growing concerns over the importance of reducing the embodied carbon (EC1) of buildings have led to a greater focus on EC-related research and policymaking. Nevertheless, the Sri Lankan building sector is currently lagging behind on this issue. While a few studies have been conducted on the EC impacts of different buildings, further research is needed on impact estimation in order to inform policies and guidelines on EC reduction, with assessment or estimation being the main driver towards reduction. Thus, this study aims to present, evaluate, and discuss EC assessment methodology and the assessment results drawn from twenty case studies in Sri Lanka, including low-, medium-, and high-rise office buildings. The results indicated that the EC extent of buildings ranged between 384.45 and 677.39 kgCO2e/m2. The average EC extent of each building category was valued at 522.18 kgCO2e/m2 (low-rise buildings), 457.85 kgCO2e/m2 (medium rise), and 567.51kgCO2e/m2 (high-rise). Irrespective of the building category, the substructure, frame, upper floors, and external walls were identified as the carbon critical elements, accounting for about 85–95% of overall EC. Internal walls and partitions, stairs and ramps, and roof elements were insignificant carbon elements, contributing less than 20% of EC. This study further revealed some practical indications on optimal EC reduction strategies for office buildings. Importantly, the overall work provided quantitative information that enables the decision-makers to make decisions on reducing EC of buildings in Sri Lanka.

Crescent-Moon Beam-To-Column Connection for Precast Industrial Buildings

The 2012 Emilia earthquakes caused significant damage to existing precast reinforced concrete (RC) industrial buildings not specifically designed to resist seismic actions. The main failure mechanisms were related to the loss of support of beams and roof elements caused by high relative displacements, to the failure of the mechanical connections and consequent fall of cladding panels, to the damage at the base of the columns and to the collapse of RC forks at the top of the columns. In all cases, the behavior of the connections, and specifically of beam-to-column connections, demonstrated to be crucial, given that they may inhibit the exploitation of strength and ductility reserves in precast elements. This paper presents a beam-to-column connection restraint-device for precast industrial buildings. The device can be applied to existing structures to transfer horizontal seismic forces between beams and columns and to increase the energy dissipation of the system. Design criteria were defined with the aim to limit the relative maximum displacement at the beam-to-column interface and to mitigate the out-of-plane overturning of the beam. Numerical analyses were carried out to define a suitable shape of the device and to investigate its effectiveness in terms of both local and global behavior. To validate the computational results, experimental tests have been also carried out. The tests allowed to classify the device as “dissipative” according to UNI EN 15129. Finally, the design procedure has been validated considering a one-story industrial building case study designed in accordance with the Italian building code.

Energy-active roof system – design, development and testing

The aim of the research is a development of a new energy effective roof system, fulfilling a function of a roof covering as well as solar active element, reducing energy performance of buildings. There were designed and tested energy active roof elements, consisted of glass-fibre-reinforced-concrete carrier with integrated photovoltaic and heat-exchange layer, which ensures cooling of photovoltaic elements as well as enables a transfer of excessive thermal energy into a storage tank for a later use. The effort of project solvers is to achieve entirely new economic efficient using solar energy by means of energy active roof covering. Current research and tests proved, that there is a possibility to create such a system using present materials and technological solutions. However, for the successful realization it is necessary to solve further technological aspects, namely mutual connection of the roof elements and prove load-bearing capacity and fire resistance of the designed system.

АНАЛІТИЧНЕ МОДЕЛЮВАННЯ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ РЕЗЕРВУАРУ ДЛЯ ЗБЕРІГАННАЯ МЕТАНОЛУ ВІД ТЕХНОЛОГІЧНИХ І КЛІМАТИЧНИХ ВПЛИВІВ

The paper contains the analytical modeling of the stress-strain state of the structures of the large-sized tanks for storing organic liquids under the technological and climatic actions on the example of a tank for storing methanol with a volume of 20,000 m3. The modeling took into account the defects and damages accumulated by the structure during long-term operation, including the form’s imperfection. As a result of the analysis of probable design situations have been revealed that the most unfavorable and dangerous for tanks structures are technological effects from vacuum which occur during emergency emptying of the tank and can lead to the occurrence of limiting states of the structure. This is especially true in areas that already have excess bends and deformations. Have been verified the most stressed and congested areas, as well as the most probable limit states. Defects of the structure were revealed as a result of visual and instrumental examination, namely, the excess deflections of the spherical roof elements, local protrusions of the cylindrical shell fragments, confirm these findings. Defects indirectly indicate that the structure during operation have been under the influence of unfavorable factors, which led to the appearance of the limiting state of loss of shape stability. Have been determined the residual safety and stability factors of the structure. Have been recommended to limit the useful volume of filling the tank to 70% of the nominal capacity based on the stress-strain calculations. Have been developed the technological regulations for further safe operation of the facility and outlined directions for further scientific research on this topic.

Research polymer coatings material properties and application features

This article describes the coating processes on the working surfaces of many parts from different polymeric materials. Obtaining coatings from polymers is superior to other coatings in terms of quality, efficiency and low cost. coatings made of polymer composite materials in order to protect working surfaces from corrosion and increase the durability of service parts made of metals. They are quite resistant to chemicals, so it will not be possible to remove the polymer layer with a solvent. The coating can only be removed with a special tool. Pural is not as resistant to plastic deformation as plastisol, and is more expensive than polyester, but in terms of price-quality ratio, it is the best option from all of the above. Pural coatings are most widely used in the production of galvanized metal roofing elements.

Thermo-mechanical and physical properties of waste granular cork composite with slag cement

Construction industry consumes a lot of energy either through the materials used or by heating and cooling. Insulation materials using waste materials could help reduce the energy consumption. Waste cork is abundant in Mediterranean countries and is rarely used as a construction material. Cork presents excellent thermal and acoustic performance and could be used in heat insulation for roof elements. This paper aims to investigate the mechanical and thermal properties of cement composites with waste cork under different curing conditions. The effect of including granulated blast furnace slag on these composites was also studied. The results indicate that the strength of cork cement composite is adequate and meets the standards requirements for heat insulation elements.

A Comparative Assessment for the Potential Energy Production from PV Installation on Residential Buildings

This paper targets the future energy sustainability and aims to estimate the potential energy production from installing photovoltaic (PV) systems on the rooftop of apartment’s residential buildings, which represent the largest building sector. Analysis of the residential building typologies was carried out to select the most used residential building types in terms of building roof area, number of floors, and the number of apartments on each floor. A computer simulation tool has been used to calculate the electricity production for each building type, for three different tilt angles to estimate the electricity production. Tilt angle, spacing between the arrays, the building shape, shading from PV arrays, and other roof elements were analyzed for optimum and maximum electricity production. The electricity production for each household has been compared to typical household electricity consumption and its future consumption in 2030. The results show that installing PV systems on residential buildings can speed the transition to renewable energy and energy sustainability. The electricity production for building types with 2–4 residential units can surplus their estimated future consumption. Building types with 4–8 residential units can produce their electricity consumption in 2030. Building types of 12–24 residential units can produce more than half of their 2030 future consumption.

Stochastic modelling and assessment of long-span precast prestressed concrete elements failing in shear

The shear behaviour of reinforced and prestressed concrete structures has been extensively studied over the last decades. However, there are still numerous open questions, concerning, e.g. the effects of normal-shear force interaction and material properties on shear performance. While the elastic behaviour of structures can be accurately captured by existing analytical approximations available within code standards, the description of the plastic behaviour of prestressed concrete elements occurring before typically quasi-brittle shear failure requires nonlinear analysis. Therefore, most prestressed concrete structures are designed to utilise only the elastic capacity of the material to avoid the performance of a complex nonlinear finite element analysis (hereinafter NLFEA) of pre-failure behaviour. In the case of mass-produced precast elements, however, the higher cost of performing NLFEA to provide valuable information on the complete loading of such element’s history might be justified and economically beneficial. NLFEA can give much more objective information on a structure’s performance and ultimate capacity, its cracking behaviour and failure indicators which can be utilised for the optimisation of the design, maintenance and inspection of produced structural elements. However, deterministic NLFEA cannot capture the naturally uncertain character of structural response. Current code standards provide a framework for NLFEA using several safety formats. The fully probabilistic approach remains the most general, straightforward and least conservative way of considering uncertainties, however. The stochastic modelling of a precast element’s shear response requires the performance of a series of fracture-mechanical experiments with material samples, the evaluation of stochastic features of material parameters, and the use of identified random parameters as inputs for highly accurate nonlinear finite element models of destructive experiments. The information on material uncertainty is then used for the virtual statistical simulation of Monte Carlo type to obtain the probability distribution of structural resistance. This paper aims to describe the application of stochastic NLFEA to the shear behaviour simulation of a for wide-span prestressed reinforced concrete lightweight roof element. Extensive experimental studies on small specimens and scaled and full-scale girders have been performed to acquire the required information for the implementation of complex material laws in advanced probabilistic nonlinear numerical analyses. This information is used together with advanced monitoring systems to investigate stochastic features of shear structural response, the probabilistic safety level in terms of code-based design levels, and the experimental findings.

Sustainable bamboo housing for the earthquake prone areas

Bamboo-based housing systems are prevalent as a vernacular type of construction in many parts of the world where bamboo is available locally. Even in India, bamboo-based houses are not so uncommon, especially in the north-eastern part, which is seismically the most vulnerable zone. Structural evaluation, chiefly seismic evaluation, significantly requires a lot of infrastructures. Prohibitively expensive infrastructure cannot be used to evaluate housing systems which themselves are extremely low-cost in nature. There is a need to evaluate the components of a bamboo-based housing system in addition to the full-scale models under seismic loads by using simple and cost-effective facilities. A seismic evaluation of a full-scale bamboo housing system was carried out on two models using a shock table test facility. This helped in identifying the extreme limits of seismic vulnerability of the bamboo-based housing system. From this study, it was observed that the model did not collapse nor did it show any signs of collapse. Also, there were no indications of any tendency of any local collapse of the roofing elements. Hence, it can be concluded that the model had fulfilled the requirement of resisting major levels of lateral forces without losing its stability.

СТВОРЕННЯ 3D БІБЛІОТЕК ЦИФРОВИХ КОМПОНЕНТІВ МОДЕЛІ БАГАТОПОВЕРХОВОЇ БУДІВЛІ

Abstract. The article is dedicated to creation of 3D libraries of building construction elements with customized annotations, analytical and other necessary parameters for interior walls, doors, windows, exterior walls, floor slabs, roof, ceiling and floor elements in REVIT software. The aim of the work is to develop a database of families of parameterized components of buildings and structures in REVIT. The research was conducted using the method of generalization, systematic approach and statistical analysis. The matter of creating families of digital components of the virtual model of construction projects in accordance to the state norms and technical requirements is relevant now. Issues of creation and application of families of digital parameterized components according to requirements of current regulatory documents, interior and exterior components, as well as the structural component of each created element are described in the article. Some of the created families conform to the specified requirements, are universal and having an ability to replace types families. For each of the loaded element, the maximum possible number of materials was selected with the inclusion in the library of all the necessary information from physical and thermal characteristics to the current price of the building materials on the Ukrainian market. Practical use of the created libraries occurs in the design of construction projects in the framework of faculty and students cooperation with the Public Union «BUILDIT UKRAINE». The information model of a multistory civil building was created by the authors. The model allows to automatically generating the necessary drawings for construction: plans, facades, schemes, sections, design specifications and other documentation. Moreover, this reduces the time for preparation of project documentation and provides control of key indicators and compliance with the deadlines. Besides, the model allows to provide information on the results of researches and tests quickly, and promptly adjust the cost of construction.

Refined Zigzag Theory: an appropriate tool for the analysis of CLT-plates and other shear-elastic timber structures

Cross laminated timber (CLT), as a structural plate-like timber product, has been established as a load bearing product for walls, floor and roof elements. In a bending situation due to the transverse shear flexibility of the crossing layers, the warping of the cross section follows a zigzag pattern which should be considered in the calculation model. The Refined Zigzag Theory (RZT) can fulfill this requirement in a very simple and efficient way. The RZT, founded in 2007 by A. Tessler (NASA Langley Research Center), M. Di Sciuva and M. Gherlone (Politecnico Torino) is a very robust and accurate analysis tool, which can handle the typical zigag warping of the cross section by introducing only one additional kinematic degree of freedom in case of plane beams and two more in case of biaxial bending of plates. Thus, the RZT-kinematics is able to reflect the specific and local stress behaviour near concentrated loads in combination with a warping constraint, while most other theories do not. A comparison is made with different methods of calculation, as the modified Gamma-method, the Shear Analogy method (SA) and the First Order Shear Deformation Theory (FSDT). For a test example of a two-span continuous beam, an error estimation concerning the maximum bending stress is presented depending on the slenderness L/h and the width of contact area at the intermediate support. A stability investigation shows that FSDT provides sufficiently accurate results if the ratio of bending and shear stiffness is in a range as stated in the test example. It is shown that by a simple modification in the determination of the zigzag function, the scope can be extended to beams with arbitrary non-rectangular cross section. This generalization step considerably improves the possibilities for the application of RZT. Furthermore, beam structures with interlayer slip can easily be treated. So the RZT is very well suited to analyze all kinds, of shear-elastic structural element like CLT-plate, timber-concrete composite structure or doweled beam in an accurate and unified way.