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1
Nagy, Balázs, and Dóra Szagri. "Hygrothermal Properties of Steel Fiber Reinforced Concretes." Applied Mechanics and Materials 824 (January 2016): 579–88. http://dx.doi.org/10.4028/www.scientific.net/amm.824.579.
Повний текст джерелаАнотація:
This paper defines the hygrothermal material properties (thermal conductivity, density, specific heat capacity, vapor diffusion coefficient and resistance, moisture storage function, water absorption coefficient and liquid transport coefficient) of steel fiber reinforced concretes that are widely used for industrial floors, based on laboratory measurements. The measured and calculated material properties are necessary to carry out a dynamic heat and moisture simulation of a component or a building containing steel fiber reinforced concrete layers.
2
Iravani, Ahmad, Volkert Feldrappe, Andreas Ehrenberg, and Steffen Anders. "Stability of concrete containing blast-furnace slag following exposure to cyclic elevated temperature." Acta Polytechnica CTU Proceedings 33 (March 3, 2022): 238–44. http://dx.doi.org/10.14311/app.2022.33.0238.
Повний текст джерелаАнотація:
Concrete is widely used in constructions such as industrial floors or airducts in steel- and casting industry where it is often exposed to long-term or cyclic elevated temperatures. For these applications, thermal stability of concrete is of vital importance. The strength reduction dueto elevated temperatures depends on the temperature level and concrete composition. In this study, the effects of blast-furnace slag cement (CEM III/A) and basaltic aggregates were investigated at temperatures 250◦C to 700 ◦C in comparison to conventional Portland cement (CEM I) containing quarzitic aggregates. The concretes were cyclically exposed to high temperatures. Special attention was paid to mass loss, residual compressive and residual flexural strength depending on type of cement and aggregate as well as the number of thermal cycles. Mass loss and strength loss increased with increasing maximum temperature level, as expected. It was generally observed that concretes containing CEM III/A displayed significantly higher residual mechanical properties for almost all temperature levels. Concretes containing a combination of CEM III/Awith basaltic aggregates showed significantly higher stability at elevated temperatures compared to other concrete mixtures. It is further shown that apart from the maximum temperature the number of thermal cycles is important for the residual mechanical properties.
3
Sedlmajer, Martin, and Jiri Zach. "Properties of Lightweight Concretes Made of Aggregate from Recycled Glass." Solid State Phenomena 249 (April 2016): 67–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.249.67.
Повний текст джерелаАнотація:
The paper describes the basic properties of newly developed lightweight cement concrete containing lightweight aggregate based on recycled glass. The basic properties of concrete were observed, i.e. bulk density in fresh and hardened state and compressive strength. Given the low bulk density of the concretes being designed, thermal conductivity is also observed in order to assess the options off improving thermal insulation properties in a structure where such concrete may be used. Thermal insulation properties are the primary parameter in the implementation of floor or ceiling structure composition.
4
Raczkiewicz, Wioletta, and Artur Wójcicki. "Implementation and usage aspects for floors in the residential houses." E3S Web of Conferences 49 (2018): 00085. http://dx.doi.org/10.1051/e3sconf/20184900085.
Повний текст джерелаАнотація:
Concrete floors at the building’s rooms are made of concrete, as well as fibre-reinforced concrete, or with the reinforcement meshes of various kinds. On one hand, such aspects have an influence on technical capabilities, as well as cost and labour-consumption when making the floors; on the other hand, they influence operational properties. The floors, as a result of significant dimensions, are particularly vulnerable to cracks, following the overlapping effects of shrinkage and thermal strains, as well as mechanical loads. Detailed design guidelines concerning the implementation method and the recommended materials (application of the respective plasticising admixtures and reinforcement, various kinds of steel meshes or a distributed reinforcement as steel or polypropylene fibres) have been developed, in order to prevent the cases above. It is visible (according to a great deal of experimental research) that the abovementioned guidelines limit the undesired shrinkage effects. Nevertheless, average typical conditions for making the floors very often differ from those in the guidelines, which may lead to the appearance of future shrinkage cracks, irrespectively to the applied reinforcement. The paper presents conclusions from the analysis of research results for three types of concrete ground floors made in the detached residential house, in the same operational conditions, differing with the reinforcement applied. The research was conducted from the moment of implementation and then, during the initial operational period.
5
E.V., Shipacheva, Pirmatov R. Kh., and Turdalieva M.K. "Heat Engineering Heterogeneity Of The Outer Walls Of Earthquake-Resistant Buildings." American Journal of Interdisciplinary Innovations and Research 02, no. 12 (December 7, 2020): 1–8. http://dx.doi.org/10.37547/tajiir/volume02issue12-01.
Повний текст джерелаАнотація:
When assessing the level of energy efficiency of civilian buildings, a special place is given to establishing the level of thermal protection of their external enclosing structures. Significant discrepancies in the results of theoretical and experimental studies of heat fluxes through the outer walls of buildings erected in seismic areas are associated with the design features of fences - the presence of reinforced concrete elements in them: anti-seismic belts at the level of floors, cores at intersections of walls and along the edges of large window openings ... In addition, in recent years, external walls have become widespread, which are filling of bricks or aerated concrete blocks between the main structural elements of the frame - monolithic reinforced concrete columns and crossbars. The introduction of reinforced concrete elements into the structure of the external wall fencing provides strength, rigidity and stability of buildings, guarantees its seismic resistance. At the same time, reinforced concrete inclusions are significant “cold bridges” in warmer brick or aerated concrete masonry. Such heat engineering heterogeneity of earthquake-resistant outer walls significantly complicates the process of determining their heat-shielding properties. This, in turn, leads to errors in the design of heating systems, which inevitably affects the thermal comfort of the premises, the formation of condensation and mold zones in the cold zones of the inner surface of the fences. The article presents the results of theoretical and experimental studies to determine the heat-shielding properties of external heat-engineering heterogeneous walls of earthquake-resistant buildings. The most reliable method for calculating the reduced resistance to heat transfer of an inhomogeneous external structure and the coefficient of its thermal inhomogeneity have been established.
6
Zach, Jiri, Martin Sedlmajer, Jan Bubenik, and Vitezslav Novak. "Utilization of Non-Traditional Fibers for Light Weight Concrete Production." Key Engineering Materials 760 (January 2018): 231–36. http://dx.doi.org/10.4028/www.scientific.net/kem.760.231.
Повний текст джерелаАнотація:
Along with energy savings for heating and cooling, the demand for thermal insulation materials is increasing and is an attempt to achieve good thermal insulation properties for some of the construction materials. In the field of porous and lightweight concrete, this is e.g. concrete for foundations, concrete for floor constructions or flat roofs. The problem with these concrete is a relatively rapid drop in mechanical properties in reducing bulk density, with using conventional silicate binders, especially in the area below 1000 kg/m3. The paper describes the possibility of using recycled organic fibers in combination with lightweight aggregates based on foam glass for the production of porous and lightweight concrete with a good ratio of mechanical and thermal insulation properties.
7
Jeong, Young-Sun, and Hae-Kwon Jung. "Thermal Performance Analysis of Reinforced Concrete Floor Structure with Radiant Floor Heating System in Apartment Housing." Advances in Materials Science and Engineering 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/367632.
Повний текст джерелаАнотація:
The use of the resilient materials in the radiant floor heating systems of reinforced concrete floor in apartment housing is closely related to the reduction of the floor impact sound and the heating energy loss. This study examined the thermal conductivity of expanded polystyrene (EPS) foam used for the resilient material in South Korea and analysed the thermal transfer of reinforced concrete floor structure according to the thermal conductivity of the resilient materials. 82 EPS specimens were used to measure the thermal conductivity. The measured apparent density of EPS resilient materials ranged between 9.5 and 63.0 kg/m3, and the thermal conductivity ranged between 0.030 and 0.046 W/(m·K). As the density of resilient materials made of expanded polystyrene foam increases, the thermal conductivity tends to proportionately decrease. To set up reasonable thermal insulation requirements for radiant heating floor systems, the thermal properties of floor structure according to thermal insulation materials must be determined. Heat transfer simulations were performed to analyze the surface temperature, heat loss, and heat flow of floor structure with radiant heating system. As the thermal conductivity of EPS resilient material increased 1.6 times, the heat loss was of 3.4% increase.
8
Grynning, Steinar, Alessandro Nocente, Lars Gullbrekken, and Kjell Skjeggerud. "Thermal mass and thermal comfort in offices – experimental studies of a concrete floor." MATEC Web of Conferences 282 (2019): 02087. http://dx.doi.org/10.1051/matecconf/201928202087.
Повний текст джерелаАнотація:
Previous studies demonstrated that the use of thermal mass in buildings can contribute to reduce the energy demand and improve the thermal comfort. The thermal mass effect strongly depends on the properties of the materials facing the internal environment. High thermal capacity and conductivity are vital to achieve the desired effects. Concrete have both and it is a common building material. However, scientifically sound experimental studies that quantify the effects in a controlled environment are scarce. The aim is to study the effects of thermal mass on indoor environment and comfort in a quantifiable way in an extensive experimental campaign where comparative measurements were carried out in The ZEB TestCell Laboratory in Trondheim, Norway. The facility consists of two identical real-weather exposed rooms the size of a single person office. One of the rooms was constructed with a 70 mm thick concrete flooring, the other with an 18 mm wood-flooring. Free-floating temperature propagations were measured in different natural ventilation scenarios. The results showed that peak temperatures were notably reduced in the test room with the concrete flooring. During the warmest periods, a temperature peak reduction of more than 10% was found compared to the wooden-floored room.
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Al-Jadiri, Rand Salih, Manolia Abed Al-Wahab Ali, and Qais Jawad Frayyeh. "Study some Mechanical and Thermal Properties of reinforced Perlite Concrete." Key Engineering Materials 924 (June 30, 2022): 233–42. http://dx.doi.org/10.4028/p-9os233.
Повний текст джерелаАнотація:
Expanded perlite as an aggregate in concrete may make insulating concrete and fire-resistant suitable for roof decks and other purposes. Expanded perlite aggregate (EPA) may be used with gypsum plasters and Portland cement to protect columns, beams, and external applications. Other building uses are chimney linings, under-floor insulation, ceiling tiles, gypsum boards, and roof insulation boards. The primary goal of this research is to learn more about the effects of employing perlite aggregate (EPA) as a partial or complete substitute for sand on various characteristics of expanded perlite concrete (EPC) at 7 and 28 days. Air-dry density, compressive strength, water absorption, flexural strength, and thermal conductivity are all investigated in this research. EPA replacement by volume of sand was used to create five EPC mixes with 0%, 25 %, 50 %, %, and 100%. The effects of introducing 0.5% polypropylene fiber on the characteristics of EPC mixes were investigated. To increase the EPC workability, superplasticizer was utilized, particularly at the higher EPA replacement levels. The test outcomes reveal that the measured mechanical and physical properties of EPC decrease when increasing the EPA content. Thermal insulation of EPC increases with increasing the percentage of perlite aggregate replacement. In addition, using polypropylene fibers in the EPC specimens cause a slight reduction in density, compressive strength, and thermal conductivity compared to unreinforced specimens. Polypropylene fibers significantly increase in modulus of rupture reach 29% at 28 days, and increase in water absorption compared with unreinforced specimens.
10
Fiala, Ctislav, Jaroslav Hejl, Vladimira Tomalova, Vlastimil Bilek, Tereza Pavlu, Tomáš Vlach, Martin Volf, Magdalena Novotna, and Petr Hajek. "Structural Design and Experimental Verification of Precast Columns from High Performance Concrete." Advanced Materials Research 1106 (June 2015): 110–13. http://dx.doi.org/10.4028/www.scientific.net/amr.1106.110.
Повний текст джерелаАнотація:
Paper presents some results of long-term research of a new optimized subtle precast construction system based on high performance silicate composites. The system is particularly aimed for building construction in passive or zero-energy standard. Subtle structural elements from high performance concrete (HPC) can be integrated into building envelope of energy efficient buildings with significant reduction of envelope structure and avoiding risk of thermal bridges. Significant advantages of subtle elements are material and energy savings during production, transport, manipulation and construction on building site.Paper presents experimental verification of connection between columns and beams ensured by Peikko ́s PCs corbels. Moreover, production of two prototypes of high performance fibre reinforced columns over two floors is presented. Prototypes were casted in ŽPSV a.s. plant, Litice nad Orlicí in June 2014. Complex LCA analysis of three various reinforced concrete columns was performed. Analysis covers construction life phase. Consequently, environmental impacts of assessed variants were compared and evaluated. Results show that it is possible to reduce some impacts on the environment from 16 up to 65% in comparison with common solution of reinforced concrete columns due to the utilization of excellent mechanical properties of high performance concrete that enables the design of subtle structural elements.
11
Wong, M. Bill. "Inelastic Behaviour of Concrete/Steel Composite Beam in Fire." Key Engineering Materials 340-341 (June 2007): 131–36. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.131.
Повний текст джерелаАнотація:
The configuration of a steel beam in a concrete/steel composite floor in fire gives rise to a non-uniform temperature profile across the depth of the cross-section. This temperature profile affects the deflection of the steel beam in two ways: thermal bowing due to non-uniform thermal strains and beam deflection due to imposed loads. The beam deflection becomes larger as the elastic properties of the steel beam deteriorate when the temperature is rising. The deflection increases rapidly when the cross-section of the steel beam starts to yield. This paper presents a method for the calculation of the total deflection of a steel beam in a steel/concrete composite floor in fire when the beam is loaded beyond its elastic limit. In this study, the steel beam is assumed to support the concrete floor slab simply at its ends without composite actions.
12
Amici, Carla Maria. "Unusual Examples of Sophisticated Iron Technology in the Heating Systems of Roman Imperial Baths." European Journal of Archaeology 18, no. 4 (2015): 658–78. http://dx.doi.org/10.1179/1461957115y.0000000002.
Повний текст джерелаАнотація:
In Roman imperial times, metallurgy reached a high degree of specialization and complexity. The use of iron extended even to building technology, leading to some very particular results, achieving a sophisticated mastery of the technology with a complete understanding of metal properties, in a social and economic context characterized by large financial resources and a high level of creativity applied to architectural projects. A still unpublished device was found in the construction of several floors in the Villa of Giulia, Augustus' daughter, in Ventotene (Italy). In the thermal area, the concrete floors of the bath tubs are supported by an iron grid held in place by vertical iron posts strongly fixed in the underfloor, allowing both widespread hot air circulation and support for superimposed loads. A curvilinear metal grid supported by metal hooks was also used to obtain a tile-line vault, creating an interspace for the circulation of hot air in calidaria; a careful analysis of the remains of two vaulted systems in Villa Adriana, Tivoli (Italy), allows a clear reconstruction of this device. The building process was difficult and complex, requiring careful planning and great accuracy in execution. However, after nearly a century of experimentation, it is possible to propose the hanging ceiling built over the calidarium of the Baths of Caracalla in Rome as the most imposing example of the grid system ever realized.
13
de Silva, Donatella, Naveed Alam, Ali Nadjai, Emidio Nigro, and Faris Ali. "Finite Element Modelling for Structural Performance of Slim Floors in Fire and Influence of Protection Materials." Applied Sciences 11, no. 23 (November 29, 2021): 11291. http://dx.doi.org/10.3390/app112311291.
Повний текст джерелаАнотація:
Slim floor systems are very common nowadays and various types are currently being used for the construction of high-rise buildings and car parks. Concrete in slim floor beams encases the steel beam section which helps to improve their fire resistance. Despite their higher fire resistance, several fire protection materials like intumescent coatings are often used to achieve a higher fire resistance where desired. The thermal properties and behaviour of various intumescent coating materials were previously studied through experimental investigations. This paper presents finite element analyses to simulate the response of unprotected and protected slim floor beams in fire using different simulation tools. For this purpose, fire tests conducted on unprotected slim floor beams and intumescent coating materials are modelled using research and commercial software. Results from the analyses are compared and verified with the available test data. These validated models are later combined to study the behaviour of protected slim floor beams in fire. Results from the study show that the research and the commercial software replicate the behaviour of slim floor beams and protection materials with good accuracy. Due to the presence of the intumescent coating, the protected slim floor beams displayed a better fire resistance as the temperature of the steel part remained below 400 °C even after 60-min of standard heating. The protected slim floor beams continued to support the external loads even after 120 min of heating.
14
Huang, Zhenyu, Fang Wang, Yingwu Zhou, Lili Sui, Padmaja Krishnan, and Jat-Yuen Richard Liew. "A Novel, Multifunctional, Floatable, Lightweight Cement Composite: Development and Properties." Materials 11, no. 10 (October 19, 2018): 2043. http://dx.doi.org/10.3390/ma11102043.
Повний текст джерелаАнотація:
This paper presents the development of a novel, multifunctional, floatable, lightweight cement composite (FLCC) using three different types of glass microspheres for structural engineering applications. Eight different mixtures of FLCC were produced and their matrix-related parameters were examined experimentally by adopting different types of microsphere fillers, fiber content (polyethylene fibers (PE)), and water-to-binder ratios. Along with the mechanical properties such as compressive, flexural, tensile strengths, and modulus of elasticity, the water tightness of the material was evaluated by sorptivity measurements and the energy efficiency by thermal conductivity. The optimal FLCC has an oven-dry density of 750 kg/m3, compressive strength (fcm) up to 41 MPa after 28-day moist curing, low thermal conductivity of 0.152 W/mK, and very low sorptivity. It is found that an optimized amount of PE fiber is beneficial for improving the tensile resistance and ductility of FLCC while a relatively large amount of microspheres can increase the entrapped air voids in the FLCC matrix and reduce its density and thermal conductivity. Microstructural analysis by scanning electron microscopy (SEM) reveals that the microspheres are distributed uniformly in the cement matrix and are subjected to triaxial compression confinement, which leads to high strength of FLCC. Segregation due to density difference of FLCC ingredients is not observed with up to 60% (by weight) of glass microspheres added. Compared to the other lightweight aggregate concretes, the proposed FLCC could be used to build floating concrete structures, insulating elements, or even load-bearing structural elements such as floor and wall panels in which self-weight is a main concern.
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Alyousef, Rayed, Omrane Benjeddou, Chokri Soussi, Mohamed Amine Khadimallah, and Malek Jedidi. "Experimental Study of New Insulation Lightweight Concrete Block Floor Based on Perlite Aggregate, Natural Sand, and Sand Obtained from Marble Waste." Advances in Materials Science and Engineering 2019 (March 3, 2019): 1–14. http://dx.doi.org/10.1155/2019/8160461.
Повний текст джерелаАнотація:
The purpose of the present study is to recover marble waste and expanded perlite aggregate (EPA) for use as an additive to cementitious matrix building materials. The main goal is to produce a new insulation block floor from lightweight concrete (LC) by mixing sand from the waste marble crushing process (SWM), natural sand, and EPA. First, optimal mixture of natural sand, SWM, and EPA was determined for a given insulation LC. To this end, plate and cubic specimens were prepared by varying the volume proportion of SWM to natural sand in percentages of 0, 20, 40, 60, 80, and 100. Mechanical and physical properties such as the compressive strength, thermal conductivity, thermal diffusivity, specific heat capacity, and sound reduction index at different frequencies were investigated. Finally, a prototype of a new insulation lightweight block floor was manufactured from the optimal mixture of the studied LC. The results showed that the incorporation of SWM significantly improved the mechanical properties and the thermal insulation of LC compared to those of the natural sand. These results are promising and give the present insulation block floor the opportunity to be used in composite slabs.
16
Valaskova, Veronika, Jozef Vlcek, and Marian Drusa. "Experimental and computational dynamic analysis of the foam concrete as a sub-base layer of the pavement structure." MATEC Web of Conferences 211 (2018): 13002. http://dx.doi.org/10.1051/matecconf/201821113002.
Повний текст джерелаАнотація:
Dynamic properties of the new materials represent the actual problem, which is solved at many departments in the world at this time. Foam concrete (FC) is a material that has wide application in the civil engineering structures. Currently, it's mainly used in the floor structures of the buildings but its usability can be much wider thanks to its specific properties. The foam concrete contains closed air pores, what achieves its low volume weight (density) and saving of material inputs. It's a building material with good mechanical properties and low thermal conductivity and at the same time with high-tech processing. Nowadays, a research aimed at the application of the foam concrete in the pavement structures takes place at the University of Zilina. Foam concrete could be utilized as a sub-base layer at the road reconstructions, excavations or as a regular layer of the new constructed pavements. The submitted paper is dedicated to the numerical simulation based on the Finite element method (FEM) in pursuance of the outputs of the experimental investigation of the dynamic effect on the pavement structure which contains the foam concrete layer. Obtained dynamic parameters will be a background for the pavement design using the foam concrete.
17
Kubenková, Kateřina, Marek Jašek, and Vladan Panovec. "Research of the Temperature Field Process in the Soil for a Home - Founded on a Foam Glass Granulate." Advanced Materials Research 1041 (October 2014): 257–60. http://dx.doi.org/10.4028/www.scientific.net/amr.1041.257.
Повний текст джерелаАнотація:
Foam glass granulate is environmentally friendly, heat-insulating building material which is made from recycled glass waste. It is a very porous material with low density, with good thermal insulation properties, high static load capacity and almost zero water absorption. The paper deals with the research of the temperature field process in the soil under the floor of a passive house built on a reinforced concrete slab foundation with a layer of compacted subsoil using raw materials friendly to the environment in the form of granules of foamed glass. This method of progressive foundation of the building addresses the elimination of thermal bridges at the base and establish a continuous thermal insulating of the building envelope without thermal bridges.
18
Keprdová, Šárka, and Jiří Bydžovský. "Possibility of Using the Technical Hemp as a Filling Component in External Thermal-Insulation Composite Systems." Advanced Materials Research 587 (November 2012): 47–51. http://dx.doi.org/10.4028/www.scientific.net/amr.587.47.
Повний текст джерелаАнотація:
Combining air or hydraulic binders with hemp shives, we can gain a set of new building materials. These products achieve excellent performance characteristics for durable, environmentally sustainable buildings. Being together, these products create natural composite building material that can be used to create insulating elements for walls, floors and roofs and also to create excellent thermal and acoustic properties of the buildings. Hemp insulation material is created by connection of technical hemp shives with a binder consisting of cement and calcium hydroxide. The production process may vary depending on whether the hemp is mineralized or not. It can be generally said that dry components should be mixed at first (binder and shives) and then water should be added. During the production, all components of insulating material must be perfectly mixed. The paper deals with the proposal and testing of new hemp insulation composites. Tests of the hemp insulation described in this paper are not typical representatives of the tests of insulation materials. Due to the doubts about the insulating properties of the proposed material, there was testing carried out in such the ways as if it was the filling material based on lightweight concretes.
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Szymczak-Graczyk, Anna. "Numerical Analysis of the Impact of Thermal Spray Insulation Solutions on Floor Loading." Applied Sciences 10, no. 3 (February 4, 2020): 1016. http://dx.doi.org/10.3390/app10031016.
Повний текст джерелаАнотація:
The paper presents the effect of considering the substrate under the floor—insulation in the form of closed-cell polyurethane spray foam, which is used for insulating surfaces particularly exposed to mechanical impact. The layer of thermal insulation was made by spraying, which prevents the occurrence of thermal bridges due to tight filling of the insulated space. It seems extremely important to adopt the appropriate material characteristics of an insulating layer. The basic thermophysical properties of polyurethane foam justifying its choice as an insulation material were the values of its thermal conductivity coefficient (0.022 W/(mK)) and density (36 kg/m3). However, what was the most important for the calculations provided in the work was to determine the stiffness of the foam subgrade so as to assess its impact on the floor load capacity. The paper includes calculations for a floor slab characterized by a static diagram, with all edges free (unfixed), loaded in strips circumferentially. The reinforced concrete slab was 6 × 6 m long, 0.25 m thick, and made of C20/25 concrete resting on an elastic substrate. Calculations were made for two variants taking into consideration two values of subgrade stiffness. The first variant concerned the subgrade stiffness for sprayed polyurethane foam insulation. On the basis of laboratory tests in situ made according to the standard procedure, its average value was assumed as K = 32,000 kN/m3. The second, comparative, computational variant included the subgrade stiffness equal to K = 50,000 kN/m3. A variation approach to the finite difference method was used for static calculations, adopting the condition for the minimum energy of elastic deformation while undergoing bending that was accumulated in the slab resting on a Winkler elastic substrate. Static calculations resulted in obtaining the values of deflections at each point of the discretization grid adopted for the slab. The obtained results have proved the necessity of calculating the floor as a layer element. For the reference substrate with the subgrade stiffness K = 50,000 kN/m3 that was adopted in the work, the value of the bending moment was 17% lower than when taking into account that there was thermal insulation under the floor slab, causing an increase in the deflection of the slab and an increase in its bending moment. If a design does not include the actual subgrade stiffness of the layer under the floor slab, it results in an understatement of the values of the bending moments on the basis of which the slab reinforcement is designed. Adherence of insufficient concrete slab reinforcement may cause subsequent damage to floor slabs.
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Gorantla, Kiran Kumar, Saboor Shaik, and Ashok Babu Talanki Puttaranga Settee. "Simulation of Various Wall and Window Glass Material for Energy Efficient Building Design." Key Engineering Materials 692 (May 2016): 9–16. http://dx.doi.org/10.4028/www.scientific.net/kem.692.9.
Повний текст джерелаАнотація:
Buildings consume huge amount of energy for forced ventilation and artificial day lighting. Use of appropriate material combinations for walls and window glass can help in reducing energy consumption for cooling and lighting. This paper presents the thermal properties of four building materials such as, laterite stone, dense concrete, burnt brick and mud brick. It also presents the experimentally measured optical properties of glass materials such as, clear glass, bronze glass, green glass and reflective. In this study building of size 5m X 5m X 3.2m with four wall materials and four glass materials were designed using design builder software. The thickness of the wall was considered as external wall with thickness 0.22m. All the walls covered with cement plaster on either side. Roof of the building is made of reinforced cement concrete and floor is dense concrete. Thermal analysis was carried out using by Energy plus software. Single sized glass windows were placed in south direction (Due to less heat gain in south direction) for Mangalore city (12.870N, 74.880E), Karnataka, India. Different window to wall ratios (20%, 40%, 60%, 80% and 100%) were maintained for buildings. Total eighty building models were investigated for heat gain into buildings. From the results, it is observed that irrespective of the window to wall ratio, mud brick walls with reflective window glass were observed to be energy efficient from the lower heat gain point of view, and laterite stone wall building with clear glass windows were observed to be the worst due to their higher heat gain values. At 60% window to wall ratio mud brick walls with reflective window glass have 24.93kWh heat gain and dense concrete walls with clear glass have 32.9 kWh heat gain. The results of the study help in establishing the best combination of wall and glass materials for minimum heat gain into buildings.
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Fontanini, Patricia Stella Pucharelli, Rosa Cristina Cecche Lintz, Luisa Andréia Gachet-Barbosa, Ana Elisabete P. G. A. Jacintho, and Lia Lorena Pimentel. "An Alternative to Paver in Living Areas of Social Interest Housing (SIH)." Advanced Materials Research 694-697 (May 2013): 2942–48. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.2942.
Повний текст джерелаАнотація:
The waste rubber from tire have been employed as aggregate in concrete due to their distinct characteristics, such as: less density, drainage properties improve thermal and acoustic isolation in construction, beyond final cost production reduced. This way, the substitution of part of natural aggregate by tire rubber, contributes to the natural aggregates preservation and offer an alternative for recycling this kind of waste. In view of these advantages, this study proposes the utilization of tire waste in projects of Social Interest Housing. The project has as mailing objective the construction of unfamiliar housing (vertical and horizontal) for low income families, searching a conciliation of sustainable development: social, environmental and economic. Social development means the worry with that low income family have a basic infrastructure; environmental development is to minimize the natural resources impact available; and economics is to offer new jobs and costs opportunities. The purpose of study the incorporation of this kind of waste in concretes used for interlocked pavers for floor to construct Social Interest Housing, aims to solve the problems of adequacy of this housings, offering a semi-rigid pavement that have a large use in landscaping for floor manufacturing, low maintenance and do not require specialist worker to their installation.
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Dovzhenko, O. A., V. V. Pohribnyi, and L. V. Karabash. "EFFECTIVE KEYED CONNECTIONS OF HOLLOW-CORE FLOOR SLABS WITH WALLS IN MODERN LARGE-PANEL HOUSE BUILDING." Science & Technique 17, no. 2 (April 13, 2018): 146–56. http://dx.doi.org/10.21122/2227-1031-2018-17-2-146-156.
Повний текст джерелаАнотація:
The paper considers large-panel constructive system of multi-storey buildings and its industrial basis creates conditions for intensive volume growth in house construction. Application of hollow-core panels are recommended as floor slabs that allows to increase a distance between bearing walls, to improve planning solutions, and also significantly to increase thermal and sound protection properties of floor discs (coatings). Keyed joints having the highest resistance to shearing forces are used to ensure joint action of the slabs with wall panels. A supporting unit of floor elements in the precast-monolithic constructive system ARKOS by means of concrete keys is considered as a prototype of the considered joint. In order to increase a bearing capacity and improve reliability of joints it is envisaged to reinforce keys with space frames. Improvement of joint units is possible to carry out with due account of total number of the factors influencing on strength. Poltava National Technical University named after Yuri Kondratyuk has developed a general methodology for assessment of bearing capacity in keyed joints which is based on the variational method in the theory of concrete plasticity and reflects specificity of stress-strain state of the failure zone. For experimental verification of this methodology investigations have been carried out with the purpose to test operation of keys when they are reinforced in mid-height and reinforcement is distributed in two tiers. The observed experimental fracture pattern in the specimens has confirmed kinematic schemes accepted for calculations and comparative analysis of experimental and theoretical values points to their closeness. Two-level reinforcement significantly improves plastic properties of concrete keys and excludes brittle failure. The proposed design of the joint unit for floor slabs with wall panels is characterized by the ratio of key dimensions and shape of reinforcing cages in the form of hollow cylinders which ensure higher strength and seismic resistance of a joint.
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Fiala, Ctislav, Jaroslav Hejl, Vlastimil Bílek, Jan Růžička, Tomáš Vlach, Magdaléna Novotná, and Petr Hájek. "Experimental Verification of Subtle Frame Components Prototypes from High Performance Concrete for Energy Efficient Buildings." Solid State Phenomena 249 (April 2016): 301–6. http://dx.doi.org/10.4028/www.scientific.net/ssp.249.301.
Повний текст джерелаАнотація:
Mechanical properties of high performance concrete (HPC) enable design of subtle structural elements. Subtle HPC frame concept comes from the effort to integrate load bearing elements into building envelope in order to reduce risks of thermal bridges. Substantial advantages of subtle structural elements are material and energy savings during production, transportation, manipulation and assembling. Paper presents preparation and implementation of construction of experimental frame at University Centre UCEEB in Buštěhrad. Individual structural elements were made in prefa plant ŽPSV a.s. in Litice nad Orlicí. Construction of frame prototype is the result of long term research when the vertical and horizontal structural elements and their connections were successively designed and experimentally verified. This article shows experimental results of horizontal load bearing structures - floor panels and beams - in detail. Samples were tested by four-point bending test and also creep of floor panels was measured. Accomplished calculations, experimental verification and analysis have showed that subtle HPC frame is the effective solution from reliability aspects as well as from environmental and economical parameters. Minimal columns cross sections enable their complete implementation into building envelope and they also contribute to high quality architectonic solution of buildings interiors.
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HLADYSHEV, Hennadii, and Dmytro HLADYSHEV. "DETERMINATION OF THE ZONE OF THERMAL INFLUENCE OF FIRE BY RESULTS INSPECTION OF FLOOR STRUCTURES." Building constructions. Theory and Practice, no. 10 (June 27, 2022): 32–41. http://dx.doi.org/10.32347/2522-4182.10.2022.32-41.
Повний текст джерелаАнотація:
The results of the study of the technical condition of 14 round-hollow slabs according to the series II-03-02 within the basement of two entrances of a residential building after a fire, lasting about 8 hours. More than 40 years passed from the commissioning of the building to the fire, and all this time the basement slabs were in a non-aggressive environment, but with high relative humidity, which had a positive effect on increasing the concrete strength of typical slabs. Inspection of slabs in adjacent rooms for a long time of operation did not reveal significant defects from their humidification and insufficient thermal insulation properties of the floor above the basement.
In the inspection area, some floor slabs above the basement were found to be defective due to high temperatures, which reduced their rigidity.
The information obtained from the survey is necessary to perform verification calculations to determine the load-bearing capacity and stiffness of the floor slabs and compare them with the data from the survey results. The data of test calculations are also needed to substantiate the need for reinforcement work on the slabs, to ensure their further normal operation on the operating loads on the ground floor.
To analyze the impact on the deflections of slabs of constant and payloads, some of their actions are considered and verified calculations of the deflections of the floor slabs for the four adopted separate stable modes of normal operation.
A histogram of the change in the actual deflections of the floor slabs above the basement is constructed, according to the analysis of which the area with the largest deflections is clearly traced, which indicates the location of the highest temperatures in this place. That is, the level of vertical deformations of floor slabs can determine the relative temperature distribution within them. Deflections of slabs due to high temperatures should be considered as damage that interferes with normal operation and significantly reduces the durability of slabs.
Considered after the fire condition of the slabs showed that in the absence of impact on them payloads, the obtained additional temperature deflections are greater than the calculated, which are obtained by verification calculations for the action of full operating loads.
Also offered different options for strengthening both the slabs themselves and the seams between them, for their joint work on different combinations of loads.
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Mohammad, Mastali, Kinnunen Paivo, Karhu Marjaana, Abdollahnejad Zahra, Korat Lidija, Ducman Vilma, Alzaza Ahmad, and Illikainen Mirja. "Impacts of Casting Scales and Harsh Conditions on the Thermal, Acoustic, and Mechanical Properties of Indoor Acoustic Panels Made with Fiber-Reinforced Alkali-Activated Slag Foam Concretes." Materials 12, no. 5 (March 11, 2019): 825. http://dx.doi.org/10.3390/ma12050825.
Повний текст джерелаАнотація:
This paper presents experimental results regarding the efficiency of using acoustic panels made with fiber-reinforced alkali-activated slag foam concrete containing lightweight recycled aggregates produced by using Petrit-T (tunnel kiln slag). In the first stage, 72 acoustic panels with dimension 500 × 500 × 35 mm were cast and prepared. The mechanical properties of the panels were then assessed in terms of their compressive and flexural strengths. Moreover, the durability properties of acoustic panels were studied using harsh conditions (freeze/thaw and carbonation tests). The efficiency of the lightweight panels was also assessed in terms of thermal properties. In the second stage, 50 acoustic panels were used to cover the floor area in a reverberation room. The acoustic absorption in diffuse field conditions was measured, and the interrupted random noise source method was used to record the sound pressure decay rate over time. Moreover, the acoustic properties of the panels were separately assessed by impedance tubes and airflow resistivity measurements. The recorded results from these two sound absorption evaluations were compared. Additionally, a comparative study was presented on the results of impedance tube measurements to compare the influence of casting volumes (large and small scales) on the sound absorption of the acoustic panels. In the last stage, a comparative study was implemented to clarify the effects of harsh conditions on the sound absorption of the acoustic panels. The results showed that casting scale had great impacts on the mechanical and physical properties. Additionally, it was revealed that harsh conditions improved the sound properties of acoustic panels due to their effects on the porous structure of materials.
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Volk, R., J. J. Steins, P. Stemmermann, and F. Schultmann. "Comparison of different post-demolition autoclaved aerated concrete (AAC) recycling options." IOP Conference Series: Earth and Environmental Science 1078, no. 1 (September 1, 2022): 012074. http://dx.doi.org/10.1088/1755-1315/1078/1/012074.
Повний текст джерелаАнотація:
Abstract Autoclaved aerated concrete (AAC) is used as masonry blocks and prefabricated reinforced elements preferably in residential buildings. Due to its porous structure and mineral composition, it combines low thermal conductivity and fire resistance properties. Consequently, the popularity of AAC increases. However, due to significant AAC production volumes in many European countries since the 1960s and 1970s and given building lifetimes, strongly increasing post-demolition AAC waste volumes can be expected in the following decades. Recycling these post-demolition AAC wastes could protect primary resources and landfill capacities and reduce greenhouse gas emissions. But, recycling of post-demolition AAC is not yet established. The majority of the waste is landfilled even though landfill capacities have decreased and the legal framework conditions in Europe regarding a circular economy are becoming stricter. Therefore, new recycling options are needed. Current research approaches propose different open-loop recycling routes for post-demolition AAC, e.g. lightweight aggregate concrete, lightweight mortar, no-fines concrete, floor screed, animal bedding, oil- and chemical binders, and insulating fills for voids and interstitial spaces. Additionally, closed-loop recycling is possible and under research. Finely ground post-demolition AAC powder can be directly used in AAC production or can be chemically converted to belite (C2S) clinker to substitute primary cement in AAC production. These promising recycling options are compared regarding environmental and economic aspects. We find that the resource consumption is lower in all recycling options since post-demolition AAC helps to save primary resources. Furthermore, greenhouse gas emissions associated with the substituted primary resources are saved - especially when substituting primary cement in closed-loop recycling. In economic terms, increasing landfill costs could be avoided, which leaves a considerable margin for the cost of pre-processing, transport and recycling. The results can help decision-makers to implement circular management for AAC by fostering post-demolition AAC recycling and reducing its landfilling.
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Baglivo, Cristina, Paolo Congedo, and Delia D’Agostino. "Multi-Objective Analysis for the Optimization of a High Performance Slab-on- Ground Floor in a Warm Climate." Energies 11, no. 11 (November 1, 2018): 2988. http://dx.doi.org/10.3390/en11112988.
Повний текст джерелаАнотація:
The building sector is responsible for a large part of the overall energy demand in Europe. Energy consumption may be reduced at the design stage by selecting the proper building elements. This study develops a multi-objective analysis for a highly efficient slab-on-ground floor, whose design is optimized for a warm climate. Possible floor configurations have been obtained using the software tools modeFRONTIER, for the multi-objective analysis, and MATLAB, for the computational code. To proceed with the optimization of the different floor layers, a dataset has been developed for several materials in relation to a number of parameters: thermo-physical properties, eco-sustainability score according to the ITACA Protocol, costs, source, and structural features. Results highlight how a high surface mass is preferable when guaranteed by concrete in the innermost and outermost layers. Furthermore, insulating materials are better placed in the middle layers, with the insulating and synthetic materials adjacent to the ground and insulating and natural materials adjacent to the floor. Results emphasize the importance of thermal transmittance close to the Italian regulation limit (0.38 W/m2 K) in the climatic zone C, to allow an adequate exchange with the ground in summer, avoiding overheating. The outcomes show that the obtained slab-on-ground floor configurations favor the use of local, recyclable, sustainable, and eco-friendly materials, which is in line with energy policies and sustainability protocols. The paper supports the decision making process that takes many variables into account at the building design stage.
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Hossain, K. M. A., and M. Lachemi. "Thermal Conductivity and Acoustic Performance of Volcanic Pumice Based Composites." Materials Science Forum 480-481 (March 2005): 611–16. http://dx.doi.org/10.4028/www.scientific.net/msf.480-481.611.
Повний текст джерелаАнотація:
Volcanic Pumice (VP) is found abundantly in various parts of the world. In this study, VP from East New Britain province of Papua New Guinea is investigated and assessed for its industrial utilization. The manufacturing of heat-insulating lightweight concrete, building blocks or composites using VP is of prime importance as an energy saver. The utilization of VP as a heatinsulating material is tested and the results are found to satisfy the ASTM requirements. This fact suggests that VP could be utilized in the manufacture of composite building blocks or concrete. Acoustic performance of composite building floors with lightweight volcanic pumice concrete (VPC) is also described based on the performance of normal concrete (NC) and Code based requirements. The performance of VPC and NC composite floors is judged based on Sound Transmission Class (STC) or Impact Insulation Class (IIC) values. VPC composite floors exhibit better acoustic performance than their NC counterparts and seem to achieve the requirements of Codes of various countries.
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Maraveas, Chrysanthos. "Fire resistance of DELTABEAM® composite beams: a numerical investigation." Journal of Structural Fire Engineering 8, no. 4 (December 11, 2017): 338–53. http://dx.doi.org/10.1108/jsfe-05-2016-0003.
Повний текст джерелаАнотація:
Purpose The DELTA® beam composite floor system is a recently developed shallow floor type that has seen many applications in contemporary construction. It involves partially encasing DELTA® steel beams in concrete, with the lower flange remaining exposed. Besides the satisfactory behavior of the system at ambient conditions, understanding its response under elevated temperatures is critical in evaluating its overall performance. Despite certification from the manufacturing company that the system has adequate fire resistance, its behavior under fire conditions has neither been investigated to depth nor reported in detail. The purpose of this paper is the detailed numerical investigation of their behavior in fire. For this reason, the finite element method was implemented in this paper to simulate the response of such beams subjected to fire. Material properties were modeled according to the Eurocodes. The coupled thermal-structural parametric analyses involved four different variations of the “shortest” and “deepest” cross-section (eight case studies in total) specified by the manufacturing company. Other simulations of these cross-sections, in which either the thermal expansion or the structural load were not taken into account, were carried out for comparison purposes. Design/methodology/approach The methodology for simulating such systems, which has been successfully implemented and validated against fire test results elsewhere (Maraveas et al., 2012) was also followed here. To investigate the statement made by Maraveas et al. (2014) and the equations proposed by Zaharia and Franssen (2012) that the insulation is not so effective for “short” cross-sections, two beams, one with a D20-200 (Deltabeam Technical Manual, 2013) cross-section (shallowest section) and one with a D50-600 (Deltabeam Technical Manual, 2013) cross-section (deepest section), were simulated in this paper for comparison purposes. Additionally, reasonable assumptions were made for the cross-sectional dimensions not specified by the manufacturer (Deltabeam Technical Manual, 2013) and parametric analyses were carried out to investigate their effect on the structural response of the system. Findings Composite DELTA® beams can achieve fire resistances ranging from 120 to 180 min, depending on the depth and geometry of their cross-section, with deeper sections displaying a better fire response. The intense thermal bowing that occurs when these beams are heated from below has a more pronounced effect, in terms of thermally induced deflections for deeper sections. The satisfactory fire resistance of these beams is achieved due to the action of the concrete encased web and the reinforcement which compensate for the loss of the exposed lower flange. Increasing the thickness of the web in deeper sections improves their fire rating up to 180 min. The thickness of the lower flange affects the fire rating of the beams only in a minor way. Practical/implications The paper describes a numerical methodology to estimate the fire resistance of complex flooring systems.
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Wang, Yudi, and Guoqiang Xu. "Numerical Simulation of Thermal Storage Performance of Different Concrete Floors." Sustainability 14, no. 19 (October 8, 2022): 12833. http://dx.doi.org/10.3390/su141912833.
Повний текст джерелаАнотація:
To improve the utilization rate of energy, the consumption of fossil energy must be reduced. In this study, a low-temperature radiant floor made of concrete is taken as the research object, and a two-dimensional low-temperature hot water radiant heating system with different concrete filling layers is numerically simulated using a computational fluid dynamics (CFD) software and finite element method. In this numerical model, a concrete sensible heat storage (SHTES) is adopted, while various types of concrete materials have been used to preliminarily analyze the influence of different concrete types on floor heat storage. The simulation results were further analyzed to determine the total heat storage during the heating period and the total heat storage and heat storage rate during the stable operation stage. The results demonstrate that the thermal conductivity coefficient of concrete floors had the most significant influence on the heat storage effect, with slag concrete demonstrating the most prominent heat storage effect. The total heat storage capacity of slag concrete after 7 h was 848.512 J. Overall, this study proposes a method to enhance the heat storage capacity of low-temperature radiant floors, while providing a design method for future solar energy storages and floor heat storages.
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Huang, Zhu Ye, Qian Wu, and Min Gui Wu. "Thermal Isolation Character of Reinforced Concrete Hollow Floor." Applied Mechanics and Materials 638-640 (September 2014): 300–303. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.300.
Повний текст джерелаАнотація:
Reinforced Concrete Hollow floor system was named by its typical inner core and worked as an excellent horizontal bearing structure. It has fine mechanical ability and good thermal isolation character. The author compared reinforced concrete hollow floors and traditional reinforced concrete floor. And studied their development in long span or large loaded building.
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Bedi, Raman, Rakesh Chandra, and S. P. Singh. "Mechanical Properties of Polymer Concrete." Journal of Composites 2013 (December 29, 2013): 1–12. http://dx.doi.org/10.1155/2013/948745.
Повний текст джерелаАнотація:
Polymer concrete was introduced in the late 1950s and became well known in the 1970s for its use in repair, thin overlays and floors, and precast components. Because of its properties like high compressive strength, fast curing, high specific strength, and resistance to chemical attacks polymer concrete has found application in very specialized domains. Simultaneously these materials have been used in machine construction also where the vibration damping property of polymer concrete has been exploited. This review deals with the efforts of various researchers in selection of ingredients, processing parameters, curing conditions, and their effects on the mechanical properties of the resulting material.
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Kornilov, Terentii, Petr Fedotov, and Aleksandr Nikiforov. "Evaluation of the effectiveness of additional thermal insulation of the basement floor of frame-monolithic buildings in extreme operating conditions." E3S Web of Conferences 263 (2021): 04041. http://dx.doi.org/10.1051/e3sconf/202126304041.
Повний текст джерелаАнотація:
The issues of saving energy resources are of particular relevance for the regions of Russia with an extremely cold climate. The increased air pressure difference in winter and the presence of volumetric cold bridges in the form of pile and column grillages, basement slabs and concrete block masonry often leads to a violation of the temperature regime of the first floors of multi-storey buildings with a monolithic reinforced concrete frame. Thermal analysis of fragments of basement floors in areas with columns and grillages with additional thermal insulation from the outside was carried out. The low efficiency of the external thermal insulation of the basement elements of the operated frame-monolithic buildings is shown.
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Tůmová, Eva, Lenka Mészárosová, and Rostislav Drochytka. "The Effect of Additives on the Properties of Lightweight Concrete Screed." Advanced Materials Research 1100 (April 2015): 170–73. http://dx.doi.org/10.4028/www.scientific.net/amr.1100.170.
Повний текст джерелаАнотація:
This contribution deals with the effect of additives on the properties of concrete screed. The main field, where are the additives studied in this entry, is the field of lightweight concrete screeds for industrial floors.
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Liu, Pei, Hai-Xin Zhu, Babak Moaveni, Wei-Guo Yang, and Shu-Qiang Huang. "Vibration Monitoring of Two Long-Span Floors Equipped with Tuned Mass Dampers." International Journal of Structural Stability and Dynamics 19, no. 09 (August 28, 2019): 1950101. http://dx.doi.org/10.1142/s0219455419501013.
Повний текст джерелаАнотація:
This paper presents the field tests and vibration performance assessment of two long-span floors with tuned mass dampers (TMDs). The floors considered are made of steel beams and concrete slabs, as part of a gymnasium with composite floors spanning 36 m in each direction and equipped with 30 TMDs. Operational modal analysis based on ambient acceleration measurements is performed to extract the modal parameters of the floors. Ambient vibration tests were conducted at three stages of construction for each floor, namely (i) after the concrete slab was completed, (ii) after one layer over the concrete slab was added, and (iii) after the flooring (surfacing) was fully finished. The effects of the layers making up the flooring system and of the TMDs on the dynamic properties of the floors are studied. The finite element models of the floors are validated using the identified modal parameters. The effects of natural frequency of TMDs on the dynamic properties of the floors are investigated using the validated model. Finally, the effects of flooring on the vibration serviceability of the two floors are studied with TMDs in operation, when the floors were subjected to crowd-induced rhythmic loading, from which the efficiency of TMDs is assessed numerically. The results show that the coupled vibrations of the two floors with TMDs turned off occur in the first two modes, while the natural frequencies of the floors decrease with the addition of layers. The TMDs in operation break the first mode of the floor into two modes with similar mode shapes, resulting in smaller vibration response and larger damping ratios, which vary with the natural frequency of TMDs. Also, the wood flooring significantly increases the human-induced vibration of the floor, while the plastic flooring shows basically no effect.
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Žiogas, Vigantas, and Svajūnas Juočiūnas. "DESIGN AND INSTALLATION PECULIARITIES OF MONOLITHIC CONCRETE FLOOR." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 11, no. 2 (June 30, 2005): 153–62. http://dx.doi.org/10.3846/13923730.2005.9636345.
Повний текст джерелаАнотація:
Monolithic concrete floors are frequently designed as plain concrete slabs. The purpose of the plain concrete floor is to transmit loading from its source to the subgrade with minimal distress. The magnitude of these stresses depends on factors such as the subgrade strength, solution of construction, the quality of construction, the magnitude and character of loads. Here is presented the joint spacing for various construction solutions of concrete floor. In practice, joint spacing should be corrected by evaluating rheological properties of concrete mix, type of aggregate, its volumetric concentration and impurity. The direct expenditures of main construction layers were investigated and used for optimization the technologies installation of monolithic concrete floors. The initial data for evaluating the multiple criteria were calculated by estimating the real and practical characteristics, which are represented in this paper. Multiple criteria complex proportional evaluation is used to find a rational decision installation of monolithic concrete floors.
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Sinha, Dr Deepa A. "Thermal Properties of Concrete." Paripex - Indian Journal Of Research 3, no. 2 (January 15, 2012): 90–91. http://dx.doi.org/10.15373/22501991/feb2014/27.
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Wegener, Konrad, and Atsushi Matsubara. "Special Issue on Advanced Material Driven Design of Machine Tools." International Journal of Automation Technology 14, no. 2 (March 5, 2020): 261–63. http://dx.doi.org/10.20965/ijat.2020.p0261.
Повний текст джерелаАнотація:
The design of machine tools strongly depends on the materials chosen. Increasing requirements on machine tools require the joint optimization of material and design and thus also drive the development of new materials in this field. Digital technologies finally creating a digital shadow of the machine in development also enable the required co-development taking into consideration dynamic, thermal and long term influences and behavior, enabling state and health monitoring to increase the performance of the machine tool to the maximum possible. The choice of material for the different components of machine tools is today even more difficult than ever. The recent review paper by Möhring et al. [1] sheds light on the vast field of properties and decision opportunities of combining materials at hand with design features. In former times, cast iron was the predominant material for machine bodies and has left its footprints on the design of machine tool bodies lasting still up to now. Because massive machine bodies have been the wealth of good properties, high accuracy, stiffness, good material damping properties have been attributed to cast iron design, then with increasing strength requirements higher strength cast irons came into fashion having much less material damping and finally lead to welded frames. Today requirements of dynamics and thermal behavior change the scene again. The goal is to achieve high productivity with high accuracy, which typically is a contradiction. But increasing dynamics requires distinguishing between moving bodies and their non-moving counterparts, and opens the floor for multimaterial design. For moving parts, which have to move with high dynamics meaning, high speed, high acceleration, high jerk, light weight design prevailed with the utilization of standard materials. Because manufacturability plays a major role, the bionic structures have to be degraded to thin walled rib structures as demonstrated in Fig. 1, while in future additive manufacturing will remove that restriction and enable some real bionic structures. Furthermore material choice has a huge impact on inertia savings which opens the door for CFRP, which becomes especially interesting, when the anisotropy of this material is exploited as shown in Fig. 2. From the manufacturability truss structures then result shown in Fig. 3. For the nonmoving elements, the base body, cast iron, welded steel, polymer cast, and concrete are typical materials chosen. Also aluminium structures are discussed despite the fact that aluminium has only one third of the stiffness of steel, but it offers much better thermal conductivity equalizing temperature differences faster and thus reduces the warp of the structure, which typically causes larger errors than an isotropic thermal expansion. For the choice of materials no generalizable guideline exists. The question which material is the better choice is not answerable in generality, because design follows material, which means that a sound comparison requires completely new design approaches for the different materials, where the difference between metal and polymer concrete or CFRP is really large, offering different potentials. As an example, a design of a fast moving bridge of a gantry machine might be considered. The guiding of a support on this bridge with roller guidings imposes severe problems to the design due to the material mix and different thermal expansion coefficients. Thus the choice of CFRP for the bridge necessarily must be followed up by a decision of the guiding principle, where in this case aerostatic bearings were considered as the most promising possibility. Also the potentials for function integration into the material are of major interest for the material choice, as this is easily possible for low temperature castings like for mineral cast, CFRP, or concrete. This integration of functionalities actually is a fairly new approach and relates again the machine body design to inspiration from biology, as for instance trees or leaves are from the point of view of materials weaker than our technical materials, but have a fine integration of functionalities as transmittance of information and nourriture. Sensor integration opens the field for “feeling machines” also inspired from biology, which enables the machine to detect its embedding environment and react accordingly. Cheap and miniaturized sensors are on the other side the developments that enable this approach of machine design. In the age of compensation, Industrie 4.0 and biological transformation, this functional integration will have a huge impact on material choice. Also in terms of thermal issues in machine tools, the material choice plays a major role, as thermal elongation is a physical property which is influenced by material choice. A much larger influence comes from design as indicated already above. With growing importance of compensation besides sensor integration, especially the thermal linearity and reproducibility are of crucial importance, which makes multi material design a non-trivial design task. The discussion on the superiority of thermally fast reacting machines or thermally slow reacting machines has not come to an end yet. Problematic are machines composed of components that react fast and those that react slow. A major step in that direction is the discovery of thermal resonances in [5], which shows that temperature change frequencies can depending on the machine design lead to higher or lower thermal displacements of the TCP and therefore need to be taken into account in the design phase and are significantly influenced by the choice of materials. Restrictions and influences are also coming from the process a machine tool has to enable. The material choice must take into account the influence of different media as for instance the metal working fluids as well as the debris like hot chips etc. The aforementioned discussion is mainly a discussion of main structural parts of machine tools. It must be pointed out that a machine tool is more than the sum of its structural elements, as also covers, which typically get forgotten in all academic discussion of behaviors of machine tools, but are significant for the influence of the environment on the machine tool. Also here the material choice plays a major role. Finally material choice to a large extent decides on the costs of a machine tool, but due to the huge amount of influence factors a sound fact based decision requires a nearly full design elaboration of various material choices and the summation of costs at the end of this process. This special issue with its various individual papers elucidates different aspects of the influence of materials on the design of machine tools without being capable of offering clear rules for material choice. ===danraku===1) Isolating material to exclude environmental influences on machine tools is proposed. ===danraku===2) A new guiding system with rollers and sliding guidings is proposed and the different materials for the sliding part are investigated. ===danraku===3) Gears from bamboo fibres are proposed and the manufacturability as well as their performance are discussed. The gears offer great advantages from the environmental point of view. ===danraku===4) CFRP for spindle shafts is evaluated and CFRP spindles are compared with steel spindles within the same geometric boundary conditions. The performance increase in compliance and thermal stability is significant. ===danraku===5) A topological optimization of a grinding machine tool structure is presented and showed drastically increased performance. The difficulty to transfer it to a mass producible machine tool structure is pointed out. ===danraku===6) A design of a CFRP ram for a high speed stamping press is presented and testing procedures to ensure the ability of the ram to withstand billions of impacts are designed and carried out. ===danraku===7) CFRP can beneficially applied for the cutting tool structure and besides enhancing dynamics in terms of mass and damping the material also is a valuable basis for smart tools. There are good arguments for each of the materials, which cover the whole scope of machine tool functionality: manufacturability, stiffness, strength, specific mass, thermal properties, function integrability, reproducibility, availability, environmental friendliness, and costs.
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Szymanowski, Jacek. "Evaluation of the Adhesion between Overlays and Substrates in Concrete Floors: Literature Survey, Recent Non-Destructive and Semi-Destructive Testing Methods, and Research Gaps." Buildings 9, no. 9 (September 11, 2019): 203. http://dx.doi.org/10.3390/buildings9090203.
Повний текст джерелаАнотація:
Non-destructive testing (NDT) and semi-destructive testing (SDT) have recently been more frequently used for the evaluation and condition assessment of concrete floors in various types of buildings. The subject of the article is to briefly introduce the reader to the problem of adhesion between overlays and substrates in concrete floors and to illustrate the current state of knowledge on the subject. The aim of this paper was to briefly describe the recently used non-destructive and semi-destructive testing methods and the parameters useful for characterizing the adhesion between overlays and substrates in concrete floors, as well as the methods useful to characterize the functional properties of the overlays. A recent literature survey, related to the adhesion between the overlays and substrates in concrete floors, is thus shown. Special emphasis was placed on the critical review of the current research results. Based on the analysis of the literature review, research gaps have been presented in order to highlight future research directions.
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Čajka, Radim, Martina Smirakova, and Pavlina Matečková. "Frequent Failures of FRC Industrial Floors." Key Engineering Materials 738 (June 2017): 217–26. http://dx.doi.org/10.4028/www.scientific.net/kem.738.217.
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Floors in industrial buildings are often loaded with heavy traffic or stored material. For this reason floors are often created by fiber-reinforced concrete. Fibers contribute to larger impact - or abrasion resistance. The issue of design of fiber concrete slabs is quite complicated. Poorly designed layer structure under slabs or poorly subsoil can have very important effect of result properties and create the first group of source of problem. The second group of causes of problems is real implementation of concrete slab primarily the amount of fibers and correct and even placement. If amount or placement of fibers are incorrectly then significant failure can arise. This paper deals with frequently failures of FRC floors in practice. It will be described several buildings in which were fiber concrete slab constructed and where some failure arose. It will be presented what kind and what range of failure arose. Causes of failures will be also described in this paper. Also possible solution of problem will be designed if it exist.
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Ivanov, A. N., and М. А. Тrеmbitskiy. "Foam concrete of certain average density for thermal insulation of attic floors." Magazine of civil engineering 26, no. 8 (December 24, 2011): 19–24. http://dx.doi.org/10.5862/mce.26.3.
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Song, Jianbin, Haibin Hu, Mingxin Zhang, Biao Huang, and Zhanhui Yuan. "Thermal aging properties and electric heating behaviors of carbon fiber paper-based electric heating wood floors." BioResources 12, no. 4 (October 31, 2017): 9466–75. http://dx.doi.org/10.15376/biores.12.4.9466-9475.
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Carbon fiber (CF) paper is an excellent material for use in electric heating wood floors systems. In this paper, a CF paper-based electric heating wood floor was prepared using a hot pressure process. The thermal aging properties and electric heating behaviors of the CF paper-based wood floors were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and a temperature recorder. The CF paper exhibited excellent thermal stability, and its structure and morphology did not show any changes after exposure to 110 °C for 15 h. The surface temperature of the CF paper increased as input voltage increased. The positioning of CF paper in the middle of wood floors was believed to be the optimum design for electric heating wood floors. Theoretical calculations showed that the CF paper based electric heating wood floors (1.1 m2) could increase room (3 m × 4 m × 2.6 m) temperature by 12.9 °C.
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Kovalov, Andrіі, Volodymyr Konoval, Anastasiia Khmyrova, and Kateryna Dudko. "Parameters for simulation of the thermal state and fire-resistant quality of hollow-core floors used in the mining industry." E3S Web of Conferences 123 (2019): 01022. http://dx.doi.org/10.1051/e3sconf/201912301022.
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The statistical data of the fire and technogenic safety in Ukrainian mines have been studied. A literary analysis has been made of advanced expertise in determining the fire resistance of building structures. It has been studied the thermal state and fire resistance of hollow-core floors using the fire tests and the calculated determination of the fire resistance degree of a structure based on a two-dimensional model of thermal conductivity and convective heat transfer implemented in the ANSYS R17.1 software complex. The fire test of hollow-core floor has been analysed and the use of a computational-experimental method is proposed to determine the parameters when simulating the thermal state and the fire resistance of both protected and unprotected hollow-core floors. A technique has been developed for simulating the thermal state and the fire resistance of hollow-core floors, which can be used in assessment of the fire resistance degree of reinforced concrete building structures both in industrial construction and in the mining industry.
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Gajzler, Marcin. "SUPPORTING OF REPAIRS PROCESSES OF CONCRETE INDUSTRIAL FLOORS." Engineering Structures and Technologies 8, no. 1 (April 17, 2016): 8–14. http://dx.doi.org/10.3846/2029882x.2016.1171954.
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In the large-scale facilities, including on-site storage or shopping malls, floor plays an important role. It has to meet special requirements regarding mechanical properties, aesthetics and durability. Despite much effort, both in the design and execution phase, cases of damage of the floor happens, causing some specific consequences – often associated with restrictions on use. In such a situation it is required to perform rapid diagnosis and effective repair. One possibility foster this process is the use of advisory system which operates in terms of material and technological solutions. The article points out the limitations resulting from the use of advisory system related to situations of individual and unique damage. In the case of such damage it is necessary to implement research procedures and the use of advisory system turns out to be ineffective.
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Meng, Xi, Junfei Du, Yating Wang, and Yanna Gao. "Thermal performance optimization of building floors under air-conditioning intermittent operation by numerical simulation." Journal of Building Physics 43, no. 2 (March 6, 2019): 99–120. http://dx.doi.org/10.1177/1744259119833401.
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Under air-conditioning intermittent operation, there may be the large difference of air temperatures in two adjacent rooms due to different operation behavior, and thereby, interior envelops may cause great heat loss. Under this condition, floors may become the most vulnerable spot of the room heat preservation due to their large proportion in interior envelops and poor thermal insulation. To optimize the thermal performance of floors, three floor models were built to compare their thermal performance characteristics under air-conditioning intermittent operation, while a heat transfer model was built by the finite volume method and verified by experimental data. The results showed that an expanded polystyrene layer located close to the upper surface can improve the thermal performance of the bottom floor, while the continuous integration of an air space ceiling placed close to the lower surface can improve the thermal performance of the top floor obviously. The daily cooling load formed by the cast-in-place-reinforced concrete floor integrated with the expanded polystyrene layer and the air space ceiling can reduce the daily cooling load by 53.27% and 47.00%, compared with the cast-in-place-reinforced concrete floor and the cast-in-place-reinforced concrete floor only integrated with the expanded polystyrene layer.
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Fangrat, J. "Combustability of building products versus fire safety." Bulletin of the Polish Academy of Sciences Technical Sciences 64, no. 4 (December 1, 2016): 709–17. http://dx.doi.org/10.1515/bpasts-2016-0080.
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Abstract The combustion process is described and analysed based on the experimental results in the context of building fire safety. Data are obtained by means of five standard methods: ISO 5657 ignitability test, ISO 5657 cone calorimeter, ISO 9705 room corner test, EN ISO 1716 small calorimeter, and EN ISO 1182 small furnace. Various categories of building products were tested: cellulose based products (particle boards, plywoods), solid wood, floor coverings, concrete, ceramics, insulations (thermal and/or acoustic), boards (wall/ceiling), mortars, adhesives, and thin coatings. The studied products exhibited very different fire properties from non-combustible to easily combustible. In order to more effectively differentiate non-combustibles and combustibles within building products, the modified heat of combustion was calculated using all test results according to EN ISO 1716 and EN ISO 1182. The revision of criteria for Euro class A1 and A2 is proposed to obtain more realistic reaction-to-fire evaluation. In conclusion, it is advised to use single limit for heat of combustion for A1 and A2 Euro class. The proposed approach for modified heat of combustion is a convenient tool for the fast and cost-effective initial test method for non-combustibility evaluation and seems to be the proper method for distinguishing between non-combustibles and combustibles within building products. It is a better reflection of the real physical process of combustion than the current one. The third A1 criterion is questionable, regarding time to auto-ignition in EN ISO 1182 cylindrical furnace. The measurement for gross heat of combustion by EN ISO 1716 method is proposed for all Euro classes of building products with different limit values.
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MORRISON, W. D., L. A. BATE, I. McMILLAN, and E. AMYOT. "OPERANT HEAT DEMAND OF PIGLETS HOUSED ON FOUR DIFFERENT FLOORS." Canadian Journal of Animal Science 67, no. 2 (June 1, 1987): 337–41. http://dx.doi.org/10.4141/cjas87-032.
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Four groups of six 28-d-old piglets (three male, three female) were assigned in a Latin square design to each of four floors, bedded concrete, bare concrete, perforated metal or raised rubber-coated metal. Each pen was equipped with a microswitch which, when pushed, turned on three 250-W infrared lamps suspended 42 m above the floor. Each group of piglets remained on each floor for 48 h and the same groups were used for a second replicate. This approach was repeated with different groups of piglets at temperatures of 14, 16, 18, 20, 22 and 24 °C. Behavior regarding activation of the microswitch was monitored by the use of a video cassette recorder. Light at 180 lx was provided continuously. On bedded concrete, piglets demanded approximately 3 min less heat per hour (P < 0.05) than on any other floor and on perforated metal demanded approximately 3 min more heat per hour (P < 0.05) than on any other floor. Supplemental heat on bare concrete was similar to that of raised rubber-coated metal. From the results it was established that the effective environmental temperature on bedded concrete is 3 °C warmer than that for bare concrete or raised rubber-coated metal and 6 °C warmer than perforated metal. Piglets showed diurnal variation in heat demand. Key words: Piglets, operant, thermal regulation
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Zhang, Xi, Qing Li, Yousan Wang, and Qiming Wang. "Numerical and Experimental Study on the Dynamic Behavior of an Innovative Steel-Concrete Composite Hollow Waffle Floor." International Journal of Structural Stability and Dynamics 20, no. 08 (July 2020): 2050087. http://dx.doi.org/10.1142/s021945542050087x.
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The U-shaped steel-concrete composite hollow waffle (CHW) floor is an innovative slender large-span floor composed of a thin slab and bidirectional orthogonal steel-concrete composite hollow beams. Large vibrations may occur under human excitations, and vibration guidelines for CHW floors are still lacking. Thus, this paper undertook a parametric and experimental study to explore the vibration performance of the CHW floors. First, the modal properties and vibration response under walking tests considering the varying frequencies and routes were obtained from the measurements, which validated the accuracy of the finite element analysis (FEA). Then, the influence of the structural parameters on the floor vibration was investigated by numerical modeling. The parametric study shows that the medium-sized long-span (MLS) (28[Formula: see text]m) CHW floors present the best vibration serviceability, the small-sized long-span (SLS) (14[Formula: see text]m) CHW floors vibrate substantially under walking excitation, and the large-sized long-span (LLS) (42[Formula: see text]m) CHW floors are vulnerable to resonance. Finally, this paper provides recommendations for design guidelines for CHW floors and indicates that controlling the span-to-height (SH) value and beam spacing (BS) at a small value are the most effective methods of vibration control.
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Miskovic, Z., A. Pavic, and P. Reynolds. "Effects of full-height nonstructural partitions on modal properties of two nominally identical building floors." Canadian Journal of Civil Engineering 36, no. 7 (July 2009): 1121–32. http://dx.doi.org/10.1139/l09-055.
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This paper presents a combined experimental and numerical investigation of the modal properties of two full-scale and nominally identical steel–concrete composite floors. The floors were one above the other in the same fully operational multi-storey building. Both floors accommodated open-plan as well as partitioned offices. Multi-input-multi-output (MIMO) modal testing was employed to measure as-built modal properties of both floors. It was found that the two nominally identical floors had different modal characteristics, likely due to the different arrangement of partitions in the floor. It was also found that the measured modes on both floor levels experienced a considerable level of complexity, likely to be caused by nonproportional damping. Finite element (FE) models were developed in ANSYS for both floors using best engineering judgement and their features and properties were then tuned to match the measured counterparts. The tuning was done manually by trial-and-error and then automatically using sensitivity-based FE model updating procedure implemented in the FEMtools software. It was found that the initial and geometrically very detailed FE models, which did not feature any nonstructural components, underestimated the measured natural frequencies by up to a considerable 20%–25%, depending on the floor level. When full-height plasterboard and glass partitions were explicitly modelled as vertical springs connected to the floor and grounded at the other end, the correlation between the experimental and FE results improved considerably.
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Yakovlev, P. V., V. A. Lebedev, and V. M. Piskunov. "Thermal conditions of load-bearing elements of radioactive waste storage facilities." E3S Web of Conferences 220 (2020): 01079. http://dx.doi.org/10.1051/e3sconf/202022001079.
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Facilities for storing radioactive waste with residual heat differ from other facilities in high safety standards in all operating conditions. A feature of these structures is the presence of biological protection in the form of walls and ceilings made of reinforced concrete with a large thickness. The combination of heat dissipation and the large thickness of walls and floors create conditions for the appearance of significant thermal stresses. This feature should be taken into account in the strength calculations of these buildings, taking into account the summation of seismic effects, gravitational forces and thermal stresses caused by uneven temperature fields in concrete. The paper presents the results of calculations of the combined effects of thermal stresses and earthquakes on a building. The data obtained made it possible to determine the features of the deformation of concrete structures with a combination of loads.