scholarly journals Screen Wall Fire Resistance Investigation

2021 ◽  
Vol 6 ◽  
Author(s):  
Tatiana Eremina ◽  
Dmitry Korolchenko ◽  
V. E. Fadeev
Keyword(s):  
Fire Resistance ◽  
Functional Dependence ◽  
Heat Exposure ◽  
Experimental Studies ◽  
Engineering Problem ◽  
Thermal Engineering ◽  
Wall Structure ◽  
Building Structures ◽  
Critical Temperatures ◽  
Fire Conditions

The assessment of fire resistance for building constructions has been carried out by the solution of the heat engineering problem for heating up building structures under the conditions of non-stationary heat exposure with standard fire conditions. The finite element method is used as the solution method. Numerical simulation of heating of considered building structures under fire conditions was carried out using the Ansys Mechanical computer complex, which allows for a thermal engineering design to be calculated on the basis of its software model. The resulting functional dependence allows for determining the actual fire resistance of Pf depending on the thickness of sheets δ of the outer skin made of the basalt fire-proof material, as well as the geometric parameters of the protective screen (δ) depending on the required fire resistance from the condition of compliance with the requirements of constructive fire safety (Pf > Preq). Experimental studies to determine the fire resistance for membrane wall structures showed that an increase in temperature on its unheated surface vs. structure temperature prior to testing more than 180° С (195°С) occurs not earlier than 31 min. Upon reaching the critical temperatures on the unheated surface of the membrane wall structure independing on its thickness, the fire resistance limits REI 30-REI 120 are reached.

scholarly journals VERIFICATION RESULTS OF THE PRESENTATION OF THE PROTECTION OF THE UNSTEADING TEMPERATURE FIELD AT THE CONCRETE CONSTRUCTION FOR THE MIND OF THESTANDARD TEMPERATURE REFRIGERATION FIRE

2018 ◽  
pp. 96-101 ◽  
Author(s):  
O. Pazen
Keyword(s):  
Temperature Field ◽  
Experimental Research ◽  
Fire Resistance ◽  
Concrete Structure ◽  
Experimental Studies ◽  
Alternative Methods ◽  
Building Structures ◽  
Fire Tests ◽  
Stationary Temperature Field ◽  
The Phoenix

The main classification indicator, in terms of fire safety, is the degree of fire resistance of the house. Depending on this indicator normalize its surface, the area of development and distance to other buildings and structures. The degree of fire resistance of the house is determined by the limit of fire resistance of its building structures and the limit of the fire spread by these structures. Therefore, the value of the fire resistance limit of building constructions, which consists of a house, significantly affect its architectural solution and the parameters of construction in general. On this basis, taking into account the approaches to ensuring normalized fire resistance limits of the design and the features of their behavior under high-temperature (fire) influence is very relevant. Most research on building constructions is based on two methods of determining the limit of fire resistance - experimental and analytical. The first one is to determine the limit of fire resistance on the basis of experimental research, and the second one is based on methods of analytical or computational and experimental research. In most countries, the experimental determination of fire resistance of building structures is carried out by means of fire tests. However, experimental studies require significant financial costs and high accuracy of fire tests. The alternative methods for assessing the fire resistance of building elements on the basis of field fire tests are the design methods used for the design of fire-resistant building constructions. In the article, the verification of the results of analytical studies on the propagation of the non-stationary temperature field in the concrete structure under the conditions of the influence of the standard temperature regime of the fire in comparison with the results of field fire tests has been carried out. The analysis of the obtained results shows that the results of the calculation of the distribution of the non-stationary temperature field in the thickness of the concrete structure without coating and with the applied flame retardant coating of the Phoenix STV, manufactured by the company "A + B Ukraine" on the front of the Phoenix Contact, obtained using mathematical models, are qualitatively and quantitatively convergent with results obtained experimentally. The difference between the theoretical and experimental data for a concrete structure without coating is 4%, and with the applied fire-retardant coating does not exceed 10%.

scholarly journals DEVELOPMENT OF FIRE-PROTECTIVE PLASTER SURFACES COMPOSITES AND DESIGN METHOD FOR DETERMINING THE FIRE RESISTANCE OF TWO-LAYER ARMOCEMENT ELEMENTS

2019 ◽  
Author(s):  
Т.А. Хежев
Keyword(s):  
Fire Resistance ◽  
Design Method ◽  
Experimental Studies ◽  
Engineering Calculation ◽  
Building Structures ◽  
Resource Base ◽  
Heat Engineering ◽  
Flame Retardant Properties ◽  
Increased Strength ◽  
Acceptable Agreement

Приведены результаты исследований составов гипсоизвестковоцементовермикулитотуфобетонных композитов. Расширение сырьевой базы, повышение прочности и огнезащитных свойств, а также снижение стоимости композита решается за счет использования в сырьевой смеси отходов пиления вулканического туфа. Приведены результаты экспериментальных исследований огнестойкости двухслойных армоцементных элементов. Разработан алгоритм теплотехнического расчета предела огнестойкости многослойных строительных конструкций, обеспечивающий приемлемое совпадение расчетных значений с экспериментальными данными. Разработано программное обеспечение теплотехнического расчета предела огнестойкости армоцементных конструкций с огнезащитным слоем из гипсовермикулитобетона, получены выражения для коэффициентов теплопроводности и теплоемкости разработанных композитов. The results of studies of gypsumlimestone cementvermiculite and concrete composites are given. Expanded resource base, increased strength and flame retardant properties, as well as reduced cost of the composite. using volcanic tuff in the raw mix. The results of experimental studies of the fire resistance of twolayer cementcontaining elements are given. An algorithm for heat engineering calculation of the fire resistance limit of multilayer building structures has been developed, which ensures acceptable agreement between the calculated values and experimental data. The software for the heat engineering calculation of the fire resistance limit of cementcement constructions with a fireproof layer made of gypsum vermiculite concrete has been developed, expressions for the thermal conductivity and heat capacity of the developed composites have been obtained.

Assessment of the volume activity of α-radioactive wastes on surface and specific contamination by portable γ-spectrometry method

2020 ◽  
pp. 468-473
Author(s):  
I. P. Korenkov ◽  
A. I. Ermakov ◽  
A. B. Mayzik ◽  
T. N. Laschenova ◽  
V. N. Klochkov ◽  
...  
Keyword(s):  
Specific Activity ◽  
Experimental Studies ◽  
Germanium Detector ◽  
Low Energy ◽  
Gamma Ray Spectrometry ◽  
Building Structures ◽  
Germanium Detectors ◽  
Volume Activity ◽  
Β Decay ◽  
Γ Spectrometry

The aim of the study is to evaluate the volume activity of radioactive waste (RW) by surface and specific alpha contamination using portable gamma-spectrometry.Materials and methods. Methods of rapid assessment of the content of α-emitting radionuclides in solid waste of various morphologies using gamma-spectrometers based on germanium detectors are considered. Computational methods for determining the effectiveness of radionuclide registration are presented.Results. The possibility of using portable gamma-ray spectrometry to assess the surface and specific activity of various materials contaminated with α-emitters (232Th, 235U, 238U, 237Np, 239Pu, 240Pu and 241Am) is shown. The calculated values of the registration efficiency of low-energy gamma-emitters obtained by modeling the spatial-energy parameters of the detector are given.To simplify the solution of this problem, the calculation program used 20 standard templates of various geometries (rectangular, cylindrical, conical, spherical, etc.). The main sources of error in the survey of contaminated surfaces, largesized equipment and building structures were investigated.Conclusions. The possibilities of portable γ-spectrometry for estimating the volume of RW based on the surface density of contamination of materials with radionuclides of uranium and transuranic elements are investigated. When using γ-spectrometer with a high-purity germanium detector with a range of γ-quanta extended in the low-energy region, radionuclides such as 232Th, 235U,238U, 237Np, 241Am were determined by their own radiation or by the radiation of their daughter products.The “problem” element is plutonium, for rapid evaluation of which it is proposed, in accordance with the radionuclide vector methodology, to use 241Am, which accumulates during the β-decay of 241Pu.According to calculations, the most likely value of the activity ratio 239Pu/241Am for the object where the work was performed (scaling factor) varies in the range from 5.0 to 9.0.Based on the results of calculations and experimental studies, the parameters of the efficiency of registration of various α-emitting radionuclides by portable γ-spectrometers. It has been found that for germanium detectors with an absolute efficiency of registering a point source of 7÷15%, it is n×10–5÷n×10–4%.

Effect of K-wire Reuse and Drill Mode on Heat Generation in Bone

Hand ◽  
2021 ◽  
pp. 155894472110031
Author(s):  
Muturi G. Muriuki ◽  
Arun K. Reddy ◽  
Alex Tauchen ◽  
Robert M. Havey ◽  
Avinash G. Patwardhan ◽  
...  
Keyword(s):  
Cell Death ◽  
Cortical Bone ◽  
Heat Generation ◽  
Kirschner Wire ◽  
Heat Exposure ◽  
Critical Temperatures ◽  
Rotary Drilling ◽  
External Cooling ◽  
K Wires ◽  
Oscillating Mode

Background We examined the effect of Kirschner wire (K-wire) reuse and use of oscillating mode on heat generation within cortical bone. Methods Two trocar-tipped K-wires were drilled through the diaphysis of each of 30 human metacarpals and phalanges: one K-wire was inserted in rotary mode and another in oscillating mode. Each wire was reused once. Thermocouples placed within the dorsal and volar bone adjacent to the K-wire drill path measured temperatures throughout each test. Results Peak cortex temperatures were 25°C to 164°C. Rotary drilling achieves peak temperatures quicker (31 ± 78 seconds vs 44 ± 78 seconds, P = .19) than oscillating drilling, but insertion time is also less, resulting in lower overall heat exposure. This effect is also seen when the K-wire is reused (34 ± 70 seconds vs 41 ± 85 seconds, P = .4). The length of time that cortical bone was exposed to critical temperatures (47°C or more) was significantly higher when a wire was reused (36 ± 72 seconds vs 43 ± 82 seconds, P = .008). Peak temperatures greater than 70°C (a temperature associated with instantaneous cell death) were observed on many occasions. Conclusions Overall heat exposure may be higher if a K-wire is reused or inserted in oscillating mode. In the absence of external cooling, K-wire insertion into cortical bone can easily expose bone to temperatures that exceed 70°C and may increase the risk of osteonecrosis.

scholarly journals Post-Fire Susceptibility to Brittle Fracture of Selected Steel Grades Used in Construction Industry—Assessment Based on the Instrumented Impact Test

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3922
Author(s):  
Mariusz Maslak ◽  
Michal Pazdanowski ◽  
Marek Stankiewicz ◽  
Paulina Zajdel
Keyword(s):  
Charpy Impact ◽  
Water Mist ◽  
Heating Regime ◽  
Building Structures ◽  
Initial State ◽  
Slow Cooling ◽  
Natural Fire ◽  
Development Scenarios ◽  
Steel Grades ◽  
Fire Conditions

The change in the value of the breaking energy is discussed here for selected steel grades used in building structures after subjecting the samples made of them to episodes of heating in the steady-state heating regime and then cooling in simulated fire conditions. These changes were recorded based on the instrumented Charpy impact tests, in relation to the material initial state. The S355J2+N, 1H18N9T steels and also X2CrNiMoN22-5-3 duplex steel were selected for detailed analysis. The fire conditions were modelled experimentally by heating the samples and then keeping them for a specified time at a constant temperature of: 600 °C (first series) and 800 °C (second series), respectively. Two alternative cooling variants were investigated in the experiment: slow cooling of the samples in the furnace, simulating the natural fire progress, without any external extinguishing action and cooling in water mist simulating an extinguishing action by a fire brigade. The temperature of the tested samples was set at the level of −20 °C and alternatively at the level of +20 °C. The conducted analysis is aimed at assessing the risk of sudden, catastrophic fracture of load-bearing structure made of steel degraded as a result of a fire that occurred previously with different development scenarios.

scholarly journals Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabhi Samant ◽  
Wei Wu ◽  
Shijia Zhao ◽  
Behram Khan ◽  
Mohammadali Sharzehee ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Patient Specific ◽  
Wall Structure ◽  
Left Main ◽  
Element Analysis ◽  
Stent Expansion ◽  
Radial Strength ◽  
Different Diameters

AbstractLeft main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.

Quantitative Experimental Study of SiO2-Water Nanofluids on Backward-Facing Step Flow under Low Reynolds Number

2018 ◽  
Vol 916 ◽  
pp. 221-225
Author(s):  
Ji Zu Lv ◽  
Liang Yu Li ◽  
Cheng Zhi Hu ◽  
Min Li Bai ◽  
Sheng Nan Chang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Volume Fraction ◽  
Pure Water ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Thermal Engineering ◽  
Heat Transfer Medium ◽  
Step Flow

Nanofluids is an innovative study of nanotechnology applied to the traditional field of thermal engineering. It refers to the metal or non-metallic nanopowder was dispersed into water, alcohol, oil and other traditional heat transfer medium, to prepared as a new heat transfer medium with high thermal conductivity. The role of nanofluids in strengthening heat transfer has been confirmed by a large number of experimental studies. Its heat transfer mechanism is mainly divided into two aspects. On the one hand, the addition of nanoparticles enhances the thermal conductivity. On the other hand, due to the interaction between the nanoparticles and base fluid causing the changes in the flow characteristics, which is also the main factor affecting the heat transfer of nanofluids. Therefore, a intensive study on the flow characteristics of nanofluids will make the study of heat transfer more meaningful. In this experiment, the flow characteristics of SiO2-water nanofluids in two-dimensional backward step flow are quantitatively studied by PIV. The results show that under the same Reynolds number, the turbulence of nanofluids is larger than that of pure water. With the increase of nanofluids volume fraction, the flow characteristics are constantly changing. The quantitative analysis proved that the nanofluids disturbance was enhanced compared with the base liquid, which resulting in the heat transfer enhancement.

The concept of calculating the actual limit of fire resistance of building structures

2021 ◽  
pp. 12-17
Author(s):  
Юрий Николаевич Шебеко ◽  
Алексей Юрьевич Шебеко
Keyword(s):  
Fire Resistance ◽  
Fire Safety ◽  
Building Structures ◽  
Safety Level ◽  
Fire Temperature ◽  
Normative Documents ◽  
Software Complex ◽  
Temperature Regimes ◽  
Actual Fire

Проведен краткий анализ понятий, связанных с расчетом пределов огнестойкости строительных конструкций. Дано определение термина «фактический предел огнестойкости», которое отсутствует в нормативных документах по пожарной безопасности. Отмечено, что это связано с использованием на практике значений пределов огнестойкости, определенных для стандартных температурных режимов пожара, в то время как на практике указанные температурные режимы, как правило, отличаются от стандартных. Предложена концепция определения фактического предела огнестойкости, основанная на моделировании воздействия на строительную конструкцию температурного режима реального пожара (например, с помощью программного комплекса FDS 6). The brief analysis of definitions connected with estimation of fire resistance limits of building structures is conducted. There is given the determination of term “actual fire resistance limit” that is absent in fire safety normative documents. It is caused by practical application of the fire resistance limits determined for standard temperature regimes of fires only, but at the same time the temperature regimes of real fires as a rule differ from the standard regimes. There is proposed the method for determination of the actual fire resistance limit based on the modeling of influence of the real fire temperature regime on buildings structures. This modeling can be made by an application of CFD methods (for example, with the help of FDS 6 software complex). The required reliability of the building structure is considered. The proposed method can solve the problem of practical applicability of certain structural unit during designing buildings and structures, for which the use of the resistance limits obtained for the standard fire temperature regimes can lead to unjustified economic expenditures without an appropriate elevation of fire safety level of the object.

Heat Generation in Bone Cutting-Implications for Thermal Necrosis

2001 ◽  
Author(s):  
Debra Chenet Millon ◽  
Darren L. Hitt ◽  
Stephan J. LaPointe
Keyword(s):  
Bone Cells ◽  
Heat Exposure ◽  
Fibrous Tissue ◽  
Metatarsal Head ◽  
Bone Cell ◽  
Frictional Heat ◽  
Fat Cell ◽  
Critical Temperatures ◽  
Cell Degeneration ◽  
Prolonged Heat

Abstract A bunion is a common foot disorder caused by an abnormal outward projection of the joint and inward turning of the toe. Surgery to correct the malformation involves cutting the first metatarsal head, repositioning and setting it; the bone is then left to heal itself over time. A potentially serious by-product of the bone cutting is the frictional heat generated. While the heat susceptibility of individual bone cells varies throughout bone and is difficult to quantify, studies have shown that when injured, bone may not always heal as bone but rather as a fibrous tissue of varying degrees of differentiation. Prolonged heat exposure at or above critical temperatures may also lead to fat and bone cell resorption, a subsequent fat cell degeneration of the tissue, local swelling of cells as well as denaturation of the enzymatic and membrane proteins (Eriksson & Albrektsson, 1983, Li et al, 1999).

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