Panel Construction Research Articles

Failure of Hexagonal and Triangular Honeycomb Core Sandwich Panels

Honeycomb sandwich panels are used in aerospace structures for their high stiffness-to-mass ratio. Reducing structural mass is critical in aircraft and spacecraft development due to its direct impact on payload capacity and operational costs. Typically, hexagonal honeycombs manufactured by cold expansion of periodically bonded strips of metal or foils of other materials are used for sandwich construction. With rapid development in additive manufacturing, other core shapes with higher specific stiffness can now be considered as an alternative. The authors of this paper had previously evaluated triangular cores to have higher or comparable specific moduli as compared with other two-dimensional core shapes. Further, the panels constructed using triangular cores had higher stiffness than traditional hexagonal core panels. To consider practical use of the triangular cores, elastic-plastic structural analysis is performed to evaluate the strength and failure of sandwich panel construction. Load bearing capacity of triangular core panels under three-point bending, in-plane compressive loading, and transverse shear loading is evaluated using finite element software ABAQUS/Explicit. The comparison made between triangular core and hexagonal core sandwich panels having the same cell size and relative density showed that triangular cores outperform hexagonal cores for applications where in-plane loading is dominant, whereas, in terms of transverse shear and out-of-plane loading, triangular core panels tend to fail at lower loads and lower deflections.

Structural Performance Analysis of a Novel Pyramidal Cellular Core Obtained through a Mechanical Expansion Process.

Stiff and strong yet lightweight cellular structures have become widely designed and used as cores for the construction of sandwich panels to reach high stiffness and strength to weight ratios. A low-density pyramidal cellular core has been proposed for investigation in this work. The novel core is manufactured from stainless steel sheet type 304 through a mechanical expansion procedure which is described in detail. The out-of-plane stiffness and strength performance is estimated by an analytical model which is successfully validated through experimental tests. A comparative study with other existing cellular core configurations made from other materials indicates an average performance behavior for the investigated structure. However, potential for a further structural performance increase is observed and discussed

Criteria for Selection of Sheathing Boards in Cold-Formed Steel Wall Panels Subjected to Bending: Construction Applications and Performance-Based Evaluation

Globally, cold-formed steel (CFS) construction is gaining popularity as an alternative to traditional methods of construction. However, there is a need for robust design specifications for each structural component and material used in the CFS construction practice. One material that is largely being used in the CFS construction process is the sheathing board for wall panel construction. However, as per the authors’ knowledge, there is no consistent criteria or specification for the selection of the sheathing board used in the construction. Besides, there are also no guidelines on parameters to be considered while selecting the sheathing material. Therefore, this paper aims to provide suggestions to select the appropriate sheathing based on the purpose and application of the sheathing. The interdependent parameters that influence the failure of the sheathing board connections such as type of screw, presence of washer, number of sheathing screw connections, edge/end distance, the failure mode of the wall frame studs, and geometry of the frame studs are discussed in the present study. The failure characteristics of four different sheathing boards are examined with the interdependent parameters. In addition, four different screw types are examined for better holding capacity and desired mode of failure. Furthermore, the suitability of existing recommendations for sheathing board requirement and installation methods are investigated. The suggested selection criteria for the sheathing boards are based on the various failure modes observed and the practical issues encountered in the CFS frame construction.

Властивості нового теплоізоляційного матеріалу з низькоякісної деревини сосни

Recently growing number of low quality wood in Ukraine, damaged by fungal sap color, stem rot leads to finding ways to use it. Today this wood is used mainly for the manufacture of wood-fuels facility in industrial and municipal energy. A possible way to use it is making insulation material from wood wool. The existing prototype of such material - fibrolite contains woody wool of healthy wood but during burning emits toxic chemicals. The construction of wooden wall panels, which include a frame of lumber and thermal insulation material of wood wool, made of low quality pine wood and binder. The binder used were inorganic (liquid glass) and organic-mineral (PVA) dispersion with the addition of flame retardant. Investigation of fire resistance, acoustic and thermal insulation of material from low quality pine wood have proved that it meets the regulatory requirements and can be used in building structures. To develop technological requirements for the manufacture of wall panels using low-quality pine wood, it is necessary to determine their density, sorption capacity and bio-stability. For this purpose, samples of thermal insulation material with different content of mass parts of wood wool and binder were made. The density of specimens of insulating material (145‒250 kg/m3), which is close to the popular hard thermal insulation materials, has been determined. Experimental studies of moisture absorption, sorption capacity and swelling values indicated that the effect of moisture on the properties of insulating material and its shape resistance are within the permissible values of regulatory documents for construction products. Wood treated with binders found to be used for the manufacture of insulation material has been found to have high biological resistance, which is more than 5-6 times the bio-resistance of untreated wood.

Dry Panels Supporting External Quality Assessment Programs for Next Generation Sequencing-Based HIV Drug Resistance Testing.

External quality assessment (EQA) is a keystone element in the validation and implementation of next generation sequencing (NGS)-based HIV drug resistance testing (DRT). Software validation and evaluation is a critical element in NGS EQA programs. While the development, sharing, and adoption of wet lab protocols is coupled with the increasing access to NGS technology worldwide, rendering it easy to produce NGS data for HIV-DRT, bioinformatic data analysis remains a bottleneck for most of the diagnostic laboratories. Several computational tools have been made available, via free or commercial sources, to automate the conversion of raw NGS data into an actionable clinical report. Although different software platforms yield equivalent results when identical raw NGS datasets are analyzed for variations at higher abundance, discrepancies arise when variations at lower frequencies are considered. This implies that validation and performance assessment of the bioinformatics tools applied in NGS HIV-DRT is critical, and the origins of the observed discrepancies should be determined. Well-characterized reference NGS datasets with ground truth on the genotype composition at all examined loci and the exact frequencies of HIV variations they may harbor, so-called dry panels, would be essential in such cases. The strategic design and construction of such panels are challenging but imperative tasks in support of EQA programs for NGS-based HIV-DRT and the validation of relevant bioinformatics tools. Here, we present criteria that can guide the design of such dry panels, which were discussed in the Second International Winnipeg Symposium themed for EQA strategies for NGS HIVDR assays.

Assessment of the Panel Support of a Seventeenth-Century Dutch Painting by Clinical Multislice Computed Tomography

ABSTRACT Clinical multislice X-ray computed tomography (MCST) was performed on a seventeenth-century panel painting from the collection of the National Academy of San Luca Gallery in Rome. The use of MSCT allowed us to detect the numerous characteristics of the wood used, the panel construction, and its condition, leading to a complete preliminary interpretation of its structural characteristics.

Construction of modular green roof panel

This article is dedicated to make people familiar with process of creating new construction of modular green roof panel. Article also shows creative process of prefabricated panel and all versions of its construction from the first attempts to final ecological modular panel for green roof. Article also describes problems of every version of modular panel which was created, and solutions which were made for final versions of green roof modular panel. Article also shows a final modular panel with its construction and possibility of its use on the roofs. In the article you can also read about tests which will be done in the future for verification of right construction of green roof panels and its behaviour in the real outside conditions.

Review: The Socialist Life of Modern Architecture: Bucharest, 1949–1964, by Juliana Maxim

Review: <i>The Socialist Life of Modern Architecture: Bucharest, 1949–1964</i>, by Juliana Maxim

АНАЛІЗ ІСНУЮЧИХ СТІНОВИХ ПАНЕЛЕЙ ТА РОЗРОБКА ВЛАСНОГО КОНСТРУКТИВНОГО РІШЕННЯ ДЛЯ ЗВЕДЕННЯ ЕНЕРГОЕФЕКТИВНИХ БАГАТОПОВЕРХОВИХ БУДИНКІВ

To date, panel construction is largely associated with Soviet "Khrushchev", which began massively erected in the late 1950s. But modern use panels can provide the necessary energy efficiency, allow and reduce the cost of multi-storey buildings. The paper presented analytical wall panels and structural wooden walls using wall panels used in the building of multi-storey buildings and structures, which satisfy all the necessary laws of Ukraine on energy efficiency of construction. Comparisons between them are offered, and they researched the living stock of Ukraine and worked constantly on modern high-rise buildings created by these methods of panel construction. In the course of the study, the latest imperfections that were made from the design of the liquid were identified and a possible reduction in the amount of data on the reduction of the negative impact on the house during its operation was put forward. Following this study, the results obtained developed their own structural solution to the wall panel for the exterior interior walls of the house, which should be made inaccessible by other wall panels.

ПЕРЕВАГИ ТА НЕДОЛІКИ Γ-МЕТОДУ ДЛЯ РОЗРАХУНКУ МІЦНОСТІ ПКД ПАНЕЛЕЙ ПРИ ЗГИНІ

Cross laminated timber or CLT is a new building material that is widely implemented in the construction of multi-storey residential and office buildings. This material has become widespread in Europe, the United States and Canada and has been in active use for over 20 years. At the present stage of the panel construction, only the German national standard DIN EN 1995-1-1 / NA (2010) and the Austrian ONORM B 1995-1-1 (2014) standard for the design of timber structures contain recommendations for the design and construction of CLT panels buildings. The calculation of the CLT panels strength for different types of stress state can be performed only on the basis of technical conclusions of laboratories and product certificates containing instructions and correction values ​​for the calculation of CLT panels of a specific manufacturer. The next revision of Eurocode-5 in 2022 will have significant regulations and requirements for the design and calculation of houses using CLT panels. There are three methods for calculating the bending strength of panels based on a specific scheme of approximation: the gamma method, the Tymoshenko method, and the shear analogy method. The gamma method treats the CLT panel as a flexible beam, similar to the beam of the Dereviagin system on lamellas or Kubler cubes, where the transverse layers of the boards are considered as pliable and not taken into account in calculating the geometric characteristics of the CLT cross sections. Each technique has its advantages and disadvantages as it has a number of specific assumptions to simplify the calculations. This paper highlights the advantages and disadvantages of the gamma method, which is more prevalent than other techniques and is found in many technical opinions of various CLT panels manufacturers. The analysis of the drawbacks of this technique avoids a number of inaccuracies in the calculation results.

ENSAYOS MECÁNICOS SOBRE MORTEROS CON AGREGADOS DE PLÁSTICO RECICLADO DOSIFICADOS SEGÚN MODELO DE CONDUCTIVIDAD TÉRMICA

Plastic waste constitutes 10 % of the solid waste worldwide. The use of plastic aggregates in concrete improves some properties such as thermal insulation and specific weight, although it produces a decrease in strength. In this work, mixtures with plastic aggregates of residual origin were dosed to satisfy thermal insulation requirements. For this purpose, a simplified model was made, calculating the required plastic thicknesses in an equivalent wall of 18 cm thick. Then, specimens were molded and tested by bending and compression. The results confirmed that the incorporation of plastic produced a drop in compressive and flexural strength, except in the case of pellets. Under the proposed multilayer wall model, a theoretical thickness of plastic between 2.4 and 6 cm was required to achieve the desired thermal insulation, compared to 37 cm that a wall exclusively made of mortar would have required. However, only one mix reached the minimum strength required for the construction of panels. It was concluded that the rounded aggregates exhibited better behavior than the leaf-shaped aggregates and that the model used for the dosage of plastic aggregates should be improved and contrasted with experimental results in a future paper.

Study of hybrid thermal system with photovoltaic panels using virtual instruments

In this paper, а novel set of virtual instruments has been developed and approved. It allows for providing on-line or off-line uncertainty calculations and statistical hypothesis testing. A novel instrument “Expansion card” has been developed in our laboratory. Several tests were performed to check the performance of some hybrid heating installation components. For this purpose, a hybrid solar thermal system, combined with photovoltaic panels has been designed and constructed by the authors. The system consists of two basic subsystems: thermal part and electrical part. Both are equipped with measuring devices to form a complex virtual test instrument. The aim of the tests was to characterize the energy efficiency of a low-cost PV/T panel construction and to check the proper operation of the developed virtual instrument tools. The tests showed that there was poor thermal contact between the pipe and the backside of the cell’s plate. That lead to the modification of the PV/T panel’s construction. It was also found that at higher temperatures, the heat exchange in the PV/T panel deteriorates and its energy output is better. So the parallel connection should be preferable for PV/T panel heat exchangers.

Environmental Impacts of Building Construction Using Cross-laminated Timber Panel Construction Method: A Case of the Research Building in Kyushu, Japan

In Japan, there has been an increase in the number of buildings built using cross-laminated timber (CLT) in order to utilize the abundant forest resources in the country. However, no studies have evaluated the environmental impact of the construction of CLT buildings in Japan. This study evaluates the environmental impacts from the start of construction to the completion of a real CLT building in Kumamoto city, Kyushu region, southern Japan. We investigated the input of the materials and energy used in the construction of the building. The environmental impact categories evaluated include climate change, ozone layer depletion, eutrophication, acidification, and photochemical oxidation. We found that the concrete used for the foundations, and the cement-based soil stabilizer used for ground reinforcement accounted for 42% of the greenhouse gas (GHG) emissions. The construction site was previously used as a seedbed field, necessitating ground reinforcement. Furthermore, the large foundations were designed in order to raise the low height of the wooden structure from the ground level. Developing and applying methods with lower environmental impacts for ground reinforcement and building foundations is recommended. In addition, we found that by using biomass-derived electricity in CLT manufacturing, the environmental impacts of CLT manufacturing could be reduced, thus reducing the environmental impacts of the entire building. The biogenic carbon fixed in the wooden parts during the building usage accounted for 32% of the total GHG emissions of the building construction. Since this biogenic carbon will be released to the atmosphere at the end-of-life stage of the building, a long-term usage of the CLT buildings and/or reuse of the CLT is recommended.

Experimental Study on the Cyclic Behavior of Integrated Panels for Cold-Formed Steel Shear Wall System

Studies on the constructability of cold-formed steel (CFS) members are lacking. In this context, this paper proposes an integrated panel to replace the studs and steel sheet in the steel-sheathed wall system used in light gauge steel frames. The integrated panel was developed, to not only exhibit better structural performance and constructability than the steel-sheathed wall system, but to also reflect the appropriate details for applications to on-site panel construction. Cyclic loading tests were performed to investigate the seismic performances of three integrated panel specimens and a steel-sheathed panel specimen. The integrated panel specimens exhibited greater deformation capacity, ductility and equivalent damping ratio than the steel-sheathed panel. Although the web slenderness of the integrated member was nearly 400, the nominal strength of the integrated panel was predictable on an AISI standard. However, for stud-reinforced integrated panels, the nominal strength was overestimated by 45%–60%, and a draft equation was proposed to predict the yield strength of these panels. The proposed equation accurately predicted the yield strength of the stud-reinforced integrated panel specimens. The study results can aid in the construction of light gauge steel frames that require reinforcing parts with a high web slenderness ratio.

Structural behaviour and design of plywood sheathed cold-formed steel wall systems subjected to out of plane loading

An experimental study was conducted to explore the strength contribution of plywood sheathing boards that are regularly used in the cold-formed steel (CFS) wall panel construction. A series of material tests and 4-point bending full-scale tests were carried out. The testing program includes various key design factors such as sheathing board thicknesses, screw spacings and slenderness of the CFS studs. The test results indicate that the plywood sheathing thickness of 12 mm is sufficient for restraining the lateral torsional buckling (LTB) of the slender CFS studs, which also increased the ultimate moment capacity of the CFS wall panel by a maximum of 150%. However, the improvement in flexural strength varies depending on the local and global slenderness of the CFS wall stud. The spacing between the sheathing-screw connection also significantly influenced the structural contribution of plywood-sheathing. The design calculations were carried out as per the AISI design provisions and latest improvements suggested by the previous research works. The design calculations indicate that the design moment capacity of the CFS wall panel can be increased by a maximum of 48%, and most of the design results are conservative compared to the experimental results. Although, it was found that the modified design provisions of AISI are reliable for the strength predictions, the failure modes predicted greatly varied compared to the experimental results. Therefore, a series of individual sheathing screw connection tests were carried out to discover the key factors that influence the bracing effect of sheathings. On the basis of the results obtained from individual sheathing connection tests, the preliminary modifications that are required for the accurate failure mode predictions are suggested.

Methodology for the formation of indicators balanced system for marketing activities of an industrial enterprise

The article presents a methodology for the formation of BSC, which is presented as a tool for strategic and operational management of marketing activities. An industrial enterprise with a large number of competitors and retaining leadership positions was chosen as the object of research. The main purpose of this article is to evaluate marketing activities. An analysis of relations with customers, sales organizations, agents, dealers, subcontractors, commercial intermediaries of subsidiaries, and representative offices was carried out. The main activity of the enterprise is: production of precast concrete for brick and partial construction; production of precast concrete for panel housing series 111.97; construction and sale of housing (primary housing in brick or panel construction); production and laying of “pavers”. Strategic goals were set based on key factors and proposed options for their achievement, as a result of which the company will be able to grow in terms of marketing management. This topic is relevant for this enterprise.

A combined approach for assessment the functionality of photovoltaic modules in real-world operation

The energy production from the solar photovoltaic power plants is highly dependent on the meteorological and physical conditions such as solar radiation, ambient and panel’s surface temperature, inclination of the photovoltaic (PV) panel construction etc. The I-V curves are the most important for estimation the functionality and production of each PV panel, as well as finding the maximum power point (MPP) of it. Because of the continuous generation of energy, the silicon crystal of the PV modules begins to depreciate and this decreases the energy production. In real-world operating conditions, revealing the energy state of the PV panels is the main point for estimating the PV panels’ efficiency. Furthermore, one complete approach, including electrical measurements and temperature distribution information over the PV panels’ surface, can reveal the risky elements (subcells) and provide data for prevention damages and working interruptions. This paper presents a method for PV monitoring in which conventional electrical instrumentation devises and thermographic camera are used, in order to estimate the real physical state of the PV panels’.

Analiza kapaciteta i uslova izgradnje fotonaponskih sistema na krovovima školskih objekata u Srbiji

School and school gym buildings represent a relevant potential for construction of photovoltaic panels, to be integrated into roofs of these buildings. Given that roof structures are passive, construction of photovoltaic systems does not interfere with the building functionality, does not it in any way adversely affect the environment. Installation of photovoltaic systems on building roofs brings the production and consumption of electricity closest possible, therefore such systems ensure significant reduction in power losses in transmission and distribution grids. In addition to locally produced electricity, construction of photovoltaic systems on the school buildings’ roofs produces an educational effect as well. By installing a measuring and acquisition system which would include the measuring data on the photovoltaic power plant production parameters and school electricity consumption into school labs, technology would be closer to students, as well as possibilities to meet the demand for electricity from this basic renewable energy source. This paper presents the results of evaluations of the available roof surfaces of school buildings in Serbia for the photovoltaic panels installation. For each category of school building, an estimate of possible annual production per unit of average roof area was made. Summarizing all the results, estimates of possible installed capacity and annual electricity production for different scenarios are given.

Construction of elastoplastic shallow panels manufactured by stretching from sheet metal

In the article, in a geometrically and physically nonlinear formulation, the problem of the stress-strain state of shallow shells on a rectangular plane under pressure loading is solved. The solving equations of the theory of flexible shallow shells are obtained on the basis of the Henki-Ilyushin deformation theory of plasticity and the equations of the geometrically non-linear theory of shells, which contain quadratic terms with respect to the angles of rotation of the normals to the median surface. The geometrical parameters of the median surface are taken in the initial undeformed state. The equations are written in a form that makes it possible to carry out numerical calculations of problems with allowance for geometric and physical nonlinearities or only with geometric nonlinearity, to take into account unloading, compressibility of the material and secondary plastic deformations. The results of numerical calculations of critical loads, unloading zones and secondary plastic deformations are presented. Recommendations are given on the choice of geometrical parameters when designing shallow shells.

Assessment of the River Habitat Quality Using Bioindication in the Piedmont Stream Handlovka in Slovakia

The paper focuses on an assessment of a river habitat quality in piedmont streams using a bioindication by the brown trout. The study was performed at four sites, piedmont streams in Slovakia, but modelling procedure herein is particularly described only for the Handlovka River, in the Nitra basin. For the field and modelling work, a natural reference reach and a regulated reach have been chosen within each stream. Hydrometric, geodetic and morphological measurements were conducted. The paper focuses on modelling in the Hydrocheck software and Computer Software System for Environmental Flow Analysis (SEFA) based on the Instream Flow Incremental Methodology (IFIM) and result output is the Area Weighted Suitability (AWS). The abiotic parameters for modelling were chosen as depth and velocity rates. The biotic parameter was chosen as an ichthyologic abundance of the brown trout. The results show significant difference between natural and modified channel, presenting natural reach as more suitable for fish abundance with higher AWS score. The regulated reaches are significantly affected by the river regulation, construction of concrete panels and sever contamination from anthropogenic runoff. On the contrary, the natural channels offer enough morphological structure and various shelter possibilities for enhancement of fish population.