Sparse Plate-Trusses

1998 ◽  
Vol 13 (3) ◽  
pp. 113-125
Author(s):  
Livna Alpar-Engelhardt ◽  
Oren Vilnay
Keyword(s):  
Structural Properties ◽  
Structural Performance ◽  
Stiffness Coefficient ◽  
Quick Method ◽  
Structural Efficiency ◽  
Stiffness Coefficients

Strategies of reducing the number of bars of a sparse plate-truss, while increasing structural height and improving structural performance are considered. Four strategies are presented by considering seven plate-trusses. The morphological and structural properties of each of the plate trusses with reduced number of bars are discussed. An approximate and quick method to find the stiffness coefficients of a periodic unit of the plate-truss is presented and an equivalent single stiffness coefficient is introduced. The stiffness coefficients enable the designer to understand the existing relationship between the morphology of a truss and its structural ability. They are very useful for a comparison of structural ability of different sparse-trusses and permit a determination of the relative structural efficiency of each strategy of reducing the bar density.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

A quick method for determination of psychoactive agents in serum and hair by using capillary electrophoresis and mass spectrometry

2015 ◽  
Vol 111 ◽  
pp. 177-185 ◽  
Author(s):  
Aneta Woźniakiewicz ◽  
Renata Wietecha-Posłuszny ◽  
Michał Woźniakiewicz ◽  
Ewelina Bryczek ◽  
Paweł Kościelniak
Keyword(s):  
Mass Spectrometry ◽  
Capillary Electrophoresis ◽  
Quick Method

Analysis of Wave Energy Sources in the North Atlantic Waters in View of Design Challenges

2016 ◽  
Author(s):  
Jose V. Taboada ◽  
Hirpa G. Lemu
Keyword(s):  
Renewable Energy ◽  
North Atlantic ◽  
Wave Energy ◽  
Energy Resources ◽  
Structural Performance ◽  
Energy Sources ◽  
Wave Power ◽  
Wave Statistics ◽  
Wave Characteristics

This paper describes a wave energy analysis of North Atlantic waters and provides an overview of the available resources. The analysis was conducted using a scatter diagram data combined with wave statistics and empirical parameters given by wave height and periods. Such an overview is instrumental for modelling of wave energy sources, design of wave energy converter (WEC) devices and determination of locations of the devices. Previous survey of wave energy resources widely focused on determination of the reliability on installations of WECs. Though the renewable energy source that can be utilized from the waves is huge, the innovative work in design and development of WECs is insignificant and the available technologies still require further optimization. Furthermore, the wave potential of North Atlantic waters is not sufficiently studied and documented. Closer review of the literature also shows that wave energy conversion technology, compared with other conversion machines of renewable energy sources such as wind energy and solar energy, seems still immature and most of the research and development efforts in this direction are limited in scope. The design of energy converters is also highly dictated by the wave energy resource intensity distribution, which varies from North to South hemisphere. The immaturity of the technology can be attributed to several factors. Since there are a number of uncertainties on the accuracy of wave data, the design, location and installation of WECs face a number of challenges in terms of their service life, structural performance and topological configuration. As a result, collection and assessment of wave characteristics and the wave state conditions data serve as key inputs for development of robust, reliable, operable and affordable wave energy converters. The fact that a number of variables are involved in wave distribution characteristics and the extraction of wave power, treating these variables in the design process imposes immense challenges for the design optimization and hence the optimum energy conversion. The conversion machines are expected to extract as high wave energy as possible while their structural performance is ensured. The study reported in this paper is to analyse wave data over several years of return periods with a detailed validation for wave statistics and wave power. The analysis is intended to contribute in better understanding of the wave characteristics with influencing parameters that can serve as design optimization parameters. A method is proposed to conduct a survey and analysis of the available wave energy resources and the potential at cited locations. The paper concludes that wave energy data accuracy is the baseline for project scoping, coastal and offshore design, and environmental impact assessments.

scholarly journals Determination of the structural efficiency of short bridges according to their physical and economic characteristics

2021 ◽  
Vol 2046 (1) ◽  
pp. 012068
Author(s):  
J R Pineda Rodríguez ◽  
J P Rojas Suárez ◽  
F A Prato Duarte
Keyword(s):  
Structural Efficiency

scholarly journals Comparação entre a eficiência estrutural de perfis soldados de aço e perfis de aço formados a frio

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Uiatan Aguiar Nogueira ◽  
Matilde Batista Melo ◽  
Daniel De Lima Araujo
Keyword(s):  
Bending Strength ◽  
Steel Beams ◽  
Steel Beam ◽  
Structural Elements ◽  
Structural System ◽  
Welded Steel ◽  
Bending Tests ◽  
Structural Efficiency ◽  
Cold Formed Steel

RESUMO: A Análise de elementos estruturais, realizadas durante as etapas de projeto de uma estrutura, é parte fundamental para garantia de bom desempenho e estabilidade do sistema estrutural. Na execução de algumas estruturas, como as coberturas em edificações, é usual o emprego de perfis leves de aço formados a frio devido ao seu baixo peso. Esta pesquisa tem por objetivo avaliar a eficiência estrutural desses perfis quando comparados, por exemplo, aos perfis soldados compactos. Para tanto, foram realizados ensaios de flexão em quatro vigas biapoiadas submetidas a duas forças concentradas, de forma a se obter flexão pura no meio do vão das vigas. Estas foram instrumentadas para a determinação da sua rigidez e da sua resistência à flexão. A principal contribuição deste trabalho é demonstrar a eficiência estrutural de perfis formados a frio em seção caixa submetidos à flexão em comparação com perfis de seção tipo “H” soldados. ABSTRACT: The analysis of structural elements, in a structure’s design, is an essential step to ensure good performance and stability of the structural system. In any types of structures, such as roofing in buildings, it’s usual using cold-formed steel beams due to their small weight. This research seeks to evaluate the structural efficiency of cold-formed steel beams when compared, for example, to compact welded steel beams. Thus, bending tests were performed in four simply supported beams submitted to two concentrated loads, in order to obtain pure flexure at the mid-span of the beams. These beams were instrumented for the determination of their rigidity and bending strength. The results showed that the cold-formed steel beam, box-shaped, presented structural efficiency similar to the welded steel beam “H” shaped.

Determination of /V-Nitrosodipropylamine in Trifluralin Emulsifiable Concentrates Using Minicolumn Cleanup and Gas Chromatography with Thermal Energy Analyzer

1988 ◽  
Vol 71 (2) ◽  
pp. 333-336
Author(s):  
Dave Wotherspoon ◽  
Ralph Hindle
Keyword(s):  
Gas Chromatography ◽  
Thermal Energy ◽  
Internal Standard ◽  
Energy Analyzer ◽  
Quick Method ◽  
Coefficients Of Variation ◽  
Significant Difference ◽  
Artifact Formation ◽  
And Control

Abstract A quick method for determining /V-nitrosodipropylamine (NDPA) levels in trifluralin emulsifiable concentrate formulations is described. At least 18 samples can be analyzed at one time in a minimum of fumehood space, with up to 90% savings on solvents and materials. A sample aliquot is mixed with a solution containing nitrosamine recovery standards, and nitrosamines are separated by minicolumn cleanup. Internal standard is added directly to the eluate containing the nitrosamines, and levels are determined by gas chromatography with thermal energy analyzer. Recoveries of spiked nitrosamines ranged from 98 to 102%. Coefficients of variation for samples containing 0.5 ppm NDPA are 13%. Minimum detectable limit, calculated as 3 times the noise, is 0.06 ppm. Comparison with the method formerly used by this laboratory shows no significant difference in the analytical results at 95% confidence limits, and control experiments were performed to ensure that there was no artifact formation of NDPA.

Floatover Deck Installation: Case Study — Structural Efficiency of Longitudinally and Transversely-Recessed Structures

2004 ◽  
Author(s):  
Lee A. O’Neill ◽  
Emmanuel Fakas ◽  
Rodney Pinna ◽  
Timothy Walsh
Keyword(s):  
Transverse Direction ◽  
Structural Integrity ◽  
Structural Performance ◽  
Structural Efficiency

Conventional floatover deck (FOD) installation on a jacket substructure requires the top of the structure to be recessed appropriately, either in the longitudinal or transverse direction to accommodate the vessel transporting the deck. The recess direction is very important to the design of the jacket and influences the outfitting of appurtenances, the shape of the deck and the floatover concept as a whole. This study investigates the structural integrity of typical longitudinal and transverse jackets suitable for FOD installation under both inplace and installation conditions. The study also assesses the structural efficiency of the two options under various installation conditions and benchmarks their structural performance against more conventional jackets associated with lift-installed decks.

Determination of absorption and structural properties of cellulose-based hydrogel via ultrasonic pulse-echo time-of-flight approach

Cellulose ◽  
2018 ◽  
Vol 25 (8) ◽  
pp. 4331-4343 ◽  
Author(s):  
Leonardo Lamanna ◽  
Francesco Rizzi ◽  
Christian Demitri ◽  
Marco Pisanello ◽  
Elisa Scarpa ◽  
...  
Keyword(s):  
Structural Properties ◽  
Time Of Flight ◽  
Ultrasonic Pulse ◽  
Echo Time ◽  
Pulse Echo
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