CONSIDERATION ON TRUSS AND SPLICE JOINT DESIGN MODELS IN EXTREMAL LOADING

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Lilita Ozola
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Beam Model ◽  
Tensile Forces ◽  
Uniqueness Of The Solution ◽  
The One ◽  
Sharp Criticism ◽  
Numerical Case Study ◽  
Ultimate Limit

In this study the behavior of elements and joints in hard loaded Warren trusses is analyzed theoretically with the purpose of disclosing the sections and elements which possibly can become extremely stressed under the design load proposed being real before the ultimate limit state. The significance of truss topology selected has been brought forth, since unfavorable loading of a tensioned chord connection is discussed in this paper. Three types of tensioned splice joints have been examined considering expected elongations of bolts in order to determine additional stresses induced due to the redistribution of tensile forces. An assumption of a continuous beam model on elastically deformed discrete supports has been adopted as a design model for the examination of stresses possibly caused in the sections of bolts. It has been proved that a joint with extended end-plates over both flanges of chord I profile may be accepted as the one which is safe and robust enough for use in tensile chords of bearing structures. The joint type with end-plates extended over a more tensioned flange only and the one with connecting bolts all hidden between flanges has been subjected to sharp criticism due to the extremely nonuniform behavior and the overloading of bolts. The results of this numerical case study promote a deeper understanding and help assessing the endplate joint behavior since they lack the uniqueness of the solution recommended by the building codes, which is particularly significant when hard-loaded structures have been designed for covering the spans of public building areas.

Back Analysis of Water and Earth Loads on Shield Tunnel and Structure Ultimate Limit State Assessment: A Case Study

2018 ◽  
Vol 44 (5) ◽  
pp. 4839-4853 ◽  
Author(s):  
Qixiang Yan ◽  
Weilie Zhang ◽  
Chuan Zhang ◽  
Hang Chen ◽  
Yongwen Dai ◽  
...  
Keyword(s):  
Limit State ◽  
Back Analysis ◽  
State Assessment ◽  
Shield Tunnel ◽  
Ultimate Limit State ◽  
Ultimate Limit

scholarly journals Analysis of relations between the moduli of elasticity in compression, tension, and static bending of hardwoods

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3278-3288
Author(s):  
João P. B. Almeida ◽  
Vinícius B. M. Aquino ◽  
Anderson R. V. Wolenski ◽  
Cristiane I. Campos ◽  
Julio C. Molina ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Geometric Model ◽  
Limit State ◽  
Accurate Estimation ◽  
Ultimate Limit State ◽  
Average Modulus ◽  
The One ◽  
Best Fit ◽  
Ultimate Limit ◽  
Two Parameter

Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) is of paramount importance for rational sizing of timber structures, given the use of this property in the estimation of stability of compressed parts (ultimate limit state, ULS) and in calculation of excessive strains (serviceability limit state, SLS). In Brazil, if values cannot be experimentally determined, ABNT NBR 7190 (1997) allows for estimation of Ec0 through relations to average modulus of elasticity both in tension parallel to the grain (Et0) (Ec0 = Et0) and in bending (EM) (Ec0 = EM/0.90). This research aimed to access the efficiency of these relations by testing 30 tropical wood species. The analysis of variance results showed that Ec0 and Et0 were statistically equal. However, Ec0 and EM/0.90 were not statistically equal, and the method of least squares resulted in a coefficient of 0.98, which was 8.89% higher than the one suggested by ABNT NBR 7190 (1997) and close to 1, thus, validating the results of ANOVA, which pointed on the equivalence between Ec0 and EM (Ec0 = EM). As an alternative to simplified equations of the standard, two-parameter regression models were used. The geometric model with R² = 91.67% proved to be the model of best fit, which demonstrated that Ec0 could be calculated as a function of EM.

scholarly journals Localization of Simulated Damage on a Steel Beam from Random Vibrations

2017 ◽  
Vol 62 (1) ◽  
pp. 112
Author(s):  
Jan Bayer ◽  
Jaromír Král ◽  
Shota Urushadze
Keyword(s):  
Limit State ◽  
Fe Analysis ◽  
New Combination ◽  
Mode Shapes ◽  
Steel Beam ◽  
Ultimate Limit State ◽  
Air Stream ◽  
Localization Criterion ◽  
Ultimate Limit

The performance of a few localization schemes using measured mode shapes was tested in an experimental case study with respect to the Ultimate Limit State (ULS). The first question to be posed was: Is it possible to indicate and locate damage under laboratory conditions before the ULS is reached? Relatively simple localization criteria were chosen, which do not require extensive FE analysis. A new combination of them, designated here as Combined Localization Criterion (CLI), was proposed that performed well in the presented case. A simple supported beam with the damage progressing in three consecutive stages was used for the experiments. Mode shapes in the range of up to 100 Hz were extracted from the response of the structure to the air stream.

scholarly journals NON-LINEAR ANALYSIS OF SLENDER MASONRY COLUMN SUBJECTED TO BIAXIAL BENDING

2021 ◽  
Vol 61 (2) ◽  
pp. 391-405
Author(s):  
Marek Vokál ◽  
Michal Drahorád
Keyword(s):  
Numerical Study ◽  
Limit State ◽  
Ultimate Limit State ◽  
Beam Model ◽  
Bending Moments ◽  
Biaxial Bending ◽  
Rigid Plastic ◽  
Internal Forces ◽  
Ultimate Limit ◽  
Current Code

The article deals with a method for analysing slender masonry columns. The proposed method uses material and geometric non-linearity. Various stress-strain diagrams can be used: linear, linear-plastic, parabolic-plastic, two various parabolic and rigid-plastic. In all cases, the tensile strength is neglected. The method can be used for analysing the column in accordance with Eurocodes in two ways: SLS (serviceability limit state) and ULS (ultimate limit state). The internal forces are calculated on a general beam model, with imperfections in both directions, which result in two bending moments in two perpendicular planes – biaxial bending. This case is not covered by the current code – Eurocode, even though all columns are more or less loaded in both directions. In this numerical study, using Matlab software, an algorithm was developed for modelling a real 3D case. The results of this study are also compared to the results of laboratory tests of masonry columns.

scholarly journals Causes of Failures in Circular Concrete Silo Walls, Particularly Under Environmental Influences

2021 ◽  
Vol 29 (4) ◽  
pp. 1-8
Author(s):  
Juraj Bilčík ◽  
Július Šoltész ◽  
Lýdia Leppakorpi Matiašková ◽  
Katarína Gajdošová
Keyword(s):  
Environmental Sustainability ◽  
Synergistic Effects ◽  
Limit State ◽  
Environmental Influences ◽  
Ultimate Limit State ◽  
Cylindrical Structures ◽  
Common Causes ◽  
Ultimate Limit State Design ◽  
Ultimate Limit

Abstract The paper reports the results of a case study for achieving longer service life and increasing the environmental sustainability of concrete silos. Damage mechanisms in concrete silo walls, and respectively in cylindrical structures (e.g., chimneys, cooling towers, and tanks), are widely diverse. The common causes of failures include those due to poor design considerations, construction deficiencies, non-compliance with operational rules and regulations, lack of maintenance, and insufficient and/or corroded reinforcements, together with the environmental conditions affecting the walls. In addition to the ultimate limit state design, temperature-induced cracking may often be underestimated in the design of reinforced concrete silos, leading to premature deterioration and losses in serviceability. Cracks from environmental or service conditions facilitate the ingress of moisture and corrosive agents. Therefore, there is an increased interest in reducing the appearance of cracks and limiting their width. The aim of this paper is to highlight the synergistic effects in the design, construction, and operation of silo walls, particularly under varying environmental influences. The research undertaken indicates that systematic errors can be identified and corrected.

Combined Reinforced Concrete Columns Strengthening with Steel Clipping and Concrete Surfacing

2021 ◽  
pp. 11-22
Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Limit State ◽  
Concrete Columns ◽  
Ultimate Limit State ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Entire Height ◽  
Complex Structural ◽  
Ultimate Limit

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.

Application potential of textile reinforcement in concrete construction for infrastructure buildings: environmental performance and availability

2021 ◽  
Author(s):  
Sara Reichenbach ◽  
Benjamin Kromoser ◽  
Philipp Preinstorfer ◽  
Tobias Huber
Keyword(s):  
High Performance ◽  
Construction Material ◽  
Limit State ◽  
Carbon Dioxide Emission ◽  
Resource Consumption ◽  
Ultimate Limit State ◽  
Textile Reinforced Concrete ◽  
Potential Applications ◽  
Application Potential ◽  
Ultimate Limit

<p>With the building industry being one of the main sources of carbon dioxide emission worldwide and concrete being the main construction material, new strategies have to be developed to reduce the carbon footprint thereof. The use of high-performance materials in structural concrete, as for example textile-reinforced concrete (TRC), seems to allow for a reduction of the resource consumption and the carbon emissions. The present paper addresses potential applications of TRC examining the global warming potential (GWP) of a rail platform barrier. The resource consumption is depicted in a parametrical study in terms of the necessary component height and reinforcement area considering both the serviceability limit state (SLS) as well as the ultimate limit state (ULS). The results clearly indicate an achievable reduction of the GWP during construction when using textile reinforcement made of high-performance fibres. Furthermore, an analysis of the European market was conducted to prove the availability of this new reinforcement type. </p>

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