The eminence exploitation of raw materials from the environment causes the natural sources to degrade and limits the future practices in the construction sector. The economy in this sector holds ...around 40% of the total flow of source materials into the GDP of the nation. The production of such materials are either consume a good amount of energy, responsible for causes of CO2, NOx, SOx, into the atmosphere or leads to the restriction on the usages of available natural sources in the future. Hence, the implementation of new practices for the incorporation of raw materials to save the extraction of available natural sources in the construction can be a beneficial foot step. The use of anagricultural by-product i.e. coconut shell can be a promising material for manufacturing the concrete in the partial replacement of coarse aggregates. Result indicates that coconut shell can be used as lightweight concrete which can be used in non-load bearing structures, strip footings and non-structural elements. Environmental concerns can also be minimizing by making such sustainable efficient practices by the use of these waste coconut shell materials.
The process of digital simulation of the design parameters of load-bearing structures when moving a cargo cart on them is developed on the example of a load-bearing beam of a crane (bridge. gantry, ......). This process includes three main stages. The first stage is the creation of appropriate mathematical multiparametric equations for automated simulation of: the values of reactions in the supports of the crane load-bearing beam; bending moments; transverse forces; displacements; beam deflection angles and maximum stresses at different positions of the cargo cart on the crane beam. The second stage is the creation of appropriate computer models in the Mathcad system using an effective functional programming language built into the system with a graphical representation of the simulation results depending on the location of the cargo cart on the load–bearing beam of the crane. The third stage is the animation simulation of the studied parameters, both for each parameter individually and all together.
The study investigates the effects of self-reacting lateral constraint on the compression load capacity of thin composite columns. A dynamic finite element analysis model is developed to aid in the ...optimization of the column lateral constraint which leads to a 50-fold increase in load capacity over the first critical buckling load. First, the model is compared against known analytical solutions for a column buckling between bi-lateral constraints. Next, the constraints are made to float and self-react, and the model is developed to study the role of column geometry, material properties, and initial gap between the column and lateral constraint on post-buckling response. Experiments are conducted over a wide range of column lengths and gap thicknesses and the load-deformation response including snap-through buckling loads, and buckling modes are measured and compared to model predictions. It is shown that the load capacity of thin composite columns can be increased to an upper bound governed by the membrane compressive strength of the column by using optimal constraint conditions.
Introduction. The article discusses the current state of the possibilities to improve the efficiency of construction processes by using fibre-reinforced concrete in the construction of transport and ...utility tunnels, as well as other critical building structures. The authors present foreign experience with widespread use of fibre-reinforced concrete in transport construction, as well as few such cases for domestic practice. The inconsistency of domestic experience with the modern state of art has been noted. The main blockers in the development of the issue are under consideration, the theoretical approach and practical application are presented. Materials and methods. The principal aspects of the current approach to the quality indicators of fibre-reinforced concrete and the classification principles of fibre-reinforced concrete based on quality criteria, which are the basis for the normalization of material characteristics, are described. The continuity of domestic and European regulatory documents is shown. Results. Illustrated examples of the possibilities of an optimization approach to the selection of structural solutions in the design of transport construction facilities used in international practice are described. Conclusion. The argumentation in favor of technology development is shown. This opens up possibilities for significant cost reduction justified by a scientific approach. In conclusion, the authors provide recommendations on the general application of the promising material in the domestic practice
This article discusses various types of protective anti-corrosion coatings for machine parts and load-bearing structures that exist today. A comparative analysis of coatings based on polymeric ...materials is given.
The reliability and safety of mobile vehicles is determined by their carrier system. Achieving a low probability of failure of structures and reducing the cost of equipment is possible by changing ...the traditional methods of predicting reliability and applying risk analysis, as well as using risk-based design. The aim of the work is to develop methods for predicting the cyclic durability of elements, fastening prefabricated load-bearing structures and analysis to achieve acceptable risks of mobile vehicles at the stages of risk-oriented design. The methods and standards were developed in order to provide methodological support of risk-based design. Those allow designers and engineers to use new methods of design and calculation of tractor and agricultural machinery. It is proposed to introduce into the existing notation system of design and technological documentation the identifiers for parameters as the priority indicators and to achieve when designing the probability of occurrence of each potential cause of failure up to a given level of risk, taking into account priority. The tool for achieving low failure probabilities is the construction of diagrams of cause-and-effect relationships of failures is the source of cause and effect based on the method of deduction and induction. A calculation and experimental method for predicting reliability, according to the criterion of cyclic durability of load-bearing structures and fasteners was developed. The technique is based on local modeling of damage initiation zones, taking into account the influence of design and technological factors of production, simulating the load mode of a mobile vehicle, its damage zones. The following are used for the calculation: finite element method, experimental load assessment, fatigue resistance characteristics of load-bearing elements, rivets and bolts, damage accumulation hypotheses. Risk analysis is carried out using the FMEA methodology. As a result of the risk analysis in a probabilistic formulation, a conclusion is made about the possible damage to the supplier the number of mobile vehicles that will not ensure the fulfillment of the stated requirements for a given resource and warranty mileage. Thus, data for assessing risks and making a decision on the advisability of redesigning equipment appear. The created methodological support for predicting cyclic durability and risk analysis for the implementation of risk-based design allows: to eliminate the uncompetitive level of product quality and production quality, as well as low efficiency and labor productivity; apply new design technologies, design and production preparation methods that reduce development time. The developed methods and means of the risk-based approach have been widely tested and are used in the practice of auto-tractor-agricultural machine building.
Thanks to the introduction of high-performance composite materials, 'metal replacement' approaches are successfully gaining ground even in the most challenging engineering applications. Among these, ...one of the most recent application challenges is improving the driving range of Battery Electric Vehicles (BEVs) by adopting innovative materials to lighten the mass of structural components, thus reducing energy requirements and enabling the use of smaller and less expensive batteries. Hence, in the present work, the employment of laminated composite panels in an electric minibus chassis is investigated as an effective way to reduce the global mass of the chassis’ structure and, at the same time, to increase its structural performances in terms of torsional stiffness and crashworthiness. By replacing specific steel tubulars with carbon-fiber-reinforced polymer (CFRP) laminated composite structures, different chassis configurations were numerically developed and detailed simulations to compare both masses and mechanical responses were carried out. The paper proves that with this approach it is possible to lighten the chassis up to 9%, while achieving a 7% increase in torsional stiffness and a 9% increase in Specific Energy Absorption (SEA).
Abstract
Die adaptive Fertigung von Fertigbetonbauteilen für modulare Tragwerke birgt das Potenzial, Ausschuss und Nacharbeit zu reduzieren. Bei diesem Ansatz wird der Fertigungsprozess auf Basis der ...Geometrien bereits gefertigter Module iterativ angepasst, sodass sich Maßabweichungen im Gesamttragwerk bestmöglich kompensieren. Im vorliegenden Aufsatz wird untersucht, wie eine solche Kompensation durch gezielte Anordnung der Module in modularen Tragwerken erfolgen kann. Hierzu wird zunächst ein Maß entwickelt, um modulare Tragwerke unter Berücksichtigung der Kompensation von Maßabweichungen geometrisch zu bewerten. Anschließend wird darauf aufbauend ein Optimierungsmodell vorgestellt, mit dem eine optimale Anordnung von Modulen mit gegebenen Maßabweichungen berechnet werden kann. Hiermit werden optimale Lösungen für ausgewählte Fälle betrachtet, um hieraus einen allgemeingültigen Zusammenhang zwischen den Geometrien der einzelnen Bauteile und der geometrischen Bewertung des resultierenden Tragwerks herzustellen. Diese Erkenntnisse dienen als Grundlage für eine adaptive Fertigung.
Abstract
Geometric evaluation and optimization of module arrangement in load bearing structures – towards adaptive manufacturing in civil engineering
Adaptive manufacturing of precast concrete components for modular structures has the potential to reduce scrap and rework. In this approach, the manufacturing process is iteratively adapted on the basis of the geometries of already manufactured modules so that dimensional deviations in the overall structure are compensated for in the best possible way. This article investigates how such a targeted compensation can be achieved by an arrangement of modules in modular structures. First, a measure is developed to geometrically evaluate modular structures with respect to the compensation of dimensional deviations. Then, based on this, an optimization model is presented with which an optimal arrangement of modules with given dimensional deviations can be calculated. Hereby, optimal solutions for selected problems are considered in order to establish a generally valid relationship between the geometries of the individual components and the geometric evaluation of the resulting structure. These findings serve as a basis for adaptive manufacturing.
Gathering knowledge and data for diagnosis is highly important for the safeguarding and conservation of architectural heritage. These data should be organised in order to create a complex list of ...procedures to find sufficiently sensitive, effective and reasonably inexpensive technical processes to survey and to repair, renew and maintain load-bearing structures of potential heritage values.
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Evaluation per Partes or Evaluation by Parts method developed by Eberhardt and Pospisil for assessing sensitivity of heritage valuable buildings and structures to invasiveness of diagnostics and repair methods.
The research is based on an analysis of the concept "heritage value"
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Grant of the Ministry of Culture of the Czech Republic NAKI DG18P02OVV033. The NAKI program's vision is to achieve the maintenance and sustainable development of a specific national and cultural identity and integrity and cultural heritage in the context of European and world culture in the 21
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century and in the conditions of expected global change through applied research and development. (see: Program na podporu aplikovaneho vyzkumu a experimentalniho vyvoje narodni a kulturni identity na leta 2016 až 2022, NAKI II, p. 6, Ministry of Culture of the Czech Republic, Prague 2013).
. As a typical multidisciplinary field of research, practical tasks in heritage preservation show that heritage value should be understood as a complex value composed of varied elementary segments coming from different fields of human activities. Whereas each field has its own logical verifying rules and its own research methodology, each elementary segment is evaluated separately.
The present article introduces the "E-P Heritage value assessment method" (E-P method) as a methodology for assessing the heritage values of buildings and structures or of their parts. The second purpose is to find a sufficiently sensitive process how to avoid invasive diagnostics on the architectural heritage. The procedure is aimed to be applied both on protected and non-protected buildings and structures.
