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Wyniki wyszukiwania dla: LOADS OF THE MECHANISM
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Estimation of wind pressure acting on the new palm house in Gdansk
PublikacjaThis paper deals with the problem of numerical simulations of wind loads acting on a Palm House with complex geometry. Flow simulations with aid of computational fluid dynamics procedures have been performed to check if the pressure distributions for the structure are greater than those calculated using the standard design codes with assumption that the Palm House horizontal cross sections are described by smooth cylinders.
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Determination of the shape of the CFGFT cylindrical column based on laboratory tests
PublikacjaAnalyses were carried out on glass-fibre-reinforced polymer tube columns with reference to laboratory tests. The angles of the glass fibre beams were 20◦, 55◦ and 85◦. The study employed non-classical operational calculus. Various modulated harmonic signal shapes were considered for columns and tubes at buckling. The buckling loads were assessed and compared for different models.
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Selection of main engines for hopper suction dredgers with the use oobability models
PublikacjaThis paper presents a new original method of selection of main engines for hopper suction dredgers with regard to probabilistic models. It was proposed to use the normal distribution to describe the operational loads of the main receivers. The principles for determination of parameters of load distribution and design power of the main engines were formulated. Lastly, the principles of selection of the size and number of main engines...
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Stability analysis of nanobeams in hygrothermal environment based on a nonlocal strain gradient Timoshenko beam model under nonlinear thermal field
PublikacjaThis article is dedicated to analyzing the buckling behavior of nanobeam subjected to hygrothermal environments based on the principle of the Timoshenko beam theory. The hygroscopic environment has been considered as a linear stress field model, while the thermal environment is assumed to be a nonlinear stress field based on the Murnaghan model. The size-dependent effect of the nanobeam is captured by the nonlocal strain gradient...
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Study on the accuracy of axle load spectra used for pavement design
PublikacjaWeigh-in-Motion (WIM) systems are used in order to reduce the number of overloaded vehicles. Data collected from WIM provide characteristics of vehicle axle loads that are crucial for pavement design as well as for the development of pavement distress prediction models. The inaccuracy of WIM data lead to erroneous estimation of traffic loads and in consequence inaccurate prediction of pavement distress process. The objective of...
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Dynamic analysis of the railway bridge span under moving loads
PublikacjaThe first part of this paper provides a review of the state of knowledge of the dynamic behaviour of railway bridges under moving loads. Particular attention is paid to developments in modelling railway bridge loading and dynamic vehicle-span (structure) interaction. The most important aspects determining the advancements in this area of knowledge are identified. The contemporary techniques for defining bridge span finite element...
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Forecasting of railway track tamping based on settlement of sleepers using fuzzy logic
PublikacjaThe sleepers in a railway track transfer vertical, transverse and longitudinal loads to the track ballast and subgrade. The sleepers allow for keeping the distance between the rails constant. The thickness of ballast should be between 16 and 35 cm depending on the design standard of the track, and it should be densified where the ballast supports the sleeper. The exploitation causes contamination of the ballast, crushing the material...
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Edgewise Compressive Behavior of Composite Structural Insulated Panels with Magnesium Oxide Board Facings
PublikacjaEdgewise compression response of a composite structural insulated panel (CSIP) with magnesium oxide board facings was investigated. The discussed CSIP is a novel multifunctional sandwich panel introduced to the housing industry as a part of the wall, floor, and roof assemblies. The study aims to propose a computational tool for reliable prediction of failure modes of CSIPs subjected to concentric and eccentric axial loads. An advanced...
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Dome over the Gdynia seaport building
PublikacjaThe paper presents the description of structure and the selected problems of the technical condition, as well as the strength analysis of the thin-walled reinforced concrete shell which has been making a covering of the main hall of the Gdynia Seaport Building through the last 80 years. The rectangle projection of four single curvature shells of the dome was shaped out of mutual perpendicular intersection of two cylindrical shells. The...
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Distortional buckling of thin-walled columns of closed quadratic cross-section
PublikacjaThe elastic stability of axially compressed column related to the cross-section distortion is investigated. Two kinds of closed quadratic cross-sections are taken into consideration with internal walls and without it. The governing differential equation is derived with aid of the principle of stationary total potential energy. The critical loads for the simply supported columns are found in an analytical form and compared with...
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PROBABILISTIC ANALYSIS OF A SPACE TRUSS BY MEANS OF A MULTIDIMENSIONAL VARIABLE DESCRIPTION
PublikacjaThe objective of this paper is to present a variant of the point estimate method (PEM) to determine mean values and standard deviations of limit loads of engineering structures. This approach is illustrated by limit state analysis of a space truss, considering geometric and material imperfections. The calculations were performed for different random models, so the influence of random parameters on the limit load of the truss can...
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THE INFLUENCE OF POLYMER STRIPS IN REDUCTION OF A STEEL GRANDSTAND VIBRATIONS
PublikacjaGrandstands are types of structures commonly used during sport events or music concerts. Dynamic loads generated by crowd movement may have significant influence on human perception as well as may lead to the destruction of a structure. Lighter and more slender structural steel members are more easily excitable by spectators. If the synchronized movement is tuned with the natural frequency of the affected part of the structure,...
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Structural Dynamics and Stability of Composite Structures
PublikacjaThis an editorial for a special Issue devoted to the application of dynamic and stability analysis of composite structures. In structural applications, past few decades have seen outstanding advances in the use of composite materials including Functionally Graded Materials (FGM). Most structures, whether they are used in civil, marine, or aerospace engineering, are subjected to dynamic loads during their operation.Therefore, dynamic...
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Smart grid technologies in electric traction: Mini inverter station
PublikacjaThe growing number of trams and trolleybuses equipped with recuperation systems contribute to the increase in the amount of energy recovered during braking. It raises questions about the possibility of its usage. One of such possibilities is the use of smart grid technology. The paper presents a case study of the use of braking energy in the trolleybus system for external loads by implementing mini inverter stations. Analysis is...
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Biobatteries and biofuel cells with biphenylated carbon nanotubes
PublikacjaSingle-walled carbon nanotubes covalently biphenylated are used for the construction of cathodes in a flow biobattery and in flow biofuel cell. Zinc covered with a hopeite layer is the anode in the biobattery and glassy carbon electrode covered with bioconjugates of single-walled carbon nanotubes with glucose oxidase and catalase is anode of the biofuel cell. The potentials of the electrodes are measured vs. the Ag/AgCl reference...
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Stability analysis of single-walled carbon nanotubes embedded in winkler foundation placed in a thermal environment considering the surface effect using a new refined beam theory
PublikacjaThis article is devoted to investigate the stability of different types of Single Walled Carbon Nanotubes (SWCNTs) such as zigzag, chiral, and armchair types which are rested in Winkler elastic foundations exposing to both the low and high temperature environments. Also, the Surface effects which include surface energy and surface residual stresses, are taken into consideration in this study. It may be noted that the surface energy...
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Effect of selective laser treatment on initiation of fatigue crack in the main part of an undercarriage drag strut
PublikacjaThis paper presents the results of material characterization and a fatigue test conducted for a laser-re-melted drag strut used in an aircraft landing gear. The drag strut was re-melted with a CO2 laser beam. Eight re-melted paths were made in the form of spiral lines along the axis of the drag strut. Next, the drag strut was subjected to variable loads on a testing machine simulating loads occurring when an aircraft lands. The...
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Optimization of the Relative Humidity of Reactant Gases in Hydrogen Fuel Cells Using Dynamic Impedance Measurements
PublikacjaWater management is a key factor affecting the efficiency of proton exchange membrane fuel cells (PEMFCs). The currently used monitoring methods of PEMFCs provide limited information about which processes or components that humidity has a significant impact upon. Herein, we propose the use of a novel approach of impedance measurements using a multi-sinusoidal perturbation signal, which enables impedance measurements under dynamic...
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Structural reliability of overhead power lines by means of Monte Carlo Method and RSM
PublikacjaThe article discusses the issue of reliability assessment of overhead power lines by means of both Monte Carlo Method and Response Surface Method. The suspension tower OS24 ON150+10 is considered, as the weakest element of the line. A comparison is made between deterministic and probabilistic approaches to wind and icing loading. The PDFs for wind and icing loads are proposed. Reliability is assessed for both critical atmospheric...
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Derivation of the scaling laws used in geotechnical centrifuge modelling-application of dimensional analysis and Buckingham Π theorem
PublikacjaGeotechnical centrifuge modelling has been a world-wide used technology in physical tests. In this paper a derivation of scaling laws by dimensional analysis for the centrifugal modelling is presented. Basic principles of centrifuge modelling are described. Scaling laws for slow events like consolidation and fast events like dynamic loads are shown. The differences in scale factors for both processes are noticed. The aim of this...
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Load capacity of steel-aluminium brackets under static and cyclic laboratory tests
PublikacjaThe aim of the research is the laboratory investigation of steel-aluminium brackets employed to fasten lightweight curtain walls to building facilities. Static pressure, suction forces, and cyclic loads parallel to end plates (horizontal – to simulate wind influence) were applied in the study. The steel-aluminium brackets were tested on a reinforced concrete substrate made of C30/37 concrete class to simulate the real working conditions....
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Assessment of Fuel Cells’ State of Health by Low-Frequency Noise Measurements
PublikacjaWe proposed applying low-frequency (flicker) noise in proton-exchange membrane fuel cells under selected loads to assess their state of health. The measurement set-up comprised a precise data acquisition board and was able to record the DC voltage and its random component at the output. The set-up estimated the voltage noise power spectral density at frequencies up to a few hundred mHz. We observed the evolution of the electrical...
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Impact of rotor geometry optimization on the off-design ORC turbine performance
PublikacjaThe paper describes the method of CFD based Nelder-Mead optimization of a 10 kW single-stage axial turbine operating in an ORC system working on R7100. The total-to-static isentropic efficiency is defined as an objective function. Multi-point linear regression is carried out to determine the significance of the objective function arguments and to pick up the set of particular variables and characteristic quantities (e.g. flow angles)...
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Design of Structure of Tension Leg Platform for 6 MW Offshore Wind Turbine Based On Fem Analysis
PublikacjaThe article presents the calculation and design stages of the TLP platform serving as a supporting construction of a 6 MW offshore wind turbine. This platform is designed to anchor at sea at a depth of 60 m. The authors presented the method of parameterization and optimization of the hull geometry. For the two selected geometry variants, the load and motion calculations of the platform subjected to wind, wave and current under...
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DYNAMIC ANALYSIS OF THE IMPACT OF VIBRATION ON HISTORICAL BUILDINGS - AN OWN PROJECT OF EXTERNAL STAIRCASE
PublikacjaThis article presents numerical simulations that concern modeling of interaction of the external staircase’s construction with the observation deck on historic water tower located at Gdansk University of Technology. The interaction occurring according to various methods of the staircase's construction support on the wall of the historic tower was compared. The external staircase that allows for entering onto the monument was subjected...
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Reliability estimation of underground horizontal fuel tank limit states
PublikacjaFuel tanks are designed with regard to standard loads and operating conditions. The investigations of the paper show the impact of such factors as tank corrosion and other means on the variation of stress fields and deformation of the underground horizontal tank shell. The introduction of probabilistic methods allows for structural reliability assessment. While the computational time of the entire tank FEM model is high, the preliminary...
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Selected problems of sensitivity and reliability of a jack-up platform
PublikacjaThe paper deals with sensitivity and reliability applications to numerical studies of an off-shore platform model. Structural parameters and sea conditions are referred to the Baltic jack-up drilling platform. The study aims at the influence of particular basic variables on static and dynamic response as well as the probability of failure due to water waves and wind loads. The paper presents the sensitivity approach to a generalized...
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The impact of air humidity on the operation of proton exchange membrane fuel cells determined using dynamic electrochemical impedance spectroscopy
PublikacjaThis paper describes the changes in the fuel cell impedance across a range of current loads and humidity changes. The changes of each equivalent circuit parameters representing specific processes occurring in fuel cells, as a function of humidity and current changes, were determined. Within the combined scope of current and humidity, the optimal working conditions of the cells were determined, corresponding to the lowest impedance...
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Laminated plates and shells - first ply failure analysis within 6-parameter shell theory
PublikacjaThis work describes Tsai-Wu and Hashin criteria modifications, dictated by nonlinear 6-parameter shell theory with asymmetric strain measures and drilling rotation. The material law is based on standard orthotropic elastic constants for a non-polar continuum, under plane state of stress. First ply failure loads of cylindrical panel subjected to pressure and flat compressed plate are estimated by means of Finite Element Analysis....
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Static Series and Shunt-series PE Voltage-quality Controllers
PublikacjaAs presented in the Chap. 7 static shunt power electronics (PE) voltage-quality controllers protect the utility electrical system from the unfavorable impact of customer loads. Shunt controllers, as shown in Chap. 6, are recommended mainly for mitigation of the causes of disturbances, and not their effects in distanced nodes of a power-electronics system. In the case when reduction of disturbances effects is required, which leads...
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HIERARCHICAL CYCLES IN MODERN POWER SYSTEMS – EXERGY ANALYSIS UNDER PART LOADS
PublikacjaThe aim of the paper is to investigate thermodynamic efficiency of advanced hierarchic power cyclesunder partial loads by using of exergy analyze. Advanced hierarchical power systems arecomposed of few energy conversion cycles, most common are steam and gas cycles in various configurations, but they may contain fuel cells, ORC, lithium bromide absorption chillers and others. Moreover hierarchical cycles can be powered by several...
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Impact of overloaded vehicles on load equivalency factors and service period of flexible pavements
PublikacjaOverloaded vehicles occur less frequently in comparison to properly loaded vehicles but due to their greater potential to cause damage they significantly contribute to the distress of pavement structure. As the studies show, the phenomena of vehicles overloading intensifies when the control of traffic is poor and the average percentage of overloaded vehicles on analyzed roads varies from 6% to 23%. The main goal of the ar-ticle...
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Experimental Research on Insufficient Water Lubrication of Marine Stern Tube Journal Bearing with Elastic Polymer Bush
PublikacjaWater-lubricated bearings with polymer bushes are steadily gaining popularity due to their advantages, including environmental friendliness, relatively simple construction and long-term operation. Nevertheless, in practice instances of damage to such bearings occur due to insufficient or absent flow of the lubricating agent. In this study, experimental tests established that elastic polymer bush bearing is capable of operating...
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Logistical Aspects of Energy Conversion Efficiency in Marine Steam Power Plants in Off-Design Conditions
PublikacjaThe paper presents logistical aspects of energy conversion efficiency in off-design conditions. The main part of the article is based on results of thermodynamic calculation for large propulsion steam turbine under partial loads. Calculations are made on extended mathematical model of two proposed steam turbine thermodynamic cycles using Stodola’s cone law. The conclusion based on calculation re-sults contains importance of off-design...
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Influence of composition of raw wastewater on removal of nitrogen compounds in multistage treatment wetlands
PublikacjaInfluence of composition of raw wastewater on the efficiency of organic matter and nitrogen removal in multistage treatment wetlands has been examined. Commonly used indicators, like COD/BOD5 and BOD5/TN ratio, determining wastewater susceptibility to biodegradation in conventional treatment technologies were assessed. It was confirmed that multistage treatment wetland may be used for treatment of wastewater with high loads of...
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Tribological performance of PTFE-metal binary coatings in rolling/sliding contact
PublikacjaTribological performance of surface coatings with embedded PTFE reservoirs in rolling/sliding contact is reported. Using two different coating materials and two shapes and patterns of PTFE reservoirs test samples in the form of discs were prepared and tested in a four-ball contact configuration under loads corresponding to nominal contact pressure of 0.5 and 1.0 GPa. It was found that one coating, namely aluminium-bronze with embedded...
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EMC disturbances in connection of driving system
PublikacjaIt is known the steep voltage changes caused by IGBT frequency inverters may cause some electromagnetic problems in driving system. Special dU/dt type as well as sinusoidal filters are used in order to limit the level of the disturbances. The paper presents investigation results of EMC disturbances in inverter supplied induction motor. Experiments have proved that disturbances in current connection differ essentially. Important...
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Impact Assessment of Electric Vehicles Integration and Optimal Charging Schemes Under Uncertainty: A Case Study of Qatar
PublikacjaThe integration of electric vehicles (EVs) is rapidly growing compared to conventional vehicles in Qatar. To assess how these electric vehicles will impact Qatar’s distribution network, it is necessary to accurately model EV loads. However, EV loads exhibit uncertainties due to driving behaviour in charging time, state of charge (SOC), number of trips, and distance travelled. This necessitates the development of a probabilistic...
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Experimental study on the effectiveness of polymer dampers in reduction of structural vibrations
PublikacjaVibrations of civil engineering structures, generated by dynamic loads, may be very dangerous to the structures themselves as well as may have significant influence on human perception and comfort. A number of different methods have been proposed in order to minimize such situations. This concern newly designed structures as well as those which dynamic properties have to be modified due to problems with excessive vibrations. One...
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Water-Lubricated Sintered Bronze Journal Bearings—Theoretical and Experimental Research
PublikacjaWater lubricated bearings are used from many years in shipbuilding, hydro power and other industries because of their advantages such as: extensive serviceable life, low coefficient of friction, longevity of shaft sleeve, good abrasion resistance, low maintenance required, unit simplicity, no danger of pollution and low price. Various types of water lubricated sliding bearings have been tested at the Technical University of Gdansk...
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Experimental study on effectiveness of polymer dampers in reduction of structural vibrations
PublikacjaVibrations of civil engineering structures, generated by dynamic loads, may be very dangerous to the structures themselves as well as may have significant influence on human perception and comfort. A number of different methods have been proposed in order to minimize such situations. This concern newly designed structures as well as those which dynamic properties have to be modified due to problems with excessive vibrations. One...
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Verification of algorithms determining wave loads on support structure of wind turbine
PublikacjaThe offshore wind turbines require determination of wave loads on their support structure. This structure is fixed and, therefore, this problem is reduced to solving only the diffraction problem, which is determined by Laplace equation and conditions on the following boundaries: on the support structure, on the sea free surface and on its bottom, and at infinity on free surface. The linear problem was applied to determine the wave...
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Experimental test results of the 150kVA 18-pulse diode rectifier with series active power filter
PublikacjaThe paper presents the control system and selected results of experimental tests of the ac/dc power converter consisting of 18-pulse diode rectifier on the basis of coupled reactors and a serial active power filter. Three configurations of the 150kVA converter were tested experimentally and compared: 18-pulse diode rectifier with and without additional grid reactor and the rectifier integrated with the active power filter. The...
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Benchmarking Scalability and Security Configuration Impact for A Distributed Sensors-Server IOT Use Case
PublikacjaInternet of Things has been getting more and more attention and found numerous practical applications. Especially important in this context are performance, security and ability to cope with failures. Especially crucial is to find good trade-off between these. In this article we present results of practical tests with multiple clients representing sensors sending notifications to an IoT middleware – DeviceHive. We investigate performance...
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Sensitivity analysis of simple random beam models by means of Monte Carlo Methods using Variance Reductions Techniques
PublikacjaA probabilistic sensitivity analysis of two nonlinear bar structures is presented. The analysis is carried out on the basis of the Monte Carlo method. The imperfections of the structures and the applied loads are adapted as random variables. Based on all of the generated input variables, an output response of the system is sought. Afterwards, a coefficient responsible for the structure failure is calculated and the limit state...
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Parametric analysis of Istanbul's Ring Road viaduct for three levels of seismic load
PublikacjaThe paper presents a numerical analysis of the Istanbul's ring road viaduct that is currently under construction within the Northern Marmara Highway project. The structure, due to its location on seismic prone areas is exposed to seismic loads of different magnitude and different return periods. The study is fo-cused on concrete bridge supports that are design to work in nonlinear range. The study, conducted in SOFISTIK environment,...
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A COMPARISON OF THE WIND SPECTRUM ACCORDING TO DIFFERENT METHODS - AN ORIGINAL PROJECT OF A BUILDING ON A CLIFF IN GDYNIA
PublikacjaThe article presents numerical simulations of the dynamic wind loads on the structure of a building designed on a cliff in Gdynia. The results obtained from the two methods: Davenport’s and Karman’s are compared. The results allowed a comparison of the two methods, and they provided an answer to the question how a construction, designed in such an unusual condition of a cliff behaves under the influence of the gusting wind. The...
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VIBRATION PROBLEMS OF AN EXAMPLE OF TEMPORARY STEEL GRANDSTAND UNDER HUMAN-INDUCED EXCITATION
PublikacjaLighter and slender structural members of a typical grandstand leads to a significant reduction in the frequencies, that is why such structures are more easily induced to vibrations. The aim of the present paper is to show the results of our experimental studies and the numerical analyses, focused on the behaviour of a part of a typical temporary steel grandstand under dynamic loads. The peak values of accelerations of a steel...
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Stability of cylindrical steel silos composed of corrugated sheets and columns based on FE analyses versus Eurocode 3 approach
PublikacjaComprehensive static and dynamic 3D stability finite element analyses of a cylindrical steel silo composed of corrugated sheets and open thin-walled vertical stiffener profiles were carried out by taking the geometric and material non-linearity into account. The silowas subjected to axisymmetric and non-axisymmetric loads imposed by a bulk solid following Eurocode 1. Theoretical and measured initial geometric imperfections were...
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Dynamic analysis of temporary steel grandstand subjected to human-induced excitations due to jumping
PublikacjaSteel grandstands are structures that are frequently used during sport games and many other non-sporting events, such as festivals, music concerts, or even politicians rallies, with participation of a large number of attendees. Unfortunately, the presence of unexpected excessive dynamic loads due to unpredictable behaviour of spectators (e.g. synchronized harmonic jumping or swaying) may lead to...