scholarly journals A Proposal to Improve the Effectiveness of the Deflection Control Method Provided by Eurocodes for Concrete, Timber, and Composite Slabs

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7627
Author(s):  
Tommaso D’Antino ◽  
Marco Andrea Pisani
Keyword(s):  
Control Method ◽  
Maximum Deflection ◽  
Structural Members ◽  
Timber Beam ◽  
Eurocode 2 ◽  
Composite Slabs ◽  
Different Types ◽  
Deflection Limit ◽  
Ultimate Limit ◽  
Curvature Control

Limited deflection of structural members represents an important requirement to guarantee proper functionality and appearance of building and infrastructures. According to Eurocodes, this requirement is ensured by limiting the maximum deflection of horizontal structural members to a fraction of their span. However, each Eurocode provides different maximum deflection limits, which are independent of the type of superstructures considered. Thus, the respect of these limits may not always guarantee the integrity of certain superstructures. In this paper, the reliability of the Eurocode deflection control methods, in guaranteeing the integrity of the superstructures, is assessed and discussed. First, different types of horizontal member, namely rib and clay (hollow) pot, composite steel–concrete, and timber beam slabs are designed to respect the deflection limit enforced by the Eurocodes. Then, the maximum curvature developed by these members is compared with the ultimate (limit) curvatures of various superstructures (e.g., ceramic and stone tile floorings). The results obtained show that the approach adopted by Eurocode 2 may provide non-conservative results, but also that the rules proposed by Eurocodes 4 and 5, albeit more reliable, do not always guarantee the integrity of the superstructure. Based on these results, an alternative method, based on the curvature control, is proposed and its advantages and limitations critically discussed. This method appears simpler and more reliable than the method currently adopted by the Eurocodes.

Research on Human-Computer Interaction Control Method in the Background of Internet of Things

2021 ◽  
Author(s):  
Yingying Hu ◽  
Zhongyang Li
Keyword(s):  
Internet Of Things ◽  
Control Method ◽  
Computer Control ◽  
Control Device ◽  
Smart Devices ◽  
The Internet ◽  
Interactive Control ◽  
Interaction Control ◽  
Different Types ◽  
The Internet Of Things

Against the background of the growing development of the Internet of Things, this article conducts research on more efficient methods for controlling the interconnection of all things, and proposes that smart devices use the same operating platform, and the human-computer interface presents universal modular controls for manipulation, it can satisfy the requirement that one device controls several different types of controlled device simultaneously. At the same time, the interactive method uses the controlled device to actively submit control content to the control device, and discusses the human-computer interactive control method applicable to the Internet of Everything, and strives to achieve a convenient and easy-to-use human-computer control experience.

An Evaluation and Comparison of Models for Maximum Deflection of Stiffened Plates Using Finite Element Analysis

2007 ◽  
Vol 44 (04) ◽  
pp. 212-225
Author(s):  
Lior Banai ◽  
Omri Pedatzur
Keyword(s):  
Finite Element ◽  
Orthotropic Plate ◽  
Lateral Pressure ◽  
Stiffened Plates ◽  
Maximum Deflection ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Element Analysis ◽  
The Past ◽  
Different Types

Stiffened plates form the backbone of most of a ship's structure. Today, finite element (FE) models are used to analyze the behavior of such structural elements for different types of loads. In the past, when usage of computers and FE models were not used very much, analytical analysis methods were required. Two well-known methods have been developed for analyses of stiffened plates under lateral loading (uniform pressure), based on two different models, namely, the orthotropic plate model and the grillage model. Both models can give estimations for the maximum plate deflection under uniform lateral pressure. The objective of this paper is to present the two methods, evaluate and compare the methods using the finite element method, and finally implement the methods as a computer program for quick estimations of the maximum deflection of stiffened plates. The degree of accuracy of the two methods when compared to FE is discussed in some detail.

APPLICATION OF UNCERTAINTY ANALYSIS TO STABILITY PROBLEMS OF STEEL-CONCRETE STRUCTURAL MEMBERS

2009 ◽  
Vol 1 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Libor Puklický ◽  
Zdeněk Kala
Keyword(s):  
Epistemic Uncertainty ◽  
Limit State ◽  
Ultimate Limit State ◽  
Load Carrying Capacity ◽  
Structural Members ◽  
Load Carrying ◽  
Steel Sections ◽  
Limit Stress ◽  
Ultimate Limit

The paper deals with the fuzzy analysis of the ultimate limit state of a steel strut with an encased web in compression. The first part of the paper lists presumptions required for the determination of the theoretical load carrying capacity for the column. Stresses in the concrete and steel sections are determined according to the principles of elasticity. The ultimate limit state is given as the limit stress attained in the most stressed section of either the steel or concrete section. A general extended principle, which takes into account the epistemic uncertainty of input parameters, was utilized for the conducted analysis.

Study of the Different Transmission Line Faults for a Grid Connected Wind Farm with Different Types of Control Method for RSC

2017 ◽  
Vol 5 (2) ◽  
pp. 338
Author(s):  
Reza Najafi
Keyword(s):  
Wind Farm ◽  
Control Method ◽  
Wind Energy Conversion ◽  
Remote Areas ◽  
Power Stations ◽  
Simulink Simulation ◽  
Different Types ◽  
Energy Conversion System ◽  
Rotor Side Converter ◽  
Proper Operation

<p>Wind power stations, many  located in remote areas; so they are characterized by weak grids and are often submitted to power system disturbance like faults. In this paper, the behaviour of a wind energy conversion system that uses the control of the rotor side converter (RSC) by three different methods  under faulty conditions is presented. The behaviour of these systems during a grid failure is an important issue.  DFIG is analysed and simulated under differing faulty conditions in the environment of MATLAB/SIMULINK. Simulation results show that the proposed method has proper operation during fault conditions.</p><p> </p>

PERIODIC RESPONSE TO EXTERNAL STIMULATION OF A CHAOTIC NEURAL NETWORK WITH DELAYED FEEDBACK

1999 ◽  
Vol 09 (04) ◽  
pp. 713-722 ◽  
Author(s):  
ALBAN PUI MAN TSUI ◽  
ANTONIA J. JONES
Keyword(s):  
Neural Network ◽  
Chaos Control ◽  
Control Method ◽  
Original System ◽  
Neural System ◽  
Delayed Feedback ◽  
Input Stimulus ◽  
Biologically Inspired ◽  
External Stimulation ◽  
Different Types

We construct a feedforward neural network so that when the outputs are fed back into the inputs and the system is iterated it behaves chaotically. We call this the "rest state". Suppose now that an input stimulus is added to one or more inputs. Following a biologically inspired model suggested by Freeman [1991], under these conditions we should want the behavior of the network to stabilize into an unstable periodic orbit of the original system. We call this the "retrieval behavior" since it is analogous to the act of recognition. Standard methods of chaos control, such as OGY for example, used to elicit the retrieval behavior would be inappropriate, since such methods involve calculations external to the system being controlled and can be considered unlikely in a biological neural network. Using a chaos control method originally suggested by Pyragas [1992] we show that retrieval behavior can occur as a result of delayed feedback and examine the variety of the responses that arise under different types of stimuli and under noise. This artificial neural system has a strong dynamical parallel to Freeman's observed biological phenomenon.

Small Satellite Modelling and Three-Axis Magnetorquer-Based Stabilisation Using Fuzzy Logic Control

2012 ◽  
Vol 152-154 ◽  
pp. 1639-1644
Author(s):  
Amirhossein Asadabadi ◽  
Amir M. Anvar
Keyword(s):  
Fuzzy Logic ◽  
Attitude Control ◽  
Fuzzy Logic Control ◽  
Control Method ◽  
Small Satellite ◽  
Electromagnetic Actuation ◽  
Small Satellites ◽  
Logic Control ◽  
Electromagnetic Coils ◽  
Different Types

Recently small satellites have become increasingly popular because of their ability to provide educational institutes with the chance to design, construct, and test their spacecraft from beginning to the possible launch due to the low launching cost and development of microelectronics (Figure 1). Clearly, using only electromagnetic coils instead of different types of actuators will serve the purpose of weight reduction where every grams counts. But some restrictions described in the paper limit utilising only “Electromagnetic” actuation for 3D stabilisation and adversely affects the efficiency of the controller. However, there are some theories developed recently that have made the aforementioned purpose feasible. In this paper a new control method based on Fuzzy Logic Control (FLC) is presented that keeps the satellite in desired conditions only by electromagnetic coils. More precisely, an approach of Fuzzy control which is incorporated with electromagnetic actuation is presented for the in-orbit attitude control of a small satellite. The design is developed to stabilize the spacecraft against disturbances with a three-axis stabilizing capability. The paper also describes the required hardware and the design and development of the magnetic torquers.

Investigation of Ultimate Limit State Safety Margins in the Structural Design Rules

2017 ◽  
Author(s):  
Kristoffer Lofthaug ◽  
Lars Brubak ◽  
Åge Bøe ◽  
Eivind Steen
Keyword(s):  
Finite Elements ◽  
Safety Factor ◽  
Limit State ◽  
Load Level ◽  
Structural Safety ◽  
Ultimate Limit State ◽  
Structural Members ◽  
Safety Margins ◽  
Non Linear ◽  
Ultimate Limit

A study to document the Ultimate Limit State (ULS) safety margins built into the DNV GL rules for Bulk and Tanker is presented. Critical structural members were identified together with the load level at which these members start to develop permanent buckling sets exceeding normal fabrication tolerances. These critical load levels are then compared with the local ULS rule strength limits in order to have a measure for the structural safety margins and hull redundancy. Non-linear finite element (NFLE) analyses were performed to estimate the structural response for different focus areas (critical structural members). Typically, critical members in bottom, deck, transverse bulkhead and hopper were chosen. Cargo hold models were developed both with linear finite elements, [1,2] and non-linear finite elements, [3]. In the non-linear FE analysis, the structural safety factor for ULS was defined as the load level giving permanent plastic deformation equal to the permissible distortion (production tolerances) for structural members. The non-linear FE results were compared with the maximum permissible load level with respect to buckling and yielding according to DNV GL Ship rules [1] inclusive Common Structural Rules for BC&OT (CSR) [4]. The structural safety factor shows a typical value of 1.2–1.4, and for most cases the plate is governing dimensioning structural member. This study has identified significant structural safety margins, typically 20–40% above rule acceptance level for typical highly utilized local areas in Bulk and Tanker hulls. It is to be noted that global Hull Girder Capacity is not addressed in present paper.

scholarly journals Method of critical control of atmospheric radiosounding data in the range of extreme deviations

2019 ◽  
pp. 23-32
Author(s):  
M. V. Savenets
Keyword(s):  
Control Method ◽  
Lower Troposphere ◽  
Threshold Values ◽  
Night Time ◽  
Total Period ◽  
Control Techniques ◽  
Second Stage ◽  
Total Percentage ◽  
Different Types ◽  
Distribution Parameters

The paper presents a new method of critical control of atmospheric radiosounding data in the range of extreme deviations of air temperature, isobaric level elevation, relative humidity and wind components. The method was developed based on atmospheric radiosounding data taken from 9 Ukrainian aerological stations over the period of 1973–2018. “Buoyant” threshold values form the basis of the developed method. These values correspond to the deviation threshold for each of aerological characteristics where statistical distribution of such characteristics reaches a zero value for the first time. Departure from constant threshold values in favor of “buoyant” values allowed for consideration of the main features of aerological characteristics dispersion, dependence from altitude and difference of distribution parameters observed during daylight and at night time. Potential errors in the range of extreme deviations may be identified when the values go beyond the thresholds of "the distribution body". The total percentage of such overrange amounts to 0.2% in the middle and upper troposphere, 0.3–1.8% in the lower troposphere, and up to 2% in the stratosphere. At the second stage of the developed method potential errors are checked using partial vertical, partial horizontal and temporal control techniques. The second stage of control is implemented for the levels where time series reach at least 3700 values. It allows for accurate calculation of average multi-year values required for performing the horizontal control. Potential errors are considered as real ones if there is a confirmation of existence of three extreme deviations taken from the “neighbor stations – neighbor observation periods – neighbor isobaric levels” set. It means that a potential error should be confirmed with at least two different types of critical control. At high altitudes two confirmations are enough provided a conclusion is made following the results of different types of control. The developed critical control method allowed rejection of the claim about incorrectness of 568 values with their maximum deviations reaching 6.2 and -6.4 σ for the total period of observation. The critical control of extreme deviations and the physical permissible limits control form necessary components of the complex critical control of atmospheric radiosounding data. They provide input information used for horizontal, vertical and hydrostatic control techniques.

scholarly journals ON SHEAR REINFORCEMENT DESIGN OF STRUCTURAL CONCRETE BEAMS ON THE BASIS OF THEORY OF PLASTICITY

2009 ◽  
Vol 15 (4) ◽  
pp. 395-403 ◽  
Author(s):  
Bjarne Christian Jensen ◽  
Andrzej Lapko
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Strength ◽  
Structural Members ◽  
Shear Reinforcement ◽  
Reinforcing Bars ◽  
Shear Design ◽  
Theory Of Plasticity ◽  
Eurocode 2 ◽  
Reinforcement Design

Modern design of reinforced concrete structural members for shear is based on the theory of plasticity. This paper is written to contribute to the understanding of the inclination of the concrete strut in the inclined strut model for design of shear reinforcement in beams, which among others are used in Eurocode 2. The problem of inclination of the compression strut in truss model is analysed depending on shear reinforcement ratio and effectiveness ratio of concrete strength for compression. Also the understanding of necessary ductility in steel reinforcing bars is discussed in the paper and especially the needs of tests on translation capacity of the shear failure are here analysed. To explain these problems the paper gives a short introduction to the theory of plasticity of reinforced concrete in shear and the background for the equations, which are used in shear design according to Eurocode 2. Santrauka Šiuolaikinis gelžbetonio elementų skersinės armatūros skaičiavimas pagrįstas plastiškumo teorijos principais. Straipsnyje pateikti sijų skersinės armatūros skaičiavimo ypatumai, taikant įstrižojo statramsčio modelį, kuris taikomas ir Eurokode 2. Išnagrinėtas gniuždomojo strypo pavertimas santvaros modelyje, atsižvelgiant į skersinės armatūros ir efektyvaus gniuždomojo betono stiprio santykį. Aptartas armatūrinio plieno strypų stamantrumas, akcentuota sijų laikomosios galios šlyčiai eksperimentinių tyrimų būtinybė. Pateiktas gelžbetoninių sijų šlyties skaičiavimas, taikant plastiškumo teorijos principus. Aptartas Eurokode 2 šlyties skaičiavimams taikomų priklausomybių teorinis pagrindas.

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