Design of initial shape of membrane structures

Tento příspěvek se věnuje otázce navrhování a výpočtu membránových konstrukcí. V teoretické části bude pojednáno o problematice hledání výchozích tvarů, tedy o takzvané teorii form-finding. V praktické části bude prezentován návrh a výpočet membránové konstrukce zastřešení stadionu na konkrétním příkladu. Tato práce byla vypracována s ohledem na záměr firem Dlubal Software, s.r.o. a FEM consulting, s.r.o. vytvořit modul pro hledání výchozích tvarů membránových konstrukcí, jenž by byl následně implementován do softwaru RFEM.The subject of this article is the question of design and analysis of membrane structures. The first part of this article deals with the problem of form-finding. It is the problem of searching for the initial shape of membrane structure. In the second part of the article, an example of design and analysis of the membrane structure of a stadium roof is presented. This work was carried out with respect to the intention of companies Dlubal Software, s.r.o. and FEM consulting, s.r.o. to create the module for finding initial shapes of membrane structures, which would be consequently implemented to the software RFEM

Návrh a výpočet membránové konstrukce

The article deals with problems in designing and analyzing the membrane structure of a stadium roof. Attention is especially given to problems relating to the optimal design of the shape of the membrane (form finding) and the supporting cable system with respect to static behavior, functionality and architectural appearance. The work was carried out with respect to the companies Ing. Software Dlubal, s.r.o. and FEM consulting, s.r.o. intention to develop a new module of the RFEM program system capable of ascertaining the initial shape of a roof’s membrane construction and also its analysis for both static and dynamic wind loads.Článek se zabývá návrhem a výpočtem membránové konstrukce zastřešení stadionu. Pozornost je věnována především problematice optimálního návrhu tvaru membrány (form finding) a nosného lanového systému z hlediska statického působení, funkčnosti i architektonického vzhledu. Práce byla zadána s ohledem na záměr firem Ing. Software Dlubal, s.r.o. a FEM consulting, s.r.o., které spolupracují na vývoji programového system pro výpočet konstrukcí RFEM, doplnit tento programový systém o modul pro hledání výchozích tvarů membránových konstrukcí a jejich výpočet pro statické zatížení, ev. pro dynamické zatížení větrem

Parametric study of the structural response of NPP containment to impact loading

Prezentovaný článek je příspěvkem k celosvětové diskusi týkající se bezpečnosti jaderných elektráren, která zesílila po katastrofě v JE Fukushima Daiichi. Byla provedena parametrická studie pro různé materiály, tloušťky stěny kontejnmentu a různé rychlosti letadla před nárazem. Cílem práce bylo stanovení rozsahu poškození různých variant konstrukce kontejnmentu. Pro účely vyhodnocení poškození konstrukce byla sledována maximální trvalá deformace a rozsah plastického přetvoření kontejnmentu. Dalším cílem práce bylo ověření možnosti použití explicitní metody pro analýzu rychlých dynamických jevů v programu RFEM.The presented article is a contribution to the discussion concerning nuclear safety which has intensified after the Fukushima Daiichi nuclear disaster. A parametric study concerning various materials, containment wall thicknesses and different aircraft speeds before impact was performed. Containment damage was evaluated by means of the value of permanent deformation and plastic strain extent. The purpose of this study was also to foster experiential suggestions for improving the explicit method in the RFEM program in order to release it for RFEM users

Gamesourcing: Perspectives and Implementations

This chapter discusses game-based methods of problem solution and data processing, analysis, and information mining. Attention is mainly focused on swarm algorithm and principles used in the task of complex problem solving using computer games. We intensively discuss the interdisciplinary intersection between swarm systems dynamics and computer science, including a variety of data sources and examples. Possibilities of the new approach based on swarm algorithm used in a game or using principles of swarm algorithms to solve the problem are demonstrated here. More precisely, this chapter discusses modern methods of calculation and crowd use, so-called gamesourcing, i.e., game-driven crowdsourcing, from various points of view such as history, motivation, or paradigm and presents several examples of contemporary projects of this kind. Ideas, results, and methodologies reported and mentioned here are based on our previous results and experiments that are fully reported here for detailed study in the case of reader’s interest. Therefore, this chapter is an overview survey of our research

Dynamic analysis of viscous material models

summary:The article deals with the analysis of the dynamic behavior of a~concrete structural element during fast dynamic processes. The constitutive material model must be chosen appropriately so that it takes material viscosity into account when describing the behavior of material. In this analysis, it is necessary to use fairly complex viscous material models which can affect, for example, vibration damping and the dependence of strength or even of the entire stress-strain curve on the strain rate. These relatively complex models are often formed via the combination of viscoelastic models with viscoplastic models or viscous damage models. Numerical simulations are performed for these models. The numerical analysis is validated by experimental measurements

New methods in collision of bodies analysis

summary:The widely used method for solution of impacts of bodies, called the penalty method, is based on the contact force proportional to the length of the interpenetration of bodies. This method is regarded as unsatisfactory by the authors of this contribution, because of an inaccurate fulfillment of the energy conservation law and violation of the natural demand of impenetrability of bodies. Two non-traditional methods for the solution of impacts of bodies satisfy these demands exactly, or approximately, but much better than the penalty method. Namely the energy method exactly satisfies the conservation of energy law, whereas the kinematic method exactly satisfies the condition of impenetrability of bodies. Both these methods are superior in comparison with the penalty method, which is demonstrated by the results of several numerical examples

Advantages of Tensile Structure Analysis During Construction Stages

This paper deals with the importance of analysing tensile structures during individual construc- tion stages. This type of analysis is usually related to conventional structures. However, results of the re- search on this topic imply that problems caused by an insufficient design are solved on a building site on a daily basis. It usually is the engineer’s responsibility to find a proper solution and a method of construction. A challenging decision is strongly dependent on expe- rience and current status. This research contributes to a more detailed description of the problem

On the Nonlinear Transient Analysis of Structures

This chapter consists of four sub-chapters the first of them is the introduction. The second sub-chapter discusses the suitability of the explicit and implicit methods for seismic analysis of buildings exposed to a substantially nonlinear response. Taking into account a duration typical for earthquakes from several seconds to about twenty seconds, it seems that the implicit method is more suitable. Because of the shape of accelerograms, it is needed to use quite short time steps. Both methods were compared for a heavily nonlinear response, typical for seismicity. The third subchapter discusses the analysis of the time-dependent behavior of concrete using nonlinear time-dependent material models during fast dynamic actions. Huge plastic yielding or damage of the material is reached. The fourth sub-chapter discusses sources of dynamical damping that are needed in earthquake analysis. This subchapter aims to take into account the influence of different kinds of damping in the dynamic analysis of structures. More advanced analysis taking into account the various sources of damping, i.e., material viscosity, plasticity/damage, and friction in connections and supports is strongly recommended in the earthquake analysis

Video analysis of response of reinforced concrete beam to impact loading during drop test

A response of concrete and reinforced concrete structures to very rapid dynamic loading shows an increase of both tensile and compressive strength. This behaviour is also accompanied by an increase of stiffness of the structure. Described response can be numerically simulated only with adequate viscous nonlinear material model of concrete. The problem of these simulations is based not only on a necessity of a derivation of the right material model but also on viscous parameters whose values are not known in advance. The proposed article deals with experimental research of the response of the reinforced concrete beam exposed to impact loading during drop test. The beam response was measured with conventional strain gauges and accelerometers and whole experiment was recorded with 1000 frames per second by slow motion camera. Measured values of vertical acceleration were then compared with results of software analysis of slow-motion video footage. The paper contains the description of the experimental research, the comparison of conventional measurements with video analysis and the simulated response of the specimen in the software based on the finite element method using the viscous material model of concrete

Ponding Effect: Nonlinear Loading on Tensile Surface Structures

This paper deals with a potentially danger- ous phenomenon known as the ponding effect that may occur on tensile surface structures. This phenomenon may cause a local disorder that might lead to a fatal damage and collapse of the structure. The aim is to create and verify a searching algorithm in order to lo- calise a possible ponding effect occurrence. Its main purpose is to scan the membrane surface deformed un- der snow load and locate areas prone to accumulation of melted snow. Thereafter the area of water pond is cal- culated and the area is loaded with an additional weight. A verification is made on the conical structure consid- ering a variety of height to length ratios