Membrane structures and their use in civil engineering

This paper is focused on the static analysis of membrane structures, which are typical for their ability to transfer only tensile forces. Membrane structures are becoming more popular owing to their lower initial cost and potential for use in structures with higher aesthetic claims. However, the designs of membrane face some challenges related to the specific properties of these support systems. This paper aims to analyse the current possibilities for using membrane structures and to evaluate these structures in terms of materials and design details and using numerical methods

Probabilistic calculation of fatigue crack progression using FCProbCalc code

Příspěvek je zaměřen na jeden z možných způsobů posouzení spolehlivosti cyklicky namáhané ocelové konstrukce s ohledem na vznik únavových trhlin z okraje a povrchu, které vede k návrhu systému prohlídek konstrukčních detailů náchylných na únavové poškození. Pro řešení pravděpodobnostní úlohy byla použita nově vyvíjená metoda Přímého Optimalizovaného Pravděpodobnostního Výpočtu (zkráceně POPV), implementovaná do programu FCProbCalc.The paper gives examples of the probabilistic assessment of a steel cyclic loaded structure. Fatigue progression of the cracks from the edge and from the surface is used as a basis for proposing a system of inspections of details which tend to be damaged by fatigue. The newly developed method Direct Optimized Probabilistic Calculation (DOProC method) was used for solution. The method was applied in FCProbCalc code

Přímý Optimalizovaný Pravděpodobnostní Výpočet

pravděpodobnostní výpočet, posudek spolehlivosti, pravděpodobnost poruchy, návrhová pravděpodobnost, funkce spolehlivosti, rezerva spolehlivosti, histogram, rozdělení pravděpodobnosti, náhodná proměnná Přímý Optimalizovaný Pravděpodobnostní Výpočet, POPV, Direct Optimized Probabilistic Calculation, DOProC, grupování, intervalová optimalizace, zónová optimalizace, trendová optimalizace, paralelizace, ProbCalc, HistAn, HistAn2D, HistAn3D, HistOp únavová trhlina, plocha oslabení, lineární lomová mechanika, přípustný rozměr, měřitelný rozměr, iniciační rozměr, šíření z okraje, šíření z povrchu, podmíněná pravděpodobnost, prohlídka konstrukce, FCProbCalc kotevní výztuž, redukovaná pevnost, geomechanický klasifikační koeficient, délka kotvy, únosnost kotvy, Ancho

Analysis of variable parameters of prediction models

The article deals with the calculation of corrosion losses of weathering steels with doseresponse functions. The environmental parameters of atmospheric corrosion incoming the dose-response functions are analysed by statistic and probabilistic methods. Between main environmental parameters belong temperature T, concentration of sulphur dioxide, relative air humidity RH, and deposition of chloride. Long-term measurements of environmental characteristics at atmospheric test sites were used for the analysis. All the environmental parameters incoming the dose-response functions are considered random variables represented by corresponding histogram. Using the probabilistic analysis it is possible to predict the expected range of corrosion rates and to analyse the impact of particular environmental characteristic on corrosion process

Probabilistic reliability assessment of truss construction in MATLAB software platform

Příspěvek se zabývá využitím pravděpodobnostních postupů při posouzení spolehlivosti příhradové nosné konstrukce. K výpočtu pravděpodobnosti poruchy posuzovaných nosných prvků i celého nosného systému byla zvolena klasická simulační technika Monte Carlo, aplikovaná v programovém systému MATLAB s využitím daného generátoru pseudonáhodných čísel a možnosti paralelizace u vícejádrových procesorů. Cílem práce byla analýza využitelnosti MATLABu pro pravděpodobnostní výpočty a pravděpodobnostní posudky spolehlivosti nosných konstrukcíThis paper deals with the use of probabilistic methods in assessing the reliability of the truss support structure. Classical Monte Carlo simulation technique was chosen for calculation of failure probability in structural elements and the entire support system under assessment. Numerical calculation was applied in MATLAB software system using the random number generator and parallelization using multi-core processors. The aim of the study was to analyse the usability of MATLAB for probability calculations and probabilistic reliability assessments of load-bearing structure

Monitoring of excessive deformation of steel structure Extra-High Voltage pylons

Reliability and security of a power transmission depends on the state of the power grid and mainly on the state of the Extra-High Voltage pylons. The paper deals with deformation analysis of existing steel structure of selected Extra-High Voltage pylons which showed excessive differences comparing to the original design. In the assessment of the situation, geodetic survey of selected pylons of power grid that showed the greatest deformation was performed. On taken images, deformation of steel structures by using the FOTOMNG system was also analyzed. The proposed method allows a modeling of the structure of the object based on precisely obtained photographic documentation of the current state. It also represents a very effective method which allows to quickly and efficiently analyze the deformation in the structure of Extra-High Voltage pylons in the critical position of the power grid. Other benefits include the possibility of repeatable and safe measurement.Web of Science62232932

Durability Analysis of Concrete Bridge Deck Exposed to the Chloride Ions Using Direct Optimized Probabilistic Calculation

Durability of reinforced concrete structures is a deeply discussed problem recently. Concrete structures in the external environment are very often affected by chloride ions from de-icing salt or sea water. Chloride ions penetrate through the concrete cover layer of the reinforcement and can cause eventually the corrosion of the steel. However, when estimating the durability of the structure, it is not sometimes possible to express the parameters by constant values; therefore, the probabilistic methods come in handy. Then, the variability of inputs and outputs can be expressed by histograms. Two probabilistic approaches were applied in this task – Monte Carlo simulation with Simulation-Based Reliability Assessment method, which is widely used for such type of problems, and the Direct Optimized Probabilistic Calculation, which is still relatively new type of approach. The result is a comparison of mentioned methods in terms of accuracy on the model of one-dimensional chloride penetration with time independent diffusion coefficient by using the Fick’s Second Law of Diffusion