Petr Janas

Using DOProC Method in Structural Reliability Assessment

Reliability of load-carrying structures has been assessed by various calculation procedures based on probability theory and mathematic statistics, which have been becoming more and more popular. The calculation procedures are well-suited for the design of elements in load-carrying structures with the required level of reliability if at least some input parameters are random and contribute to a qualitatively higher level of the reliability assessment and, in turn, higher safety of those who use the buildings and facilities. This paper discusses application of the original and new probabilistic methods – the Direct Optimized Probabilistic Calculation (“DOProC”), which uses a purely numerical approach without any simulation techniques. This provides more accurate solutions to probabilistic tasks, and, in some cases, to considerably faster completion of computations.

The Use of the Direct Optimized Probabilistic Calculation Method in Design of Bolt Reinforcement for Underground and Mining Workings

The load-carrying system of each construction should fulfill several conditions which represent reliable criteria in the assessment procedure. It is the theory of structural reliability which determines probability of keeping required properties of constructions. Using this theory, it is possible to apply probabilistic computations based on the probability theory and mathematic statistics. Development of those methods has become more and more popular; it is used, in particular, in designs of load-carrying structures with the required level or reliability when at least some input variables in the design are random. The objective of this paper is to indicate the current scope which might be covered by the new method—Direct Optimized Probabilistic Calculation (DOProC) in assessments of reliability of load-carrying structures. DOProC uses a purely numerical approach without any simulation techniques. This provides more accurate solutions to probabilistic tasks, and, in some cases, such approach results in considerably faster completion of computations. DOProC can be used to solve efficiently a number of probabilistic computations. A very good sphere of application for DOProC is the assessment of the bolt reinforcement in the underground and mining workings. For the purposes above, a special software application—“Anchor”—has been developed.

Software Package Probcalc from the Point of View of a User

Software Package Probcalc from the Point of View of a User The development of Direct Optimized Probabilistic Calculation method (DOProC) started in 2002. DOProC applications are processed in ProbCalc - this software is being improved all the time. It is rather easy to implement an analytical transformation model of the specific probabilistic application into ProbCalc. The reliability function under analysis can be expressed in ProbCalc analytically as a sign arithmetic expression or can be expressed using data from the dynamic library. Programový Systém Probcalc z Hlediska Uživatele Metoda Přímého Optimalizovaného Pravděpodobnostního Výpočtu (dále jen POPV) je vyvíjena od roku 2002. V současné době již lze metodou POPV s využitím optimalizačních kroků výhodně řešit značné množství pravděpodobnostních úloh. Pro aplikaci metody POPV je možno použít stále vyvíjený programový systém ProbCalc, do něhož lze relativně jednoduše implementovat analytický transformační model řešené pravděpodobnostní úlohy.

Designing of Anchoring Reinforcement in Underground Workings Using Doproc Method

Designing of Anchoring Reinforcement in Underground Workings Using Doproc Method The anchoring reinforcement (roof bolting) ranks currently among important reinforcing solutions available in the mining industry and underground engineering. The reinforcement is sized on the basis of various theoretical assumptions and empirical pieces of knowledge. Generally it is assumed that the input values are clearly deterministic. This is valid for both the geotechnical conditions under which the anchors will be applied as well as for properties of the anchors that are influenced also by installation procedures. But most data used as inputs in various anchor sizing methods are random. Recently, applied Direct Optimized Probabilistic Calculation (DOProC) has started developing for the assessment of the reliability of building constructions. DOProC is also applicable for the design of anchors. An assumption for the application is a sufficient database of random quantities relating to the environment where the anchors will be installed, properties of the anchors and anchoring technologies, anchor design computational models and suitable and efficient tools for the probabilistic design of the anchoring reinforcement. Využití Metody Popv K Navrhování Kotevní Výztuže Důlních Děl Při navrhování kotevní výztuže se vychází z různých teoretických předpokladů a empirických poznatků. Zpravidla se přitom předpokládá, že vstupní hodnoty jsou jednoznačně dány deterministicky. Předložený příspěvek ukazuje postup pravděpodobnostního navrhování a posuzování spolehlivosti kotevní výztuže při aplikaci metody POPV (Přímého Optimalizovaného Pravděpodobnostního Výpočtu).

Load Carrying Capacity of Steel Arch Reinforcement Taking into Account the Geometrical and Physical Nonlinearity

The paper deals with the calculation of the load carrying capacity of the steel arch reinforcements of underground and mine works with respect to the resulting large displacement and physical nonlinearities. Solution is based on the application of the so-called effective bending stiffness, which is defined as a function of the axial force and bending moment. The numerical model was verified using the values of the load carrying capacity, which have been experimentally obtained using strain-stress test, and implemented into the software that allows very effectively calculate load carrying capacity of steel arch reinforcements.

Statistical Dependence of Input Variables in Doproc Method / Statistická Závislost Vstupních Veličin V Metodě Popv

Abstract In probabilistic tasks, input random variables are often statistically dependent. This fact should be considered in correct computational procedures. In case of the newly developed Direct Optimized Probabilistic Calculation (DOProC), the statistically dependent variables can be expressed by the socalled multidimensional histograms, which can be used e.g. for probabilistic calculations and reliability assessment in the software system ProbCalc. Abstrakt V pravděpodobnostních úlohách jsou často vstupní náhodné proměnné veličiny statisticky závislé. Tato skutečnost by se měla v korektních výpočetních postupech respektovat. Statistická závislost může být vyjádřena např. korelačním koeficientem, resp. korelační maticí. V případě nově vyvíjené metody Přímého Optimalizovaného Pravděpodobnostního Výpočtu (zkráceně POPV), lze statisticky závislé veličiny vyjádřit pomocí tzv. vícerozměrných histogramů, které lze využít např. při pravděpodobnostních výpočtech a posudku spolehlivosti s využitím programového systému ProbCalc.

Nonlinear Solution of Steel Arch Supports

Steel arch supports are used widely in long workings in coal and ore mines. Their displacements are in difficult conditions often comparable with the size of the structure. Changes in the geometry of whole arch support including changes in the shape of a rod cross-section require geometric and physical nonlinear solutions. The paper is focused on methods for the geometric and physical nonlinear analyses of unyielding steel arch supports which are consisting of rolled open cross-sections. These methods are based on the knowledge of effective flexural rigidity which is defined as the function of acting internal forces. The direct stiffness method was used to solution first, but this method has some computational limitations. The modified force method was used for calculation as the second computational variant. This method can be successfully applied when the displacements are large. The results of the numerical analyses are compared with the values which have been experimentally obtained using strain-stress test of unyielding steel arch supports.

Non-Linear Solution of Steel Arc Reinforcement with Influence of Passive Forces

Non-Linear Solution of Steel Arc Reinforcement with Influence of Passive Forces Geometrically and physically non-linear solution of steel arc reinforcement with influence of passive forces is presented in this paper. The Winkler model is used to the solution. It is an elastic one-parametrical model, which is characterized by the only one constant C. A displacement method is utilized along with an iterative procedure. The software was created, which is based on derived procedure. An example was solved consequently. Nelineární Řešení Ocelové Obloukové Výztuže Při Existenci Pasivních Sil Článek se zabývá geometricky a fyzikálně nelineárním řešením ocelové obloukové výztuže. Při řešení se počítá s interakcí výztuže a okolní horniny. Je použit Winklerův jedno-parametrický model. Základem celého řešení je obecná deformační metoda a iterační postup výpočtu. Odvozený postup byl podkladem pro sestavení softwaru v prostředí Microsoft Excel a Visuál Basic, který byl následně použit k řešení příkladu.

Modelling of Closed Steel Supports for Underground and Mining Works

The closed steel supports of different shapes are used in mining and underground constructions. The yielding and unyielding supports are prefabricated from rolled, usually robust steel profiles. The load carrying capacity of the support is considerably influenced by the active loading and passive forces. The passive forces are induced by the interactions of support with the surrounding rock massif [1]. The user-friendly software was processed for the operational determination of load carrying capacity. The analysis has three parts: the first part consists of the structural geometry processing. The second part includes the numerical solution of statically indeterminate structure for the specified load. The third part is the calculation of load carrying capacity, components of internal forces and deformations. The force method and the numerical integration were used for solution. The Winkler model is applied when the support is in interaction with the surrounding environment. The load carrying capacity of support is limited by the slip resistance of the connected parts and reaching the ultimate state of the profile. The plasticity calculation is performed in accordance with EN 1993-1-1 Ed. 2. The limit values beyond the scope of this standard can be selected for an alternative computation.

Bending Test-Based Determination of Effective Cross-Section Stiffness

Bending Test-Based Determination of Effective Cross-Section Stiffness For majority of materials the stress-strain relation becomes non-linear as soon as the normal stress exceeds its limit value. The non-linear behavior manifests itself through the change of the cross-section stiffness EI. In this paper the effective (secant) stiffness EI is determined as a function of the relative cross-section rotation dφ from the bending-test. To this end, the displacement method is utilized along with an iterative procedure. Stanovení Efektivní Tuhosti Průřezu Ocelového Prvku Z Ohybových Zkoušek Pro většinu používaných materiálů platí, že při překročení limitní hodnoty napětí materiálu již není závislost mezi vektorem napětí a vektorem deformací v určitých úsecích lineární. Vliv fyzikálně nelineárního chování se projeví u konstrukce změnou tuhosti materiálu EI. V tomto článku je uveden postup určení efektivní (sečnové) tuhosti EI průřezu ocelového prvku z ohybových zkoušek v závislosti na relativním natočení průřezu dφ. K určení EI použijeme obecnou deformační metodu a iterační postup výpočtu.