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The reliability of building structures is a very important design criterion. The required level of security depends not only on the function and purpose of the facility, but also on the parameters considered at the design stage. There are factors to that with some probability they increase the uncertainty of the adopted parameters in the calculations, as a result of which the structure fails. It happens that execution errors are made during the process of creating an object. One of the significant disadvantages is the increase in the reinforcement cover thickness compared to the designed value, and hence the reduction of the effective depth of cross-section. The purpose of the analyzes presented in the article was to estimate the influence of the top reinforcement cover thickness on the reliability and bending and punching resistance in the reinforced concrete slab being part of the slab-column system. The reliability index βc was determined by the Cornell method. The analysis focused on a fragment of a cross reinforced slab, which is an element of the column-slab structure of a shopping mall. The ARSA 2019 program was used for the analysis of the structure. The impact of the coefficient of variation of the effective depth on the reliability index was also analyzed. The obtained values were compared with the target value of the reliability index read from EN 1990.

Technological progress in masonry structures has resulted in the creation of competitive solutions, which force the need for an ever deeper recognition of this type of structure. Masonry is a composite with heterogeneous strength properties. Therefore, the most appropriate way to accurately describe the behavior of the masonry structure under the influence of the working load are experimental research and their statistical and probabilistic analysis. This article presents a series of experimental tests carried out on real masonry structures. The results of the experiments were subjected to static evaluation, determining the most important parameter in the probabilistic analysis—the coefficient of variability of strength. The variability obtained in the experimental studies was used to determine the safety of the structure in the probabilistic method. Achieved values of coefficients of variation and safety coefficients proved to be satisfactory and adequate to the emerging technological progress in the production and embedding of masonry components.

The paper presents the experimental research and numerical simulations of reinforced concrete beams under torsional load. In the experimental tests Digital Image Correlation System (DIC System) Q-450 were used. DIC is a non-contact full-field image analysis method, based on grey value digital images that can determine displacements and strains of an object under load. Numerical simulations of the investigated beams were performed by using the ATENA 3D – Studio program. Creation of numerical models of reinforced concrete elements under torsion was complicated due to difficulties in modelling of real boundary conditions of these elements. The experimental research using DIC can be extremely useful in creating correct numerical models of investigated elements. High accuracy and a wide spectrum of results obtained from experimental tests allow for the modification of the boundary conditions assumed in the numerical model, so that these conditions correspond to the real fixing of the element during the tests.

The paper presents research of reinforced concrete beams loaded with a torsional moment, a bending moment and a shear force. Cantilever C35/45 concrete beams, made in a real scale with cross section 30x30 cm were analyzed. Reinforcement in the beams was formed on the basis of three-dimensional STMs (Strut and Tie Models). The first model was a spatial truss similar to the Leonhardt truss, in which the concrete compression diagonal struts, separated by cracks on each side of the vertical and horizontal element were inclined to the axis of the chords at the angle of 45°. The vertical elements of truss represent reinforcement in the shape of stirrups. The top and bottom chords of the truss represent tension reinforcement and compressed accordingly. In the second STM, the concrete compression diagonal strut were inclined to the axis of the chord at the angle of 37° but in the third STM the diagonal struts were inclined at the angle of 26.6o. Experimental tests of 6 reinforced concrete beams were performed in the laboratory of The Faculty of Civil Engineering and Architecture Environment in Rzeszow University of Technology. The beams were being loaded gradually and for each stage of the load, cracks, the angle of rotation of the cross and displacement were measured. The experimentally determined beam load-bearing capacities TR and stiffness under torsion were compared with the ones calculated from equations based on the well-known theories.

Most of the construction works carried out on masonry objects are associated with the strengthening of existing elements or assessment of their load capacity to additional load resulting from the change of use. In this situation, the proposed design solutions should always be part of a comprehensive design assessment taking into account the relevant inputs and including information on the actual material properties and the effects of interactions. The use of probabilistic design to evaluate masonry structures enables more economical approach to the issue of possible repairs and reinforcement than the commonly used method of partial factors. In the paper the normalized procedure of semi-probabilistic calculation of load capacity of masonry units and full probabilistic design, recommended in Eurocode 0 [1] are presented and compared. Because of the natural variability of the masonry structures, the information on its real mechanical properties should be obtained from in situ studies. Due to the lack of sufficient number of tests carried out on the masonry structures as well as unknown variation coefficients and distribution parameters, the analyses conducted in the article are limited to basic variables adopted for the probabilistic model based on experimental results described in the literature. The influence of each variable on the reliability index by providing sensitivity coefficients was determined. The basic element of masonry structures such as the lintel masonry was the subject of the analysis.

In recent years, the importance of assessment of structural reliability has increased significantly. This is confirmed by the recommendations of the standard PN-EN 1990 in which the rules and requirements to ensure safety, serviceability and durability of the structure are specified. It also sets out the basis for calculation and verification of constructions and provides guidance to ensure their reliability. Reliability design focuses on the ability to meet specific design requirements, taking into account the planned period of use. The concept of the planned period of use should be considered as the adopted in the project interval in which the structure or a part of the structure is to be used for its intended purpose without the need for general repairs. Typically, reliability is expressed in probabilistic metrics - using an index of reliability or probability of failure. Reliability of building structures depends on a number of correlated factors, mainly on the quality of materials, building precision and level of control, protection against environmental influences and maintenance level during exploitation, specific period of use, adopted solutions for the construction materials, design details and technologies, adopted loads (both their values and combinations), standard requirements regarding capacity, exploitation and durability, quality of computational models used in the design process and methods for assessing reliability of the structure. The performed reliability analysis concerns a reinforced concrete foundation, for which reliability index and probability of failure has been specified using the following methods: analytical method FORM, simulation methods FORM and SORM as well as Monte Carlo simulation.

Statistical conformity criteria for the compressive strength of concrete are a matter of debate. The criteria can have prejudicial effects on construction quality and reliability. Hence, the usefulness of statistical criteria for the small sample size n=3 is questioned. These defects can cause a reduction in the quality of produced concrete and, consequently, too much risk for the recipient (investor). For this reason, the influence of conformity control on the value of the reliability index of concrete and reinforced concrete has been determined. The authors limited their consideration to the recommended standards PN-EN 206-1, PN-EN 1992 and ISO 2394 method of reliability index, which belongs to the analytical methods FORM (First Order Reliability Method). It assumes that the random variables are defined by two parameters of the normal distribution or an equivalent normal: the mean and the standard deviation. The impact of conformity control for n=3 for concrete structures, designed according to the Eurocode 1992, for which the compressive strength of concrete is the capacity dominant parameter (sensitivity factor of dominating resistance parameter according to the FORM is 0.8), has been determined by evaluation of the reliability index.

This paper presents probabilistic assessment of load-bearing capacity and reliability for different STM of deep beams. Six deep beams having different reinforcement arrangement obtained on the basis of STM but the same overall geometry and loading pattern were analysed. The used strut-and-tie models for D-regions of analysed elements have been verified and optimised by different researchers. In order to assess load-bearing capacity of these elements probabilistically, stochastic modelling was performed. In the presented probabilistic analysis of deep beams designed, the ATENA software, the SARA software and the CAST (computer-aided strut-and-tie) design tool were used. The reliability analysis shown that STM optimization should be a multi-criteria issue so that the obtained models were characterized by optimal stiffness with the assumed volume or weight and maximum reliability.

The probability method of cracking estimation allows for taking all collected information about the properties of construction material, assumed loads and performance precisions into account. The article shows the results of the probability analysis in relation to the reinforcement area of the cylindrical tank walls calculated in tension zone. On the basis of the method proposed in PN-EN 1992-3 and PN-EN 1992-1-1, this reinforcement was calculated due to the uncontrolled development of cracking. The article also presents FEM analysis carried out for the tank using GID and ATENA Static software.

In this paper, the analysis of cracking due to tensile stress in a reinforced concrete pipe is presented. The tensile strength of concrete in case of the member of a high relative curvature is significantly different from the strength of uncurved elements. The current state of research indicates that only methods of nonlinear fracture mechanics lead to a satisfactory agreement between the results of calculations and experimental studies, and allow for compiling correctly the influence of basic parameters of stretched concrete and geometrical dimensions on the load capacity of crush pipes made from concrete. Obtaining consistent results of experimental and numerical research is still a very complicated issue. This paper presents the results of the experimental investigation performed on three pipes and the numerical model of the analysed element of the pipes made using the ATENA (Advanced Tool for Engineering Nonlinear Analysis) program. The numerical analyses of cracks were compared with the results of experimental studies.

Docelowe wartości poziomów (wskaźników) niezawodności według różnych zaleceń normowych krajowych i międzynarodowych nie są spójne. Zalecane wartości wskaźników niezawodności są zwykle podawane dla jednego lub dwóch okresów odniesienia (1 rok i 50 lat), bez wyraźnego odniesienia do projektowanego okresu użytkowania. W artykule podjęto próbę wyjaśnienia związku między wymaganym wskaźnikiem niezawodności i projektowanym okresem użytkowania oraz określenia zależności pomiędzy docelowym poziomem niezawodności dla zadanych konsekwencji zniszczenia a projektowanym okresem użytkowania i stopą dyskontową. Analizowano zalecenia zawarte w PN-EN 1990, PN-ISO 2394 i JCSS: 2001. Probabilistic Model Code. Ze wspomnianych tutaj norm/dokumentów nie wynika wyraźny związek między projektowanym okresem użytkowania i docelowym poziomem niezawodności. Analizując niezawodność w odniesieniu do projektowanego okresu użytkowania można stwierdzić, że zwiększenie jakości i niezawodności powoduje wzrost kosztów realizacji/wybudowania obiektu budowlanego, sprawia jednak, że maleją koszty użytkowania, eksploatacji i straty wynikające np. z pojawiających się uszkodzeń obiektu podczas użytkowania. Dokonując weryfikacji docelowych wskaźników niezawodności według różnych zaleceń normowych, krajowych i zagranicznych, można stwierdzić, że optymalne wskaźniki niezawodności zależą przede wszystkim od stosunku kosztów awarii konstrukcji (koszty nieprawidłowo użytkowanej konstrukcji), natomiast mniej istotny wpływ na projektowany okres użytkowania i docelowy wskaźnik niezawodności według M. Holicky’ego ma wartość stopy dyskonta nieruchomości.

Eurocod PN-EN 1990 „The basis for structural design” includes general principles for the differentiation of reliability taking into account the consequences of failure. Constructions are classified into three reliability classes RC1 to RC3, for which target reliability indicators have been defined. For the RC2 reliability class the basic values of partial coefficients in relation to materials and loads for persistent and transient computational situations were given. However, Eurocod PN-EN 1992-1-1, „Design concrete structures”, proposes to reduce partial coefficients by including quality control of production and available information on the heterogeneity of the materials used. The evaluation of standard recommendations regarding material partial coefficients was made on the basis of analysis of the reinforced concrete bending beam. The standard recommendations provide different levels of reliability. Elements designed in accordance with EN 1992-1-1 to reduce the value of partial factors with tighter quality control and reliability of reinforced concrete elements at RC2 reliability level may not be sufficient for load factors more than 0. 4.

Podstawowym działaniem związanym z kontrolą zgodności betonu ze specyfikacją jest kontrola wytrzymałości na ściskanie. Decyzja o zgodności lub niezgodności wytrzymałości jest podejmowana na podstawie porównania wyników badań próbek z kryterium zgodności. Kryteria zgodności wytrzymałości betonu na ściskanie są określone w normie PN-EN 206:2014 i zakładają odniesienie się do wartości średniej i minimalnej, przy założeniu, że zmienna wytrzymałości betonu na ściskanie ma rozkład normalny. W przypadku próby o małej liczebności n=3 i produkcji początkowej nie można założyć, że wytrzymałość na ściskanie ma rozkład normalny. W artykule zaprezentowano procedurę wyznaczania wartości współczynnika testowego, w przypadku, gdy rozkład wytrzymałości jest różny od normalnego. Omówiono metodę klasyczną zalecaną przez m.in. Montgomerego oraz autorską metodę szacowania wartości współczynnika testowego. Stwierdzono, iż w przypadku nieznajomości rozkładu, proponowana metoda może być stosowana do szacowania wartości współczynników testowych. Otrzymane wartości współczynników testowych 3,094 dla próby o liczebności n=3 oraz 1,842 dla próby o liczebności n=15 są zbieżne z wartościami uzyskanymi dla metody wnioskowania statystycznego oraz metody Bayesa i znanego estymatora odchylenia standardowego. Wartości współczynników testowych zweryfikowano za pomocą krzywych AOQ (średniej wadliwości po kontroli), które umożliwiają sprawdzenie proponowanych wartości liczbowych. Wykorzystanie wartości współczynników testowych szacowanych zaproponowaną metodą w kryteriach zgodności wytrzymałości betonu na ściskanie gwarantuje uzyskanie przez beton projektowanej klasy betonu.

The article presents the impact of conformity control on the value of the reliability index. The performed reliability analyses were related to the quality of C20 / 25 class concrete verified on the basis of the compliance criteria for a number of samples, n = 3 and n = 15. It was found, that the type of concrete conformity criteria significantly influences the value of the reliability index, especially for the low number of samples n. The level of reliability for concrete construction decreases when the conformity control is carried out for the number of sample n = 3. In any case of doubts concerning the quality of C20 / 25 building concrete, the influence of conformity control for number sample n = 3 should be taken into account, especially the case when the concrete is produced with a standard deviation greater than 4.0 MPa.

The main activity of open pit mining of aggregates are aggregates' exploitation of natural mineral deposits and its modification in order to obtain high-quality aggregates. The development of aggregate production is conditioned by a number of factors. The most important are: documented material resources, mining and manufacturing capabilities, the need of environmental protection (environmental aspects), the subordination of the plan of spatial development, formal and legal issues, as well as economic and financial aspects. While identifying and assessing the environmental impacts of manufacturing aggregates one may distinguish those environmental aspects that have or may have the greatest magnitude of the impact on the environment as a result of industrial activities. Manufacturers producing aggregates located in the areas covered by the special environmental protection require extra diligence in the conduct of mining activities for preservation of natural resources. The article discusses some main environmental aspects of the production of construction aggregates on the example of one of the largest producers of this material in Subcarpathian province of Poland. Environmental protection in production of aggregates may refer to four aspects: the use of natural resources, having excluded land from agriculture and forestry, land reclamation after exploitation, and use of energy from renewable energy sources. The economic and environmental impact of production volume of aggregates is evaluated by the index information capacity method and the method of graphs.

All concrete mechanical properties given in design codes of concrete and reinforced concrete structures are correlated with the characteristic compressive strength fck. According to the EN 206-1 code, the characteristic strength is defined as the strength value below which 5 % of the population of all possible strength test results for given volume of concrete can be found. The value of fck can be defined as 5 % quantile of the statistical distribution of the concrete compressive strength, tested on cylindrical samples with a diameter of 150 mm and a height of 300 mm or on cubic samples with dimensions 150 × 150 × 150 mm assuming the conversion factor of 0.8. In order to verify compliance of strength of the considered concrete with the designed characteristic strength (ascribed to concrete class), it should be checked if the test results meet the appropriate statistical criteria. The characteristic strength defined by specifying of concrete class is determined at the designing stage of the structure and it is the basic controlled parameter, providing the requirements are fulfilled by the producer. Despite numerous publications on disadvantages of the code compliance criteria, marginalization of the problem is still visible. Concepts and methods based on probabilistic or statistical approaches are often sourced of skeptical views on quality control because they are not very familiar to most engineers. In the paper the assessment of the code compliance criteria has been made using the numerical simulation on the basis of the programs which has been written in C++. The innovative method for estimation test coefficients values contained in the code compliance criteria has been proposed. This method was developed on the basis of fuzzy methods.

Ważnym zagadnieniem mającym decydujący wpływ w ocenie stanu technicznego całej konstrukcji ma jakość materiału konstrukcyjnego, z którego jest on wykonany. Dla żelbetowych wiaduktów drogowych zagrożeniem dla betonu są: dwutlenek węgla, zawarty w atmosferze, chlorki, pochodzące z soli powszechnie stosowanych do odladzania oraz związki siarki pochodzące ze spalin. W wyniku kombinacji tych agresywnych czynników następuje albo zobojętnianie betonu albo skażenie go. Głównym aspektem poruszanym w pracy są różne zalecenia normowe dotyczące zawartości chlorków w betonie konstrukcyjnym oraz próba ich weryfikacji według podejścia probabilistycznego. Celem artykułu jest ocena stanu betonu w elementach wiaduktu w oparciu o wyniki badań laboratoryjnych. Badaniami objęto rdzenie betonowe pobrane z różnych elementów badanego obiektu, które w obserwacjach makroskopowych nie wykazywały uszkodzeń korozyjnych. Wykonano badania fizyko-mechaniczne betonu, określono jego skład oraz zawartości chlorków, siarczanów i zasięg karbonatyzacji. Korzystając ze standardowej procedury stwierdzono przekroczenie wartości progowej chlorków dla spodu konstrukcji. Ryzyko inwestora dla przekroczenia wartości progowej oszacowano na podstawie przyjętych funkcji gęstości na ok. 1%.