Reliability Of Building Structures Research Articles

The influence of methods of concrete quality control by physical and mechanical parameters on the reliability of building structures

Introduction. The construction technical control system evaluates the physical and mechanical properties of concrete on the base of testing a series of samples taken from a batch of concrete. It is necessary to take into account the influence of the control method on the quality of concrete structures and their reliability.
 
 Aim. Creation of a technical control system that should eliminate the causes of the identified risks by reducing the impact of the identified causes.
 
 Materials and methods. The control method affects the reliability of concrete structures being built and is evaluated from the point of view of choosing the number of samples and discarding the minimum strength values in the series. The results of the control of a series of concrete samples for 6 samples selected in such a way as to ensure compliance with the declared class when discarding 2 minimum sample values are compared.
 
 Results. As a result of the analysis of the impact of the methodology on quality and reliability: class B turns out to be 2 steps lower than the prescribed one, the in-series coefficient of variation exceeds the permissible one by 8 %, and the reliability level is significantly lower by 36 %.
 
 Conclusions. The conducted research shows an underestimation of the methodological component of material control, which can leave significant gaps in the system of technical control of construction products and does not allow to ensure the required level of reliability of structures.

Methodology for determining the extent of soil compaction deformation zones beneath foundations

The article is dedicated to a methodology for determining the actual dimensions of the zone of long-term compressed soils under existing foundations from their previous loading. Although construction norms provide conditional criteria for this, they do not always accurately reflect the real distribution of soil deformations at the depth of the foundation. The article presents a methodology for determining the actual dimensions of the compacted soil zone under the foundations. This methodology is based on both empirical and theoretical approaches, taking into account both the strength and deformation characteristics of the soil. The application of this methodology allows obtaining more accurate results and more reliably determining the dimensions of the compacted zone, which can be useful for conducting additional research for object reconstruction or determining the permissible distance between closely located foundations. During experimental and theoretical studies, regularities in the changes of soil compaction at the depth of the foundation and its deformations over time under constant loading were identified. The developed methodology enables a more precise determination of the actual dimensions of the compacted zone, which is of great significance for ensuring the safety and reliability of building structures.

CALCULATION METHODS OF MONOLITHIC REINFORCEDCONCRETE STRUCTURES WITH POST-TENSION REINFORCING ROPES

In Ukraine, the use of "post-tensioning" technology, which consists in the use of monolithic structures with pre-tensioned ropes, is growing. Domestic construction practice uses the term "prestressed reinforced concrete structures with tension of cable reinforcement on concrete." Post-tensioning technology is a modern approach to construction that allows you to create monolithic structures with great strength and stability. Its main advantage is the use of pre-tensioned ropes, whichprovide additional structural strength.In this article, the main methods of calculating such monolithic reinforced concrete structures are presented and the experience of using this technology in the construction of public buildings in Ukraine is presented.The use of prestressed reinforced concrete structures with the tension of cable reinforcement on concrete has numerous advantages. They are more durable, resistant to deformations and able to support large loads. Such structures are used in the construction of bridges, overpasses, high-rise buildings and other industrial and civil structures.Ukraine is increasingly adopting modern and efficient construction methods, which is confirmed by the increased use of this technology. This helps to improve the quality and reliability of building structures, and also ensures optimal use of materials and resources.In general, the article aims to promote the popularization, study and development of monolithic structures with pre-tensioning of cable reinforcement on concrete, as well as the creation of an appropriate regulatory and legal environment for their design and construction. This will help improve the quality and safety of building structures and ensurefurther progress in the construction industry of Ukraine.

Risk-Informed Performance-Based Metrics for Evaluating the Structural Safety and Serviceability of Constructed Assets against Natural Disasters

The tangible and intangible value derived from the built environment is of great importance. This raises concerns related to the resilience of constructed assets to both human-made and natural disasters. Consideration of these concerns is present in the countless decisions made by various stakeholders during the decades-long life cycle of this type of physical asset. This paper addresses these issues from the standpoint of the engineering aspects that must be managed to enhance the structural safety and serviceability of buildings against natural disasters. It presents risk-informed performance-based parameterization strategies and evaluation criteria as well as design methods to embed differentiated levels of structural safety and serviceability of buildings against wind, snow, earthquakes and other natural agents. The proposed approach enables designers to assure the resilience and reliability of building structures against natural risks.

THE INFLUENCE OF CONCRETE COVER ON THE BEARING CAPACITY AND RELIABILITY OF THE REINFORCEMENT CONCRETE SLAB – COLUMN SYSTEM

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.

The ways to increase the durability of cutting tools (sintered carbide knives) in the production of steel fiber

One of the ways to increase the strength and reliability of building structures is the use of steel – fibre reinforced concrete. Steel – fibre reinforced concrete has significant advantages over conventional concrete. A high degree of resistance to cracking contributes to an increase in such physical and mechanical parameters as compressive, tensile and bending strength, water resistance, frost resistance, resistance to water and chemical penetration. In steel – fibre reinforced concrete, steel – fibre is used as a reinforcing material, evenly distributed over the volume of concrete.In the process of steel – fibre production, the fiber is cut with carbide knives. The article deals with the issues of increasing the wear resistance of carbide knives used for cutting steel – fibre, and suggests ways to increase the durability of cutting tools. The influence of the quality of tungsten-cobalt hard alloy on the wear resistance of knives is analyzed, and a knife attachment device is developed.

Reliability of building structures in case of an air blast wave

The analysis shows that the parameters of the air shock wave vary significantly and have a pronounced random nature. In general, in structural analysis, design parameters of the shock wave are random functions or random variables; therefore, the reaction parameters of the system under consideration will also be random. Then, fulfillment of certain conditions (for example, strength) is only possible with a certain probability, and the reliability of the system under consideration can be estimated using methods of building structures reliability, methods of mathematical statistics and probability theory. As a result, a probabilistic model of an air shock wave has been developed and the reliability of a free-standing wall has been estimated for random exposure parameters, as well as for random strength characteristics of materials. Based on the calculation results, it was concluded that the calculation of reliability using methods of mathematical and statistical probability theory makes it possible to bring the strength analysis of building structures closer to actual operating conditions.

SCIENTIFIC SCHOOL «RELIABILITY OF BUILDING STRUCTURES»: NEW RESULTS AND PRESPECTIVES

The article presents the results obtained by scientific school «Reliability of building structures» for the spice of five years2015 – 2019. Some aspects of the general approach to structural reliability assessment have been developed. Currentnormative calculations of structures were combined with the assessment of their reliability. Engineering methods were developed that allow to take into account an increase snow loading on coverage of building of variable height, to estimate theprocesses of snow thawing on roofs of the heated buildings and snow laying on cold roofs. It were investigated the specificwind load in the mountainous Carpathian region and loads of travelling cranes of different producers. Reliability of steelstructures of trunk pipelines and reinforced concrete beams with carbon-fiber reinforcement has been evaluated. Workfeatures of sheet steel structures were investigated. Construction accidents have been analyzed

FRICTION PILE RELIABILITY ANALYSIS WITH RESPECT TO THE FOUNDATION SOIL BEARING CAPACITY

Introduction. Friction pile reliability under the action of the central compressing force according to the Set of Rules 24.13330.2011 is calculated from the first group of the limit states — from the bearing capacity (using the pile material strength criteria and the foundation soil bearing capacity criterion) and from the second group of the limit states — from the pile load-deformation behaviour. Materials and methods. A method of calculating the friction pile reliability from the foundation soil bearing capacity is considered. Reliability appears as a quantitative measure of safety of a single pile operation. The foundation soil bearing capacity is accepted as a criterion for the pile operating capacity. The pile reliability analysis is based on the statistical information obtained during the preliminary pile testing with measuring the friction on the surface of the pile placed in the soil layers and the soil stress under the pile foot. The testing methods for obtaining the statistical information were well-known and used earlier to generate the lists of f-values and R-values in the Set of Rules 24.13330.2011. Each random parameter is measured at least three times. Results. The theory of analysis of the preliminary pile reliability in accordance with GOST 27751-2014 “Reliability of building structures and foundations” has been built on this statistical information. Reliability as the calculation result is represented by interval notation. The mathematical model of the limit state of the pile from the foundation soil bearing capacity has been borrowed from the Set of Rules. The connection (formula) between the length of the pile and the value of its reliability as a safety measure for its operation in the foundation soil has been established. Evaluation of the friction pile reliability corresponding to the characteristic value is carried out by calculation (trail-and-error method) from the mechanical properties of the soil and the load on the pile with the indication of the value of the length of the pile or the sum of the soil layers, each of the values in this case shall be not more than 2 m. The reliability analysis is described in the case studies set out in the article. Conclusions. Pile reliability analysis is based on the actual information about the pile operation in the foundation soil according to the current regulations of the Russian Federation, so the proposed method of the friction pile reliability analysis can be transferred into practice. It can also be used in the reliability calculation for other load-bearing elements, in the regulatory literature, and in the academic work of construction universities.

FRICTION PILE RELIABILITY ANALYSIS WITH RESPECT TO THE FOUNDATION SOIL BEARING CAPACITY

Introduction. Friction pile reliability under the action of the central compressing force according to the Set of Rules 24.13330.2011 is calculated from the first group of the limit states — from the bearing capacity (using the pile material strength criteria and the foundation soil bearing capacity criterion) and from the second group of the limit states — from the pile load-deformation behaviour. Materials and methods. A method of calculating the friction pile reliability from the foundation soil bearing capacity is considered. Reliability appears as a quantitative measure of safety of a single pile operation. The foundation soil bearing capacity is accepted as a criterion for the pile operating capacity. The pile reliability analysis is based on the statistical information obtained during the preliminary pile testing with measuring the friction on the surface of the pile placed in the soil layers and the soil stress under the pile foot. The testing methods for obtaining the statistical information were well-known and used earlier to generate the lists of f-values and R-values in the Set of Rules 24.13330.2011. Each random parameter is measured at least three times. Results. The theory of analysis of the preliminary pile reliability in accordance with GOST 27751-2014 “Reliability of building structures and foundations” has been built on this statistical information. Reliability as the calculation result is represented by interval notation. The mathematical model of the limit state of the pile from the foundation soil bearing capacity has been borrowed from the Set of Rules. The connection (formula) between the length of the pile and the value of its reliability as a safety measure for its operation in the foundation soil has been established. Evaluation of the friction pile reliability corresponding to the characteristic value is carried out by calculation (trail-and-error method) from the mechanical properties of the soil and the load on the pile with the indication of the value of the length of the pile or the sum of the soil layers, each of the values in this case shall be not more than 2 m. The reliability analysis is described in the case studies set out in the article. Conclusions. Pile reliability analysis is based on the actual information about the pile operation in the foundation soil according to the current regulations of the Russian Federation, so the proposed method of the friction pile reliability analysis can be transferred into practice. It can also be used in the reliability calculation for other load-bearing elements, in the regulatory literature, and in the academic work of construction universities.

Application of Green Building Technologies in Urals Region

A tendency to build high-rise buildings is common for all developing Russian cities. Sustainability and energy efficiency of such buildings are issues of foremost importance besides the strength and reliability of building structures. Nowadays, both of these terms are united in the concept of “green building”. The green building concept includes design, construction, and service of buildings aimed at creating comfortable microclimate, increasing energy efficiency, and reducing the environmental impact. In this work the analysis of distinctive features of designing green buildings in Ural region is given on the example of high-rise buildings constructed in Ekaterinburg. The influence of green building technologies on architectural, planning, and design solutions and selection of construction materials is explored as well as aspects of aerodynamics inside and outside the building. The influence of air flows on air permeability of building structures is assessed. The article also describes innovative solutions for creating required microclimate inside the building.

Assurance of reliability of high-rise building structures at design stage as exemplified by residential building complex in Yekaterinburg

The intensive expansion of high-rise construction is observed in Russia during the last several decades. Today it is hard to imagine a Russian metropolitan city without a skyscraper, whether it is a multipurpose business-center or a residential building. High-rise buildings in Ekaterinburg (which is a center of Urals) include not only office buildings, but also residential buildings higher than 100 meters. It is worth mentioning that most of these high-rise buildings were designed by local design companies without the participation of foreign specialists. The reliability and strength of the building structures received the particular attention during the high-rise building design process irrespectively of the function of a building. It is well known that the reliability of building structures shall be assured as early as the design stage, and therefore it is necessary to pay a special attention to the analysis of bearing structures under worst-case combinations of design loads in order to prevent them from influencing the strength of the building structures in the course of its service. Also it is important to note that high-rise buildings are subject to factors extrinsic to low-rises, such as aerodynamic loads. In addition to the wind loads, aerodynamic conditions of the building location in general also have a significant effect. In this work the authors review the specifics of design of high-rise building in Urals region on the example of one of the high-rise residential complexes in Ekaterinburg. Basic design conditions are described and architectural, planning, and design features of the building are reviewed. Effects of harmful factors acting on the building frame, including the wind loads, are analyzed. Some distinctive features of the analysis of the bearing structures are given. The conclusion contains the summary on specifics of high-rise buildings design and construction in Urals.

Optimization of steel frame building systems in terms of parameters and reliability requirements

The problem of ensuring safety and reliability of building structures in modern socio-economic conditions is especially urgent. An important aspect of this issue is to determine the rational costs of manufacturing the load-bearing systems. This should take into account the possible emergency situations and their consequences. The purpose of the present studies is to create a methodology for the optimal design of normally operated steel frames considering material and social losses from the possible failure of structural elements. A method for parametric optimization of steel frame systems during selection of rod cross-sections and structure reliability levels is developed. The problem is to minimize structure manufacturing costs and recover damage caused by any material and social losses in the event of possible malfunctions and damage. Constraints on the strength, stiffness, and stability of the frame have all been taken into consideration. A two-stage optimization scheme is proposed. The first stage includes several parametric optimization processes using a genetic algorithm with minimization of construction costs for various system load levels. Then the structure's reliability is assessed within a probabilistic formulation for each of the obtained parameter combinations. Eventually variant of the frame is selected based on the minimum sum of the manufacturing cost and the expected value of material and social losses possible during operation period of the structure, expressed in monetary terms. An example of optimum design of a spatial frame with personnel present in the areas of possible damage is considered. The presented method allows implementing a comprehensive approach to optimum designing, while taking into account both the manufacturing cost and the possible failures of the constructive system.

Problems and rudimental tends on implementation of European Union’s directives on Sustainable building

Over the past few years, several accidents of building structures, which had serious consequences, have occurred. The collapse of Maxima shop in Riga probably caused the biggest resonance in the Baltic States. Such accidents particularly encourage the assessment of saving trends that have recently gained popularity, their assumptions and consequences, especially the long-term ones. (In some cases, the buildings are lifeless even in short random overload cases. The latter is practically impossible to avoid both in construction and exploitation). Resource-saving trends are highlighted in parallel and at different levels (EU, Republic of Lithuania etc). Special attention is paid to non-renewable resources and their sustainability. It has become an unavoidable necessity in the modern world. It is noted that a construction process is one of the most susceptible consumers to resources and it has many opportunities to save. In this way, the contradiction between saving resources and reliability of building structures appeared. Lately, it has been one of the most important challenges in the field of construction. Both many practical lessons and modern simulation methods are necessary to solve it. The publication deals with the saving measures and the possibilities in building practice and the problems that occur. One aims at generalizing the accumulated experience. Objective resource-saving barriers on the base of truss structure design and installation are disclosed and discussed. Possible ways to mitigate these barriers are considered. DOI: http://dx.doi.org/10.5755/j01.sace.10.1.8165