Yuri Ribakov – författare

Structural control is an approach aimed at the suppressing unwanted dynamic phenomena in civil structures. It proposes the use of methods and tools from control theory for the analysis and manipulation of a structure’s dynamic behavior, with emphasis on suppression of seismic and wind responses. This book addresses problems in optimal structural control. Its goal is to provide solutions and techniques for these problems by using optimal control theory. Thus, it deals with the solution of optimal control design problems related to passive and semi-active controlled structures. The formulated problems consider constraints and excitations which are common in structural control. Optimal control theory is used in order to solve these problems in a rigorous manner. Even though there are many works in this field, none comprise optimization techniques with firm theoretical background that address the solution of passive and semi-active structural control design problems. The book begins with a discussion on models which are commonly used for civil structures and control actuators. Modern theoretical notions, such as dissipativity and passivity of dynamic systems are discussed in context of the addressed problems. Optimal control theory and suitable successive methods are reviewed. Novel solutions for optimal passive and semi-active control design problems are derived, based on firm theoretical foundations. These results are verified by numerical simulations of typical civil structures which are subjected to different types of dynamic excitations.

One of the main goals of a good and effective structural design is to decrease, as far as possible, the self-weight of structures, because they must carry the service load. This is especially important for reinforced concrete (RC) structures, as the self-weight of the material is substantial. For RC structures it is furthermore important that the whole structure or most of the structural elements are under compression with small eccentricities. Continuous spatial concrete structures satisfy the above-mentioned requirements. It is shown in this book that a span of a spatial structure is practically independent of its thickness and is a function of its geometry. It is also important to define which structure can be called a spatial one. Such a definition is given in the book and based on this definition, five types of spatial concrete structures were selected: translation shells with positive Gaussian curvature, long convex cylindrical shells, hyperbolic paraboloid shells, domes, and long folders. To demonstrate the complex research, results of experimental, analytical, and numerical evaluation of a real RC dome are presented and discussed. The book is suitable for structural engineers, students, researchers and faculty members at universities.

The book deals with modern theoretical concepts related to the impact of fly ash and metakaolin admixtures on structure formation processes of concrete. Results of the effect of fly ash, metakaolin and their composition on properties of self-compacting and self-leveling concrete are presented. Based on mathematical models, obtained using mathematical experiments planning methodology, the impact of the main factors and their combination on workability, strength and other properties that determine efficiency and durability of concrete are analyzed. Using calculated dependencies, a methodology for designing optimal compositions of concrete containing active mineral admixtures and superplasticizers is proposed. Features of industrial production of concrete for the proposed compositions are discussed. The book is intended for specialists working in the production of concrete and reinforced concrete products and elements. It can also be used by construction engineers to design compositions of cost-effective self-compacting and self-leveling concrete as well as to determine the rational direction of using technogenic raw materials like ash and metakaolin.

The book deals with modern theoretical concepts related to the impact of fly ash and metakaolin admixtures on structure formation processes of concrete. Results of the effect of fly ash, metakaolin and their composition on properties of self-compacting and self-leveling concrete are presented. Based on mathematical models, obtained using mathematical experiments planning methodology, the impact of the main factors and their combination on workability, strength and other properties that determine efficiency and durability of concrete are analyzed. Using calculated dependencies, a methodology for designing optimal compositions of concrete containing active mineral admixtures and superplasticizers is proposed. Features of industrial production of concrete for the proposed compositions are discussed. The book is intended for specialists working in the production of concrete and reinforced concrete products and elements. It can also be used by construction engineers to design compositions of cost-effective self-compacting and self-leveling concrete as well as to determine the rational direction of using technogenic raw materials like ash and metakaolin.

Structural control is an approach aimed at the suppressing unwanted dynamic phenomena in civil structures. It proposes the use of methods and tools from control theory for the analysis and manipulation of a structure’s dynamic behavior, with emphasis on suppression of seismic and wind responses. This book addresses problems in optimal structural control. Its goal is to provide solutions and techniques for these problems by using optimal control theory. Thus, it deals with the solution of optimal control design problems related to passive and semi-active controlled structures. The formulated problems consider constraints and excitations which are common in structural control. Optimal control theory is used in order to solve these problems in a rigorous manner. Even though there are many works in this field, none comprise optimization techniques with firm theoretical background that address the solution of passive and semi-active structural control design problems. The book begins with a discussion on models which are commonly used for civil structures and control actuators. Modern theoretical notions, such as dissipativity and passivity of dynamic systems are discussed in context of the addressed problems. Optimal control theory and suitable successive methods are reviewed. Novel solutions for optimal passive and semi-active control design problems are derived, based on firm theoretical foundations. These results are verified by numerical simulations of typical civil structures which are subjected to different types of dynamic excitations.

The monograph analyses the state of the art (problem) in using stone siftings and aspiration dust obtained in natural stone crushing for producing concrete aggregates and fillers for dry construction mixtures and mortars on their basis. The influence of disperse fraction in stone siftings and aspiration dust on structural, mechanical and rheological properties of cement composite construction materials is investigated. Hypothesis for obtaining technological conditions, providing positive effect of the disperse fraction on strength and other properties of cement based concrete and mortar is proposed.Experimental results on studying properties of dry mixtures and mortars on their basis using stone crushing aspiration dust as filler are presented. Efficiency of using fillers, based on igneous rocks, on adhesive and other properties of mortars is demonstrated. Methodology for design of mortars composition for given mortar properties in case, when aspiration dust is used as filler, is proposed. The monograph presents experimental results on fine-grained concrete including as a main filler stone siftings with up to 20% of disperse fraction. It is shown that it is possible to produce fine grain concrete class С20/25…С60/75. Technological parameters of vibro-pressed fine-grained concrete with raw stone siftings are developed. Methodologies for composition design of fine-grained concrete with given workability are proposed. Possibility for producing macroporous light-weight concrete for walls and filtration materials, based on stone siftings fillers is shown.

Concrete and reinforced concrete remain the main building materials for construction of modern fortifications. The book presents experimental and theoretical results allowing production of special high-strength rapid hardening concrete and fiber reinforced concrete. It describes a method for effective proportioning of high-strength fast-setting concrete and fiber reinforced concrete with high dynamic strength as well as selecting proper technological parameters, methodology for design of reinforced concrete structures using such concrete. Particular attention is paid to ensuring the early strengthening of concrete within 24 hours after casting and to constructing structures with limited energy resources at the site.

Concrete and reinforced concrete remain the main building materials for construction of modern fortifications. The book presents experimental and theoretical results allowing production of special high-strength rapid hardening concrete and fiber reinforced concrete. It describes a method for effective proportioning of high-strength fast-setting concrete and fiber reinforced concrete with high dynamic strength as well as selecting proper technological parameters, methodology for design of reinforced concrete structures using such concrete. Particular attention is paid to ensuring the early strengthening of concrete within 24 hours after casting and to constructing structures with limited energy resources at the site.

The theoretical stress-strain model for compressed concrete (Iskhakov and Ribakov, 2018), is based on the structural phenomenon and requires no empirical coefficients. It includes such main parameters of concrete behavior as stresses and strains at the border between the elastic and non-elastic behavior, ultimate elastic strains and stresses and strains at the end of the post-peak region. Particular attention was focused on the descending branch of the stress-strain diagram and on concrete elastic and plastic potentials that are important for dynamic response of concrete element section and for concrete creep.The book presents experimental and numerical results confirming this model. It deals with experimental verification of theoretical models of cracking and failure scheme for cylindrical specimens. The importance of using transverse deformations for analysis of initiation and development of inelastic deformations under high loading rates is verified. The experimental and numerical results are in good agreement with the theoretical ones, which significantly reduces the number of empirical coefficients in compressed concrete elements design.

The monograph analyses the state of the art (problem) in using stone siftings and aspiration dust obtained in natural stone crushing for producing concrete aggregates and fillers for dry construction mixtures and mortars on their basis. The influence of disperse fraction in stone siftings and aspiration dust on structural, mechanical and rheological properties of cement composite construction materials is investigated. Hypothesis for obtaining technological conditions, providing positive effect of the disperse fraction on strength and other properties of cement based concrete and mortar is proposed.Experimental results on studying properties of dry mixtures and mortars on their basis using stone crushing aspiration dust as filler are presented. Efficiency of using fillers, based on igneous rocks, on adhesive and other properties of mortars is demonstrated. Methodology for design of mortars composition for given mortar properties in case, when aspiration dust is used as filler, is proposed. The monograph presents experimental results on fine-grained concrete including as a main filler stone siftings with up to 20% of disperse fraction. It is shown that it is possible to produce fine grain concrete class С20/25…С60/75. Technological parameters of vibro-pressed fine-grained concrete with raw stone siftings are developed. Methodologies for composition design of fine-grained concrete with given workability are proposed. Possibility for producing macroporous light-weight concrete for walls and filtration materials, based on stone siftings fillers is shown.