Slavcheva Galina, Chernyshov Yevgeny
The high-strength modified concrete: law of development moistured of deformations
Voronezh State University of Architecture and Civil Engineering
Abstract. The article presents results of experimental theoretical researches of moisture state influence upon building technical characteristics of high strength modified concretes (High Perfomance Concrete), obtained using complex МB-4.Previous researches stated that high strength modified concretes are characterized with more intensive moisture stress compared to usual hard concretes. According to this applied problems of foundation of coefficient values of linear moisture deformation and operation condition coefficients of high strength modified concretes accounting their moisture state have been examined. On the basis of the results analysis of carried out researches the guidance to determine coefficient values of linear shrinkage and swelling of modified concretes and also recommendations to determine operation condition coefficients have been developed to determine design characteristics according to moisture conditions of structure operation conditions.
Keywords: the high-strength modified concrete, the operational environment, moistured deformations, specific deformations, structure parameters.
Morozov Valeriy, Pukharenko Yury, Hegay Alexey
Modeling of micro crack forming of fiber concrete using destruction mechanics
Saint-Petersburg State University of Architecture and Civil Engineering
Abstract. Methods of mechanics of destruction and the theory of cracks investigate development of the micro cracks focused along compressing efforts. The effect of braking of development of micro cracks with reduced distance between reinforcing fibers is theoretically described. In a basis of settlement model the law of change of normal pressure in a reinforcing fiber in micro crack vicinities is put. The factor value of intensity of pressure and its critical value is defined by summation of the solutions of two problems – Flaman for a semi-infinite plate influenced by tangent efforts and Irvin for a plate with the isolated crack influenced by stretching loading. The quantitative results adequately describing micro cracks formation, observed during experiments are received.
Keywords: mechanics of destructions, critical coefficient of intensity of tensions, measure of singularity.
Sukhanov Vladimir, Vyrovoy Valeriy, Dorofeev Vitaliy
Crack’s role in structural development of the constructional composite materials
Odessa State Academy of Civil Engineering and Architecture
Abstract. In the article the questions of material self-organization with the influence of the operational load on the building construction as complex open systems have been examined. It is demonstrated that the processes of a spontaneous rearrangement of the complex organized materials have been caused by non-equilibrium state of the active structure elements to which the technological cracks and inner surfaces of the partition have been applied. The possible mechanisms of the structural rearrangement by changing the data of the active elements have been analyzed and the ways of a purposeful organization of the primary material structure, which provide a safe functioning of the construction, have been proposed.
Keywords: complex system, active elements of structure, technological cracks and inner surfaces of the partition, structural units, self-organization.
Zaytsev Yuriy, Kuliev Valeh, Sultygova Pyatimat
The strength of multilayer elements of a structure with an edge crack of a longitudinal shear in the second elastic medium
Moscow State Open University named after V S Chernomyrdin
Abstract. On the basis of the destruction process of multilayer elements with an edge crack of a longitudinal shear formulas which help to research complex influence of geometrical and physical mechanical characteristics of the layers of multilayer material upon the intensive coefficient of stress KIII with given external loads have been obtained. Conditions which can precast the trajectory of forming of an edge crack of a longitudinal shear of multilayer materials have been found that gives an opportunity to manage its increasing.
Keywords: durability, fatigue, critical crack length.
Karpenko Nikolai, Karpenko Sergey, Travuch Vladimir
Method of analysis of high-rise buildings and structures made of cast-in-place reinforced concrete based on layer refining
Establishment of Scientific Research Institute of Engineering Physics of Russian Academy of Architecture and Building Sciences
Abstract. Various factors essentially influencing upon the results of calculation of buildings out of cast-in-situ reinforced concrete are discussed: precision of design finite element models (accuracy of reflection in the models actual connections of framed and flat elements, assignment of paces of finite element grid, consideration of joint behavior of carrying frame with foundation, massiveness, stages of erection, etc); influence of physical non-linearity upon the results of calculation by the two groups of limit state; current status of buildings safety under different extreme actions, including acts of terrorism. Experience in design of cast-in-situ reinforced concrete buildings erected in Moscow mainly and executed in the laboratory «Problems of strength and quality in construction» NIISF RAASN is summed up.
Keywords: high-rise buildings, methods of analysis, models, layer refining, physical nonlinearity, models of junctions, extreme effects, explosion, fire, strength, reinforcement estimation, stages of erection.
Storozhenko Leonid a, Lapenko Alexander b, Nizhnik Alexander a, Murza Sergey a
Calculation composite steel and reinforced concrete flat slab floors by the analytical method
a Yury Kondratyuk Poltava National Technical University
b National Aviation University
Abstract. The results of theoretical and computational investigations of stressed deformed states of steel reinforced concrete flat slab constructions are given in the article, they form the basis of their design technique with an analytical method using linear finite elements developed by T N Azizov [1, 2]. Used linear elements allow accounting bending elements rather exactly along with accounting shearing force of slab interaction and appearing thrust forces in structures. Solutions of combined equitation system of deformation compatibility of the method of linear finite elements are presented. This method completely accounts all the components of stressed deformed state of test subjects. Solutions of the obtained equitation system are presented as expansion in Fourier series. Using the results of analytical solutions corresponding forces and movements calculations of researched structures are made, on their basis comparative analysis with computations made by means of the method of finite elements is done. The calculation results due to this method and the method of finite elements are compared.
Keywords: composite steel and reinforced concrete flat slab floors, teamwork, a method of linear final elements.
Barashikov Arnold, Yatsko Olga
Influence research of cohesion conditions of internal surface of a pipe with concrete in guncrete structures
Kiev National University of Civil Engineering and Architecture
Abstract. The theme of an urgency of use concrete filled steel tube columns as a part of frameworks of many-storied buildings is considered. As the example, calculation of spatial computer models of the 30-storeyed house, certain dynamic characteristics and level of internal efforts in elements of frameworks taking into account seismic loading are analyzed. Results of the research and computer modeling of the stress-deformed condition concrete filled steel tube columns under the concentrated axial and vertical cyclic loading are presented. The purpose of research is the estimation of strength, plasticity and character of collapse concrete filled steel tube columns, without adhesion between steel and concrete. Considering that efforts of compression are perceived mainly by the concrete core, the distributed loading to a lateral section of a steel mantle isn’t put, on purpose visually to show drive of vertical pressure upon a tube, at the expense of concrete and steel teamwork. Results of probe have shown that in the absence of clutch between elements of the sample, deformation is concentrated in the field of a concrete core, and almost do not move to a steel mantle that essentially influences character of collapse, both a concrete core, and all design as a whole. The modeling data will be coordinated with values hypothetically provided.
Keywords: concrete filled steel tube constructions, three dimensional stress, adhesion, finite element model, seismic response.
Gubanov Vadim, Kulchitskiy Artem
The features of chimney’s local reinforcement calculation
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article consideres the peculiarities of local strengthening chimneys calculation for various kinds of damages such as the blowhole, the concavity of a shell, the run-out of cylinder shell lining-up. Chimneys as plate structures have there own damageability specificity and strengthening specificity unlike the frame construction. It has been done the constructive decisions designs classification of metal chimneys trunks with different variants of damage for the given type of construction. The considered variants of strengthening concern strengthening without essential change of the constructive form and the settlement scheme of a design. Results of numerical researches of the intense-deformed condition of sites of chimneys with various constructive decisions of strengthening are established. The most rational methods of strengthening for various kinds of damages are defined.
Keywords: chimneys, stress-deformed state (SDS), reinforcement, bearing capacity reserve, constructive designs.