Vol 17, No 3 (2021)

Analysis and design of building structures

Theoretical foundations for calculating bridges for endurance using the kinetic theory of durability of structural materials

Salamakhin P.M., Lugovtsev E.A.

Abstract

The economically effective method for determining the unknown parameters of the dependence of the durability of structural materials on the level of acting constant stresses in them and their absolute temperature for various structural materials is proposed, taking into account the data established by Academician of the USSR Academy of Sciences S.N. Zhurkov. It does not require long-term testing of materials, but is based on the use of the results of short-term standard machine failure of two groups of standard samples of materials at two significantly different temperatures. When using these parameters and the Bailey integral criterion for summing up the losses in the durability of materials, it is possible to calculate the endurance of elements of road bridge structures from any structural materials and to determine the residual durability resource of the structure under the predicted subsequent mode of loading it with real temporary vertical loads.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):219-227
pages 219-227 views

Roll-over stability as a problem of high-rise buildings’ designing

Inozemtseva O.V., Inozemtsev V.K., Murtazina G.R.

Abstract

Roll-over stability of tall buildings under wind loads is considered. The nonlinear nature of the problem is taken into account, including geometric, physical, and structural non-linearity. The problem is solved on the base of a system of linearized incremental equations of structural mechanics that describes the behavior of a system “tall building - foundation soil”. Several methods are examined for solving nonlinear problems of roll-over stability, specifically: 1) deformation method of systems’ equilibrium states’ tracing; 2) method of linearization of nonlinear equations and systems’ equilibrium states’ tracing; 3) method of linearization of nonlinear physical relations of a systems with constructive, static, geometric nonlinearity; 4) method of linearization of nonlinear physical relations of a system with constructive nonlinearity based on nonlinear incremental structural mechanics; 5) method of the deformation process tracing for a physically nonlinear soil base, given the increase of discharge zones and constructive nonlinearity. Each of these methods is used to solve a model task. These tasks take into account roll-over stability of high structures under action of wind loads. In general, the problem of roll-over stability of a high object can be represented as repeatedly nonlinear one with various types of non-linearity. In this regard, in the practice of high-rise buildings’ designing, it is necessary to develop scientifically and methodically substantiated methods of assessing roll-over stability, considering non-linear factors. Taking these factors into account will make it possible to assess the roll-over stability of a high-rise object more accurate.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):228-247
pages 228-247 views

Innovation structures of very lean roller compacted concrete dams

Lyapichev Y.P.

Abstract

Over the past 20 years, rolled compacted concrete (RCC) dams have continued to be built in many countries because of their technical and economic advantages over conventional dams of vibrating concrete and embankment dams. The aim of this study is the development of new structural and technological solutions in RCC dams in order to reduce the consumption of cement and expand their use on non-rock foundations, which will allow them to successfully compete with concrete face rockfill dams. The numerical analyses of static and seismic stress-strain state (SST) of gravitational dams in roller compacted very lean concrete dams have been made, as well as their stability, strength and cost have been assessed. For rock and dense sandy-gravel foundations the most economical is the concrete face rockfill dam and symmetrical RCC dam of very lean concrete with bases (0.5-0.7) of both slopes and outer zones of conventional concrete and central zone of rockfill strengthened by cement-ash mortar. Taking into account that the cost of diversion and spillway tunnels for very lean RCC dam will be less and the construction period - shorter than for the concrete face rockfill dam, it can be concluded that variant of symmetrical RCC dam of very lean concrete is the technically and economically effective. Symmetrical RCC dams of very lean concrete with 1V/(0.5-0.7)H slopes have more seismic resistance and technical and economic efficiency as compared with conventional gravitational RCC dams and other types of dams. These dams up to 200 m high can be built on rock foundations and up to 100 m high - on dense sandy gravel foundations.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):248-260
pages 248-260 views

Inverted pyramid Azores - an eternal hybrid structure

Sarmento Esteves L.P.

Abstract

Engineering structures are designed with observation of rules for structural performance under specific design loads, defined in the so-called structural codes. While dead loads are directly dependent from the selection of structural materials to a given structural function, live and accidental loads are often linked to the region where the structure must perform. In a complete opposition to engineering principles in Ancient Egypt, the inverted pyramid was designed to become a statement of how to bend gravitational laws, and what can be achieved by modern engineering, sill with intelligence to fulfill its function in a region where engineering structures are subjected to extreme live and accidental load regimes, e.g. high risk of earthquakes and high wind seasonal loads. A hybrid structural concept was specified, comprising lightweight structural wall elements anchored to a relatively heavyweight structural core. The suggested design concept fulfills the global equilibrium equation defined by architecture, and should become a structural example from a structural design perspective. As any other project involving non-comprehensive geometry, design and construction of the inverted pyramid is highly sensible to management options, which shall assure high precision manufacturing, and accurate control of its production.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):261-269
pages 261-269 views

Seismic resistence

The effect of story drift in a multi-story building under the influence of an earthquake

Sharapov D.A., Gebre T.H., Ali Y.M.

Abstract

This paper content is structure subjected sudden story drift as a result from earthquakes, forming hinges and eventually collapsing. The aim of this paper is to develop building thirty story building for seismic in Khartoum using finite element method (FEM) and the equivalent lateral force (ELF) procedure of American code ASCE 7-16. In current work the thirty-story reinforced concrete building was considered is to analyze the seismic behavior of the reinforced concrete structure to find the drift between the story by finding the maximum displacement from the program that causes the building to collapse, by choosing the shear wall as the support system to resist the lateral load and by looking to model the building inclined to the horizontal plane. Calculations were also made on the drift between the story to compare with the allowable drift. It is implemented in the Robot structural program - an ingenious program for designing and analyzing lateral (seismic) loads.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):270-277
pages 270-277 views

Experimental researches

Experimental verification of new features of bearing operation under combined loading conditions

Kirilovskiy V.V., Belousov Y.V.

Abstract

Bearing units of lifting machines, products of construction, road, aviation, space and other branches of technology are very important structural elements, since the failure of even one bearing can cause the failure of the entire product. The results of experimental verification of the theoretical model of bearing operation under combined loading conditions are presented. The behavior under load of bearing units in the most general case can be represented by a sequence of five design schemes, expressed in the form of five statically indeterminate beams. The purpose of the experiments was to test this model under real loading conditions. The experiments were based on the analysis of the geometric shape of the curved elastic line, which the shaft of the bearing assembly acquires under load. The experimental results confirmed the validity of the model and showed that the previously generally accepted model of a two-support beam is not implemented. The conclusion is confirmed that in responsible lifting machines, as well as in responsible products of construction, road, aviation, space and other branches of technology, it is impractical to calculate bearings according to the traditional method, since an erroneous value of bearing durability can be obtained, overestimated from 28.37 to 26.663.9 times.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):278-287
pages 278-287 views

Experimental studies of the stress-strain state of reinforced concrete structures strengthened by prestressed basalt-composite rebar

Rubin O.D., Lisichkin S.E., Zyuzina O.V.

Abstract

Relevance. In recent years, composite materials have become widespread in the construction of reinforced concrete structures for industrial, civil and transport structures. It is proposed to strengthen the reinforced concrete structures of hydraulic structures with prestressed basalt composite rebar. It took an experimental and theoretical substantiation of technical solutions to strengthen the reinforced concrete structures of hydraulic structures with prestressed basalt composite reinforcement. The aim of the work was to carry out a set of experimental and theoretical studies of the stress-strain state and internal forces in low-reinforced concrete structures of hydraulic structures reinforced with prestressed basalt composite rebar. Methods. Experimental studies of the stress-strain state and internal forces were carried out on the basis of low-reinforced concrete beam-type models with interblock construction joints, harden with prestressed basalt composite reinforcement in the stretched (compressed) zones of the models. Theoretical studies of the stress-strain state and internal forces were carried out on the basis of the theory of reinforced concrete and structural mechanics. Results. As a result of the research carried out on typical low-reinforced concrete structures of hydraulic structures with interblock construction joints, the main stages of the stress-strain state of hydraulic reinforced concrete structures were formulated. Based on the data of experimental and theoretical studies, taking into account the reinforcement with prestressed basalt composite rebar, as well as with prestressed clamps in the shear zone, a method was developed for calculating the strength of low-reinforced hydrotechnical reinforced concrete structures with interblock construction joints.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):288-298
pages 288-298 views

Reviews

Properties and behavior of light hydrophobic concrete

Kharun M., Ehsani A., Nasimi S., Gebre T.H.

Abstract

In concrete mixing plan, we usually encounter a combination of aggregates including sand, the amount of cement, which is actually the criterion of concrete grade, and the volume of water consumed. Changes in the quality and quantity of these components actually create the usual types of concrete. But the attitude that formed the basis of this research is based on the change in the nature of the components of the concrete mixing design. Removal of water and cement from the mixing plan and replacement of polymeric materials as well as the use of mixed LECA aggregates instead of aggregates is the basis of this research. In this paper, by examining and selecting LECA grain style and pre-treatment (hydrophobicity and coupling), in a constant ratio of resin, concrete samples were selected from three dimensional categories. After making the samples, flexural strength test was performed on them and the results were analyzed. Various compounds and processes have so far been proposed in the lightweight concrete mixing scheme. The distinctive point of this study is the use of lightweight expanded clay concrete with heat-treated acrylic polymer (crosslinking constituents) and related coupling agents. It is also important to select and apply the right amount of hydrophobic nanoparticles for hydrophilic surface hydrophobicity. Hydrophobicity was possible due to the non-polar nature of the acrylic polymer and the use of hydrophobic nanomaterials.

Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):299-307
pages 299-307 views

In memoriam of the colleagues

Viktor A. Bazhenov (1941-2021)

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Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):308-309
pages 308-309 views

Pavel M. Salamakhin (1930-2021)

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Structural Mechanics of Engineering Constructions and Buildings. 2021;17(3):310
pages 310 views

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