ABOUT METHODS OF SEISMIC ANALYSIS OF UNDERGROUND STRUCTURES

As is known, underground facilities are an integral part of the infrastructure of modern society. These objects have some specific characteristics such as complex construction, high cost, long life cycle, etc. Once it is destroyed, the direct and indirect losses are more seriousness than the general structure in the ground. Under-ground facilities built in areas subject to earthquake activity must withstand both seismic and static loading. Therefore, it is very important to carry on the seismic design of the underground structure in a safe and economi-cal way. The distinctive paper presents a summary of the current state of seismic analysis for underground struc-tures. Classification and brief overview of methods of seismic analysis of underground structures (force-based methods, displacement-based methods, numerical methods of seismic analysis of coupled system “soil – under-ground structure”) are presented, problems of soil-structure interaction are under consideration as well. So-called static finite element method with substructure technique for seismic analysis of underground structures is de-scribed

ABOUT SEVERAL NUMERICAL AND SEMIANALYTICAL METHODS OF LOCAL STRUCTURAL ANALYSIS

Numerical or semianalytical solution of problems of structural mechanics with immense number of unknowns is time-consuming process. High-accuracy solution at all points of the model is not required normally, it is necessary to find only the most accurate solution in some pre-known domains. The choice of these domains is a priori data with respect to the structure being modelled. Designers usually choose domains with the so-called edge effect (with the risk of significant stresses that could lead to destruction of structures) and regions which are subject to specific operational requirements. Stress-strain state in such domains is important. Wavelets provide effective and popular tool for local structural analysis. Operational and variational formulations of problems of structural mechanics with the use of method of extended domain are presented. After discretization and obtaining of governing equations, problems are transformed to a multilevel space by multilevel wavelet transform. Discrete wavelet basis is used and corresponding direct and inverse algorithms of transformations are performed. Due to special algorithms of averaging, reduction of the problems is provided. Wavelet-based methods allows reducing the size of the problems and obtaining accurate results in selected domains simultaneously. These are rather efficient methods for evaluation of local phenomenon in structures

Analysis of Mechanical Safety of Stadiums for the World Cup 2018

It is obvious that contemporary design and construction of unique buildings and structures is unthinkable without mathematical (numerical) and computer modelling and advanced analysis ofload-bearing structures under various kinds ofloads and impacts. One of the most ambitious and important construction projects is the uniquelarge-span structures. These are, in particular, stadiums, sports palaces and water parks, shopping malls, pedestrian, road and railway bridges of various design solutions. The distinctive paper is devoted to theoretical foundations and results of mathematical (numerical) modeling of the state (in terms of the analysis of stress-strain state, strength and stability) of football stadiums built for the 2018 FIFA World Cup in Russia. Finite element method is used for approximation and high-precision numerical solution of corresponding boundary problems of structural mechanics. It is the most universal and powerful numerical method of mechanics. The paper, in particular, describes some features of development of finite element models and the main results of the analysis of the mechanical (structural) safety of three- dimensionallarge-span systems "soil foundation - reinforced concrete structures of foundations and stands - steel structures of the coating and facades" of these football stadiums with the basic and specialload combinations. In addition, the key procedures of scientific support during the corresponding expertise and assessments are outlined. Generally, socially significant and knowledge-intensive problem of providing mechanical (constructive) safety of unique combined objects of construction (three-dimensional systems "foundation - reinforced concrete structures of foundations and stands - steel structures of coating and facades") has been solved at a new level as a result of the performed complex of research works

Fluorescence-Tagged Transgenic Lines Reveal Genetic Defects in Pollen Growth—Application to the Eif3 Complex

BACKGROUND: Mutations in several subunits of eukaryotic translation initiation factor 3 (eIF3) cause male transmission defects in Arabidopsis thaliana. To identify the stage of pollen development at which eIF3 becomes essential it is desirable to examine viable pollen and distinguish mutant from wild type. To accomplish this we have developed a broadly applicable method to track mutant alleles that are not already tagged by a visible marker gene through the male lineage of Arabidopsis. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence tagged lines (FTLs) harbor a transgenic fluorescent protein gene (XFP) expressed by the pollen-specific LAT52 promoter at a defined chromosomal position. In the existing collection of FTLs there are enough XFP marker genes to track nearly every nuclear gene by virtue of its genetic linkage to a transgenic marker gene. Using FTLs in a quartet mutant, which yields mature pollen tetrads, we determined that the pollen transmission defect of the eif3h-1 allele is due to a combination of reduced pollen germination and reduced pollen tube elongation. We also detected reduced pollen germination for eif3e. However, neither eif3h nor eif3e, unlike other known gametophytic mutations, measurably disrupted the early stages of pollen maturation. CONCLUSION/SIGNIFICANCE: eIF3h and eIF3e both become essential during pollen germination, a stage of vigorous translation of newly transcribed mRNAs. These data delimit the end of the developmental window during which paternal rescue is still possible. Moreover, the FTL collection of mapped fluorescent protein transgenes represents an attractive resource for elucidating the pollen development phenotypes of any fine-mapped mutation in Arabidopsis

STRUCTURAL SAFETY ANALYSIS OF STADIUMS FOR THE 2018 FIFA WORLD CUP IN RUSSIA. FORMULATION OF PROBLEMS OF STRUCTURAL ANALYSIS

The article presents structural safety analysis of the three-dimensional long-span systems “ground base – reinforced concrete foundation structures and stands - metal structures of the coating and facades” of football stadiums for the 2018 World Cup in Russia with basic and special combinations of loads and formulation problems of future in-vestigations

О ВОПРОСАХ АВТОМАТИЗАЦИИ СИСТЕМ МОНИТОРИНГА ДЛЯ ОЦЕНКИ ТЕКУЩЕГО СОСТОЯНИЯ СТРОИТЕЛЬНЫХ КОНСТРУКЦИЙ ЗДАНИЙ И СООРУЖЕНИЙ

В cтатье, носящей обзорный характер, дается понятие о системе мониторинга и управления инженерными системами зданий и сооружений, системе мониторинга инженерных (несущих) конструк-ций, приведены сведения о номенклатуре применяемых датчиков, компонентах систем мониторинга, проводных и беспроводных системах мониторинга, указаны технологии обнаружения повреждений

Numerical simulation of fluid-structure interaction between elastic thin-walled structure and transient fluid flow

The present paper deals with the verification of a numerical simulation technique of fluid-structure interaction (FSI) problems. The configuration of the task consists of viscous incompressible fluid around an elastic cylindrical thin-walled structure where the external flow is fully turbulent (Reynolds numbers Re=1.2•107). The verification is divided into three stages: 1) verification of the mechanical finite element model, 2) verification of the fluid finite volume model and 3) verification of the Fluid-Structure interaction model. Within the stage 1 the comparison of the obtained results with the full-scale measurements and the results of the alternative numerical simulations are presented below

Numerical simulation of fluid-structure interaction between elastic thin-walled structure and transient fluid flow

The present paper deals with the verification of a numerical simulation technique of fluid-structure interaction (FSI) problems. The configuration of the task consists of viscous incompressible fluid around an elastic cylindrical thin-walled structure where the external flow is fully turbulent (Reynolds numbers Re=1.2•107). The verification is divided into three stages: 1) verification of the mechanical finite element model, 2) verification of the fluid finite volume model and 3) verification of the Fluid-Structure interaction model. Within the stage 1 the comparison of the obtained results with the full-scale measurements and the results of the alternative numerical simulations are presented below

ABOUT CONTEMPORARY APPROACHES TO REDUCTION OF COMPUTATIONAL DIMENSION OF PROBLEMS OF STRUCTURAL ANALYSIS WITHIN FINITE ELEMENT METHOD

At present, as is known, there are many methods of reduction of computational dimension of problems of structural analysis within finite element method (FEM), including the reduction of the dimensions of the mass matrix and the stiffness matrix of the finite element model (to bring them, for example, in accordance with the “structural health monitoring” (or “test”) model of the object, which degrees of freedom are determined by the places of installation of accelerometers. In this respect, the following approaches are considered in this paper (with the corresponding analysis of the advantages and disadvantages): the Gaian reduction method, the IRS (Improved Reduced System) reduction method and the dynamic reduction method. In addition, the so-called static finite element method for seismic analysis of underground structures, based on the substructuring technique, is considered