the article considers behaviour of a simply supported pre-cracked beam made of elasto-plastic material. The aim of the work is to study propagation of min-span fractures in the beam, defining of its behaviour in the local area and developing of techniques and methods to prevent further growth of a crack. There were applied vary verify methods to analyse deflections, internal forces and stress intensity factor in the area of crack propagation. Analytical and numerical calculation had been used. For numerical solution ANSYS software is used, based on finite element method. According the solutions key features and conclusions are given.

Keywords: fracture, pre-cracked beam, stress intensity factor, load-bearing capacity, elasto-plastic material, finite element method

Beams are structural elements subjected to bending loads transverse to their longitudinal axis. For steel beams, which compressed flange is not laterally restrained, checking loss of overall stability is often authoritative in determining their section. In engineering practice are known various approaches to verify the assurance of the steel beam against lateral-torsional buckling. In this article the attention is focused to the methods and their characteristics, described in actual version of the European standard EN1993-1-1.

Keywords: lateral-torsional buckling, steel beams, critical bending force, FEA

The article are compared two variants of the frame of a tall building to determine the most optimal model based on the payback period of the investment project. The calculation of economic effect from the outrigger floor frame 24-storey building with underground Parking in the city of Rostov-on-don. Various models of sale of administrative and residential premises are considered and estimated.

Keywords: outrigger floor, high-rise building, investment model, profitability index, payback period, the model of sales

The paper is considered modelling the process elaboration of a pit for high-rise building in the case of dense urban area. The research is analyzed stress strain state of soil with retaning wall. The authors are developed various design solutions of the retainig wall to decrease of displacement of the nodals in soil finite element model. According the results, it has selected rational design solution of retaining wall.

Keywords: dense urban areas, retaining wall, finite element method, stress-strain state, soil massif

The paper provides summary the problems of estimating high-rise buildings to a progressive collapse. The analysis of the structure of the technique for calculating the skeleton of the building for a progressive collapse is performed. Recommendations are given on the properties of reinforced concrete carcass elements for emergency actions. An imitation simulation of the emergency response using the finite element method in calculating the building frame for progressive collapse was proposed; Modeling and investigation of the stress-strain state of individual elements of the building's frame for the effect of explosive loading; modeling and investigation of resistance to the progressive collapse of the skeleton of a high-rise building; development of constructive solutions to achieve resistance to progressive collapse.

Keywords: progressive collapse, special action, finite element method, building frame modeling, stress-strain state