Vol 17, No 5 (2021)

The aim of the research – analysis of the stress-strain state of spherical lattice dome structure during mounted assembly process. The dome has a metal frame consisting of six repeating sectors with triangular grid cells. The mesh dome has five tiers in height. The study is devoted to establishing the dependence of the stress-strain state of the fully assembled frame of the lattice dome on the method mounted assembly. Methods. A computer model of the frame of the lattice dome made of steel I-beams in its design configuration has been developed. On its basis, assembly models of an incomplete frame for different stages of installation are created. For all models of the lattice dome frame, computer calculations were performed for the effect of the load from the own weight of its bars. As a result of calculations deformations, internal forces and stresses in the frame bars were determined at all stages of assembly, which were compared with those for the design configuration scheme. Results. Diagrams of deformations, moments and stresses in the bars of the dome frame at all stages of mounted installation are obtained. Comparative diagrams of installation and design stresses in the bars of the lattice dome are presented. The assessment of the installation stress state of the frame is given, and their inevitability and influence on the initial stress state of the lattice dome are noted.

Retrofitting is a method of renovating/repairing and strengthening the weak structure that was affected due to the excessive load on structure during any uncertainty load like earthquake or due to end of service life of the infrastructure. The objectives of this paper are to design reinforced concrete and fiberreinforced polymer jacketing of failed columns of an existing building, after addition of two more storey in previous design and to compare suitability of before mentioned methods of retrofitting. The presented work also describes design procedure of reinforced concrete, carbon fiber reinforced polymer jacketing for strengthening existing columns. This study is fruitful to gauge suitability of the two retrofitting methods for weakened structural members. The existing buildings in Nepal designed as using Mandatory Rules of Thumb are most vulnerable types of building; to mitigate further crack in structural members with appropriate type of retrofit will be considered with proper management of construction related to post-earthquake activity. After analysis and design of existing building its extremely necessary to plan construction management for economic and safety concern. Most cases of such projects will lead improper work without proper construction management leading uneconomic and prolonging of completion of project.

Relevance. The article discusses the design solutions of a new pile structure, which is a monolithic reinforced concrete cone-shaped pile, enclosed in a crushed stone shell and resting on a spherical crushed stone broadening. In the course of a numerical study, carried out using the finite element method, the influence of the geometric parameters of the crushed stone formations of the pile foundation, such as the wall thickness of the crushed stone shell and the radius of the crushed stone broadening, on its bearing capacity was revealed. The aim of the study is to perform a comparative numerical analysis of the stressstrain state of a pile structure with different design solutions, operating as part of a soil massif. Materials and methods. Numerical static analysis of the structure of a monolithic reinforced concrete pile foundation operating in a soil massif was carried out using a spatial finite element model in the CAE-class software package. The article presents the results of a numerical analysis of the stress-strain state of a rammed monolithic reinforced concrete cone-shaped pile with different wall thicknesses of the crushed stone shell and different diameters of the lower spherical crushed stone broadening. The analysis showed that changes in the specified geometric parameters of the pile foundation have a significant impact on its bearing capacity under external forces. The rational choice of these parameters allows you to economically use the concrete mixture and reinforcing rods intended for the manufacture of monolithic reinforced concrete rammed piles, which, in turn, leads to a decrease in financial costs for the manufacture of the pile foundation and the entire building as a whole. The next research is supposed to carry out a comparative analysis of the numerical results with experimental data obtained in laboratory and field conditions.

Relevance. The use of shells as thin-walled structures for various industries is very diverse. Spherical shells are widely used in the aircraft industry, circular cylindrical shells are used in the oil and gas industry, and more than 30 analytical forms of shells have been used in the construction industry. All elements of shell structures are undoubtedly subject to various strength calculations. Also, a separate role in the study is occupied by the experimental part, which confirms or refutes the calculated equations, this indicates the undoubted perspective and relevance of modeling the loading of shell structures. The aim of the study is to assess the condition of a thin-walled shell under three-parameter loading by tensile, compression and torsion forces. Methods. Experimental studies on the deformation of shells carried out in laboratory conditions on prototypes made of steel 45 GOST 1050-2013 are presented, and the loading conditions of the sample are modeled, similar to the possible conditions for applying loads to existing structures. Results. Experimental diagrams of deformation of the sample material in various planes are given, the development of deformation of the shell after applying joint efforts of stretching and torsion, as well as compression and torsion to the destruction of the material is estimated. For the relevance of the conducted experiment, a real design has been selected, which, when certain conditions are created, can experience appropriate experimental loads.

Currently, the construction of buildings made of monolithic concrete and reinforced concrete is becoming increasingly relevant. The use of innovative technologies, minimum construction time, durability, reliability, the ability to perform work in various climatic conditions, architectural individuality contribute to the development of monolithic construction. Concrete and reinforced concrete are the main materials of modern construction. The quality of structures depends not only on the composition of concrete, the amount of portland cement, the chemical additives used, the water-cement ratio, the quality of fillers, etc., but also significantly on the heat and humidity regime of concrete holding. To ensure the necessary temperature conditions for hardening and strength gain of concrete, various methods of heating structures are used. One of the methods of concrete care is thermal processing during the hardening period and the acquisition of critical or design strength. The aim of the study is to improve the technology of erection of monolithic concrete and reinforced concrete structures using thermal processing of concrete by means of infrared radiation. The technology of thermal processing of the laid and compacted concrete mixture using infrared heating and a two-chamber transparent shelter for infrared rays has been developed. The obtained results permit us to provide conditions for the normal course of the chemical reaction of hydration, hardening and strength gain. This allows successfully solve the problems of concreting in the erection of buildings and structures made of monolithic concrete and reinforced concrete.

This paper presents the structural behavior of buildings located in the sloping ground level subjected to seismic load. Three different categories of building from three to five storey are considered for the numerical modelling namely set back building (SB), step back building (SBB) and step back set back building (SBSB). The dynamic response of different buildings are analyzed and compared to assess the seismic vulnerability associated with each buildings. The seismic vulnerability is accessed by comparing the base shear, drift, displacement and torsion factor values. Linear static method is used for the calculation of earthquake load using ETABS. It is observed that SBB and SBSB are highly affected by torsion compared to the SB building. It is desirable to use shear wall in periphery of the bottom storey to improve seismic performance of building. The results in this paper can be employed for construction of buildings with seismically active sloping ground.