Contemporary Problems in Architecture and Construction II

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Authors: Zbigniew Respondek
Abstract: Heat transfer through insulating glass units is a complex phenomenon. Heat exchange occurs here through conduction, convention and radiation. In practical calculations of heat losses in buildings, the declared value of the thermal transmittance (U) is most often taken into account, which is valid for vertical panes. Currently, more and more horizontal and diagonal glass partitions are made. The aim of the article is to analyze, on the basis of the adopted calculation model, the influence of the angle of glazing slope on the thermal transmittance in different weather conditions. The different wind speed and the possibility of radiative cooling were taken into account. Radiative cooling is a phenomenon manifested by a drop in temperature on the surface of horizontal and diagonal building partitions below the external air temperature. It occurs at night under a cloudless sky. It was found that in the case of horizontal or diagonal glazing heat losses increase significantly, which affects the energy balance of the building. Radiative cooling, especially in windless weather, is an additional unfavorable factor.
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Authors: Artashes Sargsyan, Grigor Sargsyan, Boris Resnik
Abstract: The main goal of bridge health monitoring is to show the condition of structure in real time mode with using special sensors, which can measure different characteristics, which can indicate about the changes in structure. One of the easier measured indicators what can be used is frequency of structure vibration. The diagnostic of the health condition of structure is dependent of correct evaluation of changes range of measured indicators. This paper presents the theoretical calculations to study the effect of cracking on the frequency response of typical reinforced concrete T type beams which has widespread in road bridges construction.
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Authors: Malgorzata Ulewicz, Jakub Jura
Abstract: The preliminary results of utilization of fly and bottom ash from combustion of biomass for the produce of cement mortars has been presented. Currently, this waste are deposited in industrial waste landfills. The chemical composition of waste materials was determined using X-ray fluorescence (spectrometer ARL Advant 'XP). ). In the studies sand was replaced by mix of fly and bottom ash from the combustion of biomass in an amount of 10-30% by weight of cement CEM I 42.5 R (Cemex). The obtained cement mortar concrete were subjected to microscopic examination (LEO Electron Microscopy Ltd.) and their compressive strength (PN-EN-196-1), frost resistance (PN-EN 1015-11 and PN-B -04500 ) and absorbability (PN-85/B-04500) were identified. The obtained results showed, the replacement of the cement by mix ashes from combustion of biomass reduce consumption of raw materials and will have a good influence on the environment.
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Authors: Zaven Davtyan, Anush Gasparyan, Avetik Melkonyan
Abstract: Problems on cracks and inclusions closely relate to problems of determination of the stress-strain state of homogeneous and inhomogeneous elastic solids that contain stress concentrators. Due to their theoretical and practical importance to the issues of construction structures, machines and their parts in machinery, in the calculation of hydro-technical structures as well as in various other spheres of applied mechanics, these problems have become a subject of investigation for many authors. This paper studies the problem of determination of the stress-strain state of a piecewise homogeneous elastic layer under torsion. The upper and lower surfaces of the compound layer are loaded with tangential forces and the interface of the heterogeneous layers contains a thin absolutely rigid coin-like inclusion. It is required to determine stress jumps on the boundary of the inclusion as well as intensity coefficients of the stresses (ICS).
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Authors: Maria Badalyan, Grigor Arakelyan, Amalya Karapetyan
Abstract: The article is devoted to the topical problem - to increase seismic resistance of erected buildings in the Republic of Armenia. Armenia is rich in volcanic rocks of glassy structure, which possess sufficient excess free energy of particles of matter and this energy can be regarded as a work stock that they can accomplish, i.e. can be regarded as kinetic energy. One of the most active rocks in the republic is the lithoid pumice of the Jrauber-Lusavan deposit, a spongy material of an acidic composition, the amorphous phase of which reaches up to 98%. We studied this rock for obtaining lightweight structural concrete using energy-saving technology. The amorphous structure of pumice gives the possibility of expensive Portland cement to be replaced in part by a cheaper bonded binder - a fine-grained mixture of quicklime and aluminosilicate rock. Due to the non-stable state of volcanic pumice, which possesses chemical activity, i.e. property to interact with lime, the composition of lightweight concrete, which can be used for the manufacture of blocks, reinforced concrete structures. In studies to regulate and give concrete the necessary properties, a plasticizing additive of the firm Sika Visco Crete 510P and a mineral additive - microsilica were used. Lightweight concrete cement was obtained, where the compressive strength increased to 43.17 MPa in 28-day increments, and 4.1 MPa in the case of bending: and with partial replacement of Portland cement with lime, the strength naturally decreased, because lime is slowly gaining strength, but for a long time, and the strength to break has increased to 4.6 MPa, which is explained by the structure of the neoplasms.
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Authors: Marine Grigoryan, Vardges Yedoyan
Abstract: The problem of stress state of an elastic piecewise-homogeneous wedge-shaped body at an antiplane deformation, consisting of heterogeneous wedges with different shear modules and opening of apex angles is considered, when a system of arbitrary finite number of collinear cracks is located on the interface line of the heterogeneous materials and the boundary faces of the compound wedge are reinforced with stringers of finite lengths. The solution of the problem is reduced to solving a system of three singular integral equations (SIE) using the Mellin integral transform, which based on quadrature formulas Gauss for calculating SIE with Cauchy kernel and ordinary integrals reduces to a system of systems of linear algebraic equations (SLAE). As a result, the characteristics of the problem are expressed by explicit simple structures algebraic formulas.
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Authors: Can Tian Yang, Ai Qun Li, Yue Chen, Lin Lin Xie
Abstract: A new type of square reinforced concrete frame column with a hollow section and spiral stirrups at the section corners is proposed. To investigate its seismic performance, three full-scale columns of this type and one full-scale conventional solid column were designed and tested under a quasi-static load. The failure mode, load-bearing, deformation, and energy-dissipation capacities of the proposed column were evaluated and compared with those of the solid column. The effects of the cavity ratio and axial load on the seismic performance were investigated.
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Authors: Gevorg Ter-Petrosyan
Abstract: The receiving of plain problem by analytical appearance with horizontal edges on the endless layer of propagation of the vertical crack and the dependence of the inner pressure of crack is observed. It supposed that the bottom edge of the layer is fixed to absolutely hard semi-flatness, but the upper edge is free. In this respect, we have tried to get the propagation measure of the opening and the analytical aspect of pressure change dependence acting inside it, by method of local modifications using the received solutions. The corresponding methods of approximate illustration of functional dependence are used. In the environment of the opening and the received measure of crack propagation the analytical expressions of distribution of stresses give the full image of peculiarities of those dependences for that immeasurable domain and correspond to the received results by method of modifications. The received formulas may be applied by solving concrete applicable problems and in studies of opportunities of cracks’ propagation for environment of fragile material. Those opportunities are increasing moreover if we take into account that the solutions are received for immeasurable environment.
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Authors: Evlin Ordoukhanian
Abstract: One of the typical features of the early Armenian culture of cemetery is its original church architecture. The radical changes in socio-economic and political relations were the basis of 301 cc to proclaim Christianity as a state religion. Church building has a great progress in the high middle Ages (9th-14th cc.) Where stone blocks are used as a building blend together with bricks. In the article, comparisons have been made between the Kirants Monastery and Makaravank, which are located in the same region and were built at the same time. As a result of the study, it is noticeable that these two monasteries, which have been high middle age construction material, have eras and similar buildings (churches, subsidiary structures, cemeteries around). Churches are a cross-shaped central dome and a domed hall volumetric spatial type. The facade is decorated with luxurious decoration, the exterior facades are decorated with colored bricks in Kirants monastery, and in Makaravank, in the form of stone carving. Similarities are seen in structured nodes - entrances and windows. There are remarkable differences in interior decorations - the interior walls of the Kirants monastery are decorated, with a small part of them preserved up to now, and there is no interior decoration in Makaravank.
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