Erected Structures Research Articles

Load Testing Application for Truss Bridge Design Verification: Dead Load Monitoring

This is the first of two papers discussing application of load testing techniques for verification of bridge design. The bridge was a truss structure in the State of New York, which atypical to conventional design, the top chords of the main trusses, floor beams, and stringers were designed to act composite with the concrete deck. Under load, in addition to axial forces, such a design creates secondary moments in the truss main members and complicates the analysis. This inspired the need for verification of the bridge design through an instrumentation, monitoring, and load testing program. The objective of this paper is to verify dead load design. Achieving this objective required instrumentation of main members of the erected structure and monitoring of strains in those members during concrete deck construction. For total dead load, a pseudo analytical approach was used to incorporate load effects due to self-weight of the structure. Five members of the downstream truss were instrumented with vibrating wire gages to record strains in those members during the first three deck pours. Finite element (FE) and deck monitoring results were utilized in the pseudo analytical approach to investigate actual axial forces and moments due to service total dead loads. The investigation indicated that those forces and moments were within 20 percent of those estimated based on FE analysis during the bridge design. The way the deck pours were accounted for in the design and presence of construction loads on the deck during the monitoring might have contributed to this difference. The paper’s major contribution is that it introduced a new approach for estimating total dead load effects by only monitoring strains in a limited number of truss members during staged deck construction, it validated the unconventional design as a viable method for design of truss bridge structures, and it supplemented the very limited literature on dead load monitoring of bridges.

Strength of masonry made of ceramic brick with ground and unground surfaces (comparison of Russian and European norms)

Introduction. In recent years, much attention has been paid to the issues of reducing labor costs and increasing the reliability of test results of masonry ceramic wall products (brick, stone, and blocks). It is noted that when determining the masonry strength limit, the levelling of brick support surfaces is performed with mortar. However, when levelling the support surfaces by grinding, the masonry strength limit is artificially overestimated by at least one grade. In order to increase the reliability of erected buildings and structures, Note 1 to Table 6.1 of SP 15.13330.2020 “Masonry and reinforced masonry structures” gives an indication of the need to introduce appropriate correction factors in determining the strength of masonry. In the previous version of the SP, the values of reduction factors were adopted without appropriate justifications.Aim. To justify reduction of design compression resistance of masonry made of ceramic soft-mud brick (when determining its compressive strength with grinding of supporting surfaces) in order to increase the reliability of erected buildings and structures.Materials and methods. Comparison of normative and calculated values of the strength of masonry made of ceramic soft-mud brick on conventional mortar according to the norms of the Russian Federation, as well as Britain and Germany, on the basis of which the European norms have been developed.Results. The conducted comparison of British, German, and Russian norms showed that the calculated values of masonry strength given in the norms of European countries are lower than those in the norms of the Russian Federation due to higher safety factors.Conclusions. The decrease in the design compressive strength of masonry made of ceramic soft-mud brick by 10 % (when grinding the supporting surfaces to determine the compressive strength) is recognized as reasonable.

Assessment of quality indicators in construction

Introduction. Ensuring proper quality of construction is one of the pressing challenges of our time. Consumers expect cheap products from developers in the form of commercial or residential real estate that meet all the required quality indicators. Most accidents in monolithic construction occur due to non-compliance with technological procedures at low temperatures. The purpose of the study is to develop a framework for assessing the quality of concrete work at subzero temperatures (during winter work) based on the results of studies of technological parameters of winter concreting, their impact on the quality and safety of erected monolithic structures of industrial and civil buildings (structures).Materials and methods. The study used the method of approximating distributions of random variables, expert estimates, the theory of multiple principles, and mathematical statistics. The experiments were carried out in the laboratories of the Don State Technical University, as well as in the conditions of actual concrete work on a construction site in winter. The work uses a correlation-regression analysis of the dependence of the organizational and technological causes of inconsistencies (factors) and quality indicators of concrete work production. Statistical information on structural damage and collapse of buildings during their operation was processed. To make organizational and technological decisions to improve the quality of concrete work, it is proposed to take the influence of defects on the load-bearing capacity of buildings as an indicator of the quality level.Results. Using practical and expert methods, the most significant reasons (factors) for the occurrence of inconsistencies in the level of quality of concrete work production have been established. Factors have been identified that have the greatest influence on the change in the load-bearing capacity and reliability of buildings and structures being erected when performing the main types of construction and installation work. The nomenclature of technological quality indicators during winter production of concrete work, their influence on quality substantiated, and methods for assessing the quality of winter concreting technology are developed. Quantitative indicators of the quality of construction of monolithic reinforced concrete structures were obtained.Discussion and conclusions. The practical value of the work lies in the development of a methodological tool for creating a regulatory framework for operational construction control of the production of monolithic and prefabricated monolithic construction and installation works under conditions of exposure to low temperatures, as well as for acceptance control of compliance of completed construction projects with quality requirements. Proposals are given for establishing regulatory tolerances, ways to improve the manufacturability of the equipment used, a new method for designing winter concreting technology, and a quality control method focused on ensuring structural safety have been developed. By developing the research, it is further possible to develop methods for calculating technology parameters taking into account technological variability, as well as establish new indicators to regulate the required level of quality and safety of buildings being built.

ESTABLISHING THE RELIABILITY LEVEL OF MASONRY BEARING STRUCTURES BASED ON ITS COMPONENT STRENGTH ANALYSIS

The article discusses aspects related to assessing the reliability of masonry structures. The authors present methods for determining the compressive strength of masonry in existing structures, taking into account reliability theory. We also consider practical solutions for calculating the design strength of masonry, which may help to assess the safety of massive brick walls and pillars that act as core structural elements of existing buildings. Thus, walls and pillars operating in compression are vital elements of stone buildings and require special attention when analysing and assessing their strength. They carry enormous loads and are critical to the stability of the entire structure. There are cases when it may be hard to obtain safe samples for testing masonry mechanical performance, making the analysis of existing masonry structures difficult. However, building codes and methods provide specific methods for determining the strength of existing structures based on reliability theory. These methods assume uniformity of masonry with regularly spaced brick layers. Although such assumptions may simplify the analysis, they can still provide sufficiently accurate results for making decisions about the safety and reliability of the building. It is essential to consider all possible factors and limitations when using these methods to ensure a reliable assessment of the condition of masonry structures. Stone materials are among the most traditional in various areas of construction production. Buildings with brick load-bearing walls represent the lion’s share of the existing housing development in Ukraine. Ensuring its high-quality operation and the safety of residents during the life cycle of such buildings are priority areas. However, changes occurring in the external environment and the state of regulatory support for construction production require a periodic return to the issues of assessing the load-bearing capacity of both previously erected building structures and those under design. Thus, lately, the territories with previously unusual force impacts on building structures, such as horizontal displacements of the base of the building, have significantly expanded. The reasons for this include seismic activity in certain regions of the country and the results of anthropogenic factors, particularly the areas with unstable soils. We should note that many buildings and structures are subject to external influence due to military operations on a large territory of Ukraine. So, in the event of a hit by warheads or the action of a blast wave, they generate new, non-typical, but dangerous effects on the load-bearing structures of the entire building. Keywords: reliability theory, reliability assessment, structural safety, stone structures, masonry strength.

IMPROVING AN EXISTING OR ERECTING A NEW OR ADDITIONAL STRUCTURE BY ESTA OCCUPIERS: AN ANALYSIS OF Daniels v Scribante 2017 (4) SA 341 (CC), Erasmus v Mtenje [2018] ZALCC 12, and De Jager v Mazibuko [2020] ZALCC 7

The conduct of occupiers (i.e., occupiers in terms of the Extension of Security of Tenure Act 62 of 1997 (ESTA)) was central in three court judgments in recent years. The first judgment in the matter of Daniels v Scribante (2017 (4) SA 341 (CC)) is widely regarded as a progressive and transformative judgment, and as having opened the door for ESTA occupiers to improve their dwellings. In Daniels v Scribante, the Constitutional Court considered whether an ESTA occupier has a right to make improvements to a dwelling to make it habitable. The court found that ESTA affords an occupier the right to make improvements to their dwelling without the consent of the owner. However, the court pointed out that meaningful engagement between an owner or person in charge and an ESTA occupier was still necessary, because the exercise of an occupier’s right to make improvements could potentially encroach on an owner’s right to property. Since the judgment in Daniels was delivered, some ESTA occupiers, without prior consent or engaging meaningfully with the owner or person in charge, have improved or erected new structures – both inside and outside the demarcated parcel of land where they reside.Despite the ESTA occupiers’ need to improve or erect new structures, Daniels is context-sensitive and is therefore not blanket authority to engage in building operations anywhere on private farmland without prior, meaningful engagement with the owner or person in charge. Furthermore, reliance on Daniels v Scribante must be clearly justified. It is in this context that the case note emphasises that, where the current dwellings of ESTA occupiers are not suitable for human habitation and it is necessary to improve them or erect new buildings, the improvement must be done after proper meaningful engagement between the ESTA occupier and the owner or person in charge in accordance with the general guidelines set out in Daniels v Scribante. This is because the principles established in Daniels v Scribante set the scene for the much-needed balancing of rights between ESTA occupiers and owners, by alluding to the fact that ESTA occupiers are obliged to engage meaningfully with owners or persons in charge prior to embarking on improving or building new structures.The first part of this case note sets out and analyses case law that has dealt with improving or building new structures. The next part explores the competing rights and interests of ESTA occupiers and owners in relation to improving or erecting new structures. The third and final part of the contribution highlights and emphasises the importance of meaningful engagement before an ESTA occupier improves or erects a new dwelling on property belonging to another.

Comparison of ultrasonic and GPR methods for investigation of reinforced concrete columns

The presence of internal concreting defects such as pores, cavities, sinks, in load-bearing vertical structures can lead to serious consequences, up to accidents. In this regard, it is especially important to identify such defects is an important and relevant task during surveys of load-bearing structures of buildings and structures. At the same time, the search for internal defects is complicated by the fact that they may not be visible on the surface, but may be present in the body of structures. In order to control the quality of the erected monolithic structures, their instrumental examination is carried out with the identification of the possible presence of internal defects by the method of through ultrasonic sounding. The article discusses the comparison of ultrasonic and GPR methods for searching for internal defects in concreting reinforced concrete columns. The studies were carried out on real construction sites in which there were suspicions of internal defects in concreting of high columns. Conclusions are drawn about the possibilities and limitations of the methods. The resolution limits of the methods are presented. The results of the conducted studies show that, despite the relative modern popularity of ground-penetrating radar, ultrasonic methods can work equally well in this type of specific research scenario and have shown a high potential to overcome some inherent limitations of ground-penetrating radar when working with saturated reinforcement.

Methodology development for assessing the reliability and quality of engineering protection to ensure the stability of the motorways earth bed

The analysis of regulatory documentation compliance in the reliability assessment field of engineering protection systems with the current scientific and technical level has been carried out. The analysis of the adopted technical regulations for the retaining walls design has revealed a significant drawback — the lack of a consistent algorithm of actions for transport works facilities diagnostics. In the framework of the current research a methodology for assessing the retaining walls operational reliability and landslide protection works on landslide highway areas has been developed. The article summarizes the main deformations of engineering protection structures, allowing to determine the retaining structures technical condition located in the territories prone to landslide processes, and also presents the concept of the standard technical solutions album for repair and walls restoration. The analysis of the main problems arising in the design, construction and operation of retaining wall structures and highlighting it from the view point of ensuring the erected structures required reliability and durability will optimize the work process and reduce the number of emergency failures and losses due to their occurrence, as well as through the classification and bringing the documentation into a

Stress and shear of steel reinforced floors with prefabricated units and steel beams

Steel-reinforced concrete floors with prefabricated reinforced concrete slabs are industrial quickly erectable structures. The use of such structures makes it possible to reduce construction time, save metal, obtain efficient structures without beam projecting up to 20 m for loads produced by buildings and car parks. Codes and foreign norms do not include prefabricated reinforced concrete floor slabs in the operation of combined structures, as designers try to avoid complex connections (welding, bolts) during construction. Of obvious interest is the inclusion of precast slabs in the operation of combined steel and reinforced concrete beam as well as grouted joints between steel and slabs in the absence of additional anchors and connections.Experimental results of structural models and 6×10 m floors with precast slabs are considered to identify the concrete shear. The effective shear deformation up to 0.5 mm is detected even without additional anchors. Simplest anchors significantly increase the joint operation of cast concrete and steel profile. The operation mechanism is determined for steel-concrete and steelconcrete-anchor contact zones, and respective diagrams are plotted for numerical calculations.Floor testing shows that the use of the simplest joining, cast reinforced concrete combining steel and precast elements involves precast slabs at a distance from the beam axis of at least two thicknesses of the floor for two different ways of the beam support.Numerical modelling, including the contact zone operation, shows good agreement with the experimental data. It is recommended to clarify the width of compressed concrete flange in normative documents for the structural analysis.

ДИАГНОСТИКА МОСТОВЫХ ПЕРЕЕЗДОВ НА МАЛЫХ РЕКАХ И МЕЛИОРАТИВНЫХ СИСТЕМАХ С УЧЕТОМ УГРОЗЫ ВНЕЗАПНОГО ПАВОДКА НА ЮГЕ РОССИИ

Purpose: to study the features of the diagnostics of bridge crossings on small rivers and reclamation systems to improve their technical efficiency operation during burst showers. Materials and methods. Climate changes in the south of Russia occur in the direction of increasing precipitation, namely, catastrophic downpours leading to flooding of both mountainous and flat territories (Nevinnomyssk 2002, Novorossiysk 2002, Krymsk 2012, Krymsk 2012, Sochi 2022). The studies were conducted in April 2022 on the example of bridge crossing over the river Ubin in stanitsa Azovskaya Krasnodar Territory. The small rivers of the south of Russia are not cleared properly, garbage accumulates, branches, whole trees, the channels of small rivers are littered almost all over. When burst showers occur, the level of small rivers instantly rises, the soil no longer absorbs anything, the flow rate increases, the river turns into a mudflow, and the jams begin to be formed at bridge crossings. Results. It has been determined that the bridge crossing begins to work as a pressure dam, in the upstream, backwater flooding, a kind of barricades are formed, leading to great damage and what is the worst, the loss of life. The bridge crossings on small rivers and reclamation systems lose their operation life due to increased technogenic loads. In connection with the increasing development of rural areas in the south of Russia, the increase in the amount of modern road transport and agricultural machinery and the number of vehicles moving along this reinforced concrete hydraulic structure, a technical problem to meet operational requirements arises. Conclusions. In the course of the survey, multiple deviations from the requirements of the current regulatory documentation and the project were revealed. Based on the combination of features, the operation of the erected hydraulic structures without the use of compensatory measures is impossible.

Implications of the compressive strength control accuracy on the probability of accepting defective concrete elements

The contribution of control method inaccuracy to the accuracy and performance of building structures while adhering to the metrological requirements for the strength determination process in reference materials is analysed. The metrological fundamentals for improving the testing and quality control methods of modern concretes and their impact on the reliability of erected structures are developed. The measurement accuracy dependence on the quality control of concrete materials and products by destructive methods is established, the number of rejected products is determined. The accuracy of concrete quality control is assessed in relation to the likelihood of defective products. A Bayesian model is proposed for the probability of missing a defective product with known control confidence and the probability of error due to measurement and testing error in the control process. The additional probability of missing concrete defects in strength when testing in standard specimens by the destructive method due to imperfect test methods is calculated. The 'non-zero probability' of missing a defect in the concrete strength control process affecting the level of reliability is assessed, provided the metrological requirements for the test are met.

3D-Concreting – Compositions, Techniques and Properties of Mixtures

The paper reflects the problems of 3D-concreting technology, which is developing quite intensively in modern conditions of construction production. The most important condition for its practical implementation is the development of concrete mixture compositions that provide the necessary rheological (technological) properties for formation of products, elements of building structures or the structure as a whole, as well as providing the required pace of work and physical and mechanical characteristics and properties of the hardened concrete. At the initial stage of research carried out in the Research and Testing Laboratory of Concrete and Building Materials of the Belarusian National Technical University a number of concrete mixtures compositions were developed that are designed and provide the necessary conditions for the implementation of 3D-concreting of self-supporting and load-bearing structural elements respectively, in the manufacture of products of small architectural forms and the erection (arrangement) of building structures for various purposes. A methodology has been developed and implemented for the selection of a rational granulometric composition of aggregate, type, properties and amount of binder, chemical and mineral additives, together providing the required technological properties of concrete mixtures after they have been mixed with water. Original methods for assessing the rheological properties of water-soluble concrete mixtures and their changes over time, leading to an increase in the plastic strength of molded concrete, as well as a method for calculating the rate of concrete work depending on the properties of the concrete mixtures used, are proposed and experimentally substantiated. As a result, prerequisites have been created for further expansion of a number of compositions of dry concrete mixes taking into account their purpose for 3D-concreting, and for developing methods and evaluating the physical and mechanical characteristics and properties of hardened concrete, taking into consideration the purpose of manufactured products and erected (arranged) building structures.

On the basic architectural styles, directions, and style flows for shells and shell structures

It was ascertained that investigations on classification of architectural styles for shells and shell structures are absent. Only one published paper is available where architectural styles with indication of dates of appearance of the styles and dates of attenuation of their application are presented and the names of their founders are given. Now, the interest for the design, analysis, and building of thin-walled shells and shell structures is rising. There are no countries without erected shell structures. Hence, it is necessary to make more exact the classification of these erections and the distribution of them into groups. An aim of this work is collection of information about all known architectural styles as applied to shells and shell structures, and grouping of them due to characteristic traits and indications. All architectural styles were divided into five groups, i.e. avant-gardism, art deco style, modernism, ecotech style, and the newest styles. A special scheme, where distribution of architectural styles on these groups is applied to the examined structures, is given. Mutual influence of styles was revealed and presence of architectural directions and style flows in several styles was shown. The conclusions presented in this paper can demand the future accurate definitions and developments because specialists do not have common views to the list of architectural styles and to their classifications.

The results of the study conducted in 2022 at the necropolis medieval settlement Syganak

A mausoleum is a monument, a funeral building that included a chamber where the remains of the dead were placed. The Turkic peoples have built mausoleums over the graves of their dead ancestors for centuries. Mausoleums were considered the afterlife home of the dead. The erected structures make it possible to determine the social status of people buried in the mausoleum or to which class they belonged. After all, it is known that huge mausoleums were built for famous people, consisting of several rooms, with internal and external walls covered with decorative ceramics. The mausoleums had one or more burials. The graves studied and the materials found in them allow us to determine the status, outlook, way of life, traditions, religious beliefs and burial rites of the inhabitants. For this reason, in this article, we set the task of analyzing the studies conducted in 2022 at mausoleums No. 6 and No. 7 and introducing the data obtained during archaeological excavations into scientific circulation. Conducted scientific research within the framework of this topic made it possible to determine the features of mausoleums No. 6 and No. 7, construction technology and construction time. As a result of a comparative analysis with the mausoleums of this type from adjacent regions, the similarities and differences between the mausoleums of Syganak were determined. In addition, in the article we considered it appropriate to present the history of the emergence and development of mausoleums. In the article, when studying the little-studied history of the formation of mausoleums located in the middle reaches of the Syr Darya River, it is known that mausoleums arose on the basis of the ancient funeral tradition of nomadic peoples living in Central Asia.

Application of Coating for Fire Protection of Textile Structures

The results of experimental research on the effectiveness of fire protection of easily erected structures made of flammable textile products are presented. Analysis of the use of structures made of flammable textile products, which are easy to build, shows a steady trend to increase their use during the temporary implementation of certain tasks of the Armed Forces of Ukraine and SES units. During the heating of such buildings, fires and rapid spread of fire are possible. Statistics on the operation of easily erected structures have shown a low level of safety due to the use of natural fibers (such as flax, cotton and mixtures), which are highly sensitive to high temperatures and fire. After the test, it is seen that the raw sample of textile material supports self-combustion for more than 5 s, the damage to the sample is more than 200 mm. After testing the flame retardant sample, it is seen that the sample of textile material does not support self-combustion; damage to the sample not more than 40 mm. Inhibition of the process of ignition and spread of flame for such a sample is associated with the decomposition of flame retardants under the action of temperature with heat absorption and release of non-combustible gases (nitrogen, carbon dioxide), changing the direction of decomposition towards non-combustible gases and flame retardant coke. This leads to an increase in the thickness of the coke layer and inhibition of heat transfer of high temperature flame to the material, which indicates the possibility of transition of textile materials when treated with a flame retardant composition to materials related to non-combustible surfaces that do not spread flame.

CENOTAPH GRAVES OF THE CHUVASH PEOPLE AND RELATED RITES AND BELIEFS

The cult of ancestors is an important and integral part of cultures of many peoples, including the Chuvash. Following this cult, the relatives of the deceased people held complex funeral and memorial rites. In addition, honoring the dead, they erected tombstones and structures in cemeteries. They were erected not only to the deceased relatives, but also to those who, due to various circumstances, died and were buried in a foreign land. In science, such structures and monuments have been given the name «cenotaphs», i.e. empty graves. The tradition of installing commemorative signs imitating the burial is common among many peoples and has been known since ancient times. The research is devoted to the study of cenotaphs of the Chuvash and related rites and beliefs. The paper analyses the data of the ethnographic literature on the subject, as well as field materials that the author obtained during the expeditions of 2014, 2021 on the territory of the Almetyevsk district of the Republic of Tatarstan and the Chelno-Vershinsky district of the Samara region. Cenotaphs in their appearance are not different from ordinary burials. They have the same traditional tombstone structures as all the others. Nevertheless, cenotaphs have the common feature – the absence of the body of the deceased. However, such burials cannot be considered completely empty because, for the symbolic replacement of the deceased, the Chuvash buried the earth brought from the place of his burial. However, according to the author, in the past, the Chuvash people could use his clothes or other personal items to replace the body of the deceased. This is indicated by some magic actions and techniques that have been preserved by the peoples neighboring the Chuvash, for example, the Mari and Udmurts. In addition, attention is focused on the unconditional location of cenotaphs away from the cemetery or on its outskirts, which was also due to the ancient religious beliefs of the Chuvash people.

Некоторые особенности культурной идентичности Шейбани-хана и монументальное строительство в Самарканде в начале XVI века

Research objective: to analyze the cultural identity of Shaybani khan and his policy of reconstructing Samarkand and to identify the origins of cultural traditions in architectural construction in Samarkand at the beginning of the 16th century. Research materials: The sources mainly used in this study are historical works of Central Asian, Persian and Turkic authors of the sixteenth century: Muhammad Salikh, Fadhlallah ibn Ruzbikhan Isfahani, Shaybani Khan, Hafiz Tanysh Bukhari, and archive materials of L. Mankovskaya and M. Masson from the Central State Archive of the Republic of Uzbekistan. The publications of Russian, Soviet and post-Soviet specialists on the history of the Central Asia – V. Bartold, A. Semenov, R. Mukminova, B. Akhmedov, R. Djalilova, A. Bodrogligeti, R. McChesney, Y. Karasoy, M. Subtelny, T. Sultanov, K. Baypakov, E. Smagulov, D. DeWeese, F. Schwartz, B. Babajanov, A. Muminov, B. Norik and others are also analyzed in detail. Results and scientific novelty: Shaybani Khan, who possessed certain knowledge in the field of Islamic theology, law, Turkic, and Persian poetry, continued the cultural traditions of the Syrdarya regions of Ulus Juchi and Khorezm, which he adapted to the conditions of the Timurid society of Maverannakhr. Unlike the representatives of the Timurid dynasty, he was defiantly dealing with theological issues and supported the importance of the Turkic language as a means of propagating his power in Maverannakhr and Khorasan. In the memorial constructions in Samarkand, Shaybani Khan founded the Sufa, a family necropolis distinguished by its simplicity in comparison with the luxurious mausoleum of the Timurids. He combined certain traditions of the memorial architecture of Dashti Kipchak and funerary structures – dahmas of the higher clergy of Bukhara and Samarkand. The construction of the Shaybani Khan Madrasah in the historical center of Samarkand near the madrasah founded by a representative of the Chingisid dynasty and Timur’s eldest wife, Sarai-mulk Khanum, was not only symbolic in its importance, but also served as the legal and theological center of his state. There is no information in the sources about Shaybani-Khan’s reconstruction of the largest Islamic shrines of Samarkand. At the same time, Shaybani Khan continued the Timurid traditions of building garden and park complexes in Samarkand and erected civilian structures in the form of a water bridge.

‘As democracy grows’

Abstract This paper investigates the metaphorical framing of the concept of democracy in Nigerian Senate debates (henceforth, NSD) in a mini-corpus of 214 meta-discursive commentaries on democracy by legislators, with insight from metaphor scenario theory. Three source concepts – “ erect structure”, “living organism”, “dividends” and their associate scenarios are analysed. These scenarios are exploited by legislators to effect specific argumentative and ideological conclusions, such as Nigerian democracy is weak, positive-self-presentation by legislators amongst others. The paper reveals the conceptual, evaluative and ideological structures that dominate the discourse about democratization in Nigeria, especially in the Fourth Republic, from the perspective of legislators.

Surface-strength approach for concrete monitoring using sensors and shock-pulse method

There are many methods used for temperature-strength control of reinforced concrete structures globally. Their majority is associated with the significant challenges of being time-consuming, costly and prone to errors. Therefore, this study investigated the potential applicability of the surface-strength approach of specimens using non-destructive testing methods to derive temperature-strength relationships as an alternative approach to the currently widely used methods. The studies were carried out by comparing the surface strength of small laboratory specimens (SS) and large specimens (LS), imitating building structures, obtained by the shock-pulse method and the strength obtained by the destructive method; and the obtained calibration dependencies were adapted to the results of specimens’ thermal control. The temperature-strength dependence was corrected by comparing the strength and temperature parameters of SS and LS. The obtained nomograms make it possible to correct changes in the temperature regime of hydration of structures curing in real climatic conditions. The final adaptation of the temperature-strength dependence to the real erected structures showed a significant potential of this method in the construction industry. The difference between the actual strength of the drilled cores and the predicted strength of concrete at 28 days was only 1.02%.

ДОСЛІДЖЕННЯ ПОВЕРХНЕВИХ ВЛАСТИВОСТЕЙ ТКАНИНИ ДЛЯ ВИГОТОВЛЕННЯ НАМЕТІВ

The operation of easily erected structures made of flammable textiles encourages the use of fire protection, as the operation may ignite tarpaulin fabric, which is a flammable material. Therefore, studies aimed at determining the patterns of formation of an elastic layer of fire-retardant coating on fabrics with a composition based on mixtures of organic and inorganic substances, characterized by the necessary technological properties, are relevant. The paper presents the results of studies of free surface energy, as well as its components (polar and dispersed) for tarpaulin fabric and methods of its change when using a fire-retardant coating. A drop of coating was applied to the sample with a pipette during the test. After reaching the equilibrium drops, its height and diameter were determined with a microscope. The sequences of polarity change and their relationship with the main component of the fabric after the formation of the flame retardant coating, which are consistent with the structural and functional features of the tarpaulin fabric. The resulting fabric is characterized by a reduced property of water absorption, as the free surface energy changes 2.3 times and the polarity 2 times, which is associated with a decrease in the surface tension of the coating. Given the above, it was found that the polarity of the canvas fabric is close to the polarity of the flame retardant coating, which is difficult to wet the material. Instead, the addition of a foaming agent reduces the polarity of the coating and increases the wettability, which allows you to effectively process the canvas fabric. Thus, when applying a comprehensive approach to the study of wettability, polarity, interfacial tension, you can choose stable technologies for new products from fire-retardant fabric and expand their scope.

Early assessment of seismic hazard in terms of Voronezh massif-Moscow Depression contact

Purpose is to develop a system approach for early assessment of areas being of high seismic hazard and characterizing by low stability of rock mass relative to external loads. Methods. Well cores have been assessed down to 30 depth and seismic observations have been accumulated. Complexes of field geophysics methods have been applied for the research as well as remote sensing materials, digital model of surface relief, and techniques of qualitative and quantitative interpretation. Findings. Seismic hazard map has been formed in terms of seismic intensification and ground displacement units. The abovementioned is quite reliable but a cost-based result involving early assessments of high seismic hazard areas to infill network of geophysical measurements in the neighbourhood of the areas for their further quantitative characterization. It has been identified that rare well network and definite geophysical lines, run under conditions of a complex terrain, cannot localize the areas of high seismic hazard to focus builders on the enforcement of certain components of the erected structures. It has been defined that end result of the prognostic developments takes a shape of mapping of local areas with the decreased stability of upper share of the geological section supported by further measurements by means of a common depth point method (CDP). Comparison of potential secondary earthquake sources with high permeability zones makes it possible to predict highly reliable areas of the increased seismic magnitude. Originality.For the first time, interpretation techniques have been adapted to describe parametrically nonpotential geofields (i.e. optical density of remote basis; and relative elevation), accepted during the steps of potential field processing, with the use of wave analogies. Practical implications.The methods have been developed helping optimize field geological and geophysical operations in terms of area and well number as well as measuring stakes under the conditions of the limited prior data amount.