Load-bearing Structures Research Articles

Evaluation of the influence of the pile cap’s spatial rigidity on the stress-strain state of pile foundations of the building

Providing citizens with housing is one of the urgent problems in Ukraine. The limited number of floors allows the use of such an architectural and planning solution for open-type city blocks (internal areas with such planning remain more open and transparent, create a feeling of free space). In order to solve this problem, first of all, it is necessary to make structurally correct and economically reasonable solutions at the stage of building design, because 60...70% of the building price is the cost of structures and materials.
 The main task of the designer is to develop structures for the safe and efficient operation of the building. These factors depend on the correctness of the development of the structural scheme of the building and the correctness of the calculation. The development of modern technologies and the availability of various calculation software complexes make it possible to perform such calculations. They make it possible to take into account the interaction of the elements of the "soil base – foundation - above-ground structures" system, which is mandatory for a modern level of design.
 Computer modeling with the use of various software complexes allows us to monitor the formation of the stress-strain state in the load-bearing structures of the building depending on the deformation properties of the soil base on the construction site, also depending on the change in the parameters of the structures of the building itself. A comprehensive analysis of the initial data, a detailed study and analysis of the engineering and geological conditions of the construction site, taking into account the planning and construction scheme of the building, as well as performing a complex numerical study of the stress-strain state of the building elements allows to monitor the influence of changes in the parameters of the foundations on the redistribution of deformations and stresses in all structural elements of the building. Therefore, performing computer simulation makes it possible to choose a rational type of foundations that will have not only reliability requirements, but will also be cost-effective at the same time.
 This article presents the results of a comparison of the options of a raft pile cap and a strip pile cap of the foundations on the stress-strain state of the foundation structures. The conducted research confirms that the transition from the strip pile cap option to the raft pile cap option causes a change in the subsidence character of the building. It is shown that the use of variable design of foundations makes it possible to design a reliable and at the same time cost-effective option of foundations. Based on the results of the study, the choice of a rational option of foundations was substantiated.

Features of measuring deformations of load-bearing structures of buildings during their field and laboratory tests under the action of static and dynamic loads

The peculiarities of measuring the deformations of load-bearing structures of buildings during their field and laboratory tests using strain gauge-based sensors are considered. An overview of various problematic issues that arise in the process of conducting experimental tests and affect the measurement results is given. The most common, which affect the accuracy of measurements, are the effects of temperature, humidity, and vibration; the difficulty of calibrating and mounting strain gauges on different surfaces of elements; complexity of measurement data processing; combination of high-quality work of strain gauges, cable conductors, measuring equipment, data collection and processing system; the selection of the connection scheme of tensor resistors in the Wheatstone bridge. The peculiarities of the organization of the experiment for testing the load-bearing structures of the building, namely pile foundations, are considered, and the main problematic issues when using strain gauges as strain gauges of building elements are given. The use of strain gauges to measure deformations of load-bearing structures of buildings is one of the common methods, which has many advantages, which are discussed in detail in the work. Strain gauges can be used to measure deformations of elements that are mechanically connected to them. They have high measurement accuracy, sensitivity to element deformation, and a wide variable measurement range. The advantages of using the Wheatstone bridge to measure the change in electrical resistance are highlighted, as this method allows measuring very small values of the change in resistance. Methods of connecting tensor resistors according to the Wheatstone scheme are considered, the choice of which depends on the purpose of the study and the required accuracy. One of the easiest ways is to connect just one strain gauge to a current or voltage source and measure the change in resistance. But this method has low sensitivity and does not compensate for the effect of temperature. A more accurate way is to connect two or four tensor resistors in the Wheatstone bridge circuit, which allows you to measure the voltage change on the diagonal of the bridge. The bridge circuit has a high sensitivity and can compensate for the effect of temperature if the tensor resistors have the same coefficient of temperature dependence of the resistance. An algorithm for measuring the deformations of a metal pipe working under compression using strain gauges has been developed.

WAYS TO IMPROVE THE ENERGY EFFICIENCY OF PIPELINES AND STRUCTURES USING AEROGEL

Problem statement. The paper explores ways of energy saving in buildings, namely, the compliance of the regulatory framework with European standards, the possibilities of reducing heat losses during the transportation of energy carriers through pipelines on the example of heat supply systems and reducing heat losses during the operation of buildings and structures. The second part of the article presents the results of analytical studies of various heat-insulating materials that are most commonly used in Ukraine. Some of these materials cannot be used on structures and pipelines of complex configuration. The issue of energy efficiency, along with improving sound insulation properties, reducing fire hazard, and reducing loads on the load-bearing structures of buildings and structures, can be addressed by using aerogels as a thermal insulation material. The material is characterized by a low dependence of the thermal conductivity coefficient on changes in ambient temperature, which makes it the best option for use in harsh operating conditions. The purpose of the article is to consider ways to improve the energy efficiency of structures and pipelines using modern aerogel insulation material. Conclusions. Having conducted analytical studies of various thermal insulation materials, it was found that aerogels in roll form, in addition to a low heat transfer coefficient, are characterized by better performance properties, namely non-flammability of the material, environmental safety, low weight, which reduces the load on structures, ease of installation, the possibility of using for structures of complex configuration, and a high rate of sound insulation.

THE POTENTIAL OF REVERSE ENGINEERING AND DIGITAL FABRICATION FOR THE REPAIR OF HIGH-TECH ARCHITECTURE

Abstract. Novel façade constructions and innovative load-bearing structures of the second half of the 20th century pose new challenges for maintenance and repair. The use of advanced technology, especially in High-Tech architecture, calls for the development of specific repair methods adapted to specific building materials and construction techniques. The conservation of these aging facades, often composed of custom-made metal components, requires the production of intricate spare parts to avoid unduly replacements. Digital fabrication presents a possible solution as it allows for the resource-efficient production of complex and non-planar geometries in small numbers while remaining cost-effective. The paper explores the use of photogrammetry and laser scanning to reverse engineer spare parts, as original plans are often missing or incomplete. A complete workflow for the fabrication of bespoke metal components is described using two examples of Swiss High-Tech architecture featuring challenging structural nodes and planar aluminum panels. Finally, the feasibility of remanufacturing spare parts is demonstrated with 3d-printed models.

Strengthening in gradient TiAl alloys

Gradient structure is emerging as an effective strategy to fabricate metals with remarkable mechanical performance, but have not been verified in intermetallic compounds for high-temperature applications. Through experiments and atomic simulations, we show that a typical intermetallic TiAl alloy with gradient structure has a significant strengthening effect both at room temperature and high temperatures. The room-temperature compressive strength of TiAl alloys with gradient grain obtained by additive manufacturing is 2.57 GPa, which is ∼2.7 times as strong as that with equiaxed grain. The strengthening effect is attributed to more sessile dislocations in gradient structure caused by the intersections of multiple slip systems in gradient grain. More importantly, the strengthening effect is still effective at high temperatures and the compressive strength is 1.28 GPa at 750 °C. The simulation results show that this strengthening effect is due to the increased Hirth dislocation at high temperatures. This study expands the applications of TiAl alloys for load-bearing structures and provides a new strategy for improving the strength of intermetallic compounds at both room temperature and high temperatures.

RESEARCH ON THE USE OF MODERN BUILDING MATERIALS AS BRICKWORK REINFORCEMENTS

The article discusses methods for reinforcing brickwork using composite materials, as well as using stainless steel threaded rods. These methods are not widely used in Kazakhstan due to the lack of a regulatory framework governing their use. Traditional amplification methods are effective, but in some cases they are not suitable for use. An example is the strengthening of the load-bearing structures of historical buildings, the determining factor of which is the preservation of the appearance. In this case, the use of the discussed methods may be a justified alternative.

Mathematical modeling and experimental investigation of a composite beam failure - Case study

Composite materials have been extensively employed in the aviation industry in recent years. The application of new materials enables significant weight savings with improved mechanical characteristics. This is also very important in the field of development of unmanned aerial vehicles (UAV). In the design phases, it is necessary to perceive all the aspects that are important for the structure and consider different load cases. The relationship between weight and strength proved to be important. This means that detailed strength analyses of each structural part are indispensable. In particular, primary load-bearing structures must sustain all types of loads without fail. Failure of the structure can affect the motion of the UAV during the mission or lead to a crash and significant losses. This paper presents the research performed on the failure analysis of a composite beam of a novel UAV. During the testing phase, under an unpredictable load condition followed by a crash landing, failure of the structure occurred on a beam element. The study was performed to determine the cause of the failure of certain layers of the composite laminate, because the previous calculation showed that it met the criteria for which it was dimensioned. Based on the telemetry data and the impact load that was registered, a complementary numerical and experimental analyses were performed to determine what happened and why. Composite test specimens were extracted from the beam and subjected to standard tensile tests, in order to determine the actual mechanical characteristics of the layered material. The paper presents in detail the comparison of the results as well as the methodology used in this research.

ДО ІСТОРІЇ ТА АРХІТЕКТУРИ КАМ’ЯНИЦІ НА ВУЛ. ДОРОШЕНКА, 14 У ЛЬВОВІ

The residential architectural heritage of Lviv of the late 19th and early 20th centuries is an important part of the history and image of the city. Given the relatively low status of small-scale owners and the lack of funding, their condition is mostly unsatisfactory and requires professional restoration. Practical work is preceded by qualitative research, part of which is a historical reference and an architectural description with valuable elements that are the subject of monument protection. Among the researchers who worked with the object, it is worth mentioning Yakub Levytskyi, Yuriy Biryulyov, Igor Melnyk. It is generally known that the information concerning the object of research is predominantly personalized, and not addressed to the processes of rebuilding the tenement house, mistakes were made in the authorship of the architect, in in the list of attractions, an error was made in the name of the object. The purpose of the article is to draw attention to the segment of monuments of local significance of the 19th - early 20th centuries, their technical condition and the importance of detailed work with archival materials when compiling a historical reference. The novelty of the research is the processing of previously unpublished archival sources based on which inaccuracies were found in previous studies of the object, the creation of a detailed architectural description. The object of study is a residential building located in the Halytskyi administrative district on P. Doroshenko Street, in a historically formed architectural environment, within the historical area and in the development regulation zone. An existing building, a monument of architecture and urban planning of local importance. The building acquired its final appearance in 1911-1912 according to the projects of architects Henrik Salver and Józef Avin. The security number of the monument is 4367-Lv. The building is four-story, atrium-type, covered with a complex roof with basements, an attic and five stairwells. The development facility tentatively consists of four blocks: the front one, with access to Doroshenko Street, the rear one - located in the depth of the site, and the eastern and western oblong ones, which connect the front and rear blocks, forming a closed inner courtyard. The backyard is not accessible for inspection. As a result of the processing of archival materials, the architectural history of the building from the beginning of the 19th to the middle of the 20th century was structured, errors of previous studies and the name of the object in the official list of monuments of local importance of the city of Lviv were revealed. Over the course of its existence, the processing object changed many owners, among them: the Panzias family, Adolf Bauman, the Kasern family. It was during the possession of the Kasserns that it acquired its modern appearance. Such well-known architects of the time as Michal Fechter, Alfred Kamenebrodskyi, Henryk Salver, Josef Avin and others worked on the object. To date, the monument has preserved its layout within the capital walls, the composition, the character of the decoration of the facades and interiors of the passageway and the main stairwell, and the high level of authentic substance that constitute the object of protection of the research object. The decoration of the facades is made in the style of mature modernism, while the interior of the passage and the main stairwell is in the neoclassical style. Despite the satisfactory condition of the load-bearing structures, the general condition of the monument should be defined as unsatisfactory. There is significant damage to the equipment of the walls of the facades and interiors, decorative elements, the courtyard balconies of the rear block are in a state of emergency. A comprehensive approach to the study of the monument will allow a professional approach to drawing up a program of restoration works at the object in the future.

Mathematical Model of Shear Stress Transfer at Fiber-Matrix Interface of Composite Material

This paper shows a mathematical model of shear stress transfer at the interface between fiber and matrix composite. The stress transfer is a key parameter determining the quality of fiber-matrix interface, which directly correlates with the composite performance as load-bearing structures. The model is derived from the energy balance approach in prior and post fiber cracking. The debonding process is included in the model by implementing traction-separation law. The results show the developed model can predict the shear stress along with the interface. There are significant differences in shear stress by considering the debonding process compared with conventional models. The debonding process must be regarded to assure an accurate evaluation of the interface quality.

Comparison of efficiency for steel and combined frames

Recently, in the practice of design, customers of design works and investors of various projects have a dilemma regarding the choice of building material for load-bearing building structures. At the same time, the choice is usually limited to two types of materials – steel and reinforced concrete. Each of these materials has its advantages and disadvantages, which results in their different efficiency of application for various types of building structures. At the same time, the main attention is paid to the estimation side, because in modern complex and dynamic conditions, it turns out to be dominant in many cases. 
 The article presents the results of research of the completed master's thesis on the comparative analysis of the effectiveness of steel and combined frames (steel-reinforced concrete) on the example of the filter station building. The building has dimensions in plan of 54 × 36 m with a total height of about 22 m. Its supporting frame is a statically nondefined flat frame consisting of columns and crossbars in the form of trusses. In the longitudinal direction of the building, the frames are united into a spatial system by means of covering structures. The building is craneless and has three floors, each about 6.5 m high. 
 In the course of research, the considered variants of the transverse frame were analyzed using the finite element method on the basis of the LIRA-CAD multifunctional design complex. As a result, appropriate cross-sections for loads according to the climatic conditions of Ukraine were obtained. A comparison of variants showed that the first design variant is 9 % cheaper. Taking into account the additional technological advantages in its manufacture, the steel frame can be considered more effective for the given construction conditions and be recommended for practical implementation. Separately, it should be noted that such a frame also has an average of 5 times less total mass, which should be considered its additional advantage.

Seismic design of reinforced concrete buildings with considering classifications of primary and secondary members according to tcvn 9386:2012

When designing seismic resistance for reinforced concrete buildings with medium ductility class (DCM) according to TCVN 9386:2012 the load bearing structures are to be designed to meet the required ductilities. The design of ductile members is quite complicated [2] and the amount of reinforcement provided for seismic members is considerable. Even so, TCVN 9386:2012 also allows to ignore the contribution of some members to the global seismic load-bearing structural system (that are secondary seismic members) when the remaining members (primary seismic members) are sufficient to ensure the safety and stability of the building. This paper presents some basic principles of the selection, the modeling methods and the design principles of primary and secondary seismic members in reinforced concrete buildings.

Load-bearing characteristics of 3D auxetic structures made with carbon fiber reinforced polymer composite

This paper presents a study of 3D novel hybrid auxetic structures made with carbon fiber reinforced polymer (CFRP) laminate composite based on the stretch-dominated mechanism. The homogenized mechanical characteristics of the designed structures, including Young's modulus, shear modulus, and Poisson's ratio, are evaluated via theoretical analysis and finite element simulation. The results exhibit that the structures have negative Poisson's ratio values in all the selected ranges of the design geometry parameters. The multi-objective optimization method is employed to achieve the optimized geometry parameters based on maximizing the stiffness and minimizing the relative density responses. Meanwhile, 2D fabricated auxetic sheets are assembled to build 3D structures through the interlocking method, and quasi-static compressive tests are performed to study their mechanical behaviors. The axial and lateral strains are evaluated by the strain gauge and video extensometer to measure the negative Poisson's ratio values through compressive tests. The results indicate that the proposed structures exhibit superior stiffness and high elongation percentage, suggesting them as a strong candidate for the next generation of load-bearing auxetic structures.

Strength assessment of concrete with copper slag as fine aggregates

Concrete is an excellent material for creating a wide range of load-bearing solid structures. Concrete is the second-most consumed resource in the world as a result of the ongoing depletion of natural resources and certain environmental issues. River sand is constantly being reduced, which affects the groundwater table because it is primarily used as a fine aggregate in concrete. Because of these factors, looking for alternative concrete materials is essential. Copper production leaves behind a sizable am looking for alternative concrete materials is an essential problem, Alternative sources for this waste material are required by environmental protection agencies and governments. As a result, an effort is made to partially replace fine aggregate in the construction industry with copper slag. The current paper examines the laboratory testing of various concrete mixes (Mix20, Mix40, and Mix60) containing copper slag waste as a partial replacement for fine aggregate (0% to 100%). The fresh properties and mechanical properties of the concrete mixes were assessed.

Properties of cement bricks containing sago fine waste (SFW) with different water-cement ratio

Cement is a key material in the construction industry. However, this widespread use adversely affects the environment. The replacement of cement with waste materials, mainly agricultural wastes, can reduce the impact of environmental pollution and result in sustainable construction. Sago fine waste (SFW) is a fibrous residue from waste from sago milling operations where physical treatment has been made. This study used SFW as a partial cement replacement material in cement brick and the effect of adding SFW to cement brick properties. Brick samples are designed with five different percentages of 2,4,6,8, and 10% of cement replacement, including control cement brick. The mortar mix is based on a ratio of 1:3, which follows Malaysian brick production standards. For compressive strength, density, and water absorption tests, all the specimens were cured for 7 and 28 days. The strength of cement bricks was investigated based on the difference of two water-cement ratios: 0.5 and 0.6. The brick properties investigated in this study are density, water absorption and compressive strength. The experimental results show that the brick’s density, compressive strength, and water absorption decreased as the replacement percentage increased. However, it still meets the requirements of the standard for load-bearing structures. Analysis of this study is according to extensive data collection, the ideal composition for SFW in cement brick was 2% and 0.6 water-cement ratios. This demonstrates SFW’s promise as a novel pozzolanic material for producing more sustainable bricks. As a result, SFW as a cement replacement material could improve bricks’ physical and mechanical properties as curing time increases.

Mechanochemistry of Collagen.

The collagen molecular family is the result of nearly one billion years of biological evolution. It is a unique family of proteins, the majority of which provide general mechanical support to biological tissues. Fibril forming collagens are the most abundant collagens in vertebrate animals and are generally found in positions that resist tensile loading. In animals, cells produce fibril-forming collagen molecules that self-assemble into larger structures known as collagen fibrils. Collagen fibrils are the fundamental, continuous, load-bearing elements in connective tissues, but are often further aggregated into larger load-bearing structures, fascicles in tendon, lamellae in cornea and in intervertebral disk. We know that failure to form fibrillar collagen is embryonic lethal, and excessive collagen formation/growth (fibrosis) or uncontrolled enzymatic remodeling (type II collagen: osteoarthritis) is pathological. Collagen is thus critical to vertebrate viability and instrumental in maintaining efficient mechanical structures. However, despite decades of research, our understanding of collagen matrix formation is not complete, and we know still less about the detailed mechanisms that drive collagen remodeling, growth, and pathology. In this perspective, we examine the known role of mechanical force on the formation and development of collagenous structure. We then discuss a mechanochemical mechanism that has the potential to unify our understanding of collagenous tissue assembly dynamics, which preferentially deposits and grows collagen fibrils directly in the path of mechanical force, where the energetics should be dissuasive and where collagen fibrils are most required. We term this mechanism: Mechanochemical force-structure causality. STATEMENT OF SIGNIFICANCE: : Our mechanochemical-force structure causality postulate suggests that collagen molecules are components of mechanochemically-sensitive and dynamically-responsive fibrils. Collagen molecules assemble preferentially in the path of applied strain, can be grown in place by mechanical extension, and are retained in the path of force through strain-stabilization. The mechanisms that drive this behavior operate at the level of the molecules themselves and are encoded into the structure of the biomaterial. The concept might change our understanding of structure formation, enhance our ability to treat injuries, and accelerate the development of therapeutics to prevent pathologies such as fibrosis. We suggest that collagen is a mechanochemically responsive dynamic element designed to provide a substantial "material assist" in the construction of adaptive carriers of mechanical signals.

Evolution of Void Fabrics and Their Effects on Liquefaction Behaviors of Granular Soils: Insight from DEM-Clump Simulation

Previous studies have demonstrated that macroscopic liquefaction behavior is closely related to the evolution of the microstructure (fabric) of soils. Here we perform three-dimensional (3D) discrete-element method (DEM) simulations of soil liquefaction considering irregular shapes of Toyoura sand particles, which are approximated by 3D clumps. We introduce the Minkowski tensor to quantify the anisotropy of the particle-void cells around each clumped particle, and propose two void fabric proxies, Ed and Ad. The evolution of Ed and Ad during the entire liquefaction process and their effects on pre- and postliquefaction behaviors are investigated. Specifically, Ed quantifies the shape elongation of particle-void distribution, while Ad represents anisotropy of the particle-void orientation, which is closely correlated with the flow strain accumulation. We further quantify irreversible changes in fabrics and anisotropic load-bearing structures developed in liquefaction processes, and propose fabric-based criteria for jamming transition in flow deformation. The volumetric strain during reconsolidation is well correlated with Ed and Ad, whereas the jamming transition during liquefaction can only occur if Ad becomes sufficiently large. The interplay between strain, stress, and fabric evolution during pre- and postliquefaction will improve fundamental understanding and modeling of liquefied soils.

Analytical and numerical case studies on tailoring stiffness for the design of structures with displacement control

This paper discusses the role that structural stiffness plays in the context of designing adaptive structures. The focus is on load-bearing structures with adaptive displacement control. A design methodology is implemented to minimize the control effort by making the structure as stiff as possible against external loads and as flexible as possible against the effect of actuation. This rationale is tested using simple analytical and numerical case studies.

FEATURES OF CONSTRUCTIVE, ORGANIZATIONAL AND TECHNOLOGICAL SOLUTIONS FOR THE RESTORATION OF REINFORCED CONCRETE BRIDGE STRUCTURES

The article provides information on effective structural and organizational-technological solutions for surveying, designing and restoring the bridge structure, which was partially destroyed as a result of the armed aggression of the Russian Federation. It was established that information from scientific and regulatory sources does not sufficiently reflect the situation with bridges, where a part of the load-bearing structures has been completely lost and it is necessary to carry out work on the construction of new structures with the possible use of a part of the old (undamaged) ones. The current operating condition of the main elements of the structure (bridge web, span structure, supports and support parts, foundations, approaches) is determined. When predicting the term of accident-free operation, it was established that the remaining resource of the bridge, taking into account the actual technical condition of the main elements at the time of the inspection (destruction), which is determined from the equation of element degradation, is completely exhausted. The obtained data made it possible to predict the technical condition of the bridge in accordance with regulatory requirements and to prescribe operational and restoration measures. The use of undamaged underground structures for the construction of new reinforced concrete supports is substantiated, where preparatory work is provided with the use of complex mechanization tools. When concreting the bodies of the supports, the rationality of the new fastening of the braces of the formwork blocks was confirmed, which ensured increased rigidity and stability of the assembled formwork, for which it was proposed to install one plate between the supports on a rigid metal frame structure with a height of corresponds to the lower limit of the concreting massif, with the possibility of attaching braces working in different planes to it. It is proposed not to change the position of the two slabs intended for braces along the axis of the bridge, while they were also placed on similar metal frames. Placing the plates for fastening the braces at the mentioned height made it possible to reduce the length of the braces and ensure their working angles within the most effective limits.

IMPROVEMENT OF THE DISMANTLING TECHNOLOGY OF EMERGENCY LARGE-PANEL BUILDINGS ACCORDING TO THE RESULTS OF ASSESSING THEIR RESISTANCE TO COLLAPSES

Problem. The complete or partial dismantling of the damaged object is an important step in eliminating the consequences of emergency destruction. Issues related to man-made destruction of buildings and structures, their temporary emergency reinforcement and establishment of the possibility of further restoration require the professional participation of civil engineers in the substantiation of urgent project decisions. Currently, there are no organizational and technological solutions that are able to simultaneously combine objective urgency and rational justification of their implementation. Method. On the example of a building that suffered significant damage as a result of an explosion of a gas-air mixture, the selection of the optimal and safe method of its partial dismantling in the conditions of compacted buildings while ensuring safety requirements and the methodology for assessing the stress-strain state of the building structures based on the subsystem method was carried out. Originality. Violation of the strength and stability of the building as a result of a man-made accident and the uncertainty of the work of its structural scheme significantly increases the urgency of optimizing the technology of dismantling emergency structures. Variants of the sequence of dismantling of a large-panel building, which suffered an emergency collapse of part of the load-bearing structures, were considered. The basis of the choice is the practice of a complex study of the "foundation - ground part of the damaged building" system at the stage of dismantling and temporary strengthening. On the basis of the LIRA-CAD software complex, a methodology has been developed that allows creating adequate computer models that change taking into account the stages of dismantling, keeping the load history and taking into account the emerging forces and deformations. The initial data for the creation of an adequate computer model were obtained by analyzing design and technical documentation, visual and instrumental examination of the emergency building. The advanced mathematical apparatus implemented in the PC "LIRA CAD" allows to perform calculations of complex construction objects taking into account man-made influences on their structural elements and to perform modeling of processes that lead to changes in the stress-strain state, the development of inelastic plastic deformations and crack formation. Practical value. Such a technique is universal, with its help it is possible to examine buildings of any type that are under the influence of man-made and emergency external influences. The technology of dismantling emergency buildings in conditions of incomplete information about their technical condition has been improved. The safety efficiency of emergency and rescue operations has been increased.

Reconstructing the earliest known composite-tiled roofs from the Chinese Loess Plateau

The origins of composite tiles, one of the oldest forms of roofing, are still unclear. This study is based on a set of over 5000 clay tile fragments excavated from a single context in the Qiaocun site on the Chinese Loess Plateau, dated to ~ 2400–2200 BCE (Early Longshan Period). By combining morphological measurement statistics, 3D modeling, computer-based simulations, and reference to historical and archaeological records, we reconstruct the earliest known composite-tile roofing techniques and demonstrate that tile production was under a low-level standardization, with manual control forming a key agent during the roofing process. The quantitative study of the composite roof tiles from Qiaocun was then placed in its archaeological context and compared with other sites on the Loess Plateau. It was found that tile-roofed buildings were, by necessity, community projects. Such structures served as nodes in larger social communication networks; additionally, their appearance was linked to intensified social complexity in public affairs during the Longshan Period. The invention of clay tiles was associated with the inception of thick rammed-earth walls which had sufficient strength to serve as load-bearing structures for heavy tiled roofs. The roof tiles excavated from Qiaocun site indicate that the Loess Plateau was a key center for the origin and spread of composite tiles and related roofing and construction methods, suggesting a Longshan–Western Zhou tradition of roofing techniques in East Asia.