Structural Elements Of Buildings Research Articles

IDENTIFICATION OF HIDDEN DAMAGE IN CONSTRUCTIVE ELEMENTS OF BUILDINGS AND STRUCTURES TO REDUCE THE RISKS OF THEIR DESTRUCTION

Problem statement. In emergency situations, which are activated by dynamic impacts from explosions, fires and earthquakes, it is necessary to monitor the stability of objects to assess their suitability for further operation. Purpose of the study. ensuring the safe operation of buildings and structures using methods, software and technical means for vibroacoustic monitoring of hidden damage in building structures. Methods. Analysis and generalization of data, computer modeling, experimental studies of the structures stability using the vibroacoustic method. Research results. Considered: loss of concrete stability, reinforced concrete, bricks and other elements of load-bearing structures; risk factors manifested in the gradual weakening of load-bearing building structures due to the accumulation of internal damage. Sudden loss of stability of structures occurs after the accumulation of a critical amount of damage in structural elements or the rapid growth of cracks, which are activated by the sudden unloading of extremely stressed structures as a result of any dynamic influences. By modeling the destruction process using the finite element method, it has been established that long before cracks on the surfaces of structures can be visually identified, zones of hidden damage can actively spread inside the wall structures of buildings. The main parameters for monitoring the condition of buildings and structures using visual and vibroacoustic methods have been determined. Due to the fact that the object of research is the partial destruction of buildings and structures (that is, not the root cause, but the consequences of the influence of a complex of negative main factors), two main groups of risk factors for assess the risks of stability loss have been proposed. The first group is associated with the detection of external structural damage identified by visual inspection methods. The second group is associated with the detection of hidden damage, the parameters of which are determined by the vibroacoustic method. The integral risk of stability loss is determined by comparing and selecting the maximum risk in the group. Scientific novelty. The methodology for identifying hidden damage in structural elements of buildings and structures has been further developed, which is distinguished by taking into account the parameters of vibroacoustic control of the destruction consequences and assessing the risks of the structures stability loss. Practical significance. The research results make it possible to improve the method for assessing changes in the structure of the medium as a result of the occurrence of observed and hidden systems of cracks using vibroacoustic monitoring.

Design and Implementation of Water PH Level and Turbidity Monitoring System

Abstract: Building collapses have become a distressing and recurring issue in Nigeria, necessitating urgent action to mitigate their occurrence. This paper introduces an innovative approach to address this challenge by developing an Automated Structural Health Monitoring System (ASHMS) utilizing a mobile app. Focusing on major cities like Lagos and Abuja, the proposed system employs strategically placed sensors to gather data from various structural elements of buildings. The collected information, encompassing seismic activity, vibrations, bending moments, shear forces, and other key parameters, is wirelessly transmitted to the cloud where it can then be accessed and visualized using mobile app. The system offers real-time insights into the structural integrity of buildings and provides early warnings, thereby contributing significantly to reducing the risk of building collapses. Key findings show that when incorporated into an automated Structural Health Monitoring (SHM) system, the user's mobile app offers essential structural insights, capturing values such as a 0.5-unit vibration level, 20 units of shear force, 50 units of bending moment, and an 89-degree vertical wall angle. The app's userfriendly interface improves the effectiveness of monitoring and overseeing structural health, in line with the overarching objective of promoting safety in construction practices

Automated Structural Health Monitoring System for Mitigating Building Collapse in Nigeria: A Mobile App Approach

Abstract: Building collapses have become a distressing and recurring issue in Nigeria, necessitating urgent action to mitigate their occurrence. This paper introduces an innovative approach to address this challenge by developing an Automated Structural Health Monitoring System (ASHMS) utilizing a mobile app. Focusing on major cities like Lagos and Abuja, the proposed system employs strategically placed sensors to gather data from various structural elements of buildings. The collected information, encompassing seismic activity, vibrations, bending moments, shear forces, and other key parameters, is wirelessly transmitted to the cloud where it can then be accessed and visualized using mobile app. The system offers real-time insights into the structural integrity of buildings and provides early warnings, thereby contributing significantly to reducing the risk of building collapses. Key findings show that when incorporated into an automated Structural Health Monitoring (SHM) system, the user's mobile app offers essential structural insights, capturing values such as a 0.5-unit vibration level, 20 units of shear force, 50 units of bending moment, and an 89-degree vertical wall angle. The app's userfriendly interface improves the effectiveness of monitoring and overseeing structural health, in line with the overarching objective of promoting safety in construction practices.

Visualization of Deformation and Stress Waves in Wooden Solid and Glued Elements of Building Structures.

The basis of the research hypothesis is the assumption that in wooden structures, deformations and stresses propagate in waves. The numerical experiment demonstrated a correct qualitative visual picture of the wave propagation of deformations, with wave manifestations and characteristic effects on the surface of the sample, at axial and corner points. Visually, the numerical model showed Rayleigh waves on the surface layer of the sample, depending on the ratio of the external geometric dimensions of the sample model, with pronounced wave interference on the outer shell. The visual manifestation of deformation on the outer sides (faces) and the reflection of deformation waves from the outer boundaries of the elastic medium of the sample in the form of Rayleigh waves confirm the correctness of the general hypothesis and the implemented model. Visualization of the process of emergence, propagation and attenuation of deformation waves on the surface of the sample shows that in the quantitative description of the deformation gradient, areas dangerous for the material can be identified.

Sound transmission loss of vertical building partitions designed to meet shear structural requirements

Vertical partitions often include structural building elements designed to meet shear requirements. Shear partitions are designed to resist lateral load due to wind or seismic activity and are required in many regions throughout North America. Nightingale et al. completed a 70-assembly series quantifying the effect of shear OSB on the sound transmission loss (STL) of both wood- and steel-framed single-stud assemblies in the National Research Council Canada (NRCC) research report NRCC-45018. This research study builds on the NRCC research with a test of over 200 wood and steel assembly partitions. This research study includes single-, staggered-, and double-stud framing as well as various forms of shear treatment such as OSB Plywood installed on one or both sides of the partition, attachment with various nail attachment patterns, and steel strapping. The effect of these partition elements on the STL will be presented and discussed. Additionally, the effect of sound isolation treatment, such as additional mass, resilient channels, resilient sound isolation clips, and constrained-layer damping will be presented and discussed.

Structures incorporating damping devices: Are we correct in our design thinking?

The use of discrete damping devices in New Zealand buildings is increasing as designers seek to limit damage to both architectural and structural building elements in moderate earthquakes. The overall damping of the structure becomes a combination of inherent material damping, hysteretic damping from yielding of building elements at specific locations and damping from discrete devices. For over 60 years, engineers have used simplified analysis procedures (e.g., modal response spectrum analysis) to predict building response under seismic actions. The design of structures incorporating viscous dampers requires a paradigm shift in approach as the force each damper resists is a function of the relative velocity between its ends. Popular pseudo-static design methodologies promote the use of a viscous strut in the analysis model to represent them. However, it is incorrect to use elastic, mode-based analysis for a structure incorporating damping devices and relying on significant inelastic behaviour. This paper elucidates the complex mechanics of damper-structure interaction by reviewing some of the established classical, modal‑based, simplified analysis techniques used in seismic design. A series of numerical investigations demonstrate how these techniques are usually invalid for structures that incorporate viscous dampers because they violate the laws of physics. The reason why mode-based techniques are invalid is explored with reference to the imaginary components of the natural modes of vibration and the effect on them of significant inelasticity within the structure. The dynamic characteristics of viscous dampers challenge conventional design approaches such as displacement-based design. This paper establishes that nonlinear time-history analysis is the only meaningful way of predicting the dynamic response of a structure incorporating viscous dampers when significant inelastic behaviour of the structure is expected.

Numerical simulation of the defect's behavior in building structure elements during ultrasonic diagnostics

One of the important scientific problems of modern construction is the detection of cracks in elements of building structures. Among a significant number of methods, ultrasound diagnostics is popular due to automation and speed of processing results. However, the accuracy of ultrasonic methods is in the range of 40%, which does not meet modern requirements. The article considers the problem of ultrasonic wave propagation in a brick and conducts a numerical analysis of the behavior of defects in the form of a crack. The results were obtained in the form of fields of displacements, deformations and stresses in the structure as a function of time. The results obtained make it possible to identify the characteristic features of the reaction of defects to dynamic impact and obtain numerical dependences of the response of the structure in comparison with samples without defects.

Planes geometry verification program written in Python

In recent years, there has been significant progress in sensor and scanning technologies in the computer vision and 3D visualization field. This has led to an increased interest in processing and analysing point clouds, which are groups of 3D points collected by laser scanners, stereo cameras, and drones. The data obtained from these devices has a wide range of applications. This article focuses on using point cloud data to verify planar structural elements of buildings. The article aims to present a methodology for analysing planar point cloud objects using 3D models in IFC format as reference data. The research includes processing data in IFC format, exporting geometric information, segmenting plane objects from a point cloud obtained by laser scanning, and analysing the data obtained. We provide the necessary graphic materials and code to enhance the content of the article. We also evaluate the results and create an outline for future work.

Finger-jointed wood compressed parallel to the grain: Experiment and modelling

Compression tests of pine specimens of two types with initial dimensions of 40x40x80 mm and 40x40x80 mm with finger-joints are considered. Tests on similar specimens without finger-joints are also analyses for comparison. The experiments showed that the finger-joint in the investigated specimens reduced the peak load on the specimen as well as the load in the post-peak stage of plastic deformation. A methodology for modelling the load-displacement relationship taking into account the plastic deformation of wood with a finger-joint in the post-peak stage is proposed. The modelling results do not contradict the experimental data. The basic equation of the proposed mathematical model can be used in further studies to analyse the energy characteristics of the deformation process of wooden elements of building structures.

Decomposition of the building into structural elements in the assessment of life cycle costs of construction objects.

The article substantiates the author's methodological approach to determining the cost of the life cycle of a construction object at the stage of preparing investor estimate documentation, taking into account the current industry regulatory and methodological framework and focusing primarily on the public customer. The necessity of calculating (grouping) investor estimate documentation is shown not by types of construction works, but by structural elements that have a generalizing and unchanging nature when determining the cost of construction, maintenance and repair of the object, which makes the structural elements the necessary unit for determining the cost of the life cycle. The possibility of decomposition of structural elements by levels of generalization related to the structure of the market of contractors and their products was also noted. The rules for the initial formation, use and subsequent clarification of value indicators during the design and development of the infestor estimate documentation and at the subsequent stages of construction, maintenance (repair) and completion of operation of the object are proposed. In this way, the evolutionary nature of the methodology is noted as the data necessary for calculations are accumulated and refined.
 The application part shows the compatibility of the proposed approach and BIM technologies, which also operate with structural elements. The procedure for displaying life cycle costs in the digital information model of the project is proposed, according to the levels of generalization and content - costs in the BIM model can be planned and actual and can be specified by value (amount) or calculation (estimate). The possibility of applying graph theory to the tasks of calculating the costs of the life cycle of a construction object is illustrated, which facilitates the development of mathematical apparatus and corresponding algorithms for estimating the cost of the life cycle using the BIM model.
 Corresponding changes to the current DSTU are proposed in terms of the development and standardization of the nomenclature of structural elements of buildings and structures and the standardization of the structure and the order of displaying information about the life cycle costs of the construction object in the BIM model.

A 3D BUILDING INDOOR-OUTDOOR BENCHMARK FOR SEMANTIC SEGMENTATION

Abstract. Both machine learning (ML) and deep learning (DL) algorithms require high-quality training samples as well as precise and thorough annotations in order to work effectively. The 3D building indoor-outdoor dataset (BIO dataset), which is a highly accurate, high level of detail, and high coverage dataset for 3D building point cloud and mesh semantic segmentation, is established as a canonical benchmark dataset. It contains 100 building models, in which building structural elements are annotated into 11 semantic categories. Each building in this dataset has an average of 75,587 triangular faces, and the total area of the dataset is 481,769 square meters. Furthermore, semantic segmentation of the dataset was carried out using the Random Forest ML algorithm to verify the dataset’s accessibility. A weighted F1 score of 96.64% was obtained with 10% of the segments of each building randomly chosen as training data. For applications involving building geometry data, the BIO dataset can support a broad class of recently developed ML and DL methodologies.

Формализация автоматизации определения амплитудно-частотных характеристик элементов зданий

The amplitude-frequency characteristics of vibrations of structural elements of buildings and structures are important design parameters when analyzing changes in the stress-strain state of a building during operation, including during surveys and monitoring of the technical condition of the building. Standardization of the method for determining the values of these parameters is carried out in accordance with the requirements of GOST 8.009 to ensure compliance with the requirements of GOST 31937 and GOST 32019. The vibrations of a building are a superposition of their own and forced vibrations caused by various internal (operation of household appliances and various technical systems of the building) and external (urban transport, construction sites, etc.) influences. To determine the values of the period, as a rule, the building's own vibrations are recorded, caused by the natural dynamic natural and man-made background of the city (if there is equipment sensitive to the levels of natural dynamic impact), therefore, no additional effects are exerted on the building during the measurement process. Industrial buildings are characterized by the presence and movement of heavy technological equipment inside buildings. Stresses during fluctuations have an alternating character, therefore they can cause fatigue of the material from which the structure is made. This, in turn, leads to the destruction of individual elements of the structure and, as a result, to accidents. The paper presents a dynamic calculation of the elements of the structure consisting of several stages: the dynamic characteristics of the nodes of the joints of the constructs with each other are determined; the dynamic degrees of freedom are determined; the theoretical calculation for vibrations is formalized.

Stability and load carrying capacity of thin-walled composite columns with square cross-section under axial compression

The study aimed to analyse the stability and load-carrying capacity of compressed thin-walled composite columns subjected to axial compression. The subject of the survey was composite columns with closed square cross-sections made of carbon-epoxy composite. Different lay-ups of the composite material characterised the test specimens - several cases of lay-ups were considered. The application of the subject of the research is closely related to the use of these elements as load-carrying elements of aerospace and building structures. The requirements for such structures are closely related to the provision of a large reserve of load-carrying capacity after buckling. Experimental testing was carried out using a universal testing machine and other testing techniques, where acoustic emission, an optical deformation measurement system, and a digital microscope, among others, were used. Numerical simulations using the finite element method were carried out parallel to the experimental studies. In the case of FEA simulations, original numerical models were developed considering known failure models of the composite material. For both empirical studies and FEM simulations, an in-depth analysis of the buckling and post-buckling states was carried out, considering the failure phase of the composite material. The novelty of the present work was the development of original FEM models, allowing faithful reproduction of experimental studies conducted on physical models, as well as the use of research methods to determine the load-carrying capacity of composite structures.

Seismic damage assessment for flexural double skin composite walls based on the modified Park-Ang model

The damage indices are widely used to evaluate the performance level and damage state of structural elements in buildings subjected to seismic actions. Despite the widespread promotion of double-skin composite walls (DSCWs) in global construction practices, the research related to the seismic damage assessment of DSCW members is still limited. In order to establish a seismic damage assessment procedure for DSCW members, an experimental database that includes 37 test results of DSCW specimens subjected to cyclic loads was built in this paper. Based on an existing modified Park-Ang model, an empirical expression of the combination coefficient is introduced. The damage state levels of DSCWs are determined as follows: Basically intact (DS0), Slight damage (DS1), Mild damage (DS2), Moderate damage (DS3), Relatively severe damage (DS4), Severe damage (DS5), and Critical collapse (DS6). The typical damage characteristics and repair methods are introduced and discussed. Subsequently, a comprehensive statistical analysis is conducted to study the probabilistic correlation between these damage states and the corresponding index specific to DSCW members. Fragility functions for each damage state associated with the damage index have been developed. The threshold values of the damage index corresponding to the damage states are also provided. This paper intends to provide a theoretical foundation for performance-based seismic design and post-earthquake damage assessment of DSCW structures.

Monitoring of structures with bearing elements in the form of long vertical rods

A building structure is considered, which in the design form consists of two vertical rectilinear interacting elements. One of them is loading, the other is carrying. The bearing element is presented in the form of a long thin rod loaded with an external axial vertical force. Due to the errors of geodetic verification and installation work, the bearing rod will be installed with some inclination and displacement relative to the coordinate axes. The external load on the bearing element is represented by the force vector, which is equivalent to the loading rod. Errors of geodetic verification and installation work will change the design direction of the force line and its design position on the supporting element. An inclined force vector will have a vertical and horizontal force component. Thus, the line of action of the loading force and the longitudinal axis of the supporting rod will be located at an angle to each other, which will cause bending momentsand transverse forces in the sections of the rod. A design "changed" in relation to the project is created. Bending moments and horizontal forces in this design will contribute to premature bending of the rod. An unevenly heated rod also acquires the ability to distort. The influence of the specified factors can be increased, and the stability of the rod significantly weakened due to uneven subsidence, horizontal displacement or tilting of the supporting structure due to dangerous exogenous geological processes. Therefore, errors in the position of elements, changes in temperature, geological processes disrupt the linear form of equilibrium of the bearing rod and its position in space. The change in shape and relative position contributes to the premature emergence of an unstable state under an increasing external load. In the changed design, the bearing rod may suddenly find itself in a critical stress-deformed state. The task of monitoring is to sense and properly record changes and dynamics of the stress-strain state. For this purpose, measuring complexes with a certain configuration are designed, which provide with the necessary specified accuracy the measurement of changes in the physical state of the elements of building structures.

A 3D INDOOR-OUTDOOR BENCHMARK DATASET FOR LoD3 BUILDING POINT CLOUD SEMANTIC SEGMENTATION

Abstract. Deep learning (DL) algorithms require high quality training samples as well as accurate and thorough annotations to work effectively. Up until now a limited number of datasets are available to train DL techniques for semantic segmentation of 3D building point clouds, except a few ones focusing on specific categories of constructions (e.g., cultural heritage buildings). This paper presents a new 3D Indoor/Outdoor building dataset (BIO dataset), which is aimed to provide a highly accurate, detailed, and comprehensive dataset to be used for applications related to sematic classification of buildings based on point clouds and meshes. This benchmark dataset contains 100 building models generated from existing polygonal models and belonging to different categories. These include commercial buildings, residential houses, industrial and institutional buildings. Structural elements of buildings are annotated into 11 semantic categories, following standards from IFC and CityGML. To verify the applicability of the BIO dataset for the semantic segmentation task, it has been successfully tested by using one machine learning technique and four different DL algorithms.

Modeling of Stochastic Material Properties with User Subroutines in SIMULIA Abaqus

This article describes a software module component integrated with the SIMULIA Abaqus engineering analysis software package and designed to simulate random values of material parameters in a finite element model based on specified statistical characteristics, with the possibility of taking into account the physical nonlinearity of material behavior under various combinations of loads and influences. The target group of materials under study is materials of load-bearing elements of building structures, such as concrete, stone, steel. This software module can be recommended for use by specialists, engineers and scientists engaged in probabilistic analysis of the reliability of structures of buildings and structures, apparatus, machines, devices, with the combined use of complexes of computer modeling and engineering analysis. Has a certificate of state registration of the computer program «AS for modeling stochastic properties of materials» No. 2019667439 dated 12.24.2019.

THE PROBLEM OF FORECASTING THE ROD STRUCTURES SURVIVABILITY

Purpose. Methods of metal structures calculation which would take into account sudden changes of the design scheme and its elements destruction as a result, are not perfect enough and are often fragmentary. The research of survivability of multi-element bar structures affected by negative factors will improve the efficiency of the such structures calculation with the prospect of further expanding the possibilities of forecasting the survivability of metal structures depending on its operation conditions. As a research object three-dimensional metal bar structures are considered, which are characterized by a high degree of production significance and responsibility during the operation. Methodology. The considered normative documents do not have a single approach regarding the identification of the problem and technique of generating possible solutions, but they combine all the listed standards. Approaches and methods for assessing the degree of a structure damage or serviceability are somewhat different: in some documents the area of damaged floor structures is limited; in others, the state of structures that have not gone out of work is assessed; as well as the economic forecast of a new building construction or restoring an old one. If we group the normative documents’ provisions of the different countries, we can single out two established approaches on "progressive destruction" protection. According to the first approach, it is necessary to use indirect protection measures, according to the second one, it is necessary to use the ability of key (bearing) elements to perceive damaging effects, the ability of structure to redistribute loads in case of some elements’ failures. Results. To increase the stability of building structures to progressive destruction, metal ones particularly, it is necessary to consider the possibility of local destruction already at the stage of building design. Its increase is facilitated by a decrease in the number of hinged joints, in some cases the use of integral structural elements, the use of building materials affected by plastic deformation, as well as the identification of building structure elements which under normal operating conditions do not perform bearing functions, but perform them in the case of the local destruction appearance. Scientific novelty. The analyses of the regulatory base and the researchers’ works in a number of countries including Ukraine regarding the progressive destruction is performed. The necessity to improve the concept of designing construction objects is justified. The basis of this concept should consist of both theoretical research and experimental confirmation of the accepted assumptions. Practical value. The necessity of forming a unified approach for determining the problem of survivability and durability of structures, redistribution of loads on undamaged structural elements is substantiated. Directions for the development of measures and design solutions regarding the prevention of the progressive destruction of multi-element bar structures are proposed.

Fire Resistance of a Building Element with Intumescent Fire Protection: Standard Assessment and Express Analysis

Introduction. The paper considers the problem of fire resistance assessment of building structures with intumescent fire protection. For the results reliability, a fire test should be carried out only when the intumescent coating at the facility is ready, which will make it possible to detect hidden factors of violation of its quality and prevent collapse in case of a possible fire. The work objective is to test the express analysis of intumescent coatings in comparison with standard methods for fire resistance assessment.Materials and Methods. The elements of building structures covered with fire-resistant intumescent paint Defender M Solvent with different diluent content were studied. The fire resistance of the coatings was determined by two methods. The first one is an express analysis. The following indicators were recorded:– general appearance of the coked cellular material (CCM);– swelling coefficient;– CCM compressive and shear-tear strength of the boundary layer.The second one is a standard approach according to the requirements of ISO 834-75 (GOST 30247.0-94). The indicators were:– time to reach the critical temperature;– critical deflection during heating.Results. In addition to the above indicators, testing also took into account the amount of diluent. The CCM swelling coefficient, CCM compression force, tensile strength and density were considered. The revealed patterns are systematized in a table. The obtained indicators were compared with the technical requirements for the material. The period during which the steel substrate of the sample reaches a critical temperature is recorded. It is established that with an increase in this time, the coefficient of swelling of the protective layer (CCM) and its shear-tear strength increases. At the same time, the values of compressive strength and CCM density decrease. When the intumescent paint is diluted beyond the norm, the fire protection parameters deteriorate and the fire resistance limit R45 is not reached. The research results are visualized in the form of diagrams. They confirm that the express analysis makes it possible to reasonably judge the suitability or unsuitability of the paint for fire protection, if the required fire resistance limit is R45.Discussion and Conclusions. In comparison with the results of the application of standard techniques, the effectiveness of the express analysis technique and the correctness of the results of the assessment of intumescent fire protection were confirmed. In construction conditions, an express CCM analysis will be sufficient to determine the quality of an intumescent fire retardant coating.

Assessing the Influence of Variations in Chemical Composition of Cement Brands in Ghana on their Setting and Workability of Concrete

The reliance on inferior on cement products for the construction of housing projects and other civil engineering infrastructural facilities has led to a number of building and other structural failures in Ghana over the years. The manufacturing of concrete utilized in the building of various structural member, such as columns, beams, slabs, footings and wall, was negatively impacted by the use of low-quality cements, rendering them unable to sustain any loads placed on them. Another observation made from the cement used was the inadequate proportioning of the chemical compounds during the manufacturing process which has negatively affected the setting of the concrete contributing to poor performance of structural elements in buildings and other infrastructural projects. In this research, the impacts of the variations in chemical constituents including SiO2, Al2O3, Fe2O3, Na2O, K2O, CaO, MgO, and SO3 in the different brands on setting times of cement and workability of fresh concrete were examined. The Vicat apparatus and the slump apparatus set-ups were used to measure the setting time and concrete workability respectively. It was found that the majority of the chemical compounds of the various cement brands evaluated in this research provided appreciable setting time as well as typical and acceptable consistencies. Most cement brands showed initial and final setting times between 30 and 271-306 minutes for cements in the 32.5R class. The initial and final setting times generated by the test were likewise observed to fall within 30 minutes and between 172-263 minutes, respectively, in the 42.5R class of cements, where a similar pattern was also observed. It was noted that for the same water-cement-ratio in all the concretes from the different brands of cement, good workability was obtained.