Load-bearing Structures Of Buildings Research Articles

Physicochemical, mechanical and thermal performance of lightweight bricks with recycled date pits waste additives

This paper assesses the effect of recycled date pits waste additive as a construction material additive to unfired clay bricks, with m Multiple waste additive proportions (0%, 1%, 3%, 7%, 15% and 20%), by weight, in terms of their physicochemical, mechanical and thermal performances. Crystalline characterization of used clay in its raw state, via X-ray Diffraction, showed its Illite type with non-swelling characteristics. While the chemical composition analysis, following X-ray Fluorescence, reflected the presence of several elements in Bensmim clay, such as Silica (SiO2) and Aluminum oxide (Al2O3) making it a suitable construction material with a rich clayey structure. The incorporation of higher waste additive content in the bricks' composition resulted in the production of more porous samples. In fact, specimens with 20% waste additive percentages, which is the highest evaluated proportion, reflected the highest recorded porosity level of 18.51%, compared to 1.17% of reference samples. This prompted in the production of brick samples with a lightweight structure, according to Moroccan testing standards NM EN 772–13 conformed to ASTM C20-00, and increased capillary water absorption coefficient of 49.75 g/(cm2.min0.5) in contrast to reference samples of 26.50 g/(cm2.min0.5). In addition, mechanical threshold analysis, produced brick samples of Earth Blocks Class 3 (EB3) and Earth Blocks Class 4 (EB4), that can be used non-load bearing and load bearing building structures, respectively. Waste additive-based samples of 20% waste additive proportion reflected samples of a 4.02 MPa and 0.98 MPa compressive and flexural strengths, respectively compared to 6.17 MPa and 4.65 MPa of reference samples. The incorporation of waste additives content in the bricks' matrix reflected enhancements in the specimens’ thermal stability. In fact, recorded gains in thermal insulating properties were of 37% for thermal conductivity and 21% specific heat capacity compared to reference samples; as well as 68% and 47% energy savings in terms of thermal cooling and heating loads, respectively, following an energy simulation of a reference house.

Functional materials based on the effect of mechanoluminescence for monitoring the state of load-bearing structures

Researches of light-generating converters based on zinc sulfide allowed us to describe the physical nature of the light signal. The description of the physical nature of light generation by semiconductors is based on the band theory of conductivity. This allowed us to determine the conditions for the possibility of registering mechanical impacts using mechanoluminescent pulse pressure sensors. One of the important conditions, as it turned out, is the presence of manganese impurities in the material, which become centers of light emission. Also a necessary condition for the appearance of luminescence is the hardness of the sensor element, it facilitates the transfer of mechanical stress to the crystal lattice of mechanoluminescent material and the changes in it with the release of energy as light. This property of these materials allows them to operate in generator mode and convert mechanical action into an optical signal without additional energy sources. As a result, theoretical and experimental data on the possibility of detecting pulsed mechanical action using distributed mechanoluminescent converters were obtained. As one of the directions of application of such converters, it is proposed to create composite materials with the insertion of light-conducting fibers with longitudinal light transmission, covered with mecanoluminophore particles. This will allow to create composite materials with a self-diagnosis function and the ability to connect to optical data channels for continuous monitoring of the technical condition of load-bearing structures of buildings. Such materials are devoid of such disadvantages as: the need for power supply or a reference light stream, sensitivity to electromagnetic interference, and a low degree of embeddability in the structure, inherent in the devices currently used.

INSPECTION OF THE TECHNICAL CONDITION OF A NON-RESIDENTIAL BUILDING

This article contains a survey of the building in a. Sary-Bulak. A detailed visual examination of the object of study, an assessment of the technical condition of the main loadbearing building structures of the building, an analysis of the causes of defects and damage, and preliminary installation of the technical condition category were carried out. As a result of the survey, design recommendations, measures for the restoration or strengthening of building structures were developed.

Область застосування та способи модифікації композиційних матеріалів на основі деревини

Проведено аналіз літературних джерел різних способів модифікації деревини. Приведено основні способи глибинної модифікації деревини. Наведено область застосування композиційних матеріалів на основі деревини в різних галузях будівництва та деревообробній промисловості. Висвітлено подальші дослідження модифікації деревини силором.

Estimation of spatial correlation for seismic design of buildings

The paper discusses a solution for the probabilistic problem of high-rise buildings oscillation exposed to seismic loads in form of a six-component random vector. Two groups of matrices for the dynamic response factors to help estimate the effects of spatial correlation between generalized coordinates and correlation in the various seismic vector components on design stresses in load-bearing building structures have been obtained. The spatial model of a building configured as a thin-wall compound bar provides a solution for the probabilistic problem in analytical form.

THE DEVELOPMENT OF INFORMATION TECHNOLOGY OF STRUCTURAL HEALTH MONITORING SYSTEMS

Objectives. The aim of the study is to develop information technology design systems for monitoring load-bearing structures of buildings and structures of a higher category of responsibility based on the initial data on the construction object and the results of engineering surveys.Method. The article discusses the approach to the formalization of the description of the procedure for developing projects for monitoring buildings and structures, based on the design features of the SMC building structures, the engineering experience of designing these systems.Result. The article presents the conceptual foundations of the developed information technology, the algorithm for determining the monitoring mode based on information about the construction object, the algorithm for the macro to determine the most loaded nodes and elements in the complex finite element modeling. Recommendations are given for determining the control parameters, the composition of the measuring equipment.Conclusion. The conceptual foundations of information technology developed in the course of the research allow for the further development of algorithms and programs for the automated analysis of information about the object and the construction site in order to obtain the automatic mode of the results necessary for developing monitoring systems for buildings and structures of a higher category of responsibility.

Optimal structures design: accounting of costs and relative accidents risk

Introduction: the article considers the formulation and solution of the problem of optimizing structures. It takes into account the ratio of the cost of manufacturing the object and the risks of material losses in emergencies related to the rapid removal of supports. The choice of the local damage scenario is justified. The assessment of risks arising from emergencies is a significant problem. The solution to it can primarily increase the safety of load-bearing building structures.
 Materials and methods: the two-step computational procedure is used, which includes an evolutionary search on discrete sets of design parameters and the calculation of the emergencies risks at different periods of the carrier system life cycle. At the first stage, a variant of the object is synthesized using a genetic algorithm. In this case, the evaluation of its stress-strain state is carried out taking into account the dynamic effects arising from possible local damage to the supports. The second stage consists of the calculation of the integral value of the relative risk of material losses in an emergency. It includes the failures related to both the statistical nature of the loads and the mechanical characteristics of materials, as well as the onset of various scenarios of local damage.
 Results: the technique for selecting a cost-effective rational design-based solution for beam structures with a higher level of responsibility has been developed. The considered example of the optimal design of a steel beam construction has illustrated the efficiency of the proposed approach.
 Conclusions: the research results showed that it is unacceptable to carry out the optimization of the design solution, considering only the minimum cost of structures in buildings of a higher level of responsibility. The most rational design decision on the criterion of minimizing costs and risks is the object that ensures the persistence of the structure during the emergency removal of only one support. The considered technique is recommended to using in computer-aided design of load-bearing structures.

The experimental study of glass multilayer columns using digital image correlation

Purpose: The purpose of the research is to study the deformability of glass multilayer columns at the central compression using digital image correlation. It becomes possible to use the method of digital image correlation for the experimental study of load bearing building structures of glass. Design/methodology/approach: The approach which has been used to solve the above problems is to conduct an experimental study of glass columns on central compression, in which deformations were measured using digital image correlation. Findings: The possibility of using load bearing building structures of glass triplex has been discovered. A program of experimental studies was developed. It included the testing of prototype samples on central compression with rigid fastening. On the basis of the obtained results, a graph of dependence of relative deformations on normal tension, graphs of the dependence of the bending of columns on load in different planes, and a modulus of elasticity of triplex glass have been determined. Research limitations/implications: The lack of a calculation methodology and regulatory documents for designing load bearing building structures of triplex glass increases their cost, since each project is individual and requires the experimental research. Practical implications: Using the approaches developed in the paper, the method of digital image correlation, which is to measure deformations when testing glass structures on central compression can be applied. Originality/value: The experimental study is probably the first one in which deformations of glass columns are determined using the method of digital image correlation, so it is new and original. The lack of a calculation methodology and regulatory documents for designing load bearing building structures of triplex glass, increases their cost, since each project is individual and requires the experimental research.

Experimental assessment of steel fibre reinforced concretes with different concentrations of fibres

At present, steel fibre reinforced concrete can be classified as a composite material commonly used for load-bearing building structures. Adding steel fibers to fresh mixture improves its mechanical properties in comparison to plain concrete. The problem is, however, the production technology, which has not been standardized by regulations so far, and thus, proposals for the amount of steel fibers added to the mixture are still based on the long-term experience and performed tests. The paper describes an experiment focused on the determination and assessment of mechanical properties of steel fibre reinforced concretes with high concentrations of fibres (40 kg/m3, 80 kg/m3 and 120 kg/m3). To better understand the behavior of test specimens during the three-point bending test, the acoustic emission method was used, which is able to capture active defects. The results show that the increasing amount of fibers has the influence on values of FRk,0.5 and FRk,res,1 (e.g. for concentration 40 kg/m3 is FRk, 0.5 = 13.27 kN and for 120 kg/m3 is FRk, 0.5 = 21.18 kN).

Reinforcement of brick historic buildings threatened by structural damages or by failure

The paper presents selected aspects of reinforcing the brick cultural heritage buildings, particularly load-carrying elements of those structures. In some cases the operational phase of many load-bearing elements of the historical buildings is shrinking or has used up. The crucial task while carrying out construction works related to reinforcing or repair of the load-bearing structure is to ensure safety. This safety should be assured regarding both the structure itself and its users. The design concept also needs to include recommendations and instructions of the conservatorinspector. The proposed scope of technical assessment and analysis of the load-bearing structures of buildings is presented on selected examples. The performed diagnostics process allowed to properly determine the occurred hazards and on this basis to properly design and carry out repair of damaged elements of structure [1]. The first of the analysed cases concerns the barracks facility near the Makowiecka Street in Przasnysz. Another example described in this paper is the brick dome of the church building of St. Anne in Wilanów district in Warsaw. The damages and failure identification process, as well as taken measures and proposed methods of reinforcement of the structure are presented with reference to the both above mentioned examples.

Resistance to the destruction of concrete in constructions of height buildings at dynamic loads

The analysis of the criterion of strength of concrete in structures of high-rise buildings under vibration and shock impacts is presented. The idea of an energy approach to ensuring the strength of concrete and the durability of building structures from reinforced concrete under the influence of shock impacts on the life of such structures is presented in a high-rise construction. A method for determining the strength and durability of concrete in load-bearing building structures made of reinforced concrete for irreversible thermodynamic processes has been developed. Dependences that determine the behavior of concrete in reinforced concrete structures of high stores on the load-bearing structures of a building under the influence of damped oscillations from the operation of air transport on the landing site are determined, taking into account the impact arising from its landing.

Wooden I-Beams Made of Round Timber with a Core Rot

Round timber with core rot was not used in the production of sawn timber for load-bearing building structures. The purpose of this work is the researches of a possibility of receiving wooden beams from round timber with a core rot. The wooden I-beam made of angular elements of the received their round forest products with decay was chosen as the object being studied. The design scheme for determining strength and deflections of the beam is a statically determinate hinged beam, loaded with a uniformly distributed load. The design spacing of the structure is assumed to be 6 meters. Under the action of a load equal to 1.5 kN/m, the beam is exposed to stress-strain state of transverse bending. A method for manufacturing I-beams from corner elements obtained as a result of cutting round logs with core rot is proposed. It has established that the calculated strength characteristics of I-beams produced according to the proposed technology may resist operational loads. Rated and tangential stresses arising from application of loads do not exceed the permissible values. Deflection of a beam does not exceed allowable deflection values. The use of round timber with core rot increases resources of wood for construction.

Stress-strain state of the structure in the service area of underground railway

The paper focuses on numerical study how vibration due to underground trains influences the load-bearing building structures. Diagrams of vibration levels for monolithic floor slab depending on frequency are obtained. Levels of vibrations on floor slabs and columns are measured. The simulation of dynamic load from underground railway onto load-bearing building structures is presented as an example with account of load transmission through the soil. Recommendations for generation of design model in dynamic analysis of structure are provided.

Estimation of seismic building structural types using multi-sensor remote sensing and machine learning techniques

Detailed information about seismic building structural types (SBSTs) is crucial for accurate earthquake vulnerability and risk modeling as it reflects the main load-bearing structures of buildings and, thus, the behavior under seismic load. However, for numerous urban areas in earthquake prone regions this information is mostly outdated, unavailable, or simply not existent. To this purpose, we present an effective approach to estimate SBSTs by combining scarce in situ observations, multi-sensor remote sensing data and machine learning techniques. In particular, an approach is introduced, which deploys a sequential procedure comprising five main steps, namely calculation of features from remote sensing data, feature selection, outlier detection, generation of synthetic samples, and supervised classification under consideration of both Support Vector Machines and Random Forests. Experimental results obtained for a representative study area, including large parts of the city of Padang (Indonesia), assess the capabilities of the presented approach and confirm its great potential for a reliable area-wide estimation of SBSTs and an effective earthquake loss modeling based on remote sensing, which should be further explored in future research activities.

Rational design methodology for fire exposed load bearing structures

The state-of-art of reliability studies in the area of fire-exposed structures or structural members is illustrated, taking examples from published papers concerning load-bearing building structures of steel, reinforced concrete, and wood. In parallel, trends are described in the present development of rational structural fire design methods, principally adapted to modern loading and safety philosophy for the non-fire state. Statistically derived results are presented for fire-exposed, insulated steel structures in office buildings, giving the breakdown of the total variance in maximum steel temperature and load-bearing capacity into component variances as a function of the insulation characteristics. The safety index and probability of failure are compared numerically for different fire design procedures. The data presented are examples of the information which is required as input in a qualified systems analysis of fire exposed load-bearing structures.