Hasil untuk "Systems of building construction. Including fireproof construction, concrete construction"

Leonid P. Vogman, Alexandr V. Ilyichev

An analysis of the relationship between the chemical structure of IA–VIIA subgroups metal hydrides (nonmetals) of D.I. Mendeleev’s periodic table and their fire and explosive properties has been performed. There is considered the difference between the following types of hydrides: ionic, covalent, metallic and complex, depending on the type of bond between metal (nonmetal) atoms and hydrogen. It is indicated that when the electronegativity of the elements is very different, the bond between the atoms is ionic. If there is no difference in the electronegativity of the elements, the bond will be nonpolar, and if there is a difference, it will be polar. Ionic hydrides are formed by the interaction of hydrogen with alkaline and alkaline earth metals of IA, IIA subgroups at elevated temperatures and pressures. Attention is drawn to the nature of the covalent bond, which is characteristic of IIIA–VIIA subgroups hydrides of the periodic table. It is more complex than the ionic bond. The fire and explosion hazard of hydrides is analyzed, which is determined by the bond between the atoms. The higher the chemical activity (reactivity) of hydrides, the greater the electronegativity of the elements (metal, nonmetal – hydrogen) and the higher the polarity of the atoms between the metal (nonmetal) and hydrogen in the hydride molecule, and, consequently, the lower the stability of the compound. The presented data on the relationship between the chemical structure of metal hydrides (nonmetals) and their fire and explosion hazard allow to predict their flammability and explosiveness level based on the known information about the nature of the bond between an element and hydrogen (ionic, covalent, metallic, or complex).

Zengkui Xie, Zhilin Chen, Chenhui Zhu et al.

Abstract Based on the newly developed technology proposed by our team, which involves reinforcing severely cracked orthotropic steel bridge decks (OSDs) with an ultra-high-performance concrete (UHPC) layer containing transverse steel-plate strips, this study conducted full-scale fatigue performance validation tests on the steel–UHPC composite bridge deck of the Junshan Yangtze River Bridge. To verify that the observed stress distribution reasonably reflects the actual structural behavior, finite-element modeling was used to derive the stress influence lines for both the actual bridge segment model and the laboratory-test specimen designed in this study across different fatigue details. The finite-element analysis showed good agreement between the model of the actual bridge segment and that of the laboratory-test specimen. The fatigue tests were conducted in three phases. In the first phase, fatigue cracks were initiated and monitored at specific critical details of the deck before reinforcement. The results indicated that cracks formed most easily and propagated most quickly at the intersections between the deck plate and U-ribs, as well as at the weld holes between U-ribs and transverse diaphragms. In the second phase, the propagation of these fatigue cracks and the changes in stress were compared before and after the UHPC layer reinforcement. The findings proved that the UHPC layer effectively suppressed crack growth and reduced the stress amplitude at fatigue-prone details (with reductions of up to 96% at the deck plate and U-ribs, and up to 57% at the U-ribs and diaphragm weld holes). In the third phase, the model underwent additional fatigue testing, including 1 million loading cycles at the diaphragm and 2 million two-point loading cycles at the mid-span, to verify the long-term fatigue resistance of the reinforced model throughout its entire service life. Data provided by the health monitoring system of the in-situ measurements on a real bridge further validated the effectiveness of the reinforcement measures in reducing stress amplitude at fatigue-sensitive locations (with stress amplitude reductions of up to 86% at the intersections of the deck plate, U-ribs, and transverse diaphragms). This study provides actionable insights into fatigue behaviors and reinforcement strategies, contributing valuable experience toward the maintenance and preservation of similar infrastructure.

Anxiang Song, XuanRui Yu, Nima Khodadadi et al.

Abstract Magnesium Phosphate Cement (MPC) is recognized as an effective rapid repair material, with compressive strength serving as a key mechanical property indicator for its mortar formulations. Nevertheless, due to MPC's complex composition and formulation, predicting its compressive strength remains a significant challenge. In this study, a comprehensive database was developed, incorporating four key input variables: the magnesium-to-phosphate (M/P) molar ratio, water-to-cement (W/C) mass ratio, sand-to-binder (S/B) weight ratio, and the borax-to-magnesia(B/M) weight ratio. This dataset was used to train and validate eight machine learning models, including the Lightweight Gradient Boosting (LGB) algorithm, Support Vector Machine (SVM), Decision Tree (DT), Extreme Gradient Boosting (XGB), Ridge Regression (RR), Random Forest (RF), Backpropagation Neural Network (BP), and Gradient Boosting (GB) models. The eight machine learning models were evaluated using performance metrics, including Mean Absolute Percentage Error (MAPE), Mean Absolute Error (MAE), Correlation Coefficient, and Root Mean Square Error (RMSE), to identify the optimal model, which was then optimized via the Gray Wolf Optimizer (GWO). The most accurate prediction of MPC compressive strength was attained using the XGB model, with the GWO-optimized XGB model showing enhancement in MAPE, MAE, R2, and RMSE by 21.8%, 60.6%, 43.9%, and 55.3% respectively, relative to the unoptimized XGB model. Employing Shapley Additive exPlanations (SHAP) values and Partial Dependence Plots (PDP), this study facilitates the identification of the most influential input variables and quantifies their effects on MPC compressive strength. The optimized model was validated against experimental data, demonstrating robust and conservative prediction behavior. While the model is trained solely to predict compressive strength, its interpretability enables rational insights into how formulation variables influence strength, thereby supporting informed mix design decisions. This framework offers a reliable and transparent computational tool for preemptive strength assessment of MPC and guides the optimization of mechanical performance in structurally demanding applications.

Mehdi Aghabagloo, Laura Carreras, Manish Prasad et al.

Abstract With the emergence and diversity of various strengthening methods in fibre-reinforced polymer (FRP) strengthened reinforced concrete (RC), understanding and comparing the bond behaviour and active bond mechanisms of these different methods is crucial before their application. In this context, a general method applicable to various strengthening techniques employed to develop accurate bond–slip models and identify the active bond mechanisms is proposed. This approach is based on experimental load–slip behaviour data and does not rely on a predefined model shape. To this end, this paper presents an experimental study on various strengthening techniques, including externally bonded reinforcement (EBR), externally bonded reinforcement on grooves (EBROG), hybrid bonded (HB), and near-surface mounted (NSM), all tested under a single lap-shear test. Here, the results of single-shear bond tests are analysed to examine the manifestation of different activated bond mechanics from various strengthening techniques in the bond–slip law and to compare their bond behaviours.

Olga S. Matorina, Oleg V. Streltsov, Andrey A. Kondashov et al.

The article is devoted to a comprehensive analysis of foreign experience in fire management in order to identify effective organizational models, technological solutions, and approaches aimed at minimizing the consequences of fires. A detailed review of the practices of the United States, the European Union, Australia, Japan, and Canada has been conducted. Special attention is paid to investigation of systems of interagency cooperation, of the introduction of digital and robotic technologies, the population training and development of volunteer initiatives. The article substantiates the feasibility of applying foreign methods and technologies in Russian practice, taking into account the specifics of natural and man-made threats.

Janusz Sobieraj, D. Metelski, J. Rosłon

The rationale for this work arose from the urgency of improving the energy efficiency of buildings at the design stage, given the changing requirements of energy efficiency standards such as the Polish Technical Conditions (WT 2014 and WT 2020). This research is novel as there is currently limited information available on the improvement of the thermal performance of ventilated stone facade systems, although they are now widely used due to their practical and aesthetic advantages. The first objective of this work is to evaluate the thermal performance of the ventilated facades of the Praski Student House (Akademik Praski) and to assess how certain design variations can help achieve a lower level of energy consumption. Using a comprehensive case study approach, this study provides accurate thermal calculations of the facade to assess its global thermal insulation coefficient (Rt) and thermal transmittance (Uc). The improvement in the actual U-value from the original design is as follows: the U-value is reduced from 0.33 originally to 0.228 for WT 2014 and to 0.198 for WT 2020, showing a reduction of about 30.9% and 13.2%, respectively. These results indicate the energy efficiency of increased insulation thickness and optimally oriented air gap dimensions. The practical contributions of this research are valuable for architects, engineers, and contractors involved in the design and construction process of buildings aiming to achieve near-zero energy buildings (nZEBs), including concrete suggestions on how to improve current construction practices as well as material recommendations. There is a need for durability studies, for example to assess the performance of such facades under different climatic conditions, as part of future work to support these findings.

Irina F. Zenkova, Evgeny V. Kozyrev, Natalia O. Shchegoleva

The article provides an overview of the main provisions of the Strategy for Scientific and Technological Development of the Russian Federation in terms of issues related to scientific and technological development of science sectors, as well as technologies fundamentally related to fire safety. Priorities and prospects of scientific and technological development are listed, the purpose and main tasks of the strategy are indicated. There are presented the indicators established by the strategy for evaluating the effectiveness of measures and instruments of state policy in the field of scientific and technological development.

Luai Mohammed Alhems, Aftab Ahmad, Mohammed Ibrahim et al.

Abstract Thermal evaluation of twin wall panel systems was assessed under vibrant hot and arid conditions of weather in the Arabian Peninsula. Two systems of wall panels (0.6 m × 0.6 m) were prepared. The first system was prepared with a 5.0 cm thick extruded polystyrene (XPS) board. While the second system was prepared with 5.0 cm thick layer of foam-mortar encompassing expanded polystyrene (EPS) beads. Both the thermal insulative layers were sandwiched between two 7.5 cm thick concrete layers. The two wall panel systems were thermally evaluated at the same time in a carefully designed test room. Comparison was accomplished between the two wall systems by measuring the U-value (thermal transmittance) and R-value (resistance). The U-value (air to air) for sandwiched XPS concrete wall system was 0.837 W/m2 K while it was 2.527 W/m2 K for sandwiched EPS beads foam-mortar concrete wall system. The mean U-values (surface to surface) of the sandwiched XPS concrete wall system was 1.143 m2 K/W and 0.293 m2 K/W for sandwiched EPS beads foam-mortar concrete wall system. The sandwiched XPS concrete wall system was more efficient than the sandwiched EPS beads foam-mortar concrete wall system in terms of thermal performance. About 4.5 h of time lag was observed for both the wall panel systems between the external surface temperature and the heat transmission in the internal surface. The output of the FEM simulation by ABAQUS is compared with the measured data for Set-1 (period 16-Aug-2022 to 26-Aug-2022). The hourly temperature change on the outer and inner surfaces has good agreement for both sandwiched XPS concrete wall system and sandwiched EPS beads foam-mortar concrete wall system. The simulation can also predict the heat flux through the two wall systems investigated.

Jawad Ahmad, Mohamed Moafak Arbili, Muwaffaq Alqurashi et al.

Abstract Many scientists are now focusing their attention on the utilization of valuable industrial or agricultural wastes as the primary raw material for the construction sector. These wastes, on the other hand, are affordable and readily accessible, making them ideal for commercial use while also contributing to the reduction of environmental degradation. Wheat straw ash (WTSA) is a kind of agricultural waste that has the potential to be utilized in concrete. Although many researchers are focused on utilization of WTSA in concrete. However, an updated review is required which provides easy access for the reader to get an idea about the benefits of WTSA in concrete. Therefore, this study provides a comprehensive review of the utilization of WTSA as a concrete ingredient. Physical and chemical compositions of WTSA, flowability, mechanical strength (compressive, flexure, tensile strength, and elastic modulus), and durability properties (permeability, carbonation, ultrasonic pulse velocity, alkali-silica reaction and chloride attacks) are the main aspects of this review. Results indicate that the performance of concrete improved with partial substitutions of cement with WTSA but simultaneously decreased the flowability of concrete. The optimum dose is important as higher dose results in decreased mechanical strength. The typical optimum dose ranges from 10 to 20% by weight of the binder. The performance of concrete in terms of durability was also improved but less research is carried out on the durability performance of concrete with WTSA. Additionally, despite WTSA's improvement in mechanical strength, concrete still exhibits lower tensile strain, which leads to brittle failure. Therefore, it was recommended that further study should be done to increase its tensile strength.

Fayu Wang

Abstract Fabric-reinforced cementitious matrix (FRCM) composites, also known as textile-reinforced mortars (TRMs), represent a new advancement in structural repair and reinforcement technology. Aiming to improve the energy efficiency and seismic performance of existing buildings, this research focused on the development of an FRCM system in combination with phase change materials (PCMs) and extruded polystyrene sheets (XPS) to achieve adequate mechanical and thermal properties for reinforced concrete (RC) and masonry structures. Accordingly, the in-plane behaviour of five FRCM-strengthened RC frames with hollow-brick wall infill was tested under cyclic loading to investigate the improvement in earthquake resistance. The system was comprehensively evaluated by calculating hysteresis curves; comparing the lateral stiffness, ductility, and energy dissipation capacity; measuring the deformations of the specimens; and analysing the failure modes mechanically. Finally, it was proved that this novel integrated approach could significantly enhance the mechanical and seismic performance of masonry-infilled RC frames.

Morteza Esmaeili, Hamid Amiri

Abstract The conversion of ballasted railway tracks into slab tracks using the preplaced aggregate concrete (PAC) technology over the bridges and in the tunnels has been introduced by many researchers but the flexural behavior of this composite system has not yet been studied. Therefore, in the first stage, a series of mortar and concrete mixture designs were proposed and evaluated. Subsequently, a concrete beam mold with dimensions of 3 * 0.6 * 0.5 m, which represented the track conditions, was developed and the bending behavior of the constructed beams in both conditions of the presence and absence of the concert B70 sleeper were investigated. The maximum bending force in the middle of the concrete beam without a sleeper (SE) equaled 177.5 kN. In addition, the average values of bending tolerance by the sleeper including a PAC beam for three specimens in the four modes of the positive moment of midspan (SPM), negative moment of midspan (SNM), positive moment of rail seat (SPR), and negative moment of rail seat (SNR) were 55.25 kN m, 32.5 kN m, 91.84 kN m, and 38.21 kN m, respectively, which met the requirements of the AREMA regulations.

Wei Wang, Xuendan Yao, Guiqiang Gao et al.

Abstract Deterioration characteristics analysis of lining structure has received intense research interests for immersed tube tunnel fire, while a considerable part of the spotlight is on numerical simulation. However, most of existing works consider concrete lining as a macroscopic homogeneous material for simulation analysis, ignoring the difference of its internal components. This paper aims at studying the mesoscopic deterioration characteristics of immersed tube tunnel roof structure towards efficient safety design of immersed tube tunnel roof. In particular, we establish a mesoscopic model of immersed tube tunnel under thermo-mechanical coupling using ANSYS. Compared with the traditional homogeneous approaches, the proposed mesoscopic model can directly simulate the fire degradation process of immersed tube tunnel roof structure, which blazes marvelous trail for related engineering applications. Our extensive simulation results reveal the progressive failure process of micro-cracks initiation, development, expansion and coalescence in the roof of immersed tube tunnel.

Victor I. Iskalin, Tamara G. Skibnevskaya, Natalia V. Tuz et al.

The article considers the application of method for identifying the significance and importance of linear correlation between indicators of the population life quality in regions of the Russian Federation and indicators of fire fatalities/injuries among children. The statistically significant presence of these correlations is shown.

Olga D. Ratnikova, Natalya V. Peregudova, Vera I. Tregubova et al.

The article considers the methodology of preventive activities performed by officials of Executive authorities of the subjects of the Russian Federation, as well as local government, organizations, and citizens in the residential sector. There is presented the system of initial data for development of a set of preventive measures in the residential sector, considering the socio-demographic development of the subjects of the Russian Federation. The list of preventive measures at residential facilities as well as an exhaustive list of requirements for implementation of preventive activities in the residential sector were developed following the results of scientific investigations in the context of research work. The procedure of preventive activities in the residential sector is presented.

Diogo Figueira, Carlos Sousa, Afonso Serra Neves

Abstract A nonlinear finite element model (FEM) is developed to assess the behaviour of a cracked concrete interface, reinforced with embedded steel bars and subjected to monotonic loading. A dowel action finite element modelling approach is conceived for that purpose. The bond between the steel bars and the surrounding concrete is also considered in the model and an interface finite element is included to simulate aggregate interlock. Then, the comparison of the model results with experimental values allowed the calibration of aggregate interlock constitutive relations for cracks in monolithic concrete restrained by embedded steel bars. New constitutive relations are also proposed for shear transfer by aggregate interlock in a concrete joint.

Rongling Zhang, Peng Liu, Lina Ma et al.

Abstract To study the influence of different water–binder ratios on the corrosion, permeability, and freezing properties of concrete, we produced different strengths of concrete with respective water–binder ratios of 0.32, 0.38, 0.50, and 0.66. The corrosion resistance of the concrete was studied via three corrosion methods: full immersion, half immersion, and dry and wet cycles. The impermeability and frost resistance of concrete with different water–binder ratios were tested and analyzed. The test results show that the corrosion modes in order from strong to weak were dry and wet cycles, half soaking, and full soaking. The relative dynamic elasticity modulus and freeze–thaw index were used to evaluate the frost resistance of concrete based on the analysis of three indices of frost resistance. To study the internal mechanism of corrosion of concrete with different water–binder ratios, microscopic pore structure testing of the concrete was conducted using a Micromeritics AutoPore IV 9500 Series instrument. The porosimeter studies show that the smaller the water–binder ratio, the more small pores and the denser the concrete. The smaller the water–binder ratio, the higher the strength and the better the corrosion, permeability, and frost resistance.

Assessing Xiaodong Peng, the Xiaohui She, of Binjian Nie et al.

Atta-ur-Rehman, Abdul Qudoos, Sadam Hussain Jakhrani et al.

Abstract Photocatalytic cementitious materials are used in the exterior of the buildings and infrastructure for self-cleaning and air-purifying purposes. These materials are exposed to the aggressive exposure conditions like acid rain, runoff water and are subjected to the deterioration due to the leaching of calcium. The knowledge of leaching attack upon photocatalytic cementitious materials after the addition of nano-materials is necessary. In the current study, the influence of nano-silica addition on the leaching attack upon photocatalytic cement mortars was thoroughly investigated. For this purpose, photocatalytic mortars were made by adding 3% TiO2 and variable amount (0–2%) of nano-silica. Accelerated leaching environment was created by immersing mortars in 6 M ammonium nitrate (NH4NO3) solution. The progressive development of the leaching depth in mortars was measured. The loss of hardened properties was monitored by evaluating the compressive strength, flexural strength, porosity, and dynamic modulus of elasticity. X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy tests were conducted to know the microstructural deteriorations. Results indicated that the leaching attack induced mechanical and microstructural damages in the mortars, but the addition of nano-silica decreased mechanical and microstructural damages in the photocatalytic mortars and increased the resistance of photocatalytic mortars to leaching attack.

H. Allahyari, Iman M. Nikbin, R. Rahimi et al.

Dichuan Zhang, Jong Kim, Saule Tulebekova et al.

Abstract A renewable energy storage system is being proposed through a multi-disciplinary research project. This system utilizes reinforced concrete pile foundations to store renewable energy generated from solar panels attached to building structures. The renewable energy can be stored in the form of compressed air inside the pile foundation with a hollowed section. The pile foundation should resist complex combined actions including structural loads, soil effects, and pressures induced from the compressed air, and thus it requires a careful analysis and design considerations to secure a sufficient structural safety. This paper presents analytical investigation results on the structural responses of the energy piles under these combined loadings. The pile foundations were designed based on the current design practices for various building geometries including the number of stories and column spacing. The magnitude of air pressure was determined from the thermodynamic cycles for the available renewable energy for storage considering building and pile foundation geometries. Finite element analyses were conducted using an elastic 3D model to determine critical tensile stresses of the pile foundation. These critical tensile stresses were used to identify required reinforcement in the pile section. On this basis, several nonlinear finite element analyses were then conducted using inelastic constitutive models of materials to investigate the crack patterns of the hollowed concrete section. Recommendations were finally presented for proper practical designs of the pile foundation serving as the renewable energy storage medium.