Vitaly I. Sibirko, Valentina S. Goncharenko, Tatyana A. Chechetina
et al.
This paper presents data on fires involving electric cars and motorcycles compared to all fires involving these vehicles for 2023–2024 and the first 9 months of 2025. The distribution of the number and share of fires involving four types of electric cars and motorcycles was analyzed by fire location (including categories of buildings and structures where the fire occurred), as well as by ignition source and cause of fire. It was found that cables and wires (electrical wiring) were the source of almost two-thirds of fires involving electric vehicles, with the main cause being violation of electrical equipment installation and operation rules.
Systems of building construction. Including fireproof construction, concrete construction
Abstract Although it is widely known that the shear strength of reinforced concrete (RC) deep beams is higher than that of general RC beams to which Bernoulli’s assumption can be applied, the maximum shear strength limit of deep beams is identical to that of general beams. Therefore, the shear strength of deep beams is limited to a low value due to the shear strength limit in many cases. Different codes currently in use have different limit values for the maximum shear strength of deep beams. The strength limit of deep beams in the ACI 318–19 code is a function of the square root of concrete compressive strength ( $$\sqrt{{{\varvec{f}}}_{{\varvec{c}}}\boldsymbol{^{\prime}}}$$ f c ′ ), but that in the AASHTO-LRFD code is a linear function of $${{\varvec{f}}}_{{\varvec{c}}}\boldsymbol{^{\prime}}$$ f c ′ . Therefore, the ACI 318–19 code tends to underestimate the shear strength of deep beams with high-strength concrete. In addition, because the strength limits of the two codes do not consider the influences of the shear span-to-depth ratio, they may overestimate the strength of large-size deep beams with a large shear span-to-depth ratio. In this study, an equation for evaluating the maximum shear strength limit of deep beams was developed and verified against the experimental results, considering the effective compressive strength of concrete, shear span-to-depth ratio. The proposed maximum strength limit of deep beams was compared with the shear strengths of 672 deep beams, and the results indicated that the prediction closely matched the measured strength limit. The coefficient of variation of the shear strength ratio of ACI318-19 code was 39.2%, while that of the proposed equation was 32.3%, which was the smallest among the three predictions.
Systems of building construction. Including fireproof construction, concrete construction
H. M. Jagadisha, Poornachandra Pandit, Shreelaxmi Prashant
et al.
Abstract The study reports the properties of slag–flyash–microsilica ternary blended one-part alkali-activated binder system. Microsilica, characterised by high surface area, helps in reducing porosity and also the presence of active silica contributes enhancing the reactivity of binders, while flyash and GGBS offer aluminosilicates to support alkali activation. Taguchi’s design of experiment, integrated with Taguchi grey relational analysis (GRA) is employed to determine the optimal precursor blends, water content and activator dosages to achieve setting times, flow characteristics and compressive strength comparable to conventional OPC. The optimised mix exhibited flowability of 120%, an IST of 46 min, FST of 95 min, and compressive strengths of 54.65 MPa and 69.75 MPa at 7 and 28 days, respectively. The predicted results of the proposed regression model were experimentally validated, with deviations not exceeding 5%. Furthermore, microstructural analyses were performed using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to examine changes in morphology, mineral phases, and molecular bonding of the binder mixes, respectively. The microanalysis has confirmed formation of dense C/N-A-S-H resembling gels as product of alkali-activation.. Carbon footprint, eco-efficiency and cost analysis were performed and found that the optimised mix is an eco-friendly alternative to OPC-based binders. Graphical Abstract
Systems of building construction. Including fireproof construction, concrete construction
Abstract Punching shear failure poses a critical risk in flat slab–column structures, potentially leading to catastrophic collapses. Retrofitting methods typically involve flexural or shear strengthening. Recent studies, however, reveal that combining indirect flexural strengthening with direct shear strengthening augments the punching shear performance. This research employed ultra-high-performance engineered cementitious composites (UHP-ECC) and ultra-high-performance steel-fiber-reinforced concrete (UHP-SFRC) as a bonded layer on the slab’s compression zone confining column as indirect flexural strengthening and galvanized threaded steel bolts as direct shear strengthening through slab thickness to augment the punching shear capacity. Six square flat slabs with central circular columns were constructed and then experimented to collapse to verify the effect of this proposed strengthening technique. The effects of various mesh and concrete types are investigated. Results showed that combining the UHP-ECC or UHP-SFRC bonded layer in the compression side with bonded galvanized threaded steel bolts significantly enhanced the punching shear strength of the slabs. The experimental findings demonstrated a remarkable increase of 62% and 111% over the unstrengthened slab for the UHP-ECC and UHP-SFRC strengthened slabs with single-layer mesh, respectively. Further enhancements were observed by adding a second steel reinforcement mesh to the UHP-bonded layer. A numerical model was developed using the finite-element (FEM) method to predict the structural behavior of tested slabs. Numerical results revealed that the FEM predicts well the performance of the slab–column connection, aligning well with experimental findings.
Systems of building construction. Including fireproof construction, concrete construction
Abstract The current research focuses on recycling construction waste by producing asphalt concrete mixtures containing varying proportions of recycled concrete aggregate (RCA), ranging from 0 to 50%. To ensure the improvement of the asphalt mixtures' properties in terms of Marshall stability, flow, bulk density, air void ratio, and splitting tensile strength, steel fibers were added at a volume fraction of 1.0%. The experimental program consisted of 12 asphalt cylinders with a diameter of 102 mm and a height of 64 mm, cast with different asphalt mixtures to study the effects of varying RCA proportions as well as the addition of steel fibers on the mechanical properties of the asphalt concrete mixtures. The stability of the asphalt mixtures decreased by 17.6%, 23.2%, and 28.8% when RCA was used at ratios of 30%, 40%, and 50%, respectively, compared to the reference mixture. The Marshall stability of asphalt mixtures containing steel fibers was higher than that of their counterparts without fibers. Moreover, 12 asphalt slabs were cast with different ratios of RCA in preparation for testing under the impact load resulting from the free fall of a 10-kg steel mass from a height of 2 m. The results revealed that the ratio between the back and front crater diameters for slabs containing 10%, 20%, 30%, 40%, and 50% RCA after incorporating steel fibers was 1.15, 1.17, 1.15, 1.28, and 1.36, respectively. These ratios were smaller than those of the counterpart slabs without steel fibers by 18%, 19%, 19%, 7%, and 18%, respectively. Moreover, due to the low accuracy of existing mathematical models for predicting the penetration depth of asphalt slabs made with RCA, this research presents a developed mathematical model capable of accurately predicting the penetration depth of such slabs. This model considers both the ratio of RCA and the steel fibers within the asphalt mixtures.
Systems of building construction. Including fireproof construction, concrete construction
Anatoly A. Shestaev, Alexey A. Novikov, Lilia V. Shcherbatykh
et al.
This article examines the potential for the integration of cataloguing and standardization systems in the Ministry of the Russian Federation for Civil Defense, Emergencies and Elimination of Consequences of Natural Disasters (EMERCOM of Russia). Current approaches to resource management are considered, as well as the advantages of synergy of these systems to improve the efficiency of emergency response are analyzed. The recommendations on the implementation of an integrated system are offered. The impact of including in the standards the requirement to use products with a federal stock number on the process of product cataloguing by manufacturers is focused on.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study was conducted to evaluate the seismic performance of an exterior precast concrete (PC) beam–column joint with ultra-high-performance fiber-reinforced concrete (UHPFRC). Currently, 45 MPa non-shrinkage mortar is used as grouting for the connection between PC beams and columns. In this study, PC joint specimens were designed using 45 MPa non-shrinkage mortar and 120 MPa UHPFRC as a grouting agent for connecting PC members. The shear reinforcement effect of UHPFRC was confirmed to reduce shear cracks in the joint core; this trend was similar in the specimens with reduced shear rebars. The maximum moment of the test specimen with the corbel was slightly increased, but there was no significant difference, and the failure pattern also showed similar results to the specimen without the corbel. In the test specimen to which the U-shaped beam was applied, the attachment surface of ultra-high-performance concrete and normal concrete were separated, and a large decrease in strength was observed. Considering workability, U-shaped beam do not seem to have any major merits in general, such as increased strength and difficulty in manufacturing, and it was judged that it was effective to separate the PC beams from the column face through corbels. Shear reinforcement through UHPFRC is effective in relieving congestion by reducing shear reinforcement bars at the joint, and it is judged that it can be used as PC joint grouting due to its excellent fluidity.
Systems of building construction. Including fireproof construction, concrete construction
Irina F. Zenkova , Dmitry S. Adamov , Natalia O. Shchegoleva
et al.
The article provides a brief overview of the legislative norms governing the use of risk indicators for violation of mandatory fire safety requirements during Federal state fire supervision in relation to fire safety means and fire extinguishing equipment. An algorithm for the formation of these risks was also proposed and there was made a conclusion that the widespread use of correctly formulated risk indicators corresponds to the common goals and objectives of improving control (supervisory) activities in the field of fire safety in the Russian Federation.
Systems of building construction. Including fireproof construction, concrete construction
Roman A. Emelyanov, Yury I. Nosach, Viktor D. Volkov
et al.
In this paper there is considered the creation of a multifunctional heavy-duty robotic fire extinguishing complex with improved tactical and technical characteristics on a tracked chassis. It is designed to eliminate man-made accidents and fires associated with the risks of fatalities and injury of personnel as well as to conduct reconnaissance in fire seats and to deliver fire extinguishing agents to them. With appropriate retrofitting, it is planned to use this system during elimination of the consequences of accidents with chemical and radiation pollution and work with explosive objects.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This paper focuses on the methodology for evaluating the degree of total curling in concrete pavement using machine learning. Deflection induced by falling weight deflectometer (FWD) testing is known as a direct correlation to total curling including built-in and daily curling. However, deflection measurement in the in-service road is also affected by others, such as environmental conditions, pavement geometry, subgrade stiffness, and mixture design. Thus, it is challenging to determine the level of curling from FWD data due to the complexity of influencing parameters. To navigate this complexity, prominent machine learning models are exploited to identify a non-linear relationship between curling and FWD deflections. A finite-element simulation of FWD is conducted to generate a vast data set, and a robust regression model is trained to estimate the total effective temperature difference (TETD) to quantify the effects of curling. Since input parameters for testing pavements can be measurable in the field, curling from TETD can be readily obtained using the proposed methodology. Comparative simulations highlight that the proposed models, with an MAE less than 0.5 °C significantly outperform the multiple regression performance, which registers an MAE of 3.45 °C in TETD, particularly in offering cost-effective and noise-tolerant prediction.
Systems of building construction. Including fireproof construction, concrete construction
Evgeny S. Mikhailov, Andrey I. Zakharov, Evgenya A. Shishkina
et al.
The article deals with the issue of ensuring the adoption of an informed decision on the use of unmanned aircraft systems (UAS) when delivering small-sized cargo to hard-to-reach and especially dangerous emergency zones. In particular, the element of environment such as the estimation of delivery duration, which is random has been considered.It is shown that it is advisable to consider the duration of delivery of small-sized cargoes using UAS subordinate to the Erlang distribution. There are also presented practical recommendations for the implementation of assessment of delivery duration.
Systems of building construction. Including fireproof construction, concrete construction
Abstract To investigate the application of iron tailings in cement-based materials as fine aggregate and mineral admixture, six iron tailings sands were selected from different places of origin, and the methods of acid and alkali activation were adopted to increase the activity of tailings powder. The strength of mortar was evaluated and the composition and microstructure were analyzed to explore the mechanism. The experimental results show that iron tailings sands had little adverse effect on the mortar strength, and there was a maximum increase of 13.2% in 28-day compressive strength compared with that of river sand mortar. The hardness values of all the iron tailings sand and the interfacial transition zone (ITZ) around them were higher than that of natural river sand, but their Ca/Si ratios in the ITZ was lower, indicating a chemical reaction occurred between the iron tailings and cement paste. Generally, the iron tailings sand with higher SiO2 content and finer particles tend to have higher activity. In addition, the pozzolanic activity of iron tailings powder could be greatly promoted by chemical activation, especially by acid activation. The activity index of cement mortar with unactivated iron tailings powder was only 63% at 28 days, whereas that of acid-activated and compound-activated samples reached up to 93%, and the heights of the maximum heat flow peak of these samples were even higher than that of the control sample without iron tailings powder, and the time to reach the peak was in some advance, moreover their impedance parameters were close to the control sample.
Systems of building construction. Including fireproof construction, concrete construction
Abstract Fly ash (FA) is the most commonly used supplementary cementitious material in the world. However, the reactivity of FA varies substantially. In this study, new machine learning (ML) model has been developed to efficiently predict the amorphous content in FA type F. Compared to the existing ML model using types F and C of FA from different countries, this study more focused on the improved prediction of FA type F only produced from South Korea. It was found that the contents of CaO and SiO2 impact high in predicting the amount of aluminosilicate glass. However, the contribution of Al2O3 and Fe2O3 are ranked differently. The improved model algorithm was proposed as a combination of three ensemble techniques of bagging, boosting, and stacking. As a result of the test, the final model shows $${R}^{2}$$ R 2 of 0.80 in predicting the amount of aluminosilicate glass in FA type F.
Systems of building construction. Including fireproof construction, concrete construction