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Masonry walls are subjected to cyclic lateral loads to study damage caused by earthquakes. Imaging techniques are useful to quantify crack networks in such tests, where preferential locations for their initiation are not present. However, detecting small cracks in large structures is challenging. It is shown that finite element (FE)-based digital image correlation (DIC) can detect and quantify cracks by combining optical and mechanical information of a cyclic shear experiment performed on a full-size masonry wall. Pixel-wise gray-level residuals and elementary crack opening displacement fields are the key quantities of the proposed framework. Detection criteria based on standard uncertainties guided the application of new DIC strategies (i.e., mechanical regularization, mesh adaption, and damage). Two damage regimes were quantified. Zigzagged cracks were first formed, for which their opening displacements were on average less than 0.5 mm with very limited damage. They were followed by sliding shear cracks, whose mean opening displacements varied between 1 and 3 mm, and damage developed in a more gradual and extended way. Such rich full-field data set may be used for validating damage models up to full-scale simulations. [ABSTRACT FROM AUTHOR]

A foundation pit's excavation area, which is determined by its radius in a circular foundation pit, exerts a considerable influence on the pit's behavior. Using a full-scale experiment on a circular foundation pit retained by a prefabricated recyclable supporting structure (PRSS), this study develops a series of axisymmetric numerical models to systematically investigate the influence of excavation radius on the pit's deformation, stress, and stability. Furthermore, simulation results from axisymmetric models are compared with those from plane strain models to illustrate the influence mechanism. The results show that at a given excavation depth, the deflection and bending moments of the supporting piles, the earth pressure on the non-excavation side, and ground surface settlement increase with the enlarged excavation radius, but the increase rate progressively decreases. However, the foundation pit's safety factor decreases with an increasing excavation radius and gradually stabilizes. When the excavation radius exceeds 50 m, its influence on the foundation pit's behavior significantly diminishes. The axisymmetric model results closely approximate those from the plane strain models, suggesting that the spatial arching effects of the circular foundation pit can be disregarded. [ABSTRACT FROM AUTHOR]

The prevalence of small-scale structures, such as sentry buildings, has become widespread, with many of these buildings exposed to the outdoor environment and exhibiting suboptimal thermal insulation in their envelopes. Through a comprehensive study of outdoor disturbances, the most unfavourable envelope was identified. In light of this finding, we have designed static air layer sentry buildings (SAL-SB) and dynamic air layer sentry buildings (DAL-SB). The study conducted experiments and numerical simulations to evaluate the impact of air layer thickness, vent opening forms, and inlet velocities on the thermal insulation of sentry buildings. The results showed that both the SAL and DAL effectively improved thermal insulation, and a thickness of 25 cm has been found to offer the best thermal insulation. However, considering the balance between thermal insulation and cost-effectiveness, a thickness of 15 cm is recommended. Additionally, for DAL, an inlet velocity of 3 m/s is the threshold for switching the heat transfer direction on the roof. These findings provide novel insights into enhancing the thermal environment. [ABSTRACT FROM AUTHOR]

In this study, a tunnel model with a length of 20 m, a width of 5 m, and a height of 5 m was used, and an experimental investigation was conducted to examine the impact of high-pressure water mist on the temperature distribution along the tunnel ceiling. Specifically, different experimental settings, such as various nozzle pressures, nozzle positions, and longitudinal ventilation speeds, in the high-pressure water mist system were employed to investigate the smoke-spreading process of tunnel fire under different conditions, and an effective method utilizing a high-pressure water mist system was proposed for blocking smoke and heat. The experimental results reveal that the high-pressure water mist system can be used to effectively improve the ceiling temperature during tunnel fires; when the nozzle pressure is set as 10 MPa, and the nozzle position is located at x7, the highest thermal insulation efficiency in the tunnel is obtained. Additionally, the joint application of the high-pressure water mist system and the mechanical smoke exhaust effectively mitigates the ambient temperature within the tunnel, thereby playing a pivotal role in enhancing the fire safety of the tunnel. [ABSTRACT FROM AUTHOR]

Prestressed concrete (PC) is increasingly used in civil engineering construction. Notably, research on shear resistance in PC beams with short shear span remains relatively limited, necessitating further comprehensive exploration. In the study, tests were conducted on bonded post‐tensioned PC T‐beams with short shear span (a/h = 1.0), subjecting them to monotonic loading destructive tests. These beams measured 24.9 m in length, 1.605 m in height, and had a top flange width of 2.0 m. They featured a uniform cross‐section with a 0.22 m web thickness. Given the size of the full‐scale test beams and space constraints for loading, an innovative loading scheme was devised to minimize the counterweight. Test results demonstrate the safety and feasibility of the loading scheme. The tests were conducted five times and the main test variables were the draped tendons and the quantity of horizontal web reinforcement. The tests revealed that horizontal web reinforcement significantly influenced crack propagation but had a minimal effect on shear strength. For the parameter values taken for the test beams, the prestressing level has less effect on the shear strength of the beam. Simultaneously, an investigation was conducted involving a total of 119 PC beams. This investigation aimed to evaluate the degree of conservatism and accuracy in shear design code provisions and shear strength equations derived from various standards, including the strut‐and‐tie model (STM) of ACI, AASHTO, and Tan, as well as the critical crack model of Yuan and the truss model of Laskar. Comparative analysis indicates that, the design method provided by Yuan exhibit relatively superior predictive capabilities. [ABSTRACT FROM AUTHOR]

Introduction. Based on a full-scale experiment, the process of forming a drawing prism in front of the blade surface was assessed and qualitative indicators that confirm theoretical studies of this process were identified.Materials and methods. In conducting experimental research, the main provisions of the theory of experimental design, based on the methods of mathematical statistics, were used. In accordance with theoretical studies, the process of formation of the drawing prism in front of the working bodies of earth-moving machines is accompanied not only by a change in the speed of soil movement on the surface, which occurs as a result of the action of adhesive forces and frictional forces, but also by the Coriolis acceleration that occurs in the process of moving soil along the curved surface of the dump, which, in our opinion, is the main reason for the uneven distribution of soil in front of the dump surface.Results. The proposed method of conducting and processing the results of the experiment made it possible to identify that the parameters characterizing the force of soil adhesion on the surface of the working body of the dump type are: volumetric mass of soil; the speed of soil movement at the i-th point of the surface of the working body; time of soil movement on the dump surface; coefficient of friction of the soil on the surface of the working body; time of interaction of the soil with the surface of the working body. The method of processing the results of the experiment made it possible to qualitatively identify and quantitatively assess the process of formation of the drag prism when moving soil on the surface of the working body in two-dimensional space, to determine the change in the velocities of soil movement at an arbitrary point of the surface and to verify the working hypothesis and theoretical studies on the nature of the change in the velocities of soil movement in front of the dump surface.Discussions and conclusions. It has been established that in order to reduce stickiness, it is necessary to optimize the parameters of the working body, the depth of digging and the time of interaction of the soil with the surface of the working body.

Ultra-High Performance Concrete (UHPC) is a new type of engineering material with high compressive strength, high tensile strength, and high fracture toughness. Its bending failure mechanism is different from that of traditional concrete beams, which requires a new computational model to describe the bending failure phenomena of the prestressed ultra-high performance concrete - reinforced concrete (UHPC-RC) beam without web reinforcement. Therefore, this paper, through full-scale tests on a 30m prestressed UHPC-RC beam without web reinforcement, captures unique bending failure phenomena, including initial cracking, development of local cracks, and rupture of prestressed steel strands. Considering the tension-compression constitutive relationship of UHPC material, an innovative computational model for bending bearing capacity is proposed. Based on this model, a study on the minimum reinforcement ratio of full prestressed-ordinary steel bars is conducted. The results show that in the bending failure of the prestressed UHPC-RC beam without web reinforcement, excessive tensile strain of steel strands will occur at the local crack location. At this time, the structure does not satisfy the assumption of plane sections, and the introduction of the calculation model of the limit state of external prestressed tendons can effectively match this model, which is highly consistent with the experimental results. The minimum reinforcement ratio of full prestressed-ordinary steel bars is revised to the auxiliary reinforcement ratio of full prestressed-ordinary steel bars, quantifying the minimum reinforcement requirements of ordinary steel bars. The research results of this paper can provide reference for the next step of theoretical research. [ABSTRACT FROM AUTHOR]

Hammerhead pier is the preferred option in many bridge sites for its limited ground occupation. Since the bearing reactions act on the short cantilever ends of the cap beam, it is usually treated as stress-disturbed region (D region) in structural concrete. Although finite element model (FEM) can predict the response of such structures, the calculation efficiency will be sharply decreased once it enters nonlinearity. Therefore, strut-and-tie model (STM) has been promoted as an alternative approach for analyzing D regions. In this study, a loading pattern was defined to relate the axial force and bending moment of the pier column with the eccentric load ratio. Sectional analysis method and associated codes were developed to generate the STM. In addition, a full-scale hammerhead pier specimen subject to varying eccentric loads was tested. Besides, nonlinear FEM was also established to numerically investigate the response of the pier. The results indicate that the proposed STM has general applicability for modeling the hammerhead pier and shows better prediction than the FEM. The failure pattern of the hammerhead pier with a prefabricated cap beam was defined. Combining the mechanical analysis of STM and experimental results, the recommended design details for hammerhead piers were proposed. [ABSTRACT FROM AUTHOR]

• Food waste ground by food waste disposers is easier to block pipes. • Liquid bridge force is the internal cause of deposits to aggregate. • Diameter of aggregations is positively correlated with adhesion on pipes. • Reducing particle size or choosing CI or HDPE pipes may reduce blockage. Food waste disposers (FWDs) streamline kitchen waste management and facilitate waste classification, whether they would increase the potential of blockage in kitchen drainage system is still unknown. This study conducted a theoretical analysis of the interactive forces between fat, oil, and grease (FOG) deposits and their aggregation on pipe walls. The study involved grading food waste particles processed by FWDs using sieving and weighing techniques to determine the mean weight diameter (MWD) of various aggregations. A full-scale experimental system, implemented in a 60-m high test tower, simulated blockages in horizontal pipes of high-rise buildings. The effect of pipeline materials and particle sizes on blockage were examined by measuring the adhesion of deposits on horizontal pipes. Energy dispersive spectrometer (EDS) analysis suggested that liquid bridge force is a primary factor in aggregate formation. Hand-cut particles formed aggregates with the highest MWD value. Particle size analysis revealed that sizes ranging from 2.36 to 4.75 mm, 1.18–2.36 mm, and 0.60–1.18 mm constituted over 80 % of particles ground by FWDs, with an average size of 2.16 mm. Results of full-scale experiment indicate particle diameters, friction coefficients and lipophilic coefficient significantly affected the propensity of these aggregates to adhere to pipes. Notably, particles processed by FWDs tended to cause blockages more frequently than hand-cut particles. These findings elucidate the deposition mechanism of FOG deposits and offer strategies to reduce blockages in kitchen drainage systems, such as reducing current grinding particle size by 18 % to 1.77 mm or selecting pipes like cast iron and high-density polyethylene. [ABSTRACT FROM AUTHOR]

To investigate the compression-shear behavior of a new circumferential joint based on the sleeve-straight bolt combination type connection of large-diameter shield tunnels, a series of full-scale joint experiments was carried out. In the process of the experiment, more attention was paid to the specimen displacement, bolt stress and joint damage mode. On the basis of these experiment phenomena, this study discussed the compression-shear bearing process of the new connector, analyzed the damage mode of the joint structure, and finally evaluated the performance of the new connector. It is found that the bearing process of the joint can be divided into four stages: the transitional stage for overcoming the friction of the concrete, the sleeve bearing stage for the sleeve bearing shear loads alone, the combined bearing stage for bearing shear loads by the connector system, and the structural damage stage for structural instability and damage. Generally speaking, affected by connector position and hand hole, the positive compression-shear stiffness of the joint is less than the negative compression-shear stiffness, and the positive shear strength of the joint is greater than the negative shear strength. The increase of longitudinal axial force will improve the compression-shear performance of the joint. The relationship between longitudinal axial force and joint stiffness is a logarithmic function. The use of new type of connector can effectively improve the compression-shear stiffness of joints under low shear loads, but the application of straight bolts will lose part of the strength performance.

To establish a practical method to detect damage to autoclaved lightweight concrete (ALC) exterior walls subjected to earthquakes, a cyclic loading test of steel structural frames equipped with ALC exterior walls was performed. In the test, several compact and cost-effective MEMS accelerometers were placed on the ALC panels and steel structural frames to evaluate their effectiveness in damage assessment. The results showed that the MEMS acceleration sensors could measure the residual in-plane and out-of-plane rotation angle of each element including ALC panels with sufficient accuracy and was concluded to be the most promising instrument for application to damage detection. [ABSTRACT FROM AUTHOR]

A foundation pit’s excavation area, which is determined by its radius in a circular foundation pit, exerts a considerable influence on the pit’s behavior. Using a full-scale experiment on a circular foundation pit retained by a prefabricated recyclable supporting structure (PRSS), this study develops a series of axisymmetric numerical models to systematically investigate the influence of excavation radius on the pit’s deformation, stress, and stability. Furthermore, simulation results from axisymmetric models are compared with those from plane strain models to illustrate the influence mechanism. The results show that at a given excavation depth, the deflection and bending moments of the supporting piles, the earth pressure on the non-excavation side, and ground surface settlement increase with the enlarged excavation radius, but the increase rate progressively decreases. However, the foundation pit’s safety factor decreases with an increasing excavation radius and gradually stabilizes. When the excavation radius exceeds 50 m, its influence on the foundation pit’s behavior significantly diminishes. The axisymmetric model results closely approximate those from the plane strain models, suggesting that the spatial arching effects of the circular foundation pit can be disregarded.

The characteristic feature of stratified flows in large bodies of water is generation of intense short-period internal waves at the front of long-wave disturbances. The nonlinear processes are most pronounced during the propagation of bottom and near-surface disturbances. The effective tool for studying wave processes in the ocean is the theory of multilayer shallow water with regard for the effects of nonlinearity and dispersion. It is shown that the developed mathematical models are suitable for describing the transformation of nonlinear internal waves both in the shelf zone of the sea and in the deep freshwater reservoirs. In particular, the structure of near-bottom internal waves in the shelf zone of the Sea of Japan and recently discovered near-surface internal waves in Lake Teletskoye are compared. The mechanism of generation of intense internal waves during excitation of seiche oscillations in narrow water reservoirs is discussed. Traveling waves in a multilayer fluid are constructed and numerical solutions to the nonstationary problem of generating internal waves are found. A comparison with the laboratory experiments on generation of a packet of short-period internal waves during seiche oscillations of a two-layer fluid in a long channel, as well as with the recorded near-surface internal solitary wave in Lake Teletskoye, is carried out. [ABSTRACT FROM AUTHOR]

Under the influence of long-term vehicle loads and large attenuation degrees, asphalt pavement performance gradually decreases, which leads to failure in fulfilling the appropriate requirements and, in turn, may affect driving safety. The purpose of this paper was to study the attenuation mechanism and rule of styrene–butadiene–styrene (SBS)-modified recycled asphalt pavement, so as to determine the applicable position and rational utilization of recycled asphalt mixture. To achieve this goal, two structures were designed, and full-scale experiments were carried out. The performance of the field test road based on accelerated loading testing (ALT) was analyzed through field monitoring data. The fatigue characteristics of stone matrix asphalt-13 (SMA-13) and asphalt concrete-20 (AC-20) mixtures before and after accelerated loading were studied via the trabecular bending fatigue test and dynamic modulus test. The microscopic components in the asphalt mixtures were determined via thin-layer chromatography on chromarods with flame ionization detection (TLC-FID). The results showed that the fatigue properties of recycled asphalt mixture can meet the requirements of ordinary asphalt mixtures and meet the technical standards of asphalt pavement design. With the increase in loading times, the British pendulum number (BPN) value of the two structures tended to be stable, and the BPN of Plan 2 was six less than that of Plan 1. Under the same test conditions, the fatigue life sequence of the recycled asphalt mixture under different loading frequencies was 20 Hz > 10 Hz > 5 Hz. The contents of four components in the reclaimed asphalt mixture were similar to those in the ordinary asphalt mixture. The light component of the reclaimed asphalt mixture of SMA-13 was reduced by 11.69%, and the light component of the ordinary asphalt mixture of SMA-13 was reduced by 15.29% through the full-scale test. In summary, recycled asphalt mixture should not be applied to the upper layer of pavement but can be rationalized in the middle layer and the bottom layer of pavement. [ABSTRACT FROM AUTHOR]

In this study, full-scale fire experiments were conducted in a hydropower station to investigate smoke propagation during tunnel construction. The flame height, smoke temperature and stratification, smoke descent and spread velocity were analyzed via measurements and on-site observations. The initial combustion stage was largely affected by ignition source during tunnel construction for diesel pool fire, and the average flame height in the fully developed stage could reach 1.4–2.1 m in experimental fire scenarios. The gradient of the smoke temperature evolution near the fire was the opposite for the upstream and downstream regions. The longitudinal temperature distribution was concentrated in a small range at the heights of the smoke layer, and gradually decreased by air entrainment as the height decreased, while further increasing in the lower half of the tunnel height in the near-fire region under heat radiation from the fire source. Moreover, distinct and stable smoke stratification formed during the fully developed combustion stage, and the smoke layer interface was at approximately half the tunnel height. Smoke descent was aggravated in the decay stage of combustion, and the fire risk remained high after the fully developed period. The smoke front spread velocity was empirically determined for the full-scale tunnel fire scenarios. Conclusions from full-scale experiments can support smoke control design and on-site fire emergency response plans for hydropower stations.

In this study, a tunnel model with a length of 20 m, a width of 5 m, and a height of 5 m was used, and an experimental investigation was conducted to examine the impact of high-pressure water mist on the temperature distribution along the tunnel ceiling. Specifically, different experimental settings, such as various nozzle pressures, nozzle positions, and longitudinal ventilation speeds, in the high-pressure water mist system were employed to investigate the smoke-spreading process of tunnel fire under different conditions, and an effective method utilizing a high-pressure water mist system was proposed for blocking smoke and heat. The experimental results reveal that the high-pressure water mist system can be used to effectively improve the ceiling temperature during tunnel fires; when the nozzle pressure is set as 10 MPa, and the nozzle position is located at x7, the highest thermal insulation efficiency in the tunnel is obtained. Additionally, the joint application of the high-pressure water mist system and the mechanical smoke exhaust effectively mitigates the ambient temperature within the tunnel, thereby playing a pivotal role in enhancing the fire safety of the tunnel.

Ultra-high performance concrete (UHPC) as a joint material for precast bridge decks might reduce the width of the joint and improve its connection performance and durability. This study proposes a type of compact UHPC wet joint based on the mechanical properties of UHPC and the force characteristics of transverse joints in prefabricated bridge decks. The shear behavior of the novel joint was investigated through experimental study and numerical simulation. In addition, the shear properties of compact UHPC wet joints were compared with epoxy joints. The results indicated that the shear resistances of compact UHPC joints are comparable to those of epoxy joints. The failure process of the precast bridge deck with new joint might be divided into three stages: elastic stage, working stage with cracks, and yield stage. No interface cracks or reinforcement slippage was observed throughout the loading process, indicating that the UHPC joint and the epoxy joint exhibited adequate shear resistance. The ultimate load capacity and corresponding mid-span deflection of UHPC joint specimens were respectively increased by 8.6 % and 75.0 %, when compared with the epoxy joint specimens. Finite element analysis reveals that the transverse shear transfer range of the compact UHPC joints is within 57.1 %. Bending failure due to the yielding of the transverse reinforcement at the bottom of the precast bridge deck is the primary failure mode for both specimens. Moreover, the stresses applied to the deck system have good continuity at the joint.

Roads play a crucial role in the socio‐economic development of a region, providing a means of transportation for people and goods. However, traffic loads, weather conditions, and other factors can lead to damage of road pavements, especially of the surface layer over time. One important factor affecting the response of surface layers under traffic loading is the bonding condition between asphalt layers. In this paper, the aim is to analyze the strains at the base of surface layers in asphalt pavement structures with two different bonding conditions: one with a tack coat and one without tack coat. To achieve this, experimental measurements on full-scale pavement tests and numerical calculations in viscoelasticity are carried out. Calculations are performed using three interface models: bonded interface, sliding interface and thin elastic interface. The findings show that structures with a tack coat exhibit significant sliding at the interface. Moreover, the use of a bonded interface in design methods cannot predict correctly the measurements. In addition, the study shows that taking into account temperature gradients in the pavement structure improves significantly measurement prediction, especially at high temperatures.

In recent years, with the development of urban rail transit, more and more attention has been paid to the vibration problems caused by its operation. As the main form of urban rail transit's underground construction, the shield tunnel is the first to bear the brunt. However, the existing researches on the vibration of shield tunnel usually take it as a homogeneous barrel and do not consider the impact of its assembly joints on the vibration propagation. In this paper, to study the influence of the joints caused by the shield tunnel's assembly forms on the propagation of vibration, two finite element models of shield tunnels with different assembly forms are established. The analysis and comparing results of these models show that the joints caused by segment assembly of shield tunnel have obvious hysteresis and reduction effect on the vibration waves and this ability is obviously related to its location. In addition, the ability to weaken the vibration wave is also related to the frequency of the vibration wave. [ABSTRACT FROM AUTHOR]

Many cultural and heritage structures are constructed using timber materials in China. Timber buildings are very common in historic and cultural blocks and rural areas of Southwest China. Many of them have been destroyed during fire and exert an inestimable loss to people and society. This work is aimed at investigating the temperature distribution, flame and smoke behavior within timber compartments. A full-scale experiment was built and carried out. The timber building groups consist of four compartments placed in two platforms of different heights. Temperature profiles were obtained by thermocouples arranged at corresponding positions. Fire behavior both in and out of compartments, as well as structural failure, were examined. A smoke detection system was applied to record the arrival time of smoke at a specific position. Cameras were also employed to observe and record the fire growth. The potential route of smoke is revealed. The results suggest that not only the common route of smoke should be taken into consideration in designing smoke detection systems but also the unconventional path of the gaps. The obtained data of temperature profiles will provide useful information for the prevention of historic and cultural timber buildings in Southwest China. [ABSTRACT FROM AUTHOR]

The effect of active generation of lift force by an electric impeller propulsion system in integral aerodynamic configurations of vertical take-off and landing aircraft with a flush intake device and an upper step in the stage of start from surface, is shown. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Full-scale loading tests were performed on shield segmental linings bearing a high earth pressure and high inner water pressure, focusing on the effects of the inner water load and assembly manner on the mechanical properties of the segmental linings. The test results indicate that the deep-buried segmental linings without inner pressure have a high safety reserve. After the action of high inner water pressure, the lining deformation will increase with the reduction of the safety reserve, caused by the significant decrease in the axial force in the linings. Because the bending moment at the segmental joints is transferred to the segment sections in the adjacent ling rings, the convergence deformation, openings of segmental joints, and bolt strains are smaller for the stagger-jointed lining than those for the continuous-jointed lining; however, dislocations appear in the circumferential joints owing to the stagger-jointed assembly. Although it significantly improves the mechanical performance of the segmental lining, stagger-jointed assembly results in compromising the waterproofing safety of circumferential joints. The stagger-jointed assembly manner can be considered to improve the service performance of shield tunnels bearing high inner water pressure on the premise that circumferential joint waterproofing is satisfied.

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Design methods for corrugated steel culverts in current design standards consider the circumferential force in culvert walls (i.e., hoop thrust) to be the dominant load-carrying mechanism in these structures. However, recent studies have shown that bending moment, rather than thrust, is often the more dominant response for corrugated steel culverts under shallow burial conditions and vehicle loading. In addition, 2D finite element analyses have historically been unable to effectively capture the effects of discrete surface loads, such as wheel loads, on the response of buried metal culverts. To investigate these issues, the bending moment and thrust responses from an experiment involving an elliptical corrugated steel culvert under shallow burial conditions and simulated vehicle loading are compared with the bending moment and thrust estimates from the Canadian bridge design code and CANDE-2019 (a commonly used public domain finite element software package) and the thrust estimates from the American AASHTO LRFD bridge design code (which does not consider moment directly). The comparisons show that the Canadian code and CANDE-2019 models with a fine mesh and the continuous load scaling elasticity-based method appear to be the most effective for the investigated culvert and loading, while there is a need to modify the American AASHTO LRFD code to consider moment more directly. In addition, the results suggest that, under these conditions, the current approaches for estimating the peak bending moment response are more effective compared with the approaches for estimating the peak thrust response. [ABSTRACT FROM AUTHOR]

Although research on the natural ventilation of single-sided buildings is progressing, research on the natural ventilation of the Mogao Grottoes, which have special shapes and structures, is relatively limited. The purpose of this paper is to develop a correlation for calculating the natural ventilation rates of such grottoes. Field experiments were carried out on two typical caves to measure their meteorological parameters and natural ventilation rates to verify the validity of the proposed correlation. The results show that our correlation has good reliability and stability when predicting the natural ventilation rates of the caves. First, the new correlation has a small average deviation of 16.35%. The average deviations in the natural ventilation rates predicted by seven established correlations are as low as 17.85% and as high as 59.39%, revealing a large gap compared with the correlation proposed herein. Second, the maximum deviation in the outputs of the proposed correlation is only 7.70% between each case. Finally, a comparison between the calculated results and the values measured in Cave 328 shows that the correlation is also suitable for large-volume caves. The developed correlation provides theoretical support and a scientific method for preventive protection and a quantitative analysis method for the study of natural ventilation in caves. [ABSTRACT FROM AUTHOR]

Proper positioning of the positive pressure ventilator is an important aspect of conducting rescue operations. The purpose of this article was to determine the effect of the parameter of the distance of setting up a mobile fan (distance from 1 to 7 m) on the efficiency of implemented ventilation in a multistory building. The volumetric airflow rate was determined by measuring the flow velocity at 120 measurement points on the surface of the window opening (which served as the measurement plane) of a four-story building. Two positive pressure ventilators were tested (one was a conventional fan and the second a turbo type). The obtained volumetric airflow values ranged from 8591 to 15,656 m3/h, depending on the type of unit and positioning distance, respectively. The analysis performed in the article showed that the general guidelines for the distance of mobile fan positioning that are present in the literature may be inaccurate and outdated. [ABSTRACT FROM AUTHOR]

In this article, an analysis was made of the use of mathematical methods for the creation of new food products, and the benefits from the use of modeling in the process of compiling the composition of mixtures in the calculation of new multicomponent products, in particular, ice cream, were shown. An improvement in the quality of this product is obtained by adding rose hips and blue tea. The most significant characteristics of the resulting ice cream were identified, models of their dependence on the composition of the added natural ingredients were compiled. The scheme for finding mathematical models using the Design-Expert software product from Stat-Ease is described in detail. The optimal plan of the experiment was built, according to which real physical experiments were performed, in which the characteristics of a new type of ice cream were evaluated depending on the ratio of the input ingredients "blue tea - rosehip". The results of a full-scale physical experiment are analyzed and the class of the desired mathematical model is selected. The experimental data were processed using the methods of regression-correlation analysis in the DesignExpert program, the numerical coefficients of the mathematical model were found. The obtained coefficients are analyzed for the adequacy of the obtained results to the initial data. In the future, this model can be used for optimal calculations of the composition of ice cream with the addition of natural ingredients. [ABSTRACT FROM AUTHOR]

Grain temperature is one of the most important factors affecting grain security. The temperature field of the underground ecological granary was investigated by field experiment and numerical simulation. The experiment was carried out in the underground grain silo (UGS), a full‐scale engineering model. The UGS temperature data for one consecutive year were obtained through daily on‐site periodic monitoring. Based on the boundary conditions of UGS, including ambient air temperature, heat transfer coefficient, and underground constant temperature zone, a two‐dimensional rotational axisymmetric model is constructed. Then the temperature field of UGS was analyzed by numerical method. The simulation results coincide with the test results, and the conclusions are as follows: (1) The average temperature of UGS is maintained at around 20°C, the upper zone is easy to be affected by the outside, but the central and bottom zone are relatively stable. (2) The average temperature of grain is always below 17°C, and the temperature of the surface layer has inevitable fluctuations due to the influence of the ambient air temperature. (3) The average temperature of grain changes significantly in the early stage, but as time goes on, the grain temperature tends to the temperature in the constant temperature zone. Practical Applications: Compared with the traditional above‐ground granaries underground granary has the advantages of land saving, grain storage capacity per unit area and long‐term storage of grain at low temperature. Now we have built two large underground granaries to study the various properties of underground granaries, which will be put into normal use later. By studying the temperature field of underground granary, exploring the change of temperature field of long‐term grain storage is beneficial to the popularization and application of underground granary, which is of great significance to ensure food security. [ABSTRACT FROM AUTHOR]

The study presents a possible innovative use of cement fiber boards (CFBs) reinforced with cellulose fibers for construction of an interior prefabricated staircase. Regarding the unusual use of traditional material that was used in all bearing elements of the staircase, a numerical simulation with the use of a material model SBETA was carried out and, subsequently, multiple experimental static loading was applied. In order to carry out experimental testing of static load capacity, a full-scale experiment method was chosen and performed on a real staircase structure for family houses. The full-scale experiment is considered the most precise method to test structures or material behavior. The obtained results show that the designed and tested staircase structure of CFBs is able to meet the requirements of technical standards related to static loading of staircases. The load test confirmed the potential use of cement fiber boards produced by the Hatschek process for real bearing structures under static loading. [ABSTRACT FROM AUTHOR]

Bar reinforced concrete structures, which include piles, in real working conditions perceive a whole range of internal force factors. Axial tension-compression forces, bending moments and shear forces are the most commonly perceived internal force factors. Of particular interest is the effect on the cross section of the shear force. If a complex curly shape is replaced by elementary form, then the calculation is not difficult. However, when calculating the composite cross section, there is no unambiguous solution. In accordance with the adopted regulatory documentation, it is necessary to accept only a main part, while discarding the surrounding areas. It is important to study the configuration of the shape of a complex section for the perception of a shear force. The purpose of the work was to refine the account of the entire complex section using numerical simulation by the finite element method, analytical calculations and small-scale experiments. Determination of further practical application of the obtained results on real structures was also the goal of the study. The parameters of the distribution of shear force between the main rib and flanges were obtained by numerical analysis and small-scale experiments. Numerical models of rectangular and tee cross sections beams have been developed. Analytical dependences were studied and full-scale tests of reinforced concrete beams of various sections were carried out. It has been established that when taking into account the work of the entire cross-section, the bearing capacity of concrete for the action of a shear force is 20% greater than when calculating only the main section without taking into account the shelves. [ABSTRACT FROM AUTHOR]

It is obligatory to verify the performance of high-energy-absorbing pocket-type rockfall protection nets by full-scale experiments. While the performance verification by full-scale experiments can provide a practical evaluation, it requires a lot of cost and time because it is necessary to conduct the experiments under several conditions depending on the structure of the rockfall protection net. Therefore, the performance verification by combining full-scale experiments and numerical analysis may be a useful tool. In this study, a full-scale experiment of a high-energy-absorbing pocket-type rockfall protection net was conducted to evaluate the net performance with respect to the required capability, and reusability and repairability of the components by understanding the behavior of the net under the action of heavy weights. Throughout the experiment, the deformation of the net, the change of the wire rope tension with time, and the displacement of the top of the net and the top of the pillar were measured in detail. Moreover, it was confirmed that it is possible to evaluate the performance verification based on the performance requirements. Then, the full-scale experiment was replicated by numerical simulations to examine the effects of the rock shape on the behavior and performance of the simulated net. Through the thorough investigations on the deformation of the net, the relation between the maximum tension of the wire rope and the slip length of the shock absorber, the temporal change of the tension of each wire rope, and the absorbed energy of each structural member, it was judged that the reproducibility of the model predictions is adequately high. Specifically, when the impact energy is constant, the effect of the rock shape on the behavior and performance is considered to be small.

Rapidly locating and assessing fires in coal mines is essential for effective response and minimizing damage. Traditional methods often struggle to swiftly and accurately pinpoint fire locations and statuses. Hence, this study introduces a particle swarm inverse tracing approach based on the quasi-steady-state heat transfer between high-temperature flue gases and mine tunnel walls. This method aims to remotely monitor smoke flow temperatures and gas concentrations to determine fire locations and combustion trends. Validation of the fire source tracing model was conducted through comprehensive tunnel fire experiments and numerical simulations. The particle swarm optimization inverse tracing method yielded a maximum 7.65 % error in fire location determination compared to actual measurements, while accurately matching the measured fire source heat release rate curve. These findings underscore the method's high precision and reliability, particularly evident during the developmental and stable stages of fire burning. [ABSTRACT FROM AUTHOR]

This study investigates the ventilation mechanism and effectiveness of a displacement ventilation (DV) system under heating conditions. A method to maintain ventilation efficiency by indirectly achieving DV was proposed. A four-bed hospital ward with prototype wall-mounted induction units (IUs) and ceiling exhaust served as the case study. Full-scale experiments assessed indoor temperature and tracer gas distribution, adjusting parameters such as cubicle and window curtains, window heaters, and window heat loss. Results showed that while the vertical temperature gradient was established, downdrafts near windows disrupted DV's stratification, leading to quasi-displacement ventilation with a normalized contaminant concentration of around 0.7 near patients. To counter this, using curtains to limit air exchange between the near-window and near-bed spaces effectively prevented the horizontal movement of contaminants toward the window. This allowed the downdraft to remain clean and diffuse along the floor, thereby reducing the normalized concentration to approximately 0.3–0.5 b y indirectly achieving DV. CFD numerical studies further examined this method under varied temperature conditions and airflow patterns. Additionally, the infection risk in this ward was evaluated for reference, showing that indirect DV can reduce infection probability by one-third compared to quasi-DV. Moreover, window heat loss valued at 50–100 W/m2 achieved the best ventilation, while smaller values generated insufficient downdraft to achieve indirect DV and larger values resulted in high floor-level velocity that accelerated contaminant dispersion. [Display omitted] • Ventilation during the heating in a hospital ward using the DV system is investigated. • DV can be indirectly achieved by the near-window downdraft during the heating season. • Blocking contaminant spread keeps the downdraft clean and enhances ventilation. • Full-scale experimental and CFD numerical study was conducted for examination. • Window heat loss and various airflow patterns' impact were addressed numerically. [ABSTRACT FROM AUTHOR]

Natural gas poses significant risks to the safe operation of utility tunnels, which house multiple critical infrastructure systems, including natural gas pipelines. To date, no full-scale gas explosion tests in utility tunnels have been published, and there is ongoing debate about whether pipelines can withstand such explosions. This study presents the first-ever 1:1-scale experiments conducted in a 710-meter-long tunnel with cross-sectional dimensions of 3.2 m × 2.6 m. Three pipelines, each approximately 25 m in length and constructed to industrial standards, were used to investigate potential damage. The experiments comprehensively captured the development of flow fields, including flame images, flame signals, temperature, and overpressure, as well as pipeline responses. Results revealed that variations in overpressure within the combustion region were driven by both positive and negative feedback loops. A significant pressure drop was also observed as airflow passed through a local expansion. The experiments further demonstrated that while pipelines within utility tunnels are unlikely to be directly damaged by gas explosions, accessories such as racks are at high risk of severe destruction. These findings offer essential insights for improving the safety design, construct, and operation of tunnel-like spaces involving flammable gases. [ABSTRACT FROM AUTHOR]

• Joint deformation stages: elasticity, crack development, yielding, and failure. • The flexural-shear failure is the main failure mode of key joints. • Increased axial force enhances loading-carrying capacity and stiffness. To improve the failure resistance of the lining and make use of the retaining structure, this paper proposed a novel method of adding the key joints to connect the lining with the retaining structure. Usually, the joint is the weak point of the whole structure. The failure mechanism of key joints significantly influences the design and safety of the prefabricated structure. In this study, full-scale loading tests were conducted on three types of key joints: sleeve joint, spiral stirrup joint, and U-shaped rebar joint. The joint deformation, failure mechanism, concrete strain, and reinforcement strain are investigated. The results demonstrated that the deformation and failure process of the key joints can be divided into four stages. The flexural-shear failure caused by the joint opening and the sliding of lining is considered as the main failure mode of the key joints. The U-shaped rebar joint exhibited the best mechanical performance. Furthermore, the finite element modes were created to analyze the influence of axial force and the reinforcement diameter. Combining the test and numerical analysis results, the failure mechanism was revealed. In addition, the joints' loading-carrying capacity was increased with the increase of axial force due to the axial force limiting the joint opening. The research results provide a theoretical basis and reference for the new-type prefabricated pile-wall composite structure (PPCS). [ABSTRACT FROM AUTHOR]

The article presents the results of study of deformation of fluoroplastic Raschig rings loaded with transverse force under conditions of operation in column apparatuses of drying and absorption departments of sulfuric acid production plant. The moduli of elasticity of F-4MB and F-4TG fluoroplastic brands under these conditions were determined by computer modeling and full-scale experiment. The permissible deformation and minimally possible wall thickness of Raschig rings from these fluoroplastic brands under the operation conditions were determined. [ABSTRACT FROM AUTHOR]

Based on a previously designed variable-stiffness load transfer component (LTC), a novel dispersed-tendon cable anchor system (CAS) was developed to increase the anchoring efficiency of large-diameter basalt-fiber-reinforced polymer (BFRP) cables. The static behaviors of the CAS are then numerically evaluated by a simplified three-dimensional finite-element (FE) model and implemented in a full-scale BFRP cable. The FE results indicated that the accuracy of the simplified dispersed-tendon model could be effectively ensured by dividing the revised compensation factor. The anchor behavior of the dispersed-tendon CAS was superior to that of the parallel-tendon CAS when the same cable was applied. The radial stress and tensile stress difference can be reduced by decreasing the tendon spacing. The testing and simulated results agreed well with the load–displacement relationship and axial displacement. All tendons fractured in the testing section, and the LTC suffered minimal damage. The ultimate force of the cable with 127 4-mm-diameter tendons was 2419 kN, and the corresponding anchoring efficiency was 93%. The cable axial tensile strain in the anchoring zone decreased linearly from the loading end to the free end. The cable shear stress concentration at the loading end can be avoided by employing a variable-stiffness anchoring method. [ABSTRACT FROM AUTHOR]

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This work experimentally determines the in-plane lateral load behavior of a full-scale WPVC composite log-wall, with and without additional through-bolts. The results indicate that the WPVC composite log-wall panel with through-bolts produced higher hysteretic parameter values in terms of strength and energy dissipation than the log-wall without through bolts due to a reduction in wall uplift (48.2% for secant stiffness of cycle, 39.5% for hysteretic energy at the last displacement level). The WPVC composite log-wall panel with through-bolts presented better structural stability and was recommended for investigation. A finite element model (FEM) of a WPVC composite log-wall panel with through-bolts was created using beam elements as log-members and multilinear plastic links as connections, and was verified by the experimental results. The verified FEM was used for further parametric study of wall dimensions and first log-foundation locations. The parametric investigations indicated that increasing panel height and width unfavorably affected lateral load capacity, monotonic and cyclic stiffness, and energy dissipation. The cyclic stiffness decreased by 39% while energy dissipation increased by 78.8%, for the last displacement level when the wall height was increased from 2.350 m to 3.525 m. The cyclic stiffness and energy dissipation of a panel with a width of 6 m decreased 14% and 24.4% compared to a panel with a width of 3.5 m. Moreover, moving log-foundation connections from the original position to the edges of the panel improved performance under monotonic and cyclic horizontal loads; an increase in the number of log-foundation connections had an insignificant effect on panel behavior. [ABSTRACT FROM AUTHOR]

This study aims to reveal the distribution and evolution law of temperature field during bridge operation of concrete-filled steel tubular (CFST) arch bridges in mountainous areas. The full-scale test and transient thermal analysis on the temperature field of the large-diameter CFST member under strong radiation and large daily ambient temperature difference are conducted based on the Yarlung Zangbo River Bridge. The simplified calculation method on temperature field of circular CFST arch bridges is developed to establish the direct relationship between temperature field and solar radiation, wind speed and ambient temperature. Results show that the radial temperature field distributes as an asymmetric three-segment polyline and the temperature at the outer end of this polyline changes sinusoidally along circumference. The temperature changes greatly from the interface to D/8 away from the interface and changes little from the center to 3D/8 away from the center along radial direction. The temperature influence depths in this study and some other literature (D/8 to D/5) are less than the specified value (D/4). The calculation method of temperature field in this study is applicable to different geometrical and environmental characteristics of CFST arch bridges. [ABSTRACT FROM AUTHOR]

Fire dynamic characteristics in multi-compartments are still not very clear. This paper presents a spreading fire test in a full-scale two-storey steel framed building to investigate the multi-compartment fire behavior. In the test program, the fuel was made by a total of 6.8 m3 discrete pine cribs and then ignited at one compartment. The spatial temperature and steel member temperature histories were recorded throughout the fire test. FDS model was then established and compared with the fire experiment results. Reasonable agreement between experimental and numerical results was achieved at the fire growth stage and spreading stage. Based on test results, it was observed that flames spread to the fire-spreading compartment in 82 min after fire when the fire in the fire-source compartment fully developed, which caused multiple temperature peaks and significant temperature gradients. The experiment revealed the possibility and characteristics of fire spread among multi-compartments. It also verified the invalidity of the homogeneous temperature assumption and provided important data for performance-based structural fire design in multi-compartment spreading fire scenarios. [ABSTRACT FROM AUTHOR]

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