Abstract:In order to study the shear mechanical properties of ultra-low energy building sealants, a monotonic loading test was conducted using a single-axis testing machine on the sealant layer. [JP+1]The influence laws of the thickness, width of the sealant layer and the elastic modulus of the sealant on the shear performance of the sealant were analyzed, and a shear stress calculation model at the sealant layer was established. The results showed that the failure types of the specimens mainly included the failure of the bonding interface and the shear failure of the sealant layer. Under the same strain conditions, the shear stress of the sealant was negatively correlated with the thickness of the sealant layer and positively correlated with the width of the sealant layer. An internal force calculation model applicable to the sealing glue between joints of ultra-low energy buildings, which is mainly shear-driven and the normal stress can be ignored, was proposed. The calculated values were basically consistent with the experimental values.

Abstract:In order to explore the axial compression performance and failure mode of steel reinforced concrete filled steel tubular (SRCFT) short columns with initial concrete imperfection, a finite element model of SRCFT short columns with initial concrete imperfection under axial compression is established, the parameters of SRCFT short columns with different gap radio, steel tube strength, steel tube thickness, concrete strength, steel strength and steel type are analyzed, and the axial compression perfor-mance and failure mode of SRCFT short columns with initial concrete imperfection are discussed. The results show that the SRCFT short columns with initial concrete imperfection increase with the increase of steel tube strength, steel tube thickness, concrete strength, steel strength and steel type. The specimens with annular debonding defects exhibited ultimate bearing capacity reductions from 19.11% to 20.91% when the debonding rate increased from 1.1% to 3.3%, while those with spherical cap debonding defects showed capacity decreases from 8.74% to 15.77% corresponding to debonding rates progressing from 2.2% to 6.6%. That is, with the increase of the gap ratio, the ultimate bearing capa-city of the specimen decreases and the axial compression performance is weakened. It can provide a theoretical basis for the study of SRCFT short columns with initial concrete imperfection.

Abstract:To study the seismic performance of low-yield point corrugated double-layer steel plate concrete composite shear walls, a finite element model was constructed using ABAQUS. The main parameters considered were the form of the steel plates (corrugated steel plates and flat steel plates) and the strength grade of the steel (low-yield point steel and ordinary steel). The results showed that the yield load of the corrugated steel plate specimens was 11.28% higher than that of the flat steel plate specimens, the peak load was 11.29% higher, and the ductility was 18.68% higher. Moreover, the stiffness degradation of the corrugated steel plate specimens was more gradual, and their energy absorption capacity was stronger, resulting in better seismic performance. Compared with the ordinary steel specimens, the low-yield point steel specimens reached yield earlier and had a certain decrease in bearing capacity, but their ductility was greatly improved, with the maximum improvement being 67.63% and the minimum improvement being 44.22%. Their energy absorption performance was more outstanding, and their seismic performance was better. In other words, both the structural change and the material change can improve the seismic performance of the specimens, and the combination of the two can achieve a greater improvement in the seismic performance of the specimens.

Abstract:To further obtain the shear capacity of the steel-concrete interface connected by bolts and epoxy, three sets of push-out tests were made and analyzed, including bolt reinforcement specimens, epoxy reinforcement specimens and bolt and epoxy reinforcement specimens. The failure mode, shear force-displacement curve, ultimate bearing capacity and shear stiffness were measured by the push-out test. The research shows that the stiffness of bolt reinforcement specimens is much smaller than that of epoxy reinforced specimens, and the slip before reaching the ultimate shear strength is much larger than that of epoxy reinforced specimen. Before reaching the peak load, for the specimens with fewer anchor bolts, the epoxy bears almost all the load, and the specimens slip obviously when the specimen was damaged. This paper puts forward a more widely used calculation formula used to calculate the shear capacity of bolt and epoxy reinforcement specimens, which can be used in the calculation of shear capacity of large-area reinforcement specimens and high-strength concrete reinforcement specimens.

Abstract:Considering the insufficient utilization efficiency of geotechnical data when using the random field theory to describe the variability of soil parameter space, by combining the Kriging theory and the data-driven random field theory based on Bayesian compressive sensing and Karhunen-Loeve(KL) series expansion method, a data-driven three-dimensional conditional random field generation method was proposed. This method was applied to characterize the variability of soil parameter space in a certain rectangular pipe-jacking project site in Suzhou City. [JP+1]A three-dimensional numerical model considering the variability of soil parameter space was established, and the settlement law caused by pipe-jacking construction was analyzed. The results were compared and verified with the on-site measured data, with the maximum error being less than 10%. The research results show that the generated data-driven conditional random field can fully utilize the survey data in the actual engineering site, achieve the optimization simulation of the conditional random field of soil parameter space variability, complete the constraint of the survey data on the known sampling points, and reduce the uncertainty. Compared with deterministic calculation, uncertain calculation can fully represent the trend and fluctuation range of surface settlement caused by the rectangular pipe-jacking construction, providing a reference basis for the design and construction of complex geotechnical engineering.

Abstract:To reveal the mechanism of the influence of temperature field, pile shape and soil confining pressure on the bearing capacity of energy piles, a bearing capacity evolution test of energy piles under the combined action of temperature, pile shape and confining pressure was carried out. The results show: (1) With the increase of temperature, the single-pile bearing capacity of both circular and X-shaped energy piles increases; (2) Under the conditions of 45 ℃ thermal cycling and the same pile-side soil pressure, the ultimate bearing capacity and the ultimate displacement of X-shaped piles are greater than those of circular piles. At loads of 100, 200 and 300 kPa, the bearing capacity of X-shaped piles is 176%, 134% and 125% of that of circular piles; (3) Comprehensive analysis reveals that the pile shape and the pile-side soil pressure have a significant impact on the single-pile bearing capacity of energy piles. The increase in temperature changes the characteristics of the pile-soil interface, thus significantly improving the single-pile bearing capacity. The bearing capacity advantage of X-shaped piles decreases with the increase of confining pressure.

Abstract:In order to clarify the response patterns of the anchored slope under the variation of seismic acceleration and the specific response process of the anchor cable under the action of earthquakes, by using the centrifugal vibration test equipment configured by the China Water Resources and Hydropower Research Institute, centrifugal model tests were carried out to study the displacement change process of the anchored slope under the action of harmonic seismic waves, as well as the strain response process and patterns of different positions of the anchor cable and different points of the same anchor cable under the action of earthquakes. The research results show that the oscillation frequency of the vertical displacement of the slope and the strain value of the anchor cable is in good synchronization with the input seismic acceleration frequency; the strain and force of the anchor cable show a decreasing state from top to bottom, and the anchor cables near the sliding surface need to play a greater reinforcing role. With the increase of seismic intensity, the anchor cable plays a greater reinforcing role, and also demonstrates the passive support function of the anchor cable. This test obtained the analysis of the displacement and response patterns of the slope and anchor cables under the action of earthquakes for the anchored slope, and also verified the strong applicability of the centrifugal model test for the research of such problems.

Abstract:To enhance the utilization rate of industrial solid waste, a study was conducted on the mechanical properties of stabilized pavement base mixtures using granulated blast furnace slag powder as the binder, with the full solid waste (steel slag, coal gangue, and recycled powder) as the raw material. The uniform design method was employed, with the proportions of steel slag, coal gangue, and recycled powder as factors, and the 7-day unconfined compressive strength, 120-day compressive rebound modulus, and 120-day splitting strength as the target response values. Six sets of test mix ratios (mass ratios) were designed for the experiments, and the test results were analyzed using JMP software. A mathematical model was established between the different material proportions and the three mechanical performance indicators. The mixed material’s splitting fracture surface images were processed using Image J software to reveal the main reasons for the mechanical strength at the micro level. The research results show that the mechanical properties of the mixture increase with the increase in steel slag proportion; the increase in recycled powder proportion has an adverse effect on the initial mechanical strength of the mixture, but the later mechanical strength shows a trend of increasing first and then decreasing with the increase in recycled powder proportion, so its proportion should not exceed 35%. The regression equation obtained through variance analysis has a high fitting degree and can provide guidance for practical engineering.

Abstract:The permeability of the soil along the railway during rainfall directly affects the stability and safety of the railway embankment. To investigate the influence of different regions and slopes, this study combined high-precision industrial CT microscopic equipment, three-dimensional reconstruction models, and on-site artificial rainfall simulation experiments to conduct in-depth analysis of the infiltration chara-cteristics of soil slopes under extreme rain conditions and the microscopic properties of soil pores. The results show that during continuous rainfall, within the range of 5° to 50° slopes, the infiltration and water absorption capacity of the slope gradually decreases and then stabilizes; the porosity at the Shiheshou Tunnel is approximately 29%, with larger sand particles, and the porosity in the Wen Tang Station area is approximately 19%, with relatively smaller particle sizes. The soil at Shiheshou has a stronger permea-bility. From a microscopic perspective, under the same conditions, the larger the equivalent radius of pores and pore throats in the soil and the greater the coordination number, the larger the soil permeability coefficient; the longer the pore length, the smaller the soil permeability coefficient.

Abstract:In order to study the problems of large errors and difficulty in quantification when using electromagnetic methods to detect steel corrosion, this paper developed a set of steel corrosion monitoring device based on the principle of electromagnetic induction by utilizing the difference in magnetic permea-bility between the steel bars and their corrosion products. This monitoring device uses permanent magnets to provide a closed magnetic field, transmits the magnetic field using silicon steel sheets, and embeds Hall elements at both ends of the silicon steel sheets to sense the changes in magnetic permeability caused by steel corrosion. Through calibration, a correction formula for the theoretical calculated corrosion rate of the internal steel bars in concrete and the actual corrosion rate was obtained based on Faraday’s formula. The maximum error between the corrosion amount of the steel bars calculated by this correction formula and the actual corrosion amount measured by the weight loss method was 1.044%. Through the concrete internal sensor test, an accurate relationship between the corrosion amount of the steel bars and the change in Hall voltage was obtained based on the linear regression model, providing a scientific method for the durability monitoring of reinforced concrete structures.

Abstract:Using densely populated student dormitories as the research site, numerical simulation methods were used to study the diffusion characteristics of infectious cough aerosols under four ventilation strategies. The results indicate that there are differences in the impact range and mass concentration of aerosols indoors under different ventilation strategies. The size of indoor ventilation area will affect the diffusion rate of cough aerosols, and the larger the ventilation area, the faster the diffusion rate of particles indoors. The ranking of indoor aerosol particle residual rates under the four ventilation strategies is as follows: small gap ventilation of doors and windows>open door ventilation>open window ventilation>fully open door and window ventilation. Under the ventilation strategies of fully opening doors and windows and small gaps in doors and windows, the relative aerosol capture rate of students in the lower bunk of the room is higher than that of students in the upper bunk. These results are of great significance for understanding the impact of different ventilation strategies on indoor air quality and student health.

Abstract:In order to prepare high-performance bonded polymer-rare earth complex luminescent mate-rials and explore the relationship between their structure and luminescent properties, functionalized polysulfone (PSF-NGly) containing naphthalene formaldehyde condensation glycine Schiff base ligand structure was prepared through three steps of macromolecular reactions. The products of each step were characterized by infrared, proton nuclear magnetic resonance, ultraviolet and ninhydrin colorimetric methods. The obtained PSF-NGly was coordinated with rare earth Eu(Ⅲ) ions to form the polymer-rare earth complex PSF-(NGly)₃-Eu(Ⅲ). The luminescent properties of PSF-(NGly)₃-Eu(Ⅲ) were determined by fluorescence spectroscopy. The results showed that the naphthalene formaldehyde condensation glycine Schiff base group was successfully bonded to the polysulfone side chain, and the macromolecular ligand PSF-NGly produced an "Antenna" effect on the Eu(Ⅲ) ion. The complex PSF-(NGly)₃-Eu(Ⅲ) had excellent luminescent properties.

Abstract:In order to objectively evaluate the impact of rural linear public space transformation on users’ physiology and emotion, this study combined electroencephalography(EEG), eye-tracking technology and Perceptual Recovery Scale to quantitatively analyze the physiological comfort, visual attention and subjective emotional response of 36 subjects before and after the transformation of main streets, roadways, paths and river scenes. The results showed that the reformed rural linear public space significantly enhanced the EEG activity in the parietal and occipital lobes of the subjects. The average pupil diameter of both sides was expanded by 4.02%, and the visual residence time was prolonged by 4.01%. The scores of the perceptual recovery scale were significantly improved in the dimensions of being away, fascination, extent and compatibility. The research shows that through the inheritance of cultural symbols, ecological design and humanistic optimization, the perception efficiency and environmental quality of rural linear public space have been significantly improved. This study innovatively integrates multimodal physiological data and subjective evaluation, and provides a scientific and evidence-based decision-making basis for rural public space design.

Abstract:The street and alley appearance is an important component of the traditional village landscape. To explore the visual perception characteristics of tourists towards the street and alley appearance in traditional villages, this paper adopts eye movement experiments, deep learning image semantic segmentation and subjective questionnaires to conduct qualitative and quantitative evaluations of the street and alley space appearance. The results show that the tourists’ gazes are mostly concentrated on buildings, landscape nodes and the end of the road, and tourists’ average fixation time on landmarks and landscape nodes is longer. Comfort and orderliness, plant configuration, color, coordination and visual hie-rarchy all show significant positive correlations. The average fixation count shows significant positive correlations with green view ratio, plant configuration and color, and a significant negative correlation with building enclosure degree. There are significant differences in tourists’ visual perception of street and alley scenes with different element proportions.