To study the mechanical behavior of 2-layer spiral strand under tension-bending coupling effect and the cooperative working mechanism of internal wires, inter-wire friction and slip were taken into consideration. Static equilibrium relationships for micro-segments of layer-wire were established and analytically derived under two typical contact conditions: inter-layer contact and coupled contact. At the same time, an improved semi-refined finite element model was proposed for numerical simulation and result comparison. Relative slip direction between wires on two contact conditions were obtained from the distribution of shear force on layer-wire, based on which the axial force limit of layer-wire after sliding was derived according to the equilibrium equation. The bending moment-local curvature relation of spiral strand was obtained by summing the bending moments contributed by each wire under tension-bending coupling effect, and a simplified bending moment-mean curvature relation was proposed to describe bending behavior of the spiral strand. The result shows that there are slip stagnation points on contact surface of adjacent wires because layer-wire rotates along the axis of spiral strand periodically, and relative slip direction on both sides of the stagnation point is opposite. The slip stagnation point and initial slip position on contact surface of layer-wire to layer-wire and layer-wire to core-wire are different. When neglecting the progression of internal slip, 2-layer spiral strand exhibits the same bending moment-mean curvature relationship under both contact conditions, and the function graph presents a bilinear form. The relative error of the bending deformation results before and after slipping between semi-refined FE model and analytical values is less than 4%, and the extracted relative slip results are in agreement with the analysis conclusions.

To study the effect of stirrup confinement on the axial compressive bearing capacity of ultra-high-strength concrete (UHSC) precast columns, this paper first conducted an axial compression contrast experiment between full-size UHSC column and ordinary column, and investigated the difference of crack development, failure pattern and ultimate bearing capacity of these two type columns. Based on the experimental results, further finite element analysis was conducted to simulate 36 full-scale UHSC columns. The study focused on analyzing the effects of stirrup configuration, stirrup spacing, and stirrup diameter on the axial compressive performance of UHSC columns. Combining the experimental findings and parametric analysis results, a modified calculation formula for the axial compressive bearing capacity of UHSC columns considering stirrup confinement was proposed. The proposed formula was then compared with the calculation formula in the current Code for Design of Concrete Structures. The results show that: the ultimate bearing capacity of equal-strength designed UHSC column is higher than that of ordinary concrete column, but it is more brittle than ordinary concrete, especially when reaching the ultimate bearing capacity; the confinement effect of stirrups on the core concrete enhances the axial compressive bearing capacity of UHSC columns. Changes in stirrup configuration, stirrup spacing, and stirrup diameter have a significant impact on the ultimate bearing capacity and peak compressive strain of UHSC columns; the proposed axial compressive bearing capacity correction formula for UHSC columns incorporates the differences between UHSC columns and ordinary concrete columns, considering the confinement effect of stirrups on the core concrete. Compared to the calculation formula provided in the code, which does not account for stirrup confinement and is primarily applicable to ordinary concrete columns, this formula better utilizes the material’s potential while ensuring safety margins. It can serve as a useful reference for practical engineering design.

Currently, there is relatively limited research on the stability analysis of spatial structures considering the initial eccentricity of members. To reveal the influence laws of the initial eccentricity of members on the stability bearing capacity of cable-supported cylindrical reticulated shells, this paper proposed a simulation method of introducing the initial eccentricity of members by the end rigid rod and presented the ratio relationship of the elastic modulus between the rigid rod and the initial eccentric rod. Based on this, the random imperfection mode method was used to sequentially introduce the initial eccentricity of members into the perfect structure and the overall imperfect structure. An elasto-plastic process analysis was then conducted to examine the impact of the initial eccentricity of members and the simultaneous application of two types of imperfections on the nonlinear buckling behavior of cable-supported cylindrical reticulated shells. The results show that when the elastic modulus of the rigid rod is taken to be more than 100 times of that of the initial eccentric rod, the calculation results show minor differences. Therefore, the ratio of the elastic modulus between them is taken as 100. The coefficients of stability bearing capacity of cable-supported cylindrical reticulated shells are not remarkably reduced when introducing the initial eccentricity of members into the perfect structure (the maximum reduction is 8.27%), indicating that the structure is not very sensitive to the initial eccentricity of members, thus the adverse effects of the initial eccentricity of members can be ignored in engineering practice by balancing the calculation work. Compared with the perfect structure, the coefficients of stability bearing capacity of cable-supported cylindrical reticulated shells are significantly reduced by 27.64% when introducing the initial eccentricity of members into the overall imperfect structure. However, the reductions are slightly smaller than the sums of reductions when the two kinds of imperfections are introduced separately. The overall imperfection and the initial eccentricity of members introduced simultaneously have a certain extent coupling effect on the structural stabi-lity bearing capacity, and the effect of the former is more significant.

Fiber-reinforced polymer (FRP) reinforcement and self-tapping screw reinforcement are two commonly used methods for strengthening timber structures. Currently, research on reinforced glued laminated timber (glulam) structures primarily focuses on changes in strength after reinforcement, with relatively limited data on lateral resistance performance. Moreover, studies on reinforcing earthquake-damaged glulam frames are scarce. To investigate the lateral resistance performance of earthquake-damaged glued laminated timber (glulam) frames reinforced using different methods, two earthquake-damaged glulam frames were strengthened separately with carbon fiber-reinforced polymer (CFRP) and self-tapping screws, along with the addition of diagonal braces. The specimens were subjected to horizontal cyclic loading, and the experimental results were compared and analyzed. The test results indicate that both reinforcement methods effectively prevented the longitudinal splitting of the timber. However, compared to the specimen reinforced by self-tapping screw, the specimen reinforced by fiber-reinforced polymer shows significantly higher initial stiffness and peak load-carrying capacity, which can better suppress the development of cracks. The hysteretic curves of both frames exhibit a relatively anti “S” shape, with an obvious pinching effects. On the basis of the tests, simplified models of two frames were established using Open Sees. The models were calibrated based on experimental data. The hysteretic curves obtained from the calibrated models were in good agreement with the experimental results, verifying the accuracy and rationality of the model and laying the foundation for further parameter analysis. Furthermore, the influence of gravity loading for the specimens on the elastic stiffness and the maximum loading capacity was also investigated. It indicates that gravity load has an undeniable impact on the lateral resistance performance of timber frames, providing a scientific parameterized analysis for the seismic damage of reinforced timber frames.

The high extreme negative pressure that occurs in the corner area of the roof of a low-rise building is the focus of the wind-resistant design of its envelope. Based on the aerodynamic principle and the standard building model of TTU (Texas Tech University), this paper designed a new streamlined add-on accessories in the corner area of roof according to the wind flow patterns in the roof corner. By altering parameters such as the height and length of additional components, it conducted a comparative study involving rigid model pressure measurements in wind tunnel tests under 10 working conditions and Large Eddy Simulation (LES). The study aimed to explore the impact of these new types of additional components on wind loads in roof corner zones, aerodynamic optimization for wind resistance of roofs, and the accuracy of LES simulations.The study shows that: 1) the wind tunnel test results show that the installation of add-on accessories in the roof corner area can effectively reduce the extreme negative pressure in the corner area, and the most unfavorable mean negative pressure in the roof corner area can be reduced by 10%, and the most unfavorable extreme negative pressure can be reduced by 25% under the 10 working conditions studied; 2) the NSRFG（Narrowband Synthesis Random Flow Generation）method is used to generate the inlet turbulence, and the wind load distribution pattern in the TTU model under various conditions is obtained by the LES simulation. Although the absolute value of the mean wind pressure coefficient of the roof under some working conditions simulation results are larger (the mean error is 13.88%), and the extreme wind pressure coefficient is smaller (the mean error is 9.72%), it is overall consistent with the wind tunnel test, indicating that the NSRFG method has good accuracy; 3) LES numerical simulation parameter study shows that the influence of the length of the add-on accessories on the wind load in the roof corner area is greater than that of the height, the extreme wind pressure coefficient in the roof corner area decreases by 6.15% after the height of the equal length add-on accessories increase by 1 times; the extreme wind pressure coefficient in the roof corner area decreases by 10.77% after the length of the equal height add-on accessories increase by 0.8 times.

Textile reinforced mortar (TRM) strengthening is a method of using mortar as an inorganic adhesive to stick textile onto the surface of components to form a strengthening layer. It has advantages such as light weight, high strength, minimal change in cross-sectional dimensions, good high-temperature resistance, and excellent durability, and thus has gained widespread attention in recent years. TRM typically uses polymer-modified cement mortar as the adhesive, but the production of cement has high energy consumption and carbon emissions. To achieve the “dual carbon” goals, this paper proposed to replace cement with geopolymer, which has much lower production energy consumption and carbon emissions while offering mechanical properties similar to cement, thus forming a textile reinforced mesh-enhanced geopolymer mortar (TRGM) strengthening method.This paper employed carbon textile reinforced geopolymer mortar to strengthen two-way reinforced concrete slabs. The flexural performance tests and finite element analysis were conducted on the unstrengthened and strengthened slabs with different aspect ratios and different numbers of TRGM layers. The strengthening effect of TRGM, the contribution of bidirectional fibers to bearing capacity, and the force transmission mechanism of the strengthened slabs were investigated. The results show that TRGM strengthening can effectively improve the post-cracking stiffness and flexural carrying capacity of two-way slabs and inhibit crack propagation, especially the widthwise cracks. The strengthening effect of TRGM increases with the increase in the aspect ratio of the two-way slabs. The bearing capacity of the strengthened slab with one layer of TRGM was greatly influenced by the overlap of the textile and strengthening construction quality, which made the strengthening efficiency of one layer of TRGM lower than that of two layers. The overlap of the fiber mesh may affect the strength of the fibers, and the design should ensure that the fibers have sufficient overlap length. After the widthwise reinforcement yielding, the ratio of bending moment borne in the widthwise direction to the lengthwise direction gradually decreased, since the contribution of the longitudinal reinforcement and fibers to the bearing capacity gradually increased. As the mid-span deflection increases, the proportion of tensile force borne by the fibers shows a wave-like trend, first decreasing, then increasing, and subsequently decreasing again.

To reduce the environmental pollution caused by waste rubber tires, it is an effective solution to process them into derived aggregates and apply them in engineering reinforcement. Currently, geogrid reinforcement technology is widely used in embankment and slope projects. However, due to the limitation of soil resources, most of the local fine aggregates are used for backfill and compaction, which leads to the geogrid not being able to give full play to the reinforcing effect. Therefore, this paper proposed the method of composite reinforced embankment of waste tire rubber particles and geogrid to solve the above problems. The influence of rubber particle content (0%, 5%, 10%, 15%, and 20%) on the shear characteristics of the mixed soil was examined using a triaxial shear testing system. Additionally, pullout tests on geogrids were conducted to investigate the effects and mechanisms of rubber particle content on the pullout characteristics of uniaxial, biaxial, and triaxial geogrids. Finally, the deformation characteristics and stability of reinforced soil embankment with rubber granular soil mixture were analyzed by indoor tests and numerical simulation methods. The results indicate that the elastic modulus of the mixed soil gradually decreases as the rubber particle content increases. At the same time, the shear strength index shows an initial increase followed by a decrease, reaching its maximum value at a content of 15%. The peak tensile force of the three types of geogrids in the mixed soil follows the same trend with its maximum value at a content of 15%. The addition of 15% rubber particles in bi-axial and tri-axial geogrid-reinforced embankments reduces the settlement of the embankment by approximately 19% and 23%, respectively, as well as the lateral earth pressure by approximately 18% and 23%. The presence of the composite reinforcement layer significantly limits the development depth of the slope failure slip surface, thus enhances the embankment’s resistance to deformation.

The steel structure has multiple advantages, including low carbon footprint, environmental friendliness, lightweight yet high strength, and excellent seismic performance. It has been widely used in high-rise buildings, large-span buildings and some civil buildings. However, its inherent problems such as buckling, corrosion and high cost hinder the further application of steel structures. The current anti-buckling and anti-corrosion measures for steel structures will greatly increase the cost of the structure and have a negative impact on the bearing capacity of the structure. Ultra-high performance concrete (UHPC) is a new type of fiber-reinforced cement-based composite material based on the maximum bulk density theory. It features high strength and excellent deformation capacity, along with outstanding durability properties, including superior resistance to water penetration, chloride ion infiltration, and freeze-thaw cycles. Nowadays, UHPC has been widely used in mechanical reinforcement and durability reinforcement of various structures. Recent research work shows that the combination of steel structure and UHPC can effectively realize the complementary advantages of the two. While giving full play to the excellent characteristics of light weight and high strength of steel structure, it greatly reduces the harm of fatigue, corrosion and instability to steel structure. This study focused on a newly developed thin-layer UHPC encased I-beam, which has been widely applied in practice. A sample database was established through finite element simulation analysis using Abaqus. At the same time, the comprehensive evaluation index of shear performance and shear cost performance of composite beams was proposed based on the radar chart method. The response surface-Monte Carlo method was employed to analyze the influence of four different response surfaces on the web size parameters of the composite beam. The analysis results show that there is a significant positive correlation between the shear performance of the composite beam and its cost performance. Moreover, as the thickness of the I-beam web increases, both shear performance and cost-effectiveness initially rise and then decline, reaching a peak at a specific thickness. This study provides valuable engineering insights for optimizing the design of I-beam encased UHPC composite beams.

As a crucial method for connecting steel structures, welding plays a vital role in ensuring structural integrity, and the fatigue performance of welded joints directly affects the overall safety of steel structures. To enhance the fatigue performance of welded joints in steel structures, this study proposed the use of laser remelting treatment on the welded joints. For this purpose, this study conducted high cycle fatigue tests on the as-welded joints and laser remelting treated welded joints of Q355 steel plate butt welding. The stress levels for high-cycle fatigue tests were determined through tensile tests on as-welded joints. Fatigue fracture surface analysis was conducted using scanning electron microscopy (SEM). Based on the experimental results, stress-life (S-N) fatigue curves were fitted for both the as-welded joints and the laser-remelted welded joints, and the results were compared with standard fatigue design curves specified in relevant codes. The experimental results show that laser remelting treatment can change the location of fatigue fracture in welded joints, prevent failure at the weld toe and thereby significantly improve the fatigue life of welded joints, with an average increase of 244% to 499%. The fatigue fracture analysis show that there were mainly ratchet crack sources and a few subsurface crack sources in the as-welded joints, and there are mainly corner crack sources and edge crack sources in the laser remelted joints; the fatigue performance design curves provided by the American Steel Structure Code ANSI/AISC360-22, European Code EN 1993-1-9:2005, and Recommended Method for Offshore Steel Structure Design DNV-RP-C203 can be applied to the fatigue performance of as-welded joints, while these curves tend to be conservative for laser-remelted welded joints.

Long-span suspension bridges are costly to construct but play a crucial role in transportation networks due to their ability to handle high traffic volumes. As a control engineering project, the safety and reliability of long-span suspension bridges are primarily assessed using deterministic analysis methods, such as the finite element method, for calculation and analysis. However, in practical engineering, structural parameters exhibit uncertainty and simultaneously variability and correlation exist in spatial distribution. Hence, the influence of random field factors was incorporated. By adopting numerical analysis methods and integrating random field theory with reliability theory, a reliability assessment method for long-span suspension bridges based on random fields was proposed. This method primarily consists of three components: the use of the center-point method and correlation functions to handle random fields; the application of the finite element method for structural numerical analysis; and the use of the first-order second-moment method, specifically the design point method, to calculate structural reliability index. The specific implementation process of the method was introduced, and corresponding analysis programs were deve-loped. Several numerical examples were used to verify the accuracy and applicability of the method and the program. Finally, taking the three-tower four-span suspension bridge, the Wenzhou Oujiang North Bridge, as an engineering case, the reliability of its deflection under normal operating limit states was assessed considering the uncertainty of structural parameters as well as their spatial variability and correlation. The impact of random fields on the deflection reliability index of the Wenzhou Oujiang North Bridge was analyzed. Results indicate that the proposed method is suitable for the reliability assessment of long-span suspension bridges. When considering the random field, the deflection reliability index under the normal use limit state is found to be smaller compared to the calculation that ignores the random field. This indicates that neglecting the spatial variability and correlation of the structural parameters in a long-span suspension bridge leads to an overestimation of the deflection reliability under normal use limit state.

Rail transit hubs naturally have advantages in terms of pedestrian flow. The development of multi-dimensional, mixed-use commercial spaces above these hubs has become a new construction model. The commercial spaces above rail transit hubs have become important places for passengers, commuters, and citizens to engage in consumption and social activities. The development of commercial spaces above most rail transit hubs is often large-scale, with complex spatial organization. This can lead to issues such as mismatched functional requirements, insufficient supply of service facilities, chaotic flow organization, low transfer efficiency, and poor spatial quality, resulting in insufficient guidance of pedestrian flow and low space utilization, which affects the vitality of commercial spaces and thus affects the healthy operation of commercial spaces. Therefore, this paper starts with the research on the vitality of commercial space above the rail transit hub. Firstly, it categorized the constituent elements of these commercial spaces, defining them in terms of functional organization, flow organization, and spatial construction across three dimensions. Then, two already constructed rail transit hub commercial spaces in China were selected for case study. Through field research and sample space screening, 15 indicators corresponding to the three dimensions were identified. The data analysis methods such as space syntax theory and SPSS correlation analysis were used to quantify the indicators. The study found that spatial vitality does not show a direct correlation with functional density, but it does exhibit a strong correlation with most flow organization indicators and all spatial construction indicators. The key factors influencing spatial vitality include functional density, spatial accessibility and visibility, entrances and exits, vertical transportation, and the location of resting areas. Finally, the specific operation of the design strategy was put forward in combination with the commercial space above the Chengdu station. The research content of this paper provides a design reference for the related design of the commercial space above the rail transit hub and offers new insights into related theoretical explorations.

Inspired by the structural configurations of ribbed cable domes, this study introduced a novel rib-patterned deployable antenna structure, aiming to explore innovative design solutions for large-aperture antennas. Firstly, this paper designed a basic deployable module with a driving-locking joint. By sequentially assembling multiple such modules, an extendable arm was constructed, which serves as a radial support rib. Furthermore, multiple extendable arms were arranged in a circumferential array, with corresponding prestressed loop cables, resulting in the construction of a novel rib-ring deployable antenna structure. In its fully deployed state, this structure can be conceptualized as a cable-beam composite system. A simulation model of the structure was created using finite element analysis software, and modal analysis was conducted. Comparative results reveal that, relative to existing configurations, the proposed rib-ring deployable structure exhibits superior structural stiffness, indicating its potential for application in large-aperture antenna design. Building on these, the study investigated the application of the rib-patterned structure to large-aperture antennas, proposing a deployable antenna design with a diameter of 58.2 meters. To assess the feasibility of this design, a simulation model of the antenna was developed using multi-body dynamics simulation software Adams, and deployment motion simulations were performed both for the individual extendable arm and the overall structure. The results demonstrate that the designed structure can successfully deploy into position and achieve reliable locking, further verifying the feasibility and effectiveness of the proposed antenna design. The study indicates that the novel rib-ring deployable antenna structure combines the advantages of truss-type deployable structures, which offer high stiffness, and rib-type deployable structures, which provide a high deployment ratio. This research offers valuable insights for the structural selection of future large-aperture antennas.

To address the issue of subjective uncertainty in the formulation and implementation of maintenance and strengthening strategies for existing bridges, this study proposed a bridge operation and maintenance decision-making framework that incorporates reinforcement time intervals. Firstly, based on the concept of interval mathematics, interval numbers were introduced to quantify subjective uncertainties that cannot be described using probability theory. Secondly, by leveraging the high efficiency and accuracy of surrogate models, the framework enables the direct mapping of the worst-case reliability index under mixed probabilistic and interval uncertainties. Finally, the multi-objective optimization algorithm NSGA-‍ Ⅱ was employed to efficiently drive the framework, ensuring optimized decision-making outcomes. To verify the applicability of the proposed framework in practical engineering scenarios, a typical prefabricated simply supported T-beam bridge was selected as a case study. Based on field data obtained from a Weigh-In-Motion (WIM) system, a probabilistic model of vehicle load effects was established. A time-dependent resistance degradation model was then introduced to optimize the operation and maintenance strategy for the T-beam bridge, culminating in the development of a decision-making library for its maintenance and reinforcement. The results indicate that strategies with smaller time intervals correspond to smaller Life Cycle Cost (LCC) and lower permissible subjective uncertainty. Conversely, strategies with longer time intervals, while resulting in higher LCC, offer greater flexibility for construction and decision-making processes. For simply supported T-beam bridges with spans ranging from 20 to 40 meters, it is possible to meet the required reliability index over the service life while minimizing LCC through appropriate reinforcement strategies. These findings demonstrate the strong applicability of the proposed framework and suggest it can serve as a methodological foundation for formulating maintenance and reinforcement strategies for existing bridges.

To investigate the temperature patterns of steel box girders in long-span cable-stayed bridges on high-speed railways, this study utilized measured temperature data from the Yuxi River Bridge on the Shangqiu-Hefei-Hangzhou High-Speed Railway, along with database resources. By employing machine learning techniques, the research explored the influence of various meteorological factors on the temperature behavior of steel box girders, as well as the temporal and spatial distribution characteristics of the temperature field. By establishing machine learning mo-dels that map various meteorological factors to the uniform temperature of the steel box girder, the superiority, inferio-rity, and applicability of each model were analyzed, and the importance ranking of meteorological factors affecting the uniform temperature of the steel box girder was obtained. A comprehensive study on the vertical distribution pattern of the temperature of the steel box girder was conducted using machine learning methods and exponential fitting. The results show that the importance ranking of meteorological factors affecting the uniform temperature of the steel box girder from high to low is: air temperature, cumulative radiation, air pressure, humidity, radiation intensity, wind direction, horizontal visibility, wind speed, and precipitation, with the temperature importance far exceeding other meteorological factors. Among them, the atmospheric temperature 2 to 3 hours ago has the greatest impact on the uniform temperature of the steel box girder, reflecting a lag of 2 to 3 hours in the impact of atmospheric temperature changes on the uniform temperature of the steel box girder. Neural networks, random forests, and XGBoost models can all accurately predict the uniform temperature of the steel box girder, with the neural network model performing better overall. The negative temperature gradient in the steel box girder exhibits lower sensitivity to meteorological factors and is more strongly correlated with the internal heat transfer characteristics of the structure itself. The exponential function can accurately fit the vertical distribution of the maximum positive temperature gradient in steel box girders, with its parameters determinable through machine learning methods. Each parameter holds distinct physical significance. The research findings provide valuable reference for predicting temperature fields and understanding distribution patterns in the steel box girders of long-span cable-stayed bridges on high-speed railways.

As an extreme case of adjacent construction in underground engineering, closely-spaced undercrossing will cause significant disturbance deformation in the existing structure, directly affecting their normal service performance. Taking the frozen, mined underpassing of an operational metro station as the research objective, a coupled simulation was conducted based on the vehicle-track dynamic interaction method and refined finite element modeling techniques，and a dynamic finite element model was established to simulate the close-proximity underpassing construction of vertically overlapping structures in soft coastal strata, which was further validated through real-time monitoring of the operational metro line. By converting the railway track irregularity induced by closely-spaced undercrossing into wheel-rail dynamic excitations and applying it to the finite element model, the time-frequency cha-racteristics of dynamic interactions between the track structure and tunnel foundation were calculated and analyzed. Furthermore, the evolution of vibration source intensity of the subway station was simulated in three construction stages: before soil freezing, after soil freezing, and after the breakthrough of the newly constructed tunnel. The results show that the wheel-rail dynamic excitation in the metro line is transmitted through the various layers of the track structure to the tunnel foundation, subsequentlly causing vibrations in the structure’s base slab and sidewalls. Due to the effects of transmission distance and direction, the system’s dynamic energy continuously atte-nuates along the transmission path, resulting in lower vibration levels in the tunnel sidewalls compared to the track bed. However, during the phase when the closely-spaced undercrossing excavation leads to increased track irregularities, the vibration amplitudes of both the track bed and tunnel sidewalls increase to varying degrees, with a more pronounced amplification observed in the track bed. The frequency distribution of vibration source intensity at metro stations was predominantly concentrated below 200 Hz. The primary frequency range of dynamic response induced by track irregularities from closely-spaced construction was below 40 Hz. Within the 8~40 Hz range, the source intensity is positively correlated with the amplitude of track irregularities, while an amplification phenomenon is observed in the tunnel sidewalls within the low-frequency range below 8 Hz.

Modern high-rise building façades often feature local elements such as sunshades and vertical decorative strips, and corner areas of buildings commonly adopt design measures like rounding or curving. The influence of these common architectural design features on wind loads cannot be ignored, and the current code needs to be improved., This paper takestook the CAARC high-rise building standard model as the research object, and studied the influence of rough strips and rounded corner on the wind load of the structure through a series of rigid model pressure measurement wind tunnel tests and high-frequency balance force tests. The studies show that: 1) Under the smooth model condition, with the increase of rounding angle from 0% to 10%, the absolute value of the peak negative pressure in the corner area of the windward surface of the building will gradually increase, and with the maximum increase is of about 38.4%; The global body shape coefficients of the structure will gradually decrease, and the maximum reduction of the global body shape coefficients in the X direction and Y direction is about 26.3% and 39.9%, respectively. 2) Under the condition of arranging vertical or grid rough strips with a thickness of 1.5 mm on the surface of the model, it is beneficial to reduce the absolute value of the peak negative pressure in the corner and middle of the structure, with a maximum reduction of 13.68%; For the global body shape coefficients of the structure, the rough strip model is slightly lower than the smooth mode. 3) The influence of arranging rough strips and rounded corner on wind pressure of building corner areas is not a simple superposition relationship. When both rough strips and rounded corner are arranged, the absolute value of the peak negative pressure in the corner area increases, with a maximum increase of 45.1%. 4) After the installation of roughness elements or the rounding of corner areas, the peak value of the crosswind power spectrum decreases, and the dimensionless frequency corresponding to the spectral peak increases.

Bistable composite structures are a novel type of deployable structure widely used across various fields. However, in complex service environments, changes in material properties may occur, which can in turn affect the bistable characteristics of the structure. By integrating theoretical and numerical studies, this study established a theoretical model of a composite cylindrical shell structure incorporating thermal and hygrothermal expansion coefficients. And it derived an analytical expression for the strain energy of the cylindrical shell under complex environmental conditions. Based on the principle of minimum potential energy, a bistable theoretical model considering the effects of temperature and humidity was developed. The influence of environmental parameters on the second stable-state strain energy, principal curvature, and twist curvature of cylindrical shells made from T700/Epoxy, T300/5028 Graphite-Epoxy, and AS7/M21 carbon fiber/epoxy composites was investigated. Using ABAQUS software, a finite element model of the cylindrical shell was built to numerically simulate the bistable deformation process, and the variations in second stable-state strain energy, principal curvature, and twist curvature under different temperature and humidity conditions were obtained. The numerical results were compared with the theoretical predictions. The results show that under temperature ranges of 20 ℃ to 120 ℃ and humidity levels from 0.0 to 1.0%, the maximum strain energy decreases by up to 32.7% and 9.1% for T700/Epoxy and AS7/M21, respectively, while the strain energy of T300/5028 Graphite-Epoxy increases by up to 914.6%. The principal curvatures of T700/Epoxy and T300/5028 Graphite-Epoxy show high sensitivity to temperature, with maximum increases of approximately 17% and 14%, respectively, whereas AS7/M21 exhibits variations of less than 5%. In terms of anti-twisting performance, T700/Epoxy and T300/5028 experience significant fluctuations under high temperature and humidity, while AS7/M21 maintains good stability. The combination of theoretical analysis and numerical simulation indicates that high temperature and humidity significantly affect the bistable performance of composite structures. By quantitatively analyzing the mechanical properties of composite materials under different temperature and humidity conditions, a scientific basis can be provided for material selection and environmental optimization of bistable structures, thereby contributing to improved reliability and durability in structural design.

To achieve rapid post-earthquake repair of structures, chevron braced steel frames with replaceable energy-dissipating joints was proposed based on the design concepts of controllable damage and replaceable energy dissipating components. The replaceable energy-dissipating joint consists of two double-U-shaped metal dissipaters, a gusset plate, a bracing end plate, and high-strength bolts. To investigate the seismic performance and post-earthquake reparability of the structure, quasi-static tests and post-repair quasi-static tests were conducted on a half-scale, single-story, single span substructure specimen. The hysteresis curves, skeleton curves, stress-strain curves and ductility indicators of the specimens were studied and compared between the initial and post-repair loading tests. The results show that the specimens exhibited full hysteresis loops and ideal energy dissipation capacity in both tests. Plastic damage was mainly concentrated at the replaceable energy-dissipating joints, while the main structure remained largely elastic. The initial loading test was terminated when the interstory drift angle reached 0.83%, with a residual drift angle of 0.28%. After replacing the energy-dissipating joints, the repaired structure exhibited mechanical performance similar to that before repair, with good agreement in the hysteresis curves, skeleton curves, and stiffness degradation curves. The simplified analytical models for chevron braced steel frames with replaceable energy-dissipating joints were established. Based on deformation compatibility relationships, a formula for calculating the elastic lateral stiffness of the structure was derived, and a formula for calculating the structural bearing capacity at the yielding of the double-U-shaped metal dissipaters was proposed. The calculated elastic lateral stiffness differed from the experimental results by a maximum of 3.72%, and the calculated horizontal bearing capacity at the yielding of the double-U-shaped metal dampers differed from the experimental results by a maximum of 9.41%.

A networked suspension cable arch bridge is a type of truss arch bridge system where at least two inclined suspension cables intersect, replacing the traditional vertical suspension cables. The cross-arranged networked suspension cables can effectively enhance the vertical stiffness and overall mechanical performance of traditional arch bridges, which has attracted attention in the field of bridge engineering. However, with the increasing span of arch bridges and the widespread use of thin-walled steel structures, structural stability issues have become more prominent. In particular, the risk of instability in steel arch ribs, which are primarily under compression, has become a key factor limiting its engineering application. To systematically analyze the stability performance of a networked suspension cable arch bridge and to explore the impact of different structural arrangement parameters on the overall stability of the structure, this study comprehensively considered geometric nonlinearity, material nonlinearity, and structural initial defects. A parametric spatial bar finite element model was established using nonlinear finite element methods to analyze the effects of varying cable tension forces on the overall stability. The displacement response and nonlinear instability critical load of key nodes on the arch ribs under load were calculated. The results from national and international standards were compared with those obtained using nonlinear finite element methods. Additionally, the study investigated the influence of different rise-to-span ratios, arch rib inclination angles, and cable inclination angles on the stability of the networked suspension cable arch bridge. Results show that variations in the suspension cable tension have little impact on the overall stability of the networked suspension cable arch bridge. The ultimate capacity of arch ribs based on standard methods is more conservative than that obtained through the nonlinear finite element method.The lateral overall stability of network arch bridges improves with increasing rise-to-span ratio and arch rib inclination, while it first increases and then decreases with the increase in cable inclination angle. The lateral stability performance of the bridge is optimal when the cable inclination angle is set between 50°and 60°.

To investigate the axial compression performance and strain compatibility of UHPC fully encased Q690 high-strength steel composite stub columns, this study designed, fabricated, and tested seven specimens under axial compression. The research parameters included the internal arrangement of steel wire mesh, the volume content of UHPC steel fibers, the stirrup spacing, and the cross-section type of steel profiles. It investigated the deformation failure process, ultimate failure mode, and peak bearing capacity of each specimen. The results showed that the UHPC fully encased Q690 high-strength steel composite stub columns exhibited excellent axial compression bea-ring capacity and deformation performance, and the strain compatibility between core UHPC and Q690 high-strength steel can be achieved at peak load. By referring to the bearing capacity calculation methods mentioned in various national codes, including China, Europe, and the United States, theoretical calculations of the axial compression ultimate bearing capacity of the UHPC fully encased Q690 high-strength steel composite stub columns were conducted and the results were compared with the experimental results. It shows that Tthe calculated results are in good agreement with the experimental results, providing a reference for calculating the axial compression bearing capacity of UHPC fully encased Q690 high-strength steel composite stub columns.

As a typical discontinuous medium, discrete granular materials’ creep behavior plays a crucial role in the formation and evolution of geological disasters such as landslides and debris flows. However, systematic research on the interaction mechanism between particle size and deviatoric stress and its impact on creep behavior remains insufficient. To reveal the coupled effects of particle size and deviatoric stress on creep behavior, this study conducted indoor creep tests on silica spherical particles under multiple conditions and systematically analyzed the influence patterns of different particle sizes and deviatoric stresses on the creep characteristics of granular materials. Based on the Derec creep model and experimental results, this study constructed a quantitative computational model of the creep state of granular materials and clarified the regulatory mechanism of particle size on the creep parameters of the system. The results indicate that the creep behavior of granular systems essentially reflects the dynamic balance between internal deformation and resistance to deformation within the particles. Creep parameters significantly influence system creep characteristics by regulating particle slip and creep behavior. Specifically, as particle size increases, the creep value of the system increases markedly, making it more prone to entering a liquid-like flow state. Concurrently, the system’s resistance to deformation declines while exhibiting heightened sensiti-vity to deviatoric stress. Furthermore, an increase in particle size not only significantly enhances the fluidity of the particle system but also amplifies its sensitivity to changes in deviatoric stress. Particles with larger diameters show a more pronounced response under high deviatoric stress conditions, and the flow characteristics of granular mate-rials are more susceptible to particle size variations. This influence manifests as a positive correlation between particle size and both the system's initial state parameters and characteristic strain, while exhibiting negative correlations with viscosity coefficient, critical creep velocity, and critical creep stress.