Abstract:To reduce the torsional effect of L-shaped irregular structures, this paper explores the control effect of three seismic joint design schemes for the isolation layer on torsional effect in seismic isolation design, and proposes an overall design process for L-shaped irregular structures. Based on the complex mode decomposition response spectrum method, an overall model of the upper structure isolation layer lower structure of an L-shaped building is established. The equivalent stiffness and damping ratio of the isolation device are determined through iterative calculation, and the modified response spectrum calculation is carried out; Add elastic-plastic time history analysis to the optimal solution in SAUSG, and ve-rify the ultimate displacement of the support and the displacement angle of the floor under rare earthquakes. The overall design method determines the seismic isolation target based on the bottom shear ratio and uses multiple calculation model envelopes to make seismic isolation design more intuitive and convenient. The scheme of setting vertical seismic joints was adopted to reduce the torsional displacement ratio from 1.60 to 1.16, and the displacement angle from 1/212 to 1/505, effectively controlling the torsional effect.

Abstract:This integrated study aims to provide a novel performance evaluation algorithm for double-layer arch-truss girder composite bridges based on an improved PCA-K-means-feature analysis method, and to apply it to the performance evaluation of cable-stayed systems in the maintenance phase based on safety monitoring. This algorithm mainly includes monitoring data collection, pre-processing of heterogeneous data from multiple sources, determination of key factors, improvement of K-means cluster analysis, determination of target thresholds, and performance evaluation based on eigenvalue analysis. By collecting bridge performance monitoring data, cleaning these data, and then using the cubic spline interpolation method to preprocess multi-source heterogeneous data. Determine key factors based on principal component analysis and classify performance parameter data into three categories using an improved K-means cluster method. Then, based on the finite element calculation results, the target threshold for the mechanical performance state of the measurement point corresponding to the measurement point position is determined. The performance state of the bridge is evaluated by comparing the extracted feature values such as mean and variance with the target threshold. Validate the method through examples and provide suggestions for practical applications and future research directions. Research has shown that the improved K-means cluster method can improve the accuracy and reliability of clustering analysis. Based on the improved PCA-K means cluster feature analysis method, the performance status of bridge structures can be evaluated.

Abstract:A simplified single tower model of the transmission tower line system was established by si-mulating the quality of the transmission line using quality units and simulating the equivalent stiffness of the transmission line inside and outside the plane using spring units as boundary conditions. Taking a self-standing steel tube transmission tower in Laoting County, Tangshan City, Hebei Province as the engineering background, the single tower simplified model was established and the traditional three tower two line model was used to calculate the wind-induced dynamic response of the structure. By comparing the wind-induced dynamic response of the two models under different wind direction angles, initial horizontal tension of transmission lines, and different transmission line spans, the applicability of the single tower simplified model was studied. The results show that under wind direction angles of 0°, 45°, and 90°, keeping the span of the transmission line unchanged, when the initial horizontal tension at both ends of the transmission line increases by 20% and decreases by 20% respectively based on the refe-rence value, the root mean square of displacement response and the root mean square of maximum main material stress obtained by the two calculation models at different heights are basically consistent, and both show a pattern of increasing deviation with the increase of transmission tower height; The deviation of structural dynamic response obtained by the two calculation models increases with the increase of transmission line span under different transmission line spans. Among them, the root mean square devia-tion of displacement response is more significantly affected by span than the root mean square deviation of main material stress. Therefore, the simplified tower model proposed is suitable for wind-induced dynamic response calculation of transmission tower line systems with spans less than 700 meters. In addition, in transmission tower line systems with smaller tower heights, the simplified model of the bill of lading tower has higher computational accuracy.

Abstract:To investigate the effect of aging of surface concrete on the internal and external humidity response of existing structures, experiments were conducted on carbonation, chloride salt erosion, and the rapid dehydration and reverse humidity response of concrete after their combined action in the marine atmospheric environment. The experimental results show that the peak water loss rate of concrete decreases first and then increases with the increase of carbonation age and chloride salt content. Among them, the peak water loss rate of concrete is the smallest when the carbonation age is 14 days and the chloride salt content is 1.5%. The water loss rate of concrete after the combined action of carbonation and chloride erosion is lower than that after the separate action of the two. The reverse humidity response of concrete shows a trend of first slowing down and then accelerating with the increase of carbonation age and chloride content. After the combined action of carbonation and chloride erosion, the reverse humidity response of concrete is slowed down compared to when they act alone.

Abstract:Based on the theory of mechanics, theoretical bearing capacity formulas for flat and bowl shaped pads are established according to the bearing performance of the pad under load. By establishing a three-dimensional numerical model of "pad rock", the influence of pad form and structural parameters on the bearing performance of the pad under load is analyzed, and the pad form and structural parameters suitable for anchor bolts are selected. The results show that under a load of 300 kN, if a bowl shaped cushion plate is selected for the anchor system, the parameters should be 300 mm×300 mm×180 mm, arch height of 35 mm, aperture radius of 34 mm, and bowl bottom radius of 60 mm; If a flat pad is selected, the parameters should be 280 mm×280 mm×255 mm, with a hole diameter of 26 mm and an anchor radius of 64 mm. The bowl shaped cushion plate has a better effect on controlling the deformation of surrounding rock under load.

Abstract:Based on the theory of elasticity, thin plate small deflection theory and mathematical calculation, the top plate deflection equation was constructed using the Burgers body, and the relationship between the deflection and time under different boundary conditions of the mining area top plate was studied. The research results show that under the condition of four sides fixed, the maximum middle deflection is 37.77 cm, and under the condition of three sides fixed and one side free, the maximum mid-dle deflection of the free side is 46.22 cm. The calculated results of the model are roughly consistent with the field monitoring data.

Abstract:Based on a thorough study of the topography, rock structure, and engineering geological characteristics of the toppling rock mass on the right bank of the Miaowei Hydropower Station, a three-dimensional block discrete element method 3DEC was used to establish a numerical model of the toppling deformation body on the upstream side of the right bank dam foundation. The stability of the toppling body under different working conditions of the natural toppling body and construction period toppling body was numerically simulated and studied, and the characteristics of the toppling body damage deformation and plastic zone distribution during each process were obtained, revealing the potential instability and failure mechanism of the toppling body; Based on field monitoring data, conduct quantitative analysis to study the time-dependent deformation characteristics of the toppling body. The research results show that the overall stability of the natural toppling body on the right bank is relatively high, and the safety factor can reach 1.39. The potential instability area is related to the excavation unloading process and exhibits a gradual damage evolution characteristic of the toppling rock mass. The slope system anchor cable has a significant controlling effect on the deformation of the toppling rock mass, greatly limiting the deformation of shallow A and B₁ toppling rock masses on the slope surface. The monitoring data shows that the deformation of the toppling body on the upstream side of the right bank dam foundation lasts for a long time after excavation at the foot of the slope, and is severely affected by rainfall, resulting in a significant time-dependent deformation process.

Abstract:Combining the pseudo dynamic method with the limit equilibrium three-dimensional Spencer method, the calculation formulas for seismic force and safety factor are derived, and corresponding calculation programs are written. A three-dimensional slope stability analysis method considering wave effects is established, and the correctness of the method and program is verified through numerical examples. This method was used to analyze the influence of geometric parameters, soil parameters, and wave effects on the pseudo dynamic and pseudo static safety factors of slopes, as well as the difference between the two. The research results show that the safety factor decreases with the increase of slope height, slope angle, and failure surface width, and the pseudo dynamic safety factor is always greater than the pseudo static safety factor. The difference between the two increases with the increase of slope height and decreases with the increase of slope angle and failure surface width; The safety factor increases with the increase of cohesion and internal friction angle, and the pseudo dynamic safety factor is always greater than the pseudo static safety factor. The difference between the two increases with the increase of cohesion and internal friction angle; The safety factor increases with the increase of ground vibration coefficient, and the pseudo dynamic safety factor is always greater than the pseudo static safety factor. The difference between the two increases with the increase of ground vibration coefficient.

Abstract:Through field tests on a four-level reinforced soil high steep slope project, the distribution law of vertical stress at the base of a multi-level spun high-strength polyester geotextile reinforced high steep slope was studied. The results showed that the vertical stress at the base exhibited a nonlinear distribution along the direction of the reinforcement material, with the maximum value occurring at the end of the reinforcement material. Using PLAXIS 2D, numerical simulations were conducted on the cross-section of a four-level reinforced soil steep slope to study the changes in structural characteristics such as horizontal soil pressure on the back of the backfill body, horizontal deformation of the slope surface at each level, geotextile strain, and potential fracture surface of the slope. The influence of factors such as reinforcement length, spacing between reinforcement materials, friction angle inside the filling material, and platform width on the horizontal deformation characteristics of the slope was also analyzed. Research has shown that the horizontal soil pressure on various levels of slopes undergoes a sudden change at the platform, exhibiting a serrated distribution along the slope height; The horizontal deformation of slope surfaces at all levels shows obvious "bulging" phenomena at different positions; The strain of geotextile at different heights shows a nonlinear distribution along the direction of reinforcement laying, and pre-sents two distribution forms: "double peak" and "single peak"; There are two types of potential fracture surfaces for slopes: integral circular sliding fracture surfaces and composite fracture surfaces. It was further found that the spacing and length of reinforcement materials significantly impact the horizontal deformation of high and steep slopes.

Abstract:To address the safety issues of the use of attached lifting scaffolding, a safety evaluation index system for the use stage of attached lifting scaffolding is first established, which includes 4 primary indicators and 18 secondary indicators. The AHP entropy method is used for weighting analysis; And based on the weight of indicators, propose a safety control framework for attached lifting scaffolding that integrates BIM technology and IoT technology. Develop a visual monitoring and management platform using JavaScript to achieve information-based monitoring and management of the construction process; Finally, evaluate the safety status of the scaffold and visualize the risk level based on BIM, in order to improve the safety management level of attached lifting scaffolding construction.

Abstract:In response to the influence of pile-soil interaction on the vulnerability of corrugated steel belly plate bridge components, a three-dimensional foundation consolidation model and pile-soil bridge model of a typical corrugated steel belly plate beam bridge were established using ABAQUS finite element software. Fifteen seismic records were selected from the PEER database, and the displacement ductility ratio was used as the damage index to conduct IDA time history analysis on the model. By comparing the vulnerability curves of bridge components under four damage conditions in the pier bottom consolidation model and the pile-soil bridge model, the influence of the pile-soil effect on the vulnerabi-lity of bridge piers and supports was obtained. The calculation results show that the probability of da-mage and failure of bridge piers and bearings in the pile-soil bridge finite element model is higher than that in the foundation consolidation model. Therefore, when conducting vulnerability analysis in practical engineering, it is necessary to consider the influence of pile-soil effect on structural vulnerability.

Abstract:In response to the urgent need to improve efficiency in traditional site selection design me-thods, an intelligent site selection method based on GIS+BIM fusion is proposed for microsite selection of wind farms. By integrating multiple sources of data such as geographic environment and business data, a digital twin containing spatial databases is constructed. Combining genetic algorithm and particle swarm optimization algorithm, visual and intelligent site selection of wind farms is achieved. Through pilot application analysis, this method meets the design accuracy requirements for the initial site selection of wind farms, increases overall efficiency by 60%, and reduces overall costs by 66%.

Abstract:In response to the problems of car slippage, wall peeling, and ground mold caused by condensation in underground garages, taking a garage in Handan as an example, the actual monitoring data was analyzed. Fluent software was used to simulate the installation of an air curtain system in the garage, set different air supply speeds, observe the temperature and humidity cloud map of the air inside the garage, and compare and analyze it with the temperature and humidity inside the garage under natural ventilation conditions. Preventive measures and ventilation operation strategies were proposed. The simulation results show that when the air supply speed of the air curtain system is 2 and 4 m/s respectively, the air temperature in the garage increases by 0.7 ℃ and 1.2 ℃ respectively, and the relative humidity decreases by 5.5% and 8.9% respectively, and the dew point temperature decreases to 13.92 ℃ and 13.73 ℃ respectively; When the air supply speed increases from 4 m/s to 6 m/s, the change is consistent with the increase in wind speed from 2 m/s to 4 m/s. In this case, the dew point temperature decreases to 13.52 ℃, which is 14 ℃ lower than the wall temperature and 15 ℃ lower than the ground temperature, and the anti-condensation effect is significant.

Abstract:A planetary gearbox fault feature extraction method based on improved adaptive noise complete set empirical mode decomposition (ICEEMDAN) and variational mode decomposition (VMD) methods is proposed. The signal was decomposed using ICEEMDAN, and the signal was filtered and reconstructed based on the kurtosis of the component envelope. Based on the maximum envelope spectral kurtosis as the fitness function, the sparrow search algorithm is used to adaptively optimize the parameters of VMD, and the reconstructed signal is decomposed into multiple modal components. Based on the kurtosis of the envelope spectrum of the components, select the optimal component for envelope demodulation analysis to achieve feature extraction of planetary gearbox faults. Finally, the consistency correlation coefficient of the method proposed in this paper was found to be between 0.472 3 and 0.793 6 through experiments, which is much higher than the EEMD-WTD method’s 0.088 1 to 0.286 3 and the envelope spectrum selection index’s 0.142 7 to 0.286 4.