The supercritical carbon dioxide power cycle system has a very positive effect on the realization of energy saving and emission reduction goals. In this paper，a calculation model is proposed for a foil gas dynamic pressure bearing structure. By fitting the non-ideal state gas supercritical carbon dioxide，the relationship between density and pressure is established. Based on the heat transfer model and the gas lubrication energy equation，the temperature rise of the bearing gas film is analyzed. The Reynolds equation of the lubricating gas is corrected in combination with the turbulent effect in the actual operation process，coupled with the mechanical analysis model，Reynolds equation and energy equations，the static characteristics of foil gas dynamic pressure bearings are analyzed，and compared with air as a medium to analyze the influence of different system parameters and turbulence parameters on the bearing characteristics. The results show that compared with air，the foil gas dynamic pressure bearing using supercritical carbon dioxide as the lubricating gas has a higher bearing capacity，and within a certain range，the bearing capacity can increase with the increase of bearing diameter and width，eccentricity，the rotational speed and the reduction of the bearing clearance. For the turbulent influencing factors，within a certain range，the bearing capacity can increase with the increase of the local Reynolds number and turbulence coefficient，aerodynamic viscosity，density for ambient gas and the decrease of ambient temperature.

At present，many rolling bearing fault diagnosis methods based on convolutional networks have the disadvantages of poor diagnosis effect and poor generalization ability under the influence of noise signals and load variations. Aiming at these problems，an improved convolutional capsule network fault diagnosis method of rolling bearing under variable operating conditions is proposed. This method designs a multi-scale asymmetric convolution module，in which asymmetric convolution layers of different scales to extract features from the input data to maximize the extraction of feature information in the data and reduce the number of parameters effectively. In this module，the channel attention mechanism is introduced to better extract useful channel features and improve the feature extraction ability of the method in this paper. By improving the fully connected layer in the network to the fully connected layer of the capsule，the capsule can avoid the loss of characteristic information in the space in the process of outputting vector feature information. Case Western Reserve University bearing dataset and Southeast University gearbox dataset are used to verify the diagnostic performance of the proposed method and compare with other deep learning methods. The experimental results show that the proposed method has a better generalization and performance.

The windowed synchronous averaging （WSA） is commonly applied to the fault detection of planetary structures since it can overcome the problem of time-varying transfer path. However，it is unsuitable for the fault feature extraction of the planet gear at the first stage in a two-stage planetary gearbox due to the vibration coupling caused by the two-stage planetary structures. To address the issue，an angle compensation synchronous averaging scheme is proposed in this paper. In the proposed scheme，the speed fluctuation of the observed vibration is eliminated by equal-angle resampling. The second-stage interference from the sun gear at the second stage is constructed by applying the synchronous averaging to the resampled vibration based on the angle compensation strategy. The second-stage interference is removed by subtracting it from the resampled vibration. The corresponding envelope signal is extracted by the envelope analysis from the residual vibration. The WSA is utilized to construct the synthetic envelope signal of the planet gear at the first stage. The envelope synchronous averaging is used to suppress the asynchronous interference and extract the fault feature of the planet gear. According to the experimental results of a two-stage planetary gearbox test rig，the effectiveness of the proposed method is verified.

Stay cables of cross-sea cable-stayed bridges will generate self-excited vibrations in non-extreme wind environments. Based on technologies of modern monitoring and data analysis，the digital features of the self-excited vibration of the stay cable can be captured immediately，and the real-time performance of dynamics about stay cables can be reflected accordingly. According to features of commonality in the long-term monitoring data of vibrating acceleration of stay cables from a main channel cable-stayed bridge of a cross-sea bridge，an automatic extraction method for the non-stationary sections of wind-induced self-excited vibration of the stay cable is proposed based on the vibrating acceleration time series signal’s Gaussian mixture model of the upper envelope and the power spectrum of the frequency domain. The strategies，that identify the dominant frequency based on the non-stationary time series of self-excited vibration，then identify the damping ratio using the data of the last descent section after band-pass filtering，are proposed. By the proposed strategies，the interference on the damping ratio identification from energy brought by the natural excitation of the ambient wind in the ascent sections of the vibration amplitude is excluded. Based on the identified results of dominant frequency-damping ratio in the non-stationary sections of the self-excited vibration，data clusters of the modal frequency-damping ratio corresponding to each order of the vibrating mode are obtained by clustering the frequency values. According to the discrete and skewed characteristics of the damping ratio data，the statistical law of using the eμ of log-normal distribution model and the quantile value of its cumulative distribution function to describe damping ratio of stay cables is proposed. The frequency centroid of each cluster，as well as the probability characteristic parameter of damping ratio are used as indicators to represent the current state of the dynamic performance of stay cables. The main conclusions for the background engineering include： the signal of vibrating acceleration of stay cables on the bridge has strong noise and large interference，they must be eliminated in the analysis of dynamic characteristic； the amplitude maximum of the acceleration of the self-excited vibration of the bridge’s stay cable has exceeded 3000 mm/s²，the vibration amplitude is large； the average level of the damping ratio of the bridge’s stay cable is about 0.03%，which is lower than the recommended value of the design code.

In order to give full play to the seismic potential of the movable support pier and improve the overall longitudinal synergistic effect of the continuous girder bridge，based on the principle of functional separation and synergistic force，a new type of mass rotation wrap rope device is proposed based on the mechanism of wrap rope. Taking a typical three-span continuous girder bridge as an example，the shaking table test is carried out by inputting actual seismic waves with different seismic spectrum characteristics and intensity as excitation，the seismic response with equal pier height model and unequal pier height model are analyzed to explore the synergistic force and shock absorption effect of the device on the continuous girder bridge. Through the test results of the response of the key positions of the structure such as the acceleration response，displacement response and strain response，it can be seen that the effect of the device on the movable bearing pier participating in the overall longitudinal synergistic force of the continuous girder bridge is more obvious，and with the increase of the ground motion input intensity，the synergistic effect of the device becomes more and more prominent，the design intention of the device is realized. At the same time，the effect of the device is related to factors such as the number of wrap rope turns of the device itself，the pier height of the movable bearing pier，etc. The design needs to determine the reasonable design parameters of the device according to different factors such as the pier height to achieve the best effect of the device.

Most of the nuclear power plants are built around the coastal or along the rivers. Below the underground water level，distribution of the water in the soil pore has a great influence on the seismic response of soil，which affects the response of the nuclear power plants. To analyze the effect of the underground water level on the seismic response of nuclear power plant，a saturated porous medium model considering the interaction of the saturated soil and structure is used in this paper. Firstly，the free field of the horizontal layered site of dry soil-saturated soil is obtained by the transfer matrix method，and the wave input of soil-structure interaction analysis is realized combined with the transmission boundary； Then，the partitioned parallel calculation method of soil-structure interaction is used to analyze the saturated soil-structure interaction. The soil with groundwater level is described by the generalized saturated porous medium model which is simulated by the lumped-mass explicit finite element combined with the transmission boundary using the self-programmed FORTRAN code，and the structure is analyzed by ANSYS using implicit finite element. Taking a nuclear power plant as an example，the dynamic response of soil-base-nuclear power plant system is analyzed in five sites with different groundwater levels of -10 m，-20 m，-30 m and -40 m，as well as pure saturated soil. The results show that the groundwater level has a great influence on the response of foundation and structure. For the calculation example in this paper，the results show that the groundwater level has little effect on the displacement of the foundation and structure，but has a great effect on the acceleration of the foundation and structure.

To address the threat of harmful vibrations of semisubmersible floating offshore wind turbine （FOWT） in complex deep-sea environments to the safety and durability，a design of distributed tuned mass dampers （TMDs） is proposed to control the platform pitch motion under the randomly combined wind and wave excitations，in combination with the geometric structure of the 5MW prototype of NREL in the United States. The distributed TMDs are installed inside the platform to form an equilateral triangle arrangement. To better describe the performance of the distributed TMDs on the semisubmersible FOWT，a 9-degree-of-freedom multi-body dynamics model is proposed and established for the coupled semisubmersible FOWT-TMDs system based on Lagrange's equation and the modal superposition method. Based on the H_∞ algorithm，whose optimization objective is the peak value of the frequency response function of platform pitch motion，the parameters of the distributed TMDs are optimally designed，where the coupling relationship between multiple TMDs is considered. The numerical simulation of the coupled FOWT-TMDs system under the combined wind and wave excitations is carried out to analyze the performance of the distributed TMDs on the platform pitch response of the wind turbine. The results show that the distributed TMDs with optimal design has good damping performance on the platform pitch motion of the semisubmersible FOWT. Under random wind and wave loads in three different working conditions，the peak and standard deviation vibration reduction rates of the power spectral density curve near the natural frequency of platform pitch can reach more than 39% and 52%，respectively. The research method and results can provide reference for dynamic analysis and vibration control design of large semisubmersible FOWT.

There is a lack of detection means for the isolation performance of the buildings built by passive control technology，so it is of great significance to test the dynamic characteristics of the isolated structures on the spot. A 4-story base isolation kindergarten was tested in the field，and the test device，method and results were displayed. The results were compared with the seismic structure model under the same conditions，and the dynamic response law and damping effect of the actual isolation structure were explored. The building was pushed away with hydraulic jack to produce 98 mm （corresponding to LNR500 shear strain 102%） horizontal initial displacement of the isolation layer，and concrete jacking rod was installed to support the building； The concrete rod was blasted with explosives and unloaded instantly to make the building vibrate freely； The dynamic response and other parameters were tested and analyzed. The results show that under the condition of horizontal initial displacement，the first-order natural vibration period of the isolated structure is significantly longer than that of the seismic structure，and the damping ratio increases； The hysteretic curve of the isolation layer is full； The dynamic response control effect of each floor is obvious，but the acceleration of the roof floor is slightly amplified compared with that of the bottom floor； After unloading，the isolation layer instantly resets，which shows that the isolation layer has rapid reset performance.

To reveal the influence of biaxial coupling effect on the multi-dimensional seismic performance of flanged reinforced concrete （RC） shear walls with different section forms，three T-shaped and two L-shaped RC shear walls were tested under low cyclic loading along their principal axes. The failure modes，hysteretic characteristics，bearing capacity，ductility，ultimate drift ratio，energy dissipation capacity and reinforcement strain of RC shear walls with flange under uniaxial and biaxial lateral loading were compared and analyzed. Test results show that failures of T-shaped walls and L-shaped walls exhibit obvious asymmetry，and the damage is concentrated at the free end of wall penal. Biaxial loading aggravates the cracking and damage degree of RC shear wall with flange，and is likely to cause local damage concentration. Compared with the RC shear wall with flange under uniaxial loading，the biaxially loaded specimens have smaller bearing capacity and deformation capacity in all directions，larger proportion of flexural deformation in the plastic hinge area of web segment，faster energy consumption，poorer energy dissipation capacity in a single direction，larger strains of vertical reinforcement in web and flange，and more obvious shear lag effect of flange. Biaxial coupling effect has more pronounced influence on the damage evolution of L-shaped walls than that of T-shaped walls，resulting in greater reduction of seismic performance index of L-shaped walls under biaxial loading than that of T-shaped walls. Considering the biaxial seismic actions，the limit value of inter-story drift ratio of RC shear walls in China's seismic design code is still relatively safe，but the safety redundancy is reduced.

In order to accurately analyze the influence of temperature and shear deformation effects on the natural vibration characteristics of the improved composite box girder with corrugated steel webs，a method for analyzing the natural vibration characteristics of an improved composite box girder with corrugated steel webs considering temperature and shear deformation effects is proposed in this paper. Considering the influence of the temperature，shear deformation and stiffness correction of the corrugated steel web，the analytical formula of the natural frequency of the improved composite box girder with corrugated steel webs is deduced by using the principle of stress equivalence； The correctness of the analytical formula of natural frequency is verified by using the ANSYS finite element results and the measured results of bridge； The effects of temperature equivalent axial eccentric force，variation of elastic modulus，shear deformation，and temperature effect under different height-span ratios and different width-span ratios on the natural frequencies of bridge are analyzed. The results show that the fundamental frequency of the improved composite box girder with corrugated steel webs is greatly affected by the temperature effect，and the influence of the temperature effect needs to be considered when calculating the fundamental frequency of this bridge type； The shear deformation effect of the corrugated steel web has a significant influence on the natural frequencies of the bridge type，and the influence of shear deformation from the 4th order natural frequencies has exceeded 50%； Under different height-span ratios，the temperature effect has a greater influence on the fundamental frequencies，and it increases linearly and sharply with the increase of the height-span ratios； Under different width-span ratios，the temperature effect has little influence on the natural frequencies and can be ignored. The research results can provide a reference for the calculation and analysis of the natural frequencies of the improved composite box girder with corrugated steel webs.