Blind source separation (BSS) can be used to extract modal coordinate vibrations from structural vibration signals. Complexity pursuit (CP) is one of the classical methods for solving the BSS problem. To improve the computational efficiency of the CP algorithm, this paper proposes two enhancements： it uses the negative log function of a Gaussian distribution as a nonlinear function to estimate signal complexity and derives formulas for rapidly computing signal complexity and its gradient； it employs a subspace search-based gradient descent algorithm to calculate the optimal mixing vector in the reduced subspace. The new formulas only require the covariance matrix of mixed signals and the covariance matrix of time delays when computing complexity and its gradient, without using all signal data. Numerical examples and structural vibration data are employed to evaluate the proposed method. The results demonstrate that the fast complexity pursuit algorithm outperforms traditional methods in terms of computational efficiency and accurately separates structural modal coordinate vibrations.

To overcome the shortcomings of traditional base isolation technology, such as non-adjustable isolation parameters, limited low-frequency isolation effect, and inability to achieve vertical isolation, magnetic levitation technology is introduced to design a magnetic levitation vibration isolation bearing. The relationships between the levitation force of the electromagnet and the coil current and levitation gap are analyzed. The nonlinear model of the magnetic levitation vibration isolation bearing is established. Combining the advantages of terminal sliding mode and super-twisting algorithm and introducing an adaptive law to adjust the coefficients in the super-twisting algorithm, an adaptive super-twisting terminal sliding mode control strategy is proposed. Through experimental verification, the proposed control scheme can suppress the chattering phenomenon in the traditional sliding mode control, with high control accuracy and good steady-state and dynamic performance. The magnetic levitation vibration isolation bearing has excellent stability and disturbance-resisting performance.

Flexible cable supported photovoltaic are prone to be significant wind induced vibrations, which can lead to various structural safety and usability issues. Currently, the law of wind induced vibrations is not clear, and there are no corresponding vibration suppression measures. This study conducted wind tunnel tests on the full aeroelastic model of flexible cable supported photovoltaic. It synchronously measured the displacement and cable force of single-layer flexible cable supported photovoltaic, analyzed the effects of wind speed, inclination angle, and wind direction angle on displacement and cable force, proposed corresponding vibration suppression measures, and verified their vibration suppression effect through experiments. The results show that the flexible cable supported photovoltaic undergoes vertical and torsional coupled vibration under strong wind. The maximum displacement response occurs at wind suction and the maximum of cable force occurs under wind pressure. Therefore, wind suction is an unfavorable working condition for designing the joints. Meanwhile, wind pressure is an unfavorable working condition for designing columns and bases. The anchor cable has a significant mitigation effect on the vertical and torsional displacement at wind suction. The larger of the tilt angle is, the better mitigation effects. For the cable end force, the anchor cable can effectively reduce the fluctuation of cable force. The larger the tilt angle is, the more effective the cable force reduction.

In order to obtain the main influencing factors of buffeting response calculation of Π‑shaped main girder cable‑stayed bridge, taking Qingzhou Minjiang River Bridge as the engineering background, the buffeting response characteristics of main girder displacement were analyzed by using three‑dimensional multi‑modal coupling buffeting calculation method on the basis of wind tunnel test. The significance of nine factors in buffeting response was tested by uniform experimental design and regression analysis method. The results show that the aerodynamic admittance, fluctuating wind correlation coefficient, vertical wind spectrum, average wind profile index, surface roughness height and air density have significant influence on the buffeting response of cable‑stayed bridge in the common range of values. The influence of structural mass and damping ratio is not significant, and its value deviation can be ignored in buffeting calculation. The horizontal wind spectrum only has a significant effect on the lateral buffeting response.

Seismic experience has shown that underground shaft structures are subjected to seismic threats and severe examples of damage have occurred. In order to obtain the seismic response of the shaft, the ‘beam-spring’ model was used to establish a system analysis model for the dynamic interaction between the large-diameter shaft and the soil based on the Pasternak foundation and the Timoshenko beam theory. On the basis of considering the normal earth pressure of site soil layer and shaft structure, the tangential shear force of site soil layer and shaft structure is further considered. The analytical solution of seismic response of large diameter shaft under horizontal earthquake was studied. The peak seismic response of the shaft along the depth direction is analyzed from the aspects of the ratio of the length to diameter of the shaft, the ratio of the inner and outer diameters, the ratio of the elastic modulus of the shaft to the site and the boundary conditions at the bottom of the shaft. The results show that the decrease of the ratio of the length to diameter of the shaft will lead to the increase of the peak response of the internal force of the shaft along the depth direction. The increase of the inner and outer diameter ratio of the shaft will reduce the peak internal force response of the shaft along the depth direction. With the increase of the ratio of the elastic modulus of the shaft to the site, the peak response of the internal force of the shaft along the depth direction will gradually increase. The displacement response of the shaft under the elastic soil foundation is larger than that of the rock-socketed foundation. The shear response under the rock-socketed foundation along the depth direction of the shaft is significantly larger than that of the elastic soil foundation, and the bending moment peak response of the rock-socketed shaft at the bottom position is larger.

The uncertainty of the combined incidence angle of seismic waves often has a significant effect on the dynamic response of faced rockfill DAMS. In this paper, the motion field of surface control points is decomposed by the principle of wave field superposition, and the time history of incident P and SV waves is obtained by two‑dimensional inversion. The angle of incident P wave and SV wave in the wave input model are randomly selected by the method of number theory. The influence of the uncertainty of combined incident angle on the seismic response of asphalt concrete faced rockfill dam is studied by the dynamic calculation of different combined incident angles. Taking a practical project as an example, by analyzing the mean value, coefficient of variation, 95% confidence interval limit and extreme value difference of the horizontal peak acceleration of foundation surface, panel stress and acceleration, dam body horizontal peak acceleration and permanent deformation, and other statistical laws and distribution type tests, and compared with the vertical incidence of seismic waves, The influence of random combination incidence Angle and input ground motion intensity on random response dispersion degree and obedience probability distribution is analyzed. The results show that considering the uncertainty of the combined incidence angle, the seismic response dispersion of the foundation surface of the dam will increase. The maximum principal tensile stress of the panel increases by at least 40% compared with the calculated result of vertical incidence. The influence of the horizontal peak acceleration on the dam crest and the panel crest is greater than that on the permanent deformation. Compared with the results of vertical incidence, the permanent deformation of the three groups of seismic waves has a transcendental probability of more than 70%. The statistical results of seismic response of dam body may not accord with normal distribution. The dispersion of seismic response results of overlay layer is greater than that of dam body.

Based on the basic concept of the generalized response displacement method, a dynamic sub-structure analysis method suitable for the longitudinal seismic response of a shield tunnel crossing longitudinally uneven sites is proposed. An explicit parallel calculation model of the longitudinal uneven free field and a three-dimensional (3D) refined explicit parallel calculation model of the surrounding rock-shield tunnel system are established by using the newly proposed sub-structure analysis method. The real-time transmission of dynamic deformation between the two models on the boundary is achieved through the sub-structure method. The free-field seismic wave at the buried depth of the tunnel is transformed into the equivalent earthquake action of the surrounding rock-shield tunnel sub-structure model. Compared with the traditional beam-spring model, the model method in this paper can achieve the 3D refined simulation of the surrounding rock-tunnel system and the longitudinal non-uniform ground motion input along the tunnel caused by the site seismic effect. The reliability of the model method in this paper is verified by comparing it with the calculation results of the 3D refined analysis model of the shield tunnel. The results show that the model method in this paper has a clear concept, simple modeling, low calculation cost and small differences in results, which can fully reflect the longitudinal seismic response of shield tunnel crossing longitudinal uneven sites. It provides a more efficient analysis method for the longitudinal seismic design of shield tunnels crossing longitudinal uneven sites with soft-hard connected media.

The non-uniform input of ground motion has a significant effect on the dynamic response of a concrete cut-off wall in deep overburden. In order to explore the response characteristics of the cut-off wall under non-uniform ground motion input at the overburden site, this study establishes the input method of P-wave three-dimensional oblique incident wave motion under any incident angle in space based on the wave field decomposition method and the viscoelastic artificial boundary method, and validates the input method. Nine non-uniform input conditions were designed to investigate the influence of different azimuthal and oblique incidence angles on the dynamic response of the cut-off wall under a combination of incidence. The results show that the maximum acceleration in the down-river direction of the cut-off wall at α=60° and γ=0° incidence is 3.89 times that of vertical incidence, and the maximum acceleration in the axial direction of the dam at α=60° and γ=90° incidence is 8.93 times that of vertical incidence. Non-uniform input causes a significant increase in the transverse riverward tensile stresses in the impermeable wall, up to 3.53 times that of the vertical incidence, with a significant change in the peak distribution region, and the vertical compressive stresses are significantly reduced at an oblique incidence angle of 90° incidence compared to the vertical incidence. The traditional vertical incidence method can ignore the expansion area of tensile stress of the cutoff wall under non-uniform input, so the non-uniformity of ground motion should be considered when analyzing the dynamic response of the cutoff wall in a deep overburden layer.

Considering the random uncertainty of landing gear parameters in design and manufacturing, this study conducts a quantitative study on the random response of carrier-based aircraft landing impact and the buffering performance of landing gear. This study established a dynamic model of the landing vibration of a carrier-based aircraft’s main landing gear. Based on the statistical characteristics of some filling parameters of the landing gear buffer (such as the initial volume of the air chamber, pressure oil area, oil shrinkage coefficient, etc.), the representative point set is divided by the direct probability integration method (DPIM), and the deterministic structural equation and probability density integration equation on the representative point set are solved. At the same time, the accuracy of DPIM application in the landing gear stochastic model is demonstrated by using the Monte Carlo Simulation (MCS) method. By outputting the buffer stroke of the landing gear, the vertical tire force, and the axial force of the strut, the mean value, standard deviation, probability density function, and related features of these responses are obtained. It is found that although the distribution of these responses are concentrated near the mean value, there is still a possibility of significant responses leading to system failure. Therefore, a functional function is defined using the buffer stroke, vertical tire force, and the axial force of the strut, and a reliability evaluation study is conducted on the landing gear structure under different threshold values.

With the continuous development of aerospace industry, the load transfer structure of spacecraft is getting more and more complicated. In practical engineering, how to distribute the loads in a reasonable way is of great significance for the lightweight design of spacecraft and the guarantee of structural load carrying capacity, and it is also necessary to take into account the non-ideal boundary conditions of the overall structure to the local structure in the process of dynamic load transfer structure design. Based on this, this paper proposes a dynamic topology optimization design method for dynamic load transfer structure based on structural boundary condition equivalence, which can fully consider the influence of the overall structure on the local structure while designing the load transfer structure. The method firstly simplifies the connection boundary between the local structure and the overall structure into a spring unit and a centralized mass unit, optimizes the unit parameters through genetic algorithm to achieve the equivalence of boundary conditions, and finally establishes a topology optimization model of the load transfer structure based on the unit density variable in conjunction with the design objective of the dynamic compliance of the structure. Numerical examples verify the effectiveness of the new method and obtain the optimization design results with the variation of volume fraction, external load frequency and load constraint interval.