The existing rectangular piezoelectric cantilever beam has the shortcomings of high intrinsic frequency and low output performance. In this paper，a piezoelectric energy harvester based on the enhanced negative Poisson’s ratio structure is designed by combining a negative Poisson’s ratio structure and X-shaped ribs in an elastic substrate. The dynamics model of the energy harvester is established by using the finite element method for the piezoelectric coupling analysis and parametric analysis. The prototypes are fabricated to verify the design. The results show that the energy harvester based on enhanced negative Poisson’s ratio structure has a low first-order resonant frequency，high output voltage and power，and the addition of X-rib increases the stiffness and nonlinearity of the structure. Compared with the conventional negative Poisson’s ratio structure，the introduction of X-rib not only improves the fatigue performance of the structure，but also broadens the bandwidth by 67.87%. The energy harvester based on enhanced negative Poisson’s ratio structure is important for solving the power supply problem of wireless sensors and portable electronic mobile devices in the future.

Aiming at the problem that the existing analysis methods for the floating offshore wind turbine （FOWT） cannot efficiently predict the random dynamic response when considering the nonlinear coupling model，a fast calculation method of the random response of the FOWT nonlinear system under coupled wave excitation based on the statistical linearization algorithm is proposed，and its application in the vibration control of FOWT is studied. Taking the Spar FOWT as the object，a nonlinear model under the wave coupling excitation of 4-DOF is established based on the Lagrange equation，and the accuracy of the model is verified. On the basis of the established nonlinear model，a random vibration analysis method for this Spar FOWT based on statistical linearization algorithm is proposed，and the method is verified in many aspects. The results show that the method can improve the calculation efficiency by 4~5 orders of magnitude and has sufficient accuracy. The method is applied to the vibration control of the FOWT. The optimization of the control parameters and performance analysis of the FOWT under the control of TMD are efficiently realized，and the optimal control parameters of TMD are obtained. It is found that the vibration control effect of TMD on the FOWT tends to decrease gradually with an increase of the sea state level. In general，the proposed method has high accuracy，high efficiency and generality in different sea conditions，and also provides an efficient analysis method for the design optimization，fatigue analysis，reliability analysis and other research based on statistical characteristics of FOWT.

Based on the dynamic response caused by moving vehicles，a recurrence quantification analysis-based structural damage detection method is proposed. The acceleration response is split into several segments using a moving window. The recurrence plots are constructed to analyze and present the characteristics of each segmented response signal. The recurrence quantification analysis is used to quantify the damages and construct the damage feature. The damage features of each relative position are assembled as a vector for the location of the structural damage. The proposed method is validated by numerical simulation with the single-damage and multi-damages. The influence of damage location，vehicle speed，noise and other factors are discussed to illustrate the robustness of the proposed method. Results show that the method is a potential way for structural damage detection under operational condition.

Structural response of quay crane should be paid more attention to with the growth of worldwide logistics demand. This paper analyzes the response mechanism of the metallic structure of the quay crane induced by trolley traveling. On-site test is conducted. The time domain of crane girder acceleration signal shows that the main influence of the trolley travelling on crane structure is the high-frequency impact as it passes through the hinge point. The spectrum shows the main frequency of structure vertical vibration and impact vibration. Based on Euler-Bernoulli beam theory，a numerical model of quay crane single beam structure is established. The influence of different working conditions on the dynamic response of the beam structure and effect of the centrifugal acceleration term in the dynamic equation on logistics equipment such as quay cranes is analyzed. A refined model of the whole structure including the critical parts of the structure，such as the hinge points，the rail girder and other structural geometric features is established. The trolley is simulated with simplified mass points，and the interaction between the trolley and the girder is realized by the contact between the mass and the shell elements in the dynamic analysis of the quay crane structure. The eccentric force of the rail girder is considered，and the acceleration response of the girder hinge point is calculated，which is basically consistent with the measured signal results. After calculation and analysis，the frequency spectrum of the measured acceleration signal and the calculated signal spectrum at the girder hinge point of the quay crane show that the main influence of the trolley traveling on the quay crane structure is the high-frequency impact. The influence of the impact on the surrounding structure cannot be ignored. At the same time，the displacement results of 10 measuring points on the girder of the quay crane model and the trolley show that when the trolley runs at a constant rated speed with the rated load，the front end of the girder of the quay crane produces a vertical quasi-static displacement. The displacement spectrum indicates that the trolley is mainly affected by the vertical direction forced vibration.

To investigate the vibration and acoustic properties of the baffled functional gradient plates with general boundary conditions under turbulent excitation，a vibro-acoustic coupling model of the functional gradient plate under turbulent boundary layer wall pressure fluctuation is developed by the energy method based on the turbulent pressure fluctuation cross-spectral density，Chebyshev spectral method，Rayleigh integral and the continuity condition of the fluid-structure coupling surface. The accuracy of the algorithm is verified by the agreement with the analytical solution and experimental results. The effects of the general boundary condition and the gradient index of the FGM plate are studied. It can be noted that when the stiffness of the boundary spring is in a certain range，the peak frequencies of the flow-induced acceleration level and sound pressure level increase with the rise of the spring stiffness. When the stiffness of the boundary spring is large，low vibration and radiated sound exist at low frequency，while the radiated sound pressure is high at high frequency. As the gradient index increases，the peak frequency increases gradually，but the peak responses of the acceleration level and sound pressure level decrease.

Seismic vulnerability analysis is one of the most effective tools to evaluate seismic performance of pile-supported wharf （PSW） structures，which can quantify the probability of structural damage under given ground motion parameters. For a typical PSW in this study，the degradation of steel and concrete materials caused by chloride ion induced erosion is explored. Based on the open-source numerical computational platform OpenSees，a two-dimensional finite element model of PSW is created. In this model，the cross-section characteristics of pile considering corrosion effect are adopted in splash zone. The influence of chloride ion induced corrosion on seismic performance of PSW structure is discussed. Pushover analysis method is used to determine the seismic demand bound limit of each damage state of PSW. By inputting 80 ground motions to wharf models with different corrosion years，the logarithm regression analysis for the ratios of the capacity and demand are adopted to develop the time-dependent seismic fragility curves. The results show that： Chloride ion induced corrosion leads to the decrease of deck displacement and pile top bending moment，and the slight increase of pile top curvature； During the whole service life of PSW，seismic vulnerability of wharf structure in different damage states increases with an increase of service time.

Self-centering brace has greater stiffness and bearing capacity after being activated. The brace connection，beam and column are subjected to more complex forces and higher risk of damage. A novel frictional prefabricated connection node in self-centering braced steel frame is proposed to control ultimate axial force of the self-centering brace by frictional slipping. It provides additional energy dissipation for the whole structure. Configuration，assembly and working principles of the connection nodes are described. By numerical simulation，its seismic performance is studied. The effects of design parameters of the connection node on performance are analyzed. The results show that the hysteretic response of the self-centering braced steel frame with the novel connection node is fuller. The energy dissipation capacity of the overall structure is increased by 20.81%. The actual limiting effect of the connection node on total shear force reaches 17.56%，effectively regarding the plastic development of connection node region. By changing the friction coefficient of the friction plate and the preload force of the high-strength bolts of the connection node，the slipping displacement and force can be adjusted.

Dynamic actions such as strong winds and earthquakes often have significant randomness and non-stationarity，which can have disastrous effects on practical engineering structures. Therefore，accurately evaluating the dynamic reliability of high-dimensional nonlinear systems under non-stationary stochastic excitations is crucial for the disaster-resistant design and optimization of these structures. This paper presents a numerical method for solving the high-dimensional nonlinear dynamic reliability under non-stationary noises，based on the globally-evolving-based generalized density evolution equation （GE-GDEE） for generic continuous processes. Specifically，if we are concerned with the first-passage reliability of a quantity of interest within a specified safe domain，an absorbing boundary process （ABP） of the quantity of interest can be constructed. This leads to a two-dimensional partial differential equation for its transient probability density function （PDF），known as the GE-GDEE for ABPs. The effective drift coefficient in the GE-GDEE，which serves as the global physical driving force for evolution of the PDF，can be identified using data from representative deterministic dynamic analyses. The solution for dynamic reliability can be obtained by solving the GE-GDEE. This paper includes two numerical examples to verify the efficiency and accuracy of the proposed method and discusses areas that require further study.

In the design phase of a mine hoist’s main bearing，the reliability analysis of its random vibration cannot obtain complete probability information of the vibration acceleration response due to insufficient experimental samples. This paper proposes a new technical route for the reliability analysis of the main bearing of a mine hoist under incomplete probability information. This route includes the dynamic model of a multi-scale coupling system for rolling element bearings，the probability density evolution of vibration acceleration，stochastic process modeling of the probability density evolution path，the probability distribution of vibration power spectral density，and the calculation of design reliability based on conditional probability. By using the collected condition data to drive the established dynamic model of multi-scale coupling system for rolling element bearings，the probability density evolution of vibration acceleration is carried out. Based on the probability density evolution and Karhunen-Loève expansion，a modeling approach for the non-stationary random process of vibration acceleration of rolling element bearings is proposed. This approach obtains the twin data of the random sequence of vibration acceleration for rolling element bearings. The probability distribution of the vibration power spectral density for the main bearing of a mine hoist is studied，and the reliability index of the main bearing of a mine hoist within the service time is calculated.

Ambient environments are rich in rotational energy resources. These can be converted into useful electric energy through energy conversion materials to，powering embedded devices and wireless sensors in the Internet of Things. As such，energy harvesting technology could potentially address the environmental pollution and high maintenance costs associated with traditional chemical batteries. This paper proposes a novel time-varying potential well magnetic-coupled bistable energy harvesting system with low potential barriers to enhance the energy harvesting performance in ultra-low frequency rotating environments （below 3 Hz）. The proposed system comprises a forward steel beam and an inverted piezoelectric beam installed on a rotational plate. Mutually exclusive magnets are attached to the free ends of both beams，creating three equilibrium positions due to the magnetic force，two of which are stable. This gives the system its coupled bistable characteristics. The free end of the forward steel beam is distanced from the center of the rotational plate，making it a centrifugal hardening beam. Conversely，the free end of the inverted piezoelectric beam is closer to the center，making it a centrifugal softening beam. Taking into account the influence of the centrifugal effect，the distributed parameter electromechanical coupling equation of the system is derived in the rotational coordinate system using the energy method，Lagrange equation，piezoelectric theory，and more. A magnetic calculation model is used to analyze the influence of magnetic spacing and the centrifugal effect on the potential energy well and the energy harvesting performance of the system. Finally，numerical simulations and experimental results verify that，compared to the linear energy harvesting system，the proposed magnetic-coupled bistable energy harvesting system has a wider operating frequency range （0~2.67 Hz） and higher output voltage （greater than 2 V）.