The boundaries of the honeycomb-cells are considered to be free and the stresses of the soils at the cavities are zero, the conformal mapping method of complex functions for regular hexagon to circle and expansion method of wave functions are adopted, and then the theoretical solutions are obtained about the isolation problem of incident plane SV waves by the honeycomb-cell barriers. By studying the normalized displacements which are the ratios of the displacements caused by the incident and scattering SV waves to those only by the incident SV waves, the isolation effects of the honeycomb-cell barriers are analyzed, and some important conclusions are drawn out, which are that: (1) the isolation effects of the barriers are better for SV waves with higher frequencies than those with lower frequencies; (2) the areas near the two side edges of the barriers have better isolation effects than the middle; (3) the isolation effects increase with the total length and the row number of the honeycomb-cell barriers; (4) the isolation effects and construction and maintenance costs are considered, and three rows of honeycomb-cell barriers are better selection for vibration isolation design. In the end, vibration isolation effects of three types are compared and the conclusions are that: three rows of honeycomb-cell barriers are between open trench and three rows of cavities and near to open trench.

The uncertainty dynamic response of a spatial flexible beam with large overall motion is investigated in this work. The stochastic differential equation of a three-dimensional beam with large overall motion is derived using the virtual work principle. The polynomial chaos method and a regression-based collocation method are applied to derive a set of completely implicit differential equations. The resulting system of deterministic equations is then solved using the variable rank method to obtain the numerical characteristics of the response. For illustration, the dynamic modeling of a spatial spinning beam with probabilistic geometric and physical parameters is considered. The accuracy and efficiency of the method are verified by comparing the results with those given by the Monte Carlo simulation method. The results indicate that probabilistic parameters affect the dynamic response of the flexible body. It is expected that dynamic modeling with probabilistic parameters can objectively reflect the actual dynamic behavior of elastic systems.

General method is directly used the measured frequency response functions (FRFs) to identify the characteristics of bolted joints. However, the system’s ill-posed problems arise from the measurement error, the noise effect and the measurement at the mechanical joints may be obstructed by joining mechanisms. A new identification method with FRFs is developed to avoid the ill-posed problem. Firstly, the whole structure composed of substructures and bolted joints finite element model is established, the value range of equivalent stiffness and equivalent damping are obtained by the relationship between the parameters of bolted joints and the normalized frequency. The averages of the value range of equivalent stiffness and equivalent damping are used for the initial value of the bolted joints model, using the minimal FRFs calculation error of experiment and simulation as the objective. Finally, the equivalent stiffness and equivalent damping of bolted joints are obtained. From the results of simulation, experiment and Ref [16], results show that the proposed method can significantly improve the accuracy of identification.

The highway beam bridge was modeled by beam elements, and each car was simulated by multi-body model, vehicles and bridge were taken as an interactive system, and then the vertical vibration equation of the vehicle–beam bridge coupling time-varying system was established. The three-Hermite interpolation function was introduced, the time variability of element interpolation function (TVEIF) which was caused by vehicle-bridge interaction was considered, the contribution of TVEIF to the equation of the bridge-vehicle system was deduced and a program was compiled. The effect of TVEIF on the vertical vibration response of vehicle- beam bridge system was analyzed by a specific example. The results show that the effect of TVEIF on vehicle-bridge coupling vertical vibration of highway beam bridges is significant when the vehicles are crossing the bridge by high speed, so it should be considered during vibration simulation calculation for vehicle-beam bridge coupling system.

In order to investigate the fatigue crack growth process of steel orthotropic bridge deck, and provide theoretical guidance for the anti-fatigue design and reinforcement, the real bridge’s finite model based numerical simulation method and process of the fatigue crack growth of steel orthotropic bridge deck was proposed. Firstly, the critical locations that are apt to suffer fatigue failure of the whole bridge are ascertained by the field survey results and the analysis of the whole structure under the dead load and the live load. Then, the refined finite element model with typical welded details for the locations is established to analyze the stress amplitude. According to the vehicle-bridge vibration based analysis method, the influence of the stress impact factor on the stress amplitude is taken into account. Determine the fatigue crack propagation direction, path, and fatigue life, and then analysis the total process of fatigue crack propagation. Finally, take the fatigue crack propagation analysis of an existing long-span cable stayed bridge with steel orthotropic bridge deck as example, which indicates the feasibility and accuracy of the method and calculation process, and provides a theoretical basis for the bridge fatigue failure repair and reinforcement in operation period.

Selecting the old barracks and the fort relics, which are situated at Humen, Dongguan, as the research object, the whole 3D model was established for numerical simulation. In order to calculate the structural vibration response caused by the different vehicle speed, the axle weight, the time-historical analysis was completed by using finite element method. The vibration acceleration and velocity was investigated and the effect of moving vehicle load on the relics was analyzed. The results show that if the vehicle speed increases from 40km/h to 80 km/h, the velocity response of the fort base has increased by 4%-13%; also that of the foundation of barracks has increased by 6%-30%. Similarly, if the axle load increases from 15t to 55t, the response of the relics base appears positive correlation with the increasing of the axle weight. By changing the frequency of the vertical harmonic force, the harmonic response analysis was finished. It was shown that the predominant frequencies of the model were close to 10Hz and 40Hz. When the loading frequency was about 10Hz, vibration response of the foundation of the old barracks and the fort reached the maximum value.

Quantum-behaved Particle Swarm Optimization, as a development of Particle Swarm Optimization, is an optimization algorithm based on Swarm Intelligence. Thank to its advantages of less parameter, simple programming, easy to convergence and fast convergence, Quantum-behaved Particle Swarm Optimization received much concern. The minimization of difference between theoretical and test value of frequency response function, the former is a formula including modal parameters, and the later is calculated based on the input and output data of structure, will be adopted as an objection function of optimization issue. The optimal objective value can be gained through searching reasonable modal parameters. Then, the issue of structural modal identification is converted to an optimization issue. During the optimization procedure, Quantum-behaved Particle Swarm Optimization is adopted and the modal parameters are identified. Finally, the modal parameter identification method based on Quantum-behaved Particle Swarm Optimization presented herein will be verified by a numerical simulation of six-story frame structure. The calculation results show that the method can effectively identify the structural modal parameters.

Laboratory tests had been conducted on the helical strakes of the riser, the aim of the present work is to further improve the understanding of the response performance of VIV for the riser with helical strakes. The experiment was accomplished in the towing tank and the relative current was simulated by towing the flexible riser in one direction. Based on the modal analysis method, the displacement responses can be obtained by the measured strain. The strakes with different pitches were analyzed here, and the response parameters like strain response and displacement response were studied. The analysis has indicated that the in-line response is as important as the cross-flow response. The results also show that the response characteristics of a bare riser can be quite distinct from that of a riser with helical strakes, and the response performance is depend on the geometry on the helical strakes closely.

The change of single bolt preload made little difference to the vibration mode of labyrinth disc, and the assembly state of rod fasten rotor could not be detected effectively through the time domain and frequency domain analysis of the vibration response signal. Aiming at the problem, the fractal method was adopted as a new method to analyze the assembly vibration signals of rod fasten rotor. The vibration response signals were obtained by the assembly vibration detection test. Then the fractal theory was used to analyze the test result. And the rectangle box dimension and multi-fractal spectrum parameters of three bolt preload state were figured out. The multi-fractal spectrum parameters were applied as the feature vectors of support vector machine, by which the assembly state of the rod fasten rotor was identified. The result shows that when the bolt of rod fasten rotor loosing, the box dimension of the vibration response signal will increase accordingly. When the box dimension is bigger than 1.25, it shows that the rotor assembly is unqualified. When the support vector machine is used for classification, the correct ratio reached 93.7008% while the multi-fractal spectrum is taken as the feature for assembly state prediction.

Based on the background of Heritage Impact Assessment project in the range of Humen Fort related areas, a whole process of research of performance-based analysis, measurement and anti-vibration measures to the vibration safety of ancient structure in road planning stage is studied in this paper. The vibration of the related soil layers and ancient structure under heavy vehicles excited is measured, and the key technical parameters of finite element model (FEM) combine with” vehicle, road structure, related site’s soil layers and ancient structure” are calibrated by the measurement results. And then, the key parameters of vehicle axle load, vehicle speed, multi-vehicle effect and isolation trench dimensions are researched on by the calibrated FEM, and the vibration response of ancient structure is also obtained in the FEM. The performance-based indexes are accepted to evaluate the vibration safety of ancient structure, and the reasonable anti-vibration measures are proposed according to the finite element analysis results. The measurement and analysis show that, the proposed whole process performance-based analysis method combined measurement with analysis can be used for transportation planning and conservation research, and spacing 50m away from the road can guarantee vibration safety of ancient structure in this project.

A numerical method is used to analyze the nonlinear aerostatic stability for a 420m-main-span suspension pedestrian bridge. Based on aerostatic coefficients of the main girder measured by wind tunnel tests, nonlinear influences caused by structure and aerostatic load are included in this incremental double iteration method. Numerical results are presented as follows: (1) The structure deformation with wind speed show obvious nonlinearity, and the aerostatic instability form has the characteristic of space deformation of bending-twisting coupling significantly; (2) Comparing with the highway bridge, torsional stiffness from main cables accounts for greater proportion in long-span suspension pedestrian bridge. The critical wind velocity and the reason of aerostatic stability can be got by tracing the stress of the main cable; (3) Nonzero initial wind attack angle can reduce the critical wind speed;(4) Central buckles and wind cables can raise the critical wind speed. The aerostatic instability form applied the central buckles measures is bending-twisting coupling of main girder, and the aerostatic instability form applied the wind cables measures is local structural buckling due to the wind cables and hangers stress relaxation. Meaningful references are provided for the research of narrow bridge span aerostatic stability and enhance its aerostatic stability.

According to the damage characteristics of skew bridges during earthquakes and the stiffness and strength of rubber bearings changing with low temperatures, the seismic behavior of a skew bridge isolated with lead rubber bearings (LRBs) was studied. 3-D nonlinear dynamic models of the bridge with various skew angles, which considering the pounding between girder and abutment by Hertz-damp impact model, were developed using the computational platform OpenSees. The distribution of pounding force at abutments with various skew angles was discussed. The seismic response of isolated bridge with two methods mechanical properties of the bearings were compared with each other. By investigating the relationships between seismic response of piers and skew angles, and various ambient temperature, it is shown that the seismic pounding is happened firstly at the obtuse corners of bridge deck due to the coupling of bidirectional translation and in-plane torsion motion of superstructure; and the in-plane rotation of skewed bridge deck is further increased by pounding response. The seismic response of isolated skew bridge is increased due to mechanical properties of LRBs changed by low temperature. If the effect of low temperatures is not considered, the shear and bending moment of piers was underestimated by about 10%,20% and 40% while the isolated bridge at low temperatures of 0℃、-10℃ and -30℃ than the case at nomal temperature.

Aerodynamic admittance describes the transfer behavior between wind spectra and buffeting forces spectra, which directly determines the precision of the buffeting response prediction. Due to the aerodynamic interference effect in the paralleled double bridges, the aerodynamic admittances of windward and leeward girder will be different from that of single girder. And the aerodynamic interference effect is related to the shapes of girders and distance between girders. Therefore, an practical engineering was taken as a background in this article, and the aerodynamic interference effect on the aerodynamic admittances was been researched by the method of sectional model force measurement in wind tunnel test. It was shown that there are some differences between the aerodynamic admittances of double girders and that of single girder, which is because of the aerodynamic interference effect; It is similar of the aerodynamic interference effect caused by the same girder, and vice versa; The aerodynamic interference caused by the girders with different distances affects the windward girder weekly, thus there was no obvious change law of the aerodynamic admittances of windward girder. With the increase of distance between windward and leeward girders, the aerodynamic interference effect on the aerodynamic admittances of leeward girder weakens gradually and can be ignored while the distance is larger enough.

In recent years, the number of coastal wind power farms and wind power structures is growing up rapidly. However, the coastal wind power structures are always damaged by typhoon. This paper employs a typhoon fluctuating wind power spectrum which does not change with height, the linear filtering method and a simplified expression based on the vertical correlation to simulate the typhoon wind field model of a coastal wind farm. The power spectral density function is adopted to verify the accuracy of the simulated wind field. Wind power structure- pile foundation structure coupling finite element model is set up, and the wind power structure dynamic response under the lower limit and upper limit speed of typhoon is calculated, in order to analysis the possible failure modes of the main structure under extreme wind. The results show that the yield region mainly located in the bottom of the tower drum about 4m height within the scope of a cone-shaped distribution. The joint of the tower drum bottom and the embedded ring is the most unfavorable position. The tower horizontal displacement exceeds the permissible value under the upper limit speed of typhoon, but the most unfavorable single pile axial force are not beyond the limit in neither situations. This work lays an important foundation for the further research on nonlinear collapse of wind power structure under the extreme wind situation.

A new non-stationary signal processing technique called Hilbert vibration decomposition (HVD) is introduced to fault diagnosis of roller bearings. The HVD and empirical mode decomposition (EMD) are both based on Hilbert transform, and both methods can decompose multi-component signals adaptively. However, compared with EMD, the HVD method does not involve spline fitting and empirical algorithms and has a better frequency resolution. Moreover, the HVD method can decompose more effectively the multi-component signals which can cause mode mixing while decomposed by the EMD method. Based on this consideration, the HVD method is applied to the experimental data of roller bearing with induced faults. The envelope analysis is performed to the component including dominant fault information, and then the characteristic defect frequency of roller bearing can be identified by means of the envelope spectrum. The experimental results validate the effectiveness of the proposed method for roller bearing fault diagnosis.

Multi-scale stick-slip dry friction at contact interface plays a significant role in the nonlinear system dynamics. Classic coulomb friction model cannot reflect the complex dry friction phenomenon accurately. In this paper, a dry friction system with multi-scale stick-slip characteristics was studied. A displacement-based Iwan hysteretic constitutive model was used to model interface friction. After the equation of motion was established, numerical solution of the system under harmonic excitation was obtained with the central difference method. The steady state dynamic response was obtained under 1:1 and 1:2 resonance condition. It is showed that, in the case of 1:1 resonance, the dynamic behavior is extremely sensitive with transversal heteroclinic point, and double-periodic motion and chaos happen at characteristic parameters. In the case of 1:2 resonance, there are infinitely homoclinic points, and chaotic motion may emerge under small perturbations.