With the development of wind power resource advantageous areas gradually saturated, the focus of wind power development has shifts to low wind speed areas with relatively poor wind resource conditions. Distributed, high power, high tower and long blades have become the trend in the wind power industry. Based on the above, a new rectangular concrete filled steel tube bundle wind turbine tower is proposed. The tower is made of rectangular concrete filled steel tube bundles, which has the advantages of high strength, rigidity and energy consumption capacity. To study the wind vibration response characteristics of this tower structure, the Kaimal pulsating wind speed power spectrum was chosen and the wind load time curve was simulated using the harmonic synthesis method to carry out the dynamic time analysis. Wind vibration coefficients and equivalent static wind loads were calculated for the tower. The results show that the maximum displacement of the top of this new tower at rated wind speed is 911.84 mm, which corresponds to a horizontal displacement angle of 1/154 and meets the code requirements. The tower components are of good strength and have a large safety margin. The wind vibration coefficient obtained by the displacement-equivalent gust load factor method is lower. Under the equivalent static wind loads calculated by the inertial wind load method, the structural displacements and basal shear forces are basically the same as those obtained from the structural random vibration analysis.

Flexural performance tests on 11 beams of full-scale reinforced concrete (RC) with HRB635 high-strength reinforcement were carried out to investigate their damage mechanism, failure mode as well as strength and ductility. The feasibility of the Chinese code formulae for calculating the ultimate flexural load bearing capacity and the maximum crack width of flexural components was also assessed for RC beams with high-strength reinforcement. The results indicate that the mechanical behavior and damage mechanism of the RC beams with HRB635 high-strength reinforcement are basically identical to those of RC beams with common reinforcement. The tensile high-strength reinforcements yielded first, then the compressive concrete crushed, and the tensile strength of the high-strength reinforcements can be fully utilized. The ultimate flexural moments of the test specimens calculated by the Chinese code were close to those of the test values, indicating that the flexural load bearing capacity of the beams with high-strength reinforcement can still be calculated according to the current Chinese code. The tested maximum crack widths of the specimens under serviceability limit state all exceeded the limit value of flexural structural components under short-term load, indicating that the design of RC beams with high-strength reinforcements may be controlled by the serviceability limit state rather than ultimate limit state. The calculated maximum crack widths were close to the tested ones, while the calculated results were slightly larger.

An innovative amalgamation of the very short shear link (VSSL) and shear slotted bolted connection (SSBC), referred to as the VSSL-SSBC, ingeniously enhances the ductility and energy dissipation capacity of the VSSL, resulting in minimal damage. Consequently, the seismic resilience of eccentrically braced frames is markedly augmented. Cyclic loading tests were carried on a VSSL specimen, three VSSL-SSBC specimens with friction slip and a VSSL-SSBC specimen with ultimate deformation respectively, so the failure modes, hysteretic curves, bond curves and mechanical curves can be investigated. The experimental findings indicate that the mechanical property of the VSSL-SSBC exhibits a bifurcated developmental trajectory, characterized by initial stages involving friction slip within the SSBC and subsequent severe damage within the VSSL. Moreover, the ultimate bearing capacity and failure mechanisms of the VSSL-SSBC are observed to be congruent with those of the standalone VSSL. As for the mechanical curves, the VSSL exhibits distinct stages, encompassing elastic, elastic-plastic, and failure phases. In contrast, the SSBC is characterized by an initial elastic and subsequent slip phase. The VSSL-SSBC, a hybrid configuration, undergoes an extended sequence of elastic, slip, elastic-plastic, and failure stages. Notably, the deformation and damage of the VSSL within the VSSL-SSBC are significantly mitigated at equivalent displacements when compared to the standalone VSSL.Ultimately, the utilization of the finite element method (FEM) has been employed to corroborate the hysteretic curve and failure mechanisms with specimen VSSL-SSBC. The findings from the FEM simulations demonstrate a high degree of concordance with the experimental data.

The socket connection is convenient in construction and has a large tolerance error, but the durability is poor. In order to improve the construction quality and optimize the durability, we proposed a new type of assembled bridge pier tenon-socket prefabricated bridge per by combining the wet joint connection technology of ultra-high performance concrete (UHPC). One tenon-socket prefabricated bridge per specimen and one comparative pier specimen (integral cast-in-place bridge pier) were designed and fabricated. The damage mechanism and seismic performance of the assembled specimens were studied by using the proposed static test method combined with numerical simulation. The test results show that: the damage of both specimens is mainly ductile damage in the form of bending damage, mainly manifested by a large amount of concrete crushing and spalling in the plastic hinge area at the bottom of the pier, while the damage of the assembled joint and grout is smaller, and the residual deformation of the assembled specimen is only 79.09% of the overall cast-in-place specimen when the ultimate load is reached, indicating that UHPC grout can enhance the damage tolerance of the pier and make it easier to repair after earthquakes. The tenon-socket prefabricated specimens with short socket depth and lap length of reinforcement achieve reliable connection, and exhibit bearing capacity, ductility, energy dissipation capacity and stiffness close to those of cast-in-place piers under the same hysteretic displacement. With socket depth of 0.4D(D is the width of the specimen section) and above, the joints are reliably connected, and the integrity and seismic performance are basically equivalent to those of cast-in-place. Increasing the modulus of elasticity of grout has an improvement effect on the stiffness of piers. The influence of longitudinal reinforcement diameter on the seismic performance of bridge piers is more significant than that of lap reinforcement in the abutment. Increasing the reinforcement rate of longitudinal reinforcement improves the horizontal bearing capacity and energy dissipation capacity more obviously, but increases the residual deformation of bridge piers.

To investigate the vibration comfort level of reinforced truss composite slabs applied in residential building floors, the vibration response of the integral connection reinforced truss composite slabs under human-induced excitation loads was studied through experiments. Three types of loading excitations, including single-person walking, three-person asynchronous walking, and three-person synchronous walking, were designed for experiments. For the single-person walking load experiment, three different walking paths including longitudinal, transverse, and diagonal were designed. The vibration response of the composite slabs under various human-induced excitations and walking paths was investigated. A refined finite element model of the composite slabs was established to analyze the influence of the protective layer thickness at the plate bottom, truss height, density ratio and modulus ratio of concrete to reinforcement on the natural frequency of vibration of the composite slabs. The results show that the peak acceleration under human-induced excitation increases with the layer height. The peak accelerations under different human-induced loading conditions decrease in the following order: three-person synchronous walking, three-person asynchronous walking, and single-person walking, and the peak acceleration under single-person walking condition is independent of the walking path. The natural frequency of the composite slabs decreases with the increase of the thickness of the protective layer at the plate bottom, and reaches the maximum when the truss height is 80 mm. The natural frequency is inversely proportional to the concrete-to-reinforcement density ratio, and is directly proportional to the concrete-to-reinforcement modulus ratio.

In order to solve the rail corrugation in the curve section of steel spring floating slab track in a metro, firstly, the characteristics of rail corrugation were tested on site. Secondly, according to the characteristics of rail corrugation, the precise tuning and development of wide-frequency tuned mass damper (WTMD) were carried out. Then, the parameters such as mass, stiffness and damping of WTMD were input to the established Vehicle-WTMD-Steel spring floating slab coupled dynamic model. The floating slab and foundation were considered as flexible bodies in the model. The wheel-rail contact was solved by the Kik-Piotrowski model, a multi-point non-Hertzian contact model. The 5th grade power spectral destiny formula from USA superimposed on the measured corrugation irregularity spectrum were used as excitation. The finite element software ANSYS and the multi-body dynamics simulation software UM were used to carry out the coupled dynamics analysis, and the WTMD parameters were optimized iteratively. At the same time, the rail vibration accelerations obtained by simulation analysis with or without WTMD were compared with the field measured data, and the influence of WTMD on rail vibration was studied. Finally, the total rail vibration level, track decay rate and three times corrugation tracking tests, with or without WTMD, were carried out to study the influence of WTMD on the rail vibration, the track decay rate and the corrugation development. The results show that: The first three dominant frequencies of the designed WTMD are 518 Hz, 700 Hz and 759 Hz, which are consistent with the vehicle passing frequency (520~830 Hz). The simulation and measured data are in good agreement, and the rail vertical vibration acceleration RMS is reduced from 200 g to 20 g after the installation of WTMD, and the vibration reduction effect is 8.1 dB. The WTMD can improve the vertical and lateral track decay rate and suppress the vertical and lateral rail pinned-pinned resonance. The three times corrugation tracking tests find that the rail corrugation develops slowly after the installation of WTMD, the rail corrugation is invisible.

In order to study the vibration response of saturated foundation caused by train moving load under irregular track conditions, and further improve the vibration propagation and attenuation law of saturated foundation, the track irregularity load is introduced into the saturated foundation 2.5D finite element in this paper. The track irregularity load is transformed into frequency domain-wave number domain through Fourier transform, and the vibration response caused by the quasi-static load is compared and analyzed. The results indicate that when the vehicle speed is low, the vibration difference caused by the following two conditions is very small. As the vehicle speed increases, track irregularity significantly increases the amplitude of acceleration and displacement of saturated foundation, and the time-history curves show stronger fluctuation. Track irregularity has little influence on the acceleration spectrum at the center of the track. When the train runs at low speed and high speed, the frequency spectrum rules of the two loads are basically the same, and the main frequency distribution is basically the same. Under the condition of track irregularity, only the acceleration in each frequency band increases slightly. In addition, the pore water pressure of saturated foundation caused by high-speed railway will be greatly increased by track irregularity, and the pore water pressure decreases rapidly with the increase of depth.

The pervious conditions of seabed sediments can directly affect their dynamic response characteristics during earthquakes, but most existing theoretical studies directly assume that the bottom of the sediments was an impermeable boundary. Therefore, based on Biot’s saturated porous media theory, through the analytical and semi-analytical solutions of the seabed transient response or steady-state response, the influence of the bottom water permeability conditions of the sedimentary layer on its dynamic response characteristics in earthquakes is studied. It is found that under the condition of bottom displacement excitation, fast wave or slow wave will generate the same type of compression wave when passing through the impermeable boundary of the sediment layer, and two types of compression waves will be generated when passing through the completely permeable boundary of the sediment layer. Even under the same excitation conditions, the vibration amplitudes of the two types of compression waves generated in the sediment layers with different permeabilities are significantly different. Permeable conditions at the bottom of the sediment layer also affect the frequency response characteristics of the seabed, and the displacement amplification coefficient of the bottom permeable sediment layer is large at low frequency. On the contrary, at high frequency, the displacement amplification coefficient of the bottom impermeable sediment layer is large.

Artificial boundaries are introduced to simulate the infinite domain in the analysis of soil-structure dynamic interaction, and the viscoelastic artificial boundary is one of the commonly used artificial boundaries. When the artificial boundary is used, the selection of the reference wave field as the input of seismic wave is very important, different reference wave field selection methods will lead to great differences in calculation accuracy. In this paper, four kinds of two-dimensional site models, including homogeneous half space, layered site, depressed terrain and underground structure are assumed. Then ANSYS finite element software and viscoelastic artificial boundary are used to simulate the above four site models considering SV wave vertical incidence and 30° oblique incidence. The calculation accuracy of three different reference wave fields is compared in detail. The results show that when the free wave field is selected as the reference wave field for all artificial boundaries of the soil-structure dynamic interaction calculation model, the accuracy of the calculation results is the highest.

The ground vibration input method based on viscous-spring boundary simulates the incidence of plane SV and P waves at different angles, and the acoustic structure coupling method is used to simulate the dynamic water pressure inside the lock chamber to study the seismic response of the lock roof displacement, acceleration and plastic damage in the ultra-high head lock chamber at different water depths. The study shows that when the seismic waves are obliquely incident, the seismic response of the ultra-high head locks varies significantly with the water depth compared to the vertical incidence, and the general degree of seismic response is greater than that of the vertical incidence. Under the same water depth conditions, the peak horizontal relative displacement and peak horizontal acceleration of the top of locks increases with the increases of the incidence angle in most cases. The seismic response of the lock chamber structure of the ultra-high head lock is significantly affected by the variation of the water depth. The area near the general gate wall with relative height of 0.2 is more likely to have serious damage, and when the relative water depth is 0.97, the tensile damage range on the waterfront side of the gate wall reaching serious damage is the largest. It is suggested that the combined effect of oblique incident seismic waves and different water depths within the gate should be considered.