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High-rise television towers are prone to external wind and earthquake-induced oscillations in severe environments. To avoid excessive vibration under strong earthquakes, a large television tower requires certain measures to abate its dynamic responses. Friction dampers are simple and low-cost solutions for realizing the response control of television towers. In this study, response mitigation and performance assessment are conducted on a large-scale television tower with friction dampers under strong earthquakes. A 3D finite element static model of the high-rise television tower is first established, and then a 2D lumped mass dynamic model is developed. The mechanical model for the friction dampers is presented with the axial stiffness considered. The equations of motion of the damper–tower system under seismic excitations are then determined. The control force transformation, displacement increment transformation, and numerical integration of the coupled damper–tower system’s equations of motion are defined on the basis of the two aforementioned models. Finally, the seismic responses of a high-rise television tower system constructed in China are taken as an example to investigate the validity of the proposed control approach using the friction dampers. The results demonstrate that the implementation of friction dampers with optimal parameters in a large truss tower can substantially suppress the structural seismic responses in terms of peak responses and vibrant energy.

The seismic response of buried pipeline is significantly affected by the soil around the pipeline. In this study, a numerical analysis model of the pipeline and the soil around the pipeline is built, and the finite element numerical analysis of its seismic response law is conducted to address the problem of pipeline soil seismic coupling response. A shaking table test of the seismic response of buried pipeline under two-way seismic excitation is performed based on the developed two-way layered shear continuum model soil box. The peak strain response at the middle section of the pipeline grows fastest, the peak strain of the pipeline under non-uniform seismic excitation constantly exceeds that under uniform excitation, and the axial strain of the pipeline exhibits more sensitivity to earthquake than the bending strain, as indicated by the results of numerical analysis and shaking table test. The peak value of soil acceleration response under non-uniform excitation exceeds under uniform excitation. The displacement of soil increases with the height. The pipeline soil interaction becomes more intense under non-uniform excitation, and the relative movement between pipeline and soil becomes more significant. The seismic excitation more significantly affects the axial displacement of soil. The peak value of soil acceleration response varies from larger along the pipeline to larger along the axis with the increase of the loading grade. A slight difference exists between the peak value of axial and transverse acceleration response of the pipeline. The peak value of pipeline acceleration response declines in the axial direction than the peak value of soil acceleration response, whereas it rises in the transverse direction than the peak value of soil acceleration response, especially under non-uniform excitation. As revealed by the above results, the effect of bidirectional non-uniform seismic excitation on the lateral pipeline soil interaction is enhanced, and soil is more seriously damaged.

Foundations can be exposed to seismic loads in addition to static loads in seismic active areas. Thus, it might be necessary in this situation to use deep foundations rather than shallow foundations in order to prevent bearing capacity failure, improve the system’s dynamic stiffness, and/or minimize dynamic oscillations. In a seismically active area, the pile designer is expected to obtain at least the maximum earthquake-induced frictional resistance of the pile in order to achieve the necessary strength to ensure the structural integrity of the pipe pile is not compromised. However, determining the frictional resistance of the pipe pile is considered challenging. Therefore, in this study, design charts and new equations have been proposed to provide straightforward means to the designers to predict the frictional resistance of pipe piles embedded in dry and saturated cohesionless soils. The proposed charts and equations are for closed ended (CE) and open ended (OE) pipe piles. The charts have been developed based on the results of a validated three-dimensional finite element analysis. In addition, the equations were developed using regression analysis, where a high coefficient of correlation values is obtained (ranging between 0.94 and 0.98). The proposed predictive tools could assist designers in preliminary checks of the frictional capacity of pipe piles in seismic active areas.

The main bridge in North Branch of Xiamen-Zhangzhou Cross-Sea Bridge is a 5-span continuous steel box girder double-pylon cable-stayed bridge with 780m main span and the basic earthquake intensity at the bridge site is VII. In order to ensure the safety of the bridge under earthquake, the special seismic design of the bridge must be carried out. In this paper, the critical issues in seismic design of the bridge are studied. Firstly, the seismic fortification objectives and criteria are determined, then the influence of seismic excitation method, pylon(pier)-girder connection type, pile-soil interaction, liquefaction and scouring on the bridge is analyzed, and finally the optimization design of the damper is conducted through the sensitivity analysis of parameters. This paper provides the general idea of the seismic design of long-span cable-stayed bridges, which can be adopted by the seismic design of similar bridges.