Seismic performance is particularly important for life-line structures, especially for long-span transmission tower line system subjected to multi-component ground motions. However, the influence of multi-component seismic loads and the coupling effect between supporting towers and transmission lines are not taken into consideration in the current seismic design specifications. In this research, shake table tests are conducted to investigate the performance of long-span transmission towerline system under multi-component seismic excitations. For reproducing the genuine structural responses, the reduced-scale experimental model of the prototype is designed and constructed based on the Buckingham\'s theorem. And three commonly used seismic records are selected as the input ground motions according to the site soil condition of supporting towers. In order to compare the experimental results, the dynamic responses of transmission tower-line system subjected to single-component and two-component ground motions are also studied using shake table tests. Furthermore, an empirical model is proposed to evaluate the acceleration and member stress responses of transmission tower-line system subjected to multi-component ground motions. The results demonstrate that the ground motions with multi-components can amplify the dynamic response of transmission tower-line system, and transmission lines have a significant influence on the structural response and should not be neglected in seismic analysis. The experimental results can provide a reference for the seismic design and analysis of long-span transmission tower-line system subjected to multi-component ground motions.
The progressive collapse of a multi-story building and its protective effect with aluminum foam under an explosion in its basement are numerically investigated in this paper. The three-dimensional coupling model composed of a multi-story frame structure with a basement and the surround soil is modeled using ANSYS/LS-DYNA. The progressive collapse of the entire structure under explosive impact and the protective effect of the aluminum foam are simulated using the proposed three-stage simulation method (TSSM). The result shows that, the aluminum foam as a protective layer can reduce the impact effects very well, and then can prevent progressive collapse effectively. The same model is also simulated by direct simulation method (DSM) and alternative load path method (ALPM). By comparison with the two methods, the TSSM is illustrated practical, accurate and economic for the analysis of progressive collapse.
An in-depth understanding of car-body vibration characteristics is the key to developing more reasonable operational safety and discomfort evaluation indicators. However, few scholars or research institutions have focused on this topic, and the car-body vibration characteristics that are caused by different complex aerodynamic factors are not clear. Therefore, in this study, different train car-body vibrations under different conditions were investigated using full-scale tests from 2014 to 2016. The results revealed that the car-body vibration for different aerodynamic conditions was mainly low-frequency rolling and traversing motion below 1 Hz, and the primary frequency was close to the car-body lower-centre rolling natural frequency. In addition, the evaluations of the train operational safety and the vibrational comfort could be considered coupled under strong wind conditions. There was a strong line relationship between the car-body roll angle and the train overturning coefficient under strong wind conditions, hence, predicting the train's overturning risk by the car-body roll angle was feasible.
In this paper, multiple tuned liquid dampers control for rain-wind-induced response of long span transmission tower is investigated. Equations of motion for a structure-TLD system are derived. According to the mechanism of vibration control, rain-wind-induced vibration control for tower model with multiple tuned liquid dampers is carried out by using numerical simulation. Three-dimensional finite element model of tower based on a real project is established. Rain-wind load time history is simulated based on wind and rain theory. Time history curves and the maximum responses without and with tuned liquid damper under rain-wind excitation are analyzed and discussed. The results show that the tuned liquid damper could decrease the rain-wind-induced response of long span transmission tower, and the device could be installed in tower when the response too large.
Along with the high-speed development of information technology and network application,the digitalization of our country's broadcasting television industry has made great progress.This paper introduces some kinds of advanced digital products produced by several famous Japanese companies such as Sony,Panasonic and JVC nowadays.Moreover,this paper also probes into non-linear editing system and its network and describes the fashionable virtual studio techniques.
Using a trace experiment, the trace response concentrations of different axial locations in an air lifted external loop reactor, which is approached to a scale of pilot reactors, were obtained through measuring the conductivity of the solution. A rational mathematical model was set put, and the defining solution conditions were also given. Based on the optimization technology with the experimental trace response data, the values of Pe were ranged in 27.0~46.0 on all of the operating conditions.
Some basic problems related directly to the landslide prediction are discussed in the paper,such as the classification of landslide predictions and their definitions, the forecast parameters and the determination of their monitoring sites, the analysis and treatment of saltation displacement in deformation curves as well as the quantitative determination of slope deformation stages.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)