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Tian H.-W.,Tongji University | Li Y.-Q.,Tongji University | Li Y.-Q.,State Key Laboratory of Disaster Reduction in Civil Engineering | Yu C.,University of North Texas
Thin-Walled Structures

This research is focused on the behavior of a novel cold-formed steel (CFS) shear wall system- steel sheathed cold-formed steel trussed shear wall (SSCFSTSW), which is different in skeleton configuration compared to conventional steel sheathed CFS framed shear wall. A test program was conducted on shear walls of various configurations. The walls differed in sheathing, chord studs and skeleton configurations. The results indicated that SSCFSTSW gave a significantly higher ultimate strength than that obtained from conventional shear walls. Based on the results, detailed discussion of the influence of different configurations on the performance of shear walls is given. © 2015 Elsevier Ltd. All rights reserved. Source

Xie Q.,Tongji University | Xie Q.,State Key Laboratory of Disaster Reduction in Civil Engineering | Zhu R.,Tongji University
IEEE Power and Energy Magazine

An Overview is Provided of the Damage to Electric Power grid infrastructure caused by three types of natural disasters that have taken place in the past few years in China: severe windstorms, ice and freezing rain, and earthquakes. Interruptions of electric service caused by these natural disasters have led to devastating economic losses in China and reduced the restoration and reconstruction speed of other related lifeline infrastructures, such as water supply systems and communication systems. The lessons learned from these disasters and their consequences for the Chinese power systems are described, as are actions taken to reduce the impact of such events in the future. © 2006 IEEE. Source

Jie L.,Tongji University | Jie L.,State Key Laboratory of Disaster Reduction in Civil Engineering | Xiaodan R.,Tongji University
Science China: Physics, Mechanics and Astronomy

The research of modern mechanics reveals that the damage and failure of structures should be considered on different scales. The present paper is dedicated to establishing the multi-scale damage theory for the nonlinear structural analysis. Starting from the asymptotic expansion based homogenization theory, the multi-scale energy integration is proposed to bridge the gap between the micro and macro scales. By recalling the Helmholtz free energy based damage definition, the damage variable is represented by the multi-scale energy integration. Hence the damage evolution could be numerically simulated on the basis of the unit cell analysis rather than the experimental data identification. Finally the framework of the multi-scale damage theory is established by transforming the multi-scale damage evolution into the conventional continuum damage mechanics. The agreement between the simulated results and the benchmark results indicates the validity and effectiveness of the proposed theory. © Science China Press and Springer-Verlag Berlin Heidelberg 2010. Source

Xie Q.,Tongji University | Xie Q.,State Key Laboratory of Disaster Reduction in Civil Engineering | Sun L.,Tongji University
Gaodianya Jishu/High Voltage Engineering

In order to study the failure pattern and collapse mechanism of transmission tower under ice loading, a one-panel and a two-panel tower subassemblages of a typical 500 kV transmission tower which were severely damaged during the ice disasters were fabricated. Both of two subassemblages were tested under simulated ice loading statically. The mechanical behavior, failure pattern, strain and deformation of substructures were investigated. The FEM software ANSYS was employed to analyze the behavior of two subassemblages by using shell elements. The experimental results showed that buckling of main leg was the basic failure mode of the structures, although the strains of the diagonal braces were relatively small. The out-of-plane deformations in the joints of the diagonal braces of the structures were considerable, and would significantly weaken the lateral constraining for main member of the structure. The effective length of the main angles would be increased. Meanwhile, the instability modes would exhibit obvious torsional-flexural buckling. The corresponding load-carrying capacity would be decreased notably. It can be concluded that restraining the out-of-plane deformation of the cross-bracings is one of the effective methods to enhance the ice load-carrying capacity of transmission tower. Source

Xie Q.,Tongji University | Xie Q.,State Key Laboratory of Disaster Reduction in Civil Engineering | Wang W.,Tongji University | Li H.,Tongji University
Zhongguo Tiedao Kexue/China Railway Science

A 2:1 scale model of the contact wire applied to China high-speed railway was made to carry out a wind tunnel test. The test was to measure along-wind drag force, crosswind lift force and vertical torsion moment at different wind velocities and in different turbulent flow fields. The change laws of the model's drag coefficient, lift coefficient and torque coefficient under different wind attack angles were analyzed. The influences of the model's section groove on its aerodynamic characteristics were studied. Den Hartog vertical vibration theory was used to analyze the galloping stability of the model. The results show that the aerodynamic drag force of the model increases obviously near -45° and 45° wind attack angles, because the wind direction is nearly perpendicular to the hypotenuse of the model's section groove. The aerodynamic stability of contact wire drops with the increase of turbulence flow field, and it shows a nonlinear relationship. Under no icing condition, the torsion moment of the model is very small, which suggests that the galloping of contact wire is caused by the change of crosswind lift force. The critical wind speed of contact wire galloping is proportional to its natural vibration circular frequency and mechanical damping. Source

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