The three-stage simulation method based on LS-DYNA was introduced in this study to simulate the progressive collapse of a continuous girder bridge after a ship-bridge collision. The pile-soil dynamic interaction and t...The three-stage simulation method based on LS-DYNA was introduced in this study to simulate the progressive collapse of a continuous girder bridge after a ship-bridge collision. The pile-soil dynamic interaction and the initial stress and deformation of the whole bridge before the collision were considered. By analyzing the damage, deformation, stress distribution and collapse process of the whole bridge, the results show that the displacement response of the cap beam lags behind the pile cap. The response order of the whole bridge's components depends on their distances from the collision region. The plastic deformation of soil around piles has a positive effect on delaying the further increase in the displacement of piles. The impacted pier's losing stability and its superstructure's excessive deformation are the main reasons leading to the progressive collapse of the continuous girder bridge.展开更多
Objective: To observe osteogenetic rate of alveolar bone on the tension side in orthodontic tooth movement through distraction osteogenesis of the periodental ligament quantificationally. Methods: The experiment was c...Objective: To observe osteogenetic rate of alveolar bone on the tension side in orthodontic tooth movement through distraction osteogenesis of the periodental ligament quantificationally. Methods: The experiment was carried in 6 dogs. The left side of jaws of each one was set as test or control side, and the other side was control or test side. On the control side, the first premorlar was moved by traditional method on the test side. A self-made distraction device was used on the test side. The newly formed alveolar bone on the tension side of moved tooth was labeled by serial tetracycline fluorochrome. Sections were observed by fluorescence microscope and pictured. Newly formed bone was measured by computer image analysis. Results: The quantity of newly formed bone was significantly different between the two methods. Newly formed bone in rapid tooth movement by distraction osteogenesis of the periodental ligament was more than that in traditional method. Conclusion: The distraction through periodental ligament could induce more rapid bone formation and excite higher osteogenetic activity than traditional method.展开更多
基金Supported by the National Natural Science Foundation of China(No.51178310)the Foundation of China Scholarship Council(No.201308120137)
文摘The three-stage simulation method based on LS-DYNA was introduced in this study to simulate the progressive collapse of a continuous girder bridge after a ship-bridge collision. The pile-soil dynamic interaction and the initial stress and deformation of the whole bridge before the collision were considered. By analyzing the damage, deformation, stress distribution and collapse process of the whole bridge, the results show that the displacement response of the cap beam lags behind the pile cap. The response order of the whole bridge's components depends on their distances from the collision region. The plastic deformation of soil around piles has a positive effect on delaying the further increase in the displacement of piles. The impacted pier's losing stability and its superstructure's excessive deformation are the main reasons leading to the progressive collapse of the continuous girder bridge.
基金Supported by the Youth Science Foundation of Stomatological Hospital, Xi'an Jiaotong University
文摘Objective: To observe osteogenetic rate of alveolar bone on the tension side in orthodontic tooth movement through distraction osteogenesis of the periodental ligament quantificationally. Methods: The experiment was carried in 6 dogs. The left side of jaws of each one was set as test or control side, and the other side was control or test side. On the control side, the first premorlar was moved by traditional method on the test side. A self-made distraction device was used on the test side. The newly formed alveolar bone on the tension side of moved tooth was labeled by serial tetracycline fluorochrome. Sections were observed by fluorescence microscope and pictured. Newly formed bone was measured by computer image analysis. Results: The quantity of newly formed bone was significantly different between the two methods. Newly formed bone in rapid tooth movement by distraction osteogenesis of the periodental ligament was more than that in traditional method. Conclusion: The distraction through periodental ligament could induce more rapid bone formation and excite higher osteogenetic activity than traditional method.
