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A three-step damage identification method based on dynamic characteristics is proposed to improve the structure reliability and security and avoid serious accident. In the proposed method, the frequency and difference of modal curvature （DMC） are used as damage indexes. Firstly, the detection of the occurrence of damage is addressed by the frequency or the square of frequency change. Then the damage location inside the structure is measured by the DMC. Finally, with the stiffness reduction rate as a damage factor, the amount of damage is estimated by the optimization algorithm. The three-step damage identification method has been validated by conducting the simulation on a cantilever beam and the shaking table test on a submerged bridge. The results show that the method proposed in this paper can effectively solve the damage identification problem in theory and engineering practice. 相似文献
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Shaking table test of pile-water-pier superstructure 总被引：1，自引：1，他引：0
The model test of seismic simulation shaking table is an important method to study the seismic design of bridge structure. In order to evaluate the seismic response and dynamic characteristics of pile-water-pier system for developing more reliable design procedures, shaking table model tests of a submerged bridge pier system, including pile groups-cap-pier and inertia mass, were conducted. Since different similitude laws corresponding to different test objectives affected the validity of test results, the similitude law with the aim to consider the effect of hydrodynamic pressure was proposed and confirmed through an actual example. Based on the test results, the effect of water around model on seismic response under seismic excitation input was analyzed and the failure level was judged by observing the variation of basic frequency. The test results indicate that the transfer function of analytical model with water is different from that without water, the natural frequency without water is always higher than that with water, and the first modal shapes are various. It is also concluded that the similitude law is suitable for practical application and the dynamic characteristics and seismic response of the structure system can be changed because of the existence of the surrounding water, which should be paid much attention in the further investigation. 相似文献
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in order to evaluate the seismic reliability of water distribution system and make rehabilitation decisions correspondingly, it is necessary to assess pipelines damage states and conduct functional analysis based on pipe leak- age model. When an earthquake occurred, the water distribution system kept serving with leakage. By adding a virtual node at the centre of the pipeline with leakage, an efficient approach to pressure-driven analysis was developed for simulating a variety of low relative scenarios, and a hydraulic leakage model was also built to perform hydraulic analy- sis of the water supply network with seismic damage. Then the mean-first-order-second-moment method was used to analyse the seismic serviceability of the water distribution system. According to the assessment analysis, pipes that were destroyed or in heavy leakage were isolated and repaired emergently, which improved the water supply capability of the network and would constitute the basis for enhancing seismic reliability of the system. The proposed approach to seismic reliability and rehabilitation decision analysis on water distribution system is demonstrated effective through a case study. 相似文献
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柳春光 《教育前沿(综合版)》2014,(10)
笔者多角度梳理高一物理教学的因素,从实际物理学习过程解剖高一学生物理学习困难的原因,指出了初中至高一物理学科课程的难度跃变的各个方面(内容的系统性、知识密度;对思维品质的要求;跨学科分支综合要求;与物理学科相关的个人体验或经历要求),并指出学生物理学习方法从初中进入高中没有及时转变、与初中相比高中物理教学模式有明显变化、学生学习心理调适能力进入高一后没有提高等,是导致许多学生进入高一感到物理学习困难的主因。提出多个针对性解决方案,对高一物理教学具有切合实际的参考价值。 相似文献
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科学合理地选择和有效地运用教学方法,对教师和学生完成共同的教学目标有很大的促进作用。本文主要探讨了初中地理学科的一些教学方法。 相似文献
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新课程理念下，摩擦力方向的确定 总被引：1，自引：0，他引：1
本文从摩擦力的定义、力的作用效果以及摩擦力的计算方式这三个方面探讨了如何确定摩擦力的方向,希望能以案例教学的角度来让摩擦的学习对学生更有利。 相似文献
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To overcome the excessive computational cost and/or bad accuracy of traditional approaches,the probabilistic density evolution method(PDEM) is introduced.The dynamic reliability of a double-layer cylindrical latticed shell is evaluated by applying PDEM and Monte Carlo Method(MCM) respectively,and four apparent wave velocities(100 m/s,500 m/s,800 m/s and 1 200 m/s) and five thresholds(0.1 m,0.2 m,0.3 m,0.4 m and 0.5 m) are taken into consideration.Only the difference between threshold and maximal deformation... 相似文献
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本文从摩擦力的定义、力的作用效果以及摩擦力的计算方式这三个方面探讨了如何确定摩擦力的方向,希望能以案例教学的角度来让摩擦的学习对学生更有利. 相似文献
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