The stochastic response of a noisy system with non-negative restoring force is investigated. The generalized cell mapping （GCM） method compute the transient and stationary probability density functions （PDFs） real...The stochastic response of a noisy system with non-negative restoring force is investigated. The generalized cell mapping （GCM） method compute the transient and stationary probability density functions （PDFs） real-power is used to Combined with the global properties of the noise-free system, the evolutionary process of the tran- sient PDFs is revealed. The results show that stochastic P-bifurcation occurs when the system parameter varies in the response analysis and the stationary PDF evolves from bimodal to unimodal along the unstable manifold during the bifurcation.展开更多
The generalized ray method(GRM) has been successfully used to study the transient elastic wave transmitting in the beams,planar trusses,space frames and infinite layered media.In this letter,the GRM is extended to inv...The generalized ray method(GRM) has been successfully used to study the transient elastic wave transmitting in the beams,planar trusses,space frames and infinite layered media.In this letter,the GRM is extended to investigate the early short time transient responses of laminated composite cylindrical shells under impact load.By using the Laplace transformation and referring to the boundary conditions,the ray groups transmitting in the finite laminated cylindrical shells under the shock load are obtained and the transient response related to each ray group can be derived via FFT algorithm.From the numerical results,it is shown that the early short time transient accelerations of the laminated composite cylindrical shell under impact loads are very large.But the short time transient shear strain and displacement are very small.展开更多
超高层建筑属风敏感结构,对建筑外形进行适当气动优化可有效降低结构风荷载及风致响应。基于大涡模拟(LES)方法,采用一种新的入口湍流生成方法——NSRFG(narrow-band synthesis random flow generation)方法,进行超高层建筑标准模型(CAA...超高层建筑属风敏感结构,对建筑外形进行适当气动优化可有效降低结构风荷载及风致响应。基于大涡模拟(LES)方法,采用一种新的入口湍流生成方法——NSRFG(narrow-band synthesis random flow generation)方法,进行超高层建筑标准模型(CAARC)角区开槽的气动优化研究。首先进行了CAARC高层建筑标准模型绕流模拟,并将模拟结果与风洞试验结果对比,以验证NSRFG方法的适用性;然后以CAARC模型为基础,设计了4种开槽气动优化方案,通过LES模拟得到基底弯矩功率谱,以估算建筑顶部位移响应和顶部峰值加速度响应。结果对比显示:对于矩形截面高层建筑标模,无论原型还是4种开槽气动优化方案,横风向脉动响应和峰值加速度响应整体比顺风向大;与全封闭原型相比,采取不同开槽方案均能降低顺风向和横风向风振响应,其中角区开槽对顺风向响应的优化效果最好,周向开槽对横风向响应的优化效果最好;4种开槽方案对于横风向响应的优化效果明显优于顺风向,其中相对而言周向开槽优化效果相对最好,使横风向脉动位移响应和横风向峰值加速度响应分别降低28.4%、32.8%。因此,从减小矩形截面超高层建筑结构横风向响应角度考虑,建议采用周向开槽方案。展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11172233,11302169,11302170,and 11472212)the Fundamental Research Funds for the Central Universities(No.3102014JCQ01079)
文摘The stochastic response of a noisy system with non-negative restoring force is investigated. The generalized cell mapping （GCM） method compute the transient and stationary probability density functions （PDFs） real-power is used to Combined with the global properties of the noise-free system, the evolutionary process of the tran- sient PDFs is revealed. The results show that stochastic P-bifurcation occurs when the system parameter varies in the response analysis and the stationary PDF evolves from bimodal to unimodal along the unstable manifold during the bifurcation.
基金supported by the National Basic Research Program of China(2011CB711102)the National Natural Science Foundation of China(10672017)
文摘The generalized ray method(GRM) has been successfully used to study the transient elastic wave transmitting in the beams,planar trusses,space frames and infinite layered media.In this letter,the GRM is extended to investigate the early short time transient responses of laminated composite cylindrical shells under impact load.By using the Laplace transformation and referring to the boundary conditions,the ray groups transmitting in the finite laminated cylindrical shells under the shock load are obtained and the transient response related to each ray group can be derived via FFT algorithm.From the numerical results,it is shown that the early short time transient accelerations of the laminated composite cylindrical shell under impact loads are very large.But the short time transient shear strain and displacement are very small.
文摘超高层建筑属风敏感结构,对建筑外形进行适当气动优化可有效降低结构风荷载及风致响应。基于大涡模拟(LES)方法,采用一种新的入口湍流生成方法——NSRFG(narrow-band synthesis random flow generation)方法,进行超高层建筑标准模型(CAARC)角区开槽的气动优化研究。首先进行了CAARC高层建筑标准模型绕流模拟,并将模拟结果与风洞试验结果对比,以验证NSRFG方法的适用性;然后以CAARC模型为基础,设计了4种开槽气动优化方案,通过LES模拟得到基底弯矩功率谱,以估算建筑顶部位移响应和顶部峰值加速度响应。结果对比显示:对于矩形截面高层建筑标模,无论原型还是4种开槽气动优化方案,横风向脉动响应和峰值加速度响应整体比顺风向大;与全封闭原型相比,采取不同开槽方案均能降低顺风向和横风向风振响应,其中角区开槽对顺风向响应的优化效果最好,周向开槽对横风向响应的优化效果最好;4种开槽方案对于横风向响应的优化效果明显优于顺风向,其中相对而言周向开槽优化效果相对最好,使横风向脉动位移响应和横风向峰值加速度响应分别降低28.4%、32.8%。因此,从减小矩形截面超高层建筑结构横风向响应角度考虑,建议采用周向开槽方案。
