基于实测响应的斜拉人行桥人致振动舒适度研究

研究了大跨轻柔斜拉人行桥人致振动舒适度问题。基于有限元方法建立了某大跨度斜拉人行桥的分析模型并进行了动力特性分析;进行了该桥在环境脉动激励作用下的动力特性实测和不同人行荷载作用下的动力响应测试;依据英国规范BS5400评价了该桥的振动舒适度状况。结果表明,该桥在人行荷载作用下存在较为显著的振动响应和一定程度的振动舒适度问题。     

横向剪切和旋转惯性影响下管道内流动液体的小振动

当考虑旋转惯性的影响时,流经管道横截面的液体在剪切作用下,会产生小振动.本文推导出无量纲参数表示的系统微分方程.对于某些问题的确定值,使用Galerkin方法,可以得到主振动频率和临界速度.在此基础上,还将研究结果和经典理论值进行了比较.     

行走作用下梁板结构振动舒适度的烦恼率分析

人行走作用引起的振动舒适度是梁板结构正常使用极限状态设计的重要内容,现行规范给出的静力挠度控制并不能充分体现这一要求。利用最大加速度反应谱法计算行走作用下结构的加速度响应,结合烦恼率模型,给出了基于烦恼率模型的舒适度分析方法,同时将分析结果与使用振动舒适度标准获得的结果进行比较,结合算例分析表明,这两种分析方法给出的分析结论基本一致,而烦恼率方法则具有更为定量化的特点。     

地震作用下侧移验算对比及弹塑性侧移计算公式(1)

中日欧美4个国家和地区的规范和设计建议中对地震作用下侧移的验算规定进行总结,经比较发现,各国的规定有4个不同层次的侧移验算,分别是:重现期为8～95年的使用极限状态验算、地震作用标准值、设防烈度地震和罕遇地震下的侧移验算四种,各国之间差别非常大,限制侧移出发点有:不影响设备的使用、限制围护材料的破坏、限制混凝土构件开裂和设防烈度地震或罕遇地震下不倒等等,其中,中国的最为严格,罕遇地震下侧移验算只有中国才要求。     

高速列车引起高架车站振动舒适度分析

针对京沪高铁沿线某高架火车站的振动舒适度问题,建立高架车站结构的有限元模型,充分考虑桥墩桩和土的相互作用,输入高铁列车的行驶荷载,计算结构振动在时域内的动力响应。基于目前常用的国际标准,评价各楼层的舒适度。     

Service reliability of offshore wind turbines

A probabilistic formulation is proposed to assess the performance of the support structure of offshore wind turbines based on their probability and expected time of exceeding specified drift thresholds. To this end, novel probabilistic models are developed to predict the mean and standard deviation of the drift ratio response of wind turbine support structures operating under day-to-day loads as a function of the wind turbine geometry and material properties, and loading conditions. The proposed models are assessed using a database of virtual experiments generated using detailed three-dimensional (3D) nonlinear finite element (FE) models of a set of representative wind turbine configurations. The developed models are then used in a random vibration formulation to estimate the probability and expected time of exceeding specified drift thresholds. As an example, the probability and expected time of exceeding specified drift thresholds are estimated for a typical offshore wind turbine at different wind speeds. A comparison is made between the results obtained based on the proposed models, those obtained using simulators commonly used in practice and detailed 3D nonlinear FE analyses.     

钢筋混凝土桥梁受弯构件最大裂缝宽度的可靠度研究

基于结构可靠度理论和《公路钢筋混凝土及预应力钢筋混凝土桥涵设计规范》JTGD 62-2004关于最大裂缝宽度的规定,对钢筋混凝土桥梁受弯构件按正常使用极限状态设计的可靠度进行了计算分析,并对比研究了作用效应比、计算模式不定系数、钢筋弹性模量、配筋率、钢筋直径和截面尺寸等随机变量对最大裂缝宽度可靠指标的影响程度.研究表明:最大裂缝宽度计算公式的可靠度基本满足设计要求,可变作用与永久作用的效应比对最大裂缝宽度的可靠度影响很大,而其他因素对最大裂缝宽度的可靠度影响较小.     

竹炭改性涤纶/棉混纺针织物的性能研究

探讨了竹炭改性涤纶/棉混纺针织物的性能,对5种不同混纺比的竹炭改性涤纶棉混纺针织物的主要服用性能进行了测试分析。结果表明,随着竹炭改性涤纶纤维含量的增加,混纺针织物的透气性、悬垂性、刚柔性和保暖性越来越好,而耐磨性变化不明显,但顶破强力减小。     

行车荷载下大跨度钢筋混凝土楼盖舒适度评价

收集了国内外对钢筋混凝土大跨度楼盖舒适度的评价标准,采用时程分析方法,对瑞安客运中心停车站房的一块大跨度钢筋混凝土楼盖在汽车行驶荷载作用下的动力反应和最大加速度进行了有限元分析和舒适度评价,讨论了汽车荷载作用位置和行驶速度对舒适度的影响。     

Wind‐induced vibration control of tall buildings using hybrid buckling‐restrained braces

A buckling‐restrained brace (BRB) is a system with excellent earthquake‐proof performance, but it does not dissipate energies caused by the load from weak earthquakes or winds. A hybrid BRB (H‐BRB), which improved the performance of the BRB, is a type of composite damper system consisting of a BRB and a viscoelastic damper. To explain the wind‐induced vibration control performance of H‐BRB, a 40‐story steel building was designed and used as an analysis model in this study, on the basis of the damping ratio from a structural performance test, using normal steel braces, BRB and H‐BRB. In addition, to evaluate the optimal location of H‐BRB, a time‐history analysis of four models was conducted in the study. For such time‐history analysis, wind‐load data in a 10‐year recurrence interval, which were calculated from the wind tunnel test, were used. The result of the time‐history analysis showed that H‐BRB is effective in improving both the lateral stiffness and serviceability of a building using the existing BRB. It also confirmed that it is most effective to position H‐BRBs mainly on the lower stories. Copyright © 2012 John Wiley & Sons, Ltd.