Optimum design and application of non‐traditional tuned mass damper toward seismic response control with experimental test verification

A variant type of tuned mass damper (TMD) termed as ‘non‐traditional TMD (NTTMD)’ is recently proposed. Mainly focusing on the employment of TMD for seismic response control, especially for base‐isolated or high‐rise structures, this paper aims to derive design formulae of NTTMDs based on two methodologies with different targets. One is the fixed points theory with the performance index set as the maximum magnitude of the frequency response function of the relative displacement of the primary structure with respect to the ground acceleration, and the other is the stability maximization criterion (SMC) to make the free vibration of the primary structure decay in the minimum duration. Such optimally designed NTTMDs are compared with traditional TMDs by conducting both numerical simulations and experiments. The optimum‐designed NTTMDs are demonstrated to be more effective than the optimum‐designed traditional TMDs, with smaller stroke length required. In particular, the effectiveness of the TMDs combined with a base‐isolated structure is investigated by small‐scale model experimental tests subjected to a time scaled long period impulsive excitation, and it is demonstrated that the SMC‐based NTTMD can suppress structural free vibration responses in the minimum duration and requires much smaller accommodation space. Additionally, a small‐scale shaking table experiment on a high‐rise bending model attached with a SMC‐based NTTMD is conducted. This study indicates that NTTMD has a high potential to apply to seismic response control or retrofit of structures such as base‐isolated or central column‐integrated high‐rise structures even if only a limited space is available for accommodating TMDs. Copyright © 2015 John Wiley & Sons, Ltd.     

基于分数阶时间导数的黏弹性衰减VTI介质中平面波传播

目前在地震勘探频带范围内通常假设品质因子Q与频率无关,且呈衰减各向同性.事实上,相比较速度各向异性,介质的衰减各向异性同样不可忽视.本文将衰减各向异性和速度各向异性二者与常Q模型相结合,建立了黏弹性衰减VTI介质模型,并基于分数阶时间导数理论,给出了对应的本构关系和波动方程.利用均匀平面波分析和Poynting定理,推导出准压缩波qP、准剪切波qSV和纯剪切波SH的复速度、相速度、能量速度以及品质因子的解析表达式.对模型的正确性进行了数值验证,并分析了qP,qSV和SH波在介质中的传播特性.数值试验结果表明：本模型能够实现理想的恒定Q行为,表现了品质因子和速度的各向异性特征,显示出黏弹性增强将导致能量速度和相速度的频散曲线变化剧烈;速度和衰减各向异性参数与传播角度之间的耦合效应对qP,qSV和SH波的速度和能量影响明显;qP,qSV和SH波的频散曲线和波前面随着衰减各向异性强度的改变发生显著变化,其中耦合在一起的qP和qSV波变化趋势相同,而SH波与它们呈现相反的变化规律.本研究为从常Q模型角度分析地震波在衰减各向异性黏弹性介质中的传播特征奠定了理论基础.

     

高液限土路堤填筑的双指标控制方法研究

对于高液限土（包括改良的高液限土）填筑的路堤只用单一的压实度指标控制常常易导致质量隐患。通过试验研究提出一个采用空气率Va和压实度Dc双指标控制高液限土路堤填筑质量的方法,并给出了具体的控制标准。当压实度控制指标Dc≥93%时,高液限黏土和粉土空气率控制标准为4%≤Va≤8%,含砂高液限黏土和粉土空气率控制标准为6%≤Va≤13%。通过系统的试验研究,验证了双指标质量控制的可行性和有效性。研究结果表明,采用空气率和压实度双指标控制,不仅可以保证高液限土填筑路堤的强度和刚度,而且具有较好的水稳定性,为进一步充分利用高液限土作为路堤填料提供了技术支持。     

Influence of salinity on permeability characteristics of marine sediments

Abstract

Laboratory tests were conducted on compacted marine sediments to study the effect of salt concentration of permeating fluid on its permeability characteristics. Deep sea sediment samples were collected from water depths varying from 3700 to 4500 m off Mauritius coast. Liquid limit and plasticity index varied widely from 45 to 75 and 10 to 35, respectively. Permeability was found at different void ratios with distilled water and 0.2, 0.4, and 0.8 N NaCl solutions as permeating fluid. It was found that permeability increases with an increase in salt concentration for a given void ratio. This is explained by diffused double layer theory. Also, the rate of increase in permeability decreases with increase in salt concentration. The effect of salt concentration seemed to be less at higher void ratios.     

基于“点—轴系统”理论的鲁南旅游长廊建构

＂点—轴系统＂理论是区域开发的基础性理论,对于区域旅游开发同样具有重要的理论价值和现实指导意义。基于＂点—轴系统＂理论,在对旅游规划概念上的鲁南经济带进行修正的基础上,结合鲁南经济带旅游资源状况和旅游发展现状,提出重点打造以曲阜、日照、枣庄、临沂、菏泽、东平为核心的6个一级旅游增长点;以日东高速、105国道、206国道为发展轴线的3个一级旅游发展轴;形成圣人文化旅游板块、日照滨海旅游板块、湖滨红色休闲养生旅游板块、蒙山沂水红色逍遥游旅游板块、水浒休闲生态旅游板块六大各具特色的旅游板块。从而＂点-线-面＂共同组成＂双十字＂开发模式的鲁南旅游长廊,以此来最大限度地发挥鲁南地区旅游资源的潜力,实现鲁南旅游的腾飞。     

岩石爆破损伤模型的比选与改进

归纳了目前应用较为广泛的爆破损伤模型关于损伤变量的定义方法,基于FORTRAN与LS-DYNA自定义接口,将5种典型的爆破损伤模型成功导入LS-DYNA。根据具体的工程实例,对5种爆破损伤模型计算的精确性进行了对比计算和验证。结果表明,KUS模型与RFPA模型对应的结果与实测值更接近。选取计算结果较为准确的KUS模型进行改进,考虑压缩损伤,并修正了宏观弹性常数的确定方法,建立了拉压损伤模型,并对该模型的计算精确性进行验证,结果表明,该拉压损伤模型可以更好地定量描述岩体爆破损伤范围。