自复位支撑-摇摆框架结构体系及其基于位移抗震设计方法

本文提出一种可恢复功能结构体系——自复位支撑-摇摆框架结构体系，旨在同时实现较大刚度、自复位能力以及构件间的变形协调。针对可恢复功能结构体系防震能力强的特点，已建立了可恢复功能结构体系“小震及中震不坏，大震可更换、可修复，巨震不倒塌”的抗震设防四水准目标。文中结合可恢复功能结构体系四水准性能指标，采用基于位移的抗震设计方法，进行了自复位支撑-摇摆框架结构设计。以一幢四层结构为例，给出了四水准抗震设防目标下的基于位移设计方法算例，并建立了ABAQUS有限元数值模型，进行了弹塑性时程分析。分析结果表明，按文中方法设计的自复位支撑-摇摆框架体系可满足可恢复功能结构体系抗震设防目标，达到各性能指标要求。     

用高分辨X射线衍射面扫描评估4H-SiC晶片结晶质量

介绍了高分辨X射线衍射(HRXRD)面扫描技术在评估4H-SiC抛光片整体结晶质量方面的应用。对4H-SiC抛光片整片及局部特定位置进行HRXRD摇摆曲线面扫描,并拟合摇摆曲线半高宽(FWHM)峰值得到的极图,观察4H-SiC抛光片表面的FWHM分布范围、分布特点和多峰聚集区。结合表面缺陷测试仪和偏振光显微镜测试方法,对因螺旋生长产生的晶界分布聚集区以及边缘高应力晶界聚集区进行了表征。二者测试结果与HRXRD摇摆曲线面扫描的结果一致。对多片样品在不同区域使用不同测试方法得到的结果均验证了HRXRD摇摆曲线面扫描可以宏观识别晶畴界面聚集区,清楚辨别出位于晶片中心附近由于螺旋生长面交界形成的晶畴界面,以及位于晶片边缘、受生长热场影响晶粒畸变产生的高应力晶畴界面。     

饱和地基中埋置基础摇摆振动的动力放大系数

基于Biot动力控制方程,研究均质饱和半空间中埋置刚性圆柱基础在摇摆简谐力矩作用下的振动特性.土与基础在四周及基底保持完全黏着接触,相互之间无滑移.利用一种简化的解析方法求解相应的动力响应问题,并给出埋置基础摇摆振动时的动力放大系数随量纲一激振频率的变化曲线.为验证本文结果的正确性,将地基退化为单相弹性介质,计算相应的动力放大系数曲线,并与已有的结果进行对比.可以看出,量纲一激振频率、基础埋深比、基础质量比和渗透系数均对饱和地基中埋置基础摇摆振动的动力放大系数有很大的影响.     

高层钢结构中BRC跷动技术的减震影响分析

利用有限元分析软件SPA2000,建立12层的钢框架结构,在原框架底层柱X方向、Y方向添加BRC结构.分析三种结构方案在EL-Centro波、Taft波和TRI_TREASURE ISLAND_90这三种地震波作用下的顶层最大位移、基底剪力和顶层绝对加速度时程分析这几种结构反应.结果表明:BRC结构与传统钢结构相比,自振周期有所增加,对顶层最大位移和基底剪力的控制效果非常明显,具有显著的减震效果.     

基于某伺服转台的摇臂设计分析

桁架是工程及建筑中常见的一种结构形式,由于其在结构中的重要作用,设计后必须对其进行力学分析。以桁架的结构形式设计了一个伺服转台摇臂,利用ANSYS Workbench软件对其进行强度分析、屈曲分析以及模态分析,得到合理的结构。通过强度分析确定摇臂的结构形式,然后结合屈曲分析得到摇臂的合理尺寸,最后再对摇臂进行模态分析。     

Pushover and shaking table tests on a rocking-governed column-footing model on dry dense sand

Footings are normally used on firm ground. Previous studies have indicated that footings with large vertical bearing capacity have small settlement and recentering characteristics during excitation. The rocking foundation design is, therefore, considered quite suitable for a firm ground condition; however, some 1 g shaking table tests have shown that rocking structures still might have stability problems leading to toppling. In this study, we conducted pushover and shaking table tests on a rocking-governed column-footing model on dry dense sand to investigate the performance of a rocking structure on sturdy ground. Even in a dense soil condition, the structure had a longer period response than in the fixed-base condition, but this did not necessarily reduce the seismic demand on the structure. The major source of rocking isolation is that the maximum acceleration response of the structure is limited by the ultimate moment capacity of the footing; however, it is important to note that extensive rocking may induce a larger permanent rotation, which may influence the functionality of structures, and also may lead to structure instability, such as foundation twisting observed in this study.     

Inverse reliability-based design of shear buildings supported by springs with stochastic stiffnesses

A straightforward and efficient stiffness design method is developed for a shear building supported by a pair of swaying and rocking springs with stiffnesses given as statistically independent normal variates. The story stiffnesses are determined with the use of the closed form stiffness solution for specified fundamental frequency and translational eigenmode so that the probability of the seismic mean maximum interstory drifts not exceeding prescribed values would coincide with the specified value. The proposed method consists of two steps: (1) find the stiffnesses of swaying and rocking springs that can achieve the constrained nonexceedance probability by derived approximate formulas; (2) determine the story stiffnesses of the shear building so that the mean maximum interstory drifts would coincide with the prescribed values. The validity and good accuracy of the proposed method are demonstrated by use of Monte Carlo simulation.     

关于活塞式压缩机基础振动简化计算的讨论

通过对GB 50040—96《动力机器基础设计规范》中活塞式压缩机基础振动简化计算的分析表明,这种简化计算在一定范围内误差较大,在实际设计中应谨慎采用。     

Evaluation of seismic behavior improvement in RC MRFs retrofitted by controlled rocking wall systems

Using rocking wall systems is a recent technique to improve seismic behavior in reinforced concrete structures. This paper compares three 10‐story and three 20‐story reinforced concrete frames (moment‐resisting frames) with intermediate ductility, reinforced concrete frames with shear wall, and reinforced concrete frames with controlled rocking wall (RCRW) by the use of pushover analysis. At the end of the research, the wall in a 20‐story RCRW system is post‐tensioned then analyzed, and its results were compared with RCRW results. Simulation and numerical analysis were performed with OpenSees software. The results show that plastic hinge formation and inter‐story drifts are well distributed in the structure with rocking wall system in comparison with the other systems. Meanwhile, energy dissipation and displacement ductility are increased in RCRW frames. With post‐tensioning wall in RCRW, the drift ratios are more uniformed. Copyright © 2013 John Wiley & Sons, Ltd.     

自复位摇摆结构的发展与应用

首先回顾了摇摆结构的发展历史,自复位摇摆结构因为后张预应力筋提供的回复力,使得地震后结构的残余变形极小。但自复位摇摆结构也存在一些问题,针对这些问题,一些国外学者也提出了解决方法。