金属橡胶支座剪切性能试验研究

针对一种金属橡胶支座,研究其剪切性能。进行3种压应力下的拟静力试验,分析竖向压力和水平剪切变形对支座剪切性能的影响;以试验数据为基准,建立支座剪切性能与压应力之间的相关性经验公式,提出能够近似模拟试验曲线的三线性恢复力模型。试验研究表明,随着支座剪切变形的增大,支座等效刚度及耗能增大,等效阻尼比减小,屈服力基本保持不变,滞回曲线由梭形逐渐变为反S型,当剪切应变大于25%时支座出现刚度硬化现象;随着支座压应力增大,支座的耗能、屈服力、等效刚度及等效阻尼比均增大。     

海南橡胶的气象灾害分析

对海南省橡胶生产的气候条件、气象灾害及橡胶风害的机制、影响因素等进行分析,找出影响海南橡胶的主要气象灾害,为开展海南省橡胶风害评估提供科学依据。     

基于FAST测点的大幅宽HJ星图像几何精纠正方法

针对环境与灾害监测预报小卫星(HJ)图像存在较大整体几何误差,且无规律可循,难以使用全局模型模拟整景图像几何变形,而基于手动方式选取控制点的全局模型和局部模型都不适合于HJ图像几何精纠正的问题,提出一种基于加速分段测试特征(features from accelerated segment test,FAST)算法测点并用局部模型进行几何精纠正的优化方法。首先以FAST算法获取大量地面控制点(ground control point,GCP);再使用多项式模型对GCP的均方根误差阈值、潜在不匹配和实际不匹配GCP数量进行相关分析,据此修正FAST参数,筛查GCP误点;最后使用局部模型完成几何精纠正。此外,使用散点图和空间插值等方法建立适合于HJ图像几何精纠正结果的评价指标。检验结果表明,该方法能使纠正误差控制在1.5个像元内,纠正后的图像能满足中分辨率尺度的应用要求。     

TRENDS IN THE URBANIZATION PROCESS

Matthiessen, Christian Wichmann: Trends in the urbanization process. The Copenhagen case. Geografisk Tidsskrift 80: 98–101. Copenhagen, June 1980.

Within the framework of the international comparative research project (Cost of Urban Growth) new trends in urban development have recently been observed. The object of this article is to discuss the trends and give impirical evidence on Danish data.     

A nonlinear impact model for simulating the use of rubber shock absorbers for mitigating the effects of structural pounding during earthquakes

During strong earthquakes, structural poundings may occur between adjacent buildings because of the limited separation distance and the deformations of their stories. A potential mitigation measure for this problem is the incorporation of layers of soft material, such as rubber, which can act as collision bumpers, in order to prevent the sudden impact pulses. In an effort to investigate the effectiveness of such an impact mitigation measure, relevant numerical simulations and parametric studies can be performed. However, none of the known impact models, which are available in the literature, is able to represent the usage of rubber bumpers with sufficient accuracy. The current study presents a simple but efficient methodology that can be used to simulate the incorporation of rubber layers between neighboring structures with relatively narrow seismic gaps. Such methodology will enable us to numerically investigate the effectiveness of using rubber bumpers to mitigate potential earthquake‐induced pounding. In particular, a new nonlinear inelastic force‐based impact model, able to appropriately describe the behavior of rubber under impact loading, taking also into account the limited thickness of the bumper, is introduced. Finally, a numerical example of simulating earthquake‐induced pounding between two multistory buildings with the consideration of rubber bumpers at impact locations is presented. Copyright © 2012 John Wiley & Sons, Ltd.     

天然橡胶产业生态系统管理(英文)

天然橡胶产业生态系统管理是实现天然橡胶产业可持续发展的生态途径。本文在系统分析天然橡胶产业生态系统结构和功能的基础上,以海南为例,提出了天然橡胶产业生态系统管理的基本模式,其中重点探讨了天然橡胶产业生态系统管理的基本原则、管理步骤及管理途径,旨在为天然橡胶产业生态系统健康和可持续发展提供理论依据和实践指导。     

基于汶川地震的LRB与RB隔震连续梁桥地震响应对比研究

为了研究铅芯橡胶支座(LRB)和板式橡胶支座(RB)对连续梁桥地震响应及隔震效果的影响,分别采用Bouc - Wen滞回恢复力模型模拟LRB的力-位移非线性特性,采用直线型恢复力模型模拟RB的本构关系,通过结构离散建立了非隔震、LRB隔震和RB隔震3种连续梁桥的有限元计算模型,运用四阶显式Runge - Kutta迭代法和Newmark时间积分法联合求解增量形式的全桥动力微分方程,并结合算例对3种连续梁桥有限元计算模型分别输入汶川地震波进行非线性时程对比分析.结果表明:LRB在控制梁体与支座位移,降低结构加速度和墩、台底内力响应方面均比RB的效果要显著;采用RB隔震后,梁体与支座的位移响应均较大,在桥梁隔震设计时要予以充分重视.     

废轮胎颗粒与黄土混合物剪切特性研究

废轮胎应用于岩土工程不仅开辟了废轮胎处置的新途径,还为解决岩土工程问题提供了新型复合材料。为了更好地模拟实际回填土受力工况,采用不固结不排水三轴试验研究了掺量为10%～50%的废轮胎颗粒与黄土混合物（以下简称GR-LM,granulated rubber loess mixtures）的剪切特性,考察了掺量、围压对剪切强度的影响。对试验结果进行了机制探讨。研究表明,所有GR-LM试样均表现出应变硬化特点,纯废轮胎颗粒在试验所有围压范围内呈近似线性的偏应力-应变特性;GR-LM应力-应变特性与掺量和围压有关,低围压下存在剪切强度增大的掺量为30%,其GR-LM强度高于其他各掺量混合土并略高于纯压实黄土的剪切强度;GR-LM剪切强度机制与GR-LM孔隙填充状态、基质土物理状态、弹性骨架颗粒有关,总体上随骨架颗粒的不同接触关系而表现出粉土与粒状土的强度特性,在剪切强度特性上体现出掺量与围压作用的相互耦合,而与压实粉土或砂土有所不同。