瑞利波特性刚度矩阵分析方法   总被引：3，自引：2，他引：1  

柴华友  白世伟  刘明贵  卢应发 《岩土力学》2006,27(2):209-213

沿水平方向从半无限体分层系统截取出有限厚度分层固体系统,截取边界设置为刚性边界。将固体系统分层细化,由刚度矩阵方法可得到表面波在该系统频散特性,利用瑞利波位移在底层衰减特性从表面振型波可筛选出瑞利振型波,这些瑞利振型波与某一频率范围半无限体分层系统瑞利振型波对应,其频率下限与截取厚度有关,截取厚度越大,频率下限越小。同时还分析了分层细化厚度、截取厚度与分析频率关系。  相似文献   

考虑时间效应的滑坡风险评估和管理   总被引：4，自引：1，他引：3  

李典庆  吴帅兵 《岩土力学》2006,27(12):2239-2245

提出了考虑时间效应的滑坡风险评估和管理方法。以香港地区近20年的16 000个切破的观测资料为基础,从统计学的角度提出了边坡的时变可靠性分析方法。推导了新建边坡在未来服役时间内的年失效概率的计算公式,并对现役边坡在未来服役时间内的年失效概率进行了预测。确定了基于年死亡人数的滑坡风险接受准则,并分析了基于滑坡时变风险的边坡加固时间。结果表明,考虑时间效应的滑坡风险评估和管理方法能够更加真实地反映滑坡随时间变化的特性。新建边坡的年失效概率随边坡服役时间逐渐增大,尤其是当边坡服役超过10年时,每年发生滑坡的概率急剧增大。现役边坡的年失效概率基本与继续服役时间呈线形关系。此外,香港斜坡维修指南规定的边坡加固时间能够有效地将滑坡风险降低到ALARP区或可接受的风险区。  相似文献   

盾构衬砌管片接头力学分析及双直线刚度模型研究   总被引：8，自引：2，他引：6  

朱伟  钟小春  秦建设 《岩土力学》2006,27(12):2154-2158

盾构管片接头弯曲刚度K? 是盾构衬砌结构计算中的一个重要参数。根据管片接头构造特征,在传力衬垫和弹性密封橡胶试验资料的基础上,对管片接头进行受力分析,得到管片接头弯曲刚度与接头内力的非线性关系。为了应用方便,建立了实用的管片接头弯曲刚度的双直线模型。该接头刚度模型为梁-弹簧模型法和修正惯用法中的关键参数确定提供了基础,管片的内力计算也更加合理。  相似文献   

Quantitative approach for damage detection of reinforced concrete frames     

Yoshio?KanekoEmail author  Akira?Mita  Hirozo?Mihashi 《地震工程与工程振动(英文版)》2003,2(1):147-158

The objective of this paper is to provide an analytical basis for the quantitative evaluation of damage to a reinforced concrete structure based on the vibration data obtained by using the damage detection technique. A partial reinforced concrete system of a weak beam/strong column moment frame is chosen as an example. A pushover analysis is carried out in order to numerically examine both the story shear-relative displacement characteristics and the associated damage level. In the analysis, a two dimensional nonlinear finite element analysis is employed considering several constitutive models. As a result, the degradation of the stiffness at the damaged story is characterized in association with the story relative displacement. It is also pointed out that the rotation angle of the column-base is highly correlated with the story relative displacement. Based on the analytical findings, quantitative approaches for a structural health monitoring system are suggested considering both the current sensor technologies and those available in the future. Supported by: Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (Base Research (c) (1), Research No. 14550555)  相似文献   

Theoretical and experimental research on a new system of semi-active structural control with variable stiffness and damping     

周福霖  谭平  阎维明  魏陆顺 《地震工程与工程振动(英文版)》2002,1(1):130-135

In this paper, a new system of semi active structural control with active variable stiffness and damping (AVSD) is suggested. This new system amplifies the structural displacement to dissipate more energy, and in turn, effectively reduces the structural response in the case of relatively small story drifts, which occur during earthquakes. A predictive instantaneous optimal control algorithm is established for a SDOF structure equipped with an AVSD system Comparative shaking table tests of a 1/4 scale single story structural model with a full scale control device have been conducted. From the experimental and analytical results, it is shown that when compared to structures without control or with the active variable stiffness control alone, the suggested system exhibits higher efficiency in controlling the structural response, requires less energy input, operates with higher reliability, and can be manufactured at a lower cost and used in a wider range of engineering applications.  相似文献   

In-service deterioration of compressed earth blocks     

A.?G.?KeraliEmail author 《Geotechnical and Geological Engineering》2005,23(4):461-468

With the increasing backlog of shelter in most of the third world, attempts are being made to evolve low-cost but durable walling units. The introduction of compressed earth blocks (CEBs) some 50 years ago was seen as a major milestone. These blocks are made by compressing a damp mix of soil (90–95%), and cement (5–10%) to form strong and dense blocks used for walling. While considerable knowledge is available regarding their initial performance characteristics, little research has so far been conducted on their long-term durability and deterioration due to prolonged exposure to environmental factors. It is now widely recognised that rapid and premature deterioration does take place when the material is used in unrendered walling in most humid tropical environments. Premature defects such as roughening, pitting, erosion, volume reduction, cracking as well as crazing, etc., have all been witnessed within periods ranging from 1 month to 5 years after completion of construction. This paper reports on recent research conducted in Uganda where in-service defects such as pitting and cracking where measured directly from existing exposed walling to quantify their nature and extent. It can be concluded that the greatest deterioration was found to occur on east–west facing facades, and on the lower wall sections. The deterioration was also found to correspond to the age of the structure.  相似文献   

Decomposition of Mangrove Wood by Marine Fungi and Teredinids in Belize   总被引：1，自引：0，他引：1  

J. Kohlmeyer    B. Bebout  B. Vlkmann-Kohlmeyer   《Marine Ecology》1995,16(1):27-39

  相似文献   

Salt and ice crystallisation in porous sandstones   总被引：1，自引：0，他引：1  

Joerg Ruedrich  Siegfried Siegesmund 《Environmental Geology》2007,52(2):225-249

Salt and ice crystallisation in the pore spaces causes major physical damage to natural building stones. The damaging effect of these processes can be traced back to physically induced stress inside of the rock while crystallizing. The increasing scientific research done during the past century has shown that there are numerous parameters that have an influence on the weathering resulting from these processes. However, the working mechanisms of the stress development within the rock and its material dependency are still subject to discussion. This article gives an overview of salt and ice weathering. Additionally, laboratory results of various sandstones examined are presented. Salt crystallisation tests and freeze/thaw tests were done to obtain information about how crystallisation weathering depends on material characteristics such as pore space, water transportation, and mechanical features. Simultaneous measuring of the length alternating during the salt and ice crystallisation has revealed detailed information on the development of crystal in the pore spaces as well as the development of stress. These findings can help to understand the damaging mechanisms.  相似文献   

A symmetric time‐domain model for 3D dam–reservoir interaction including radiation damping     

C. Birk  P. Ruge 《地震工程与结构动力学》2007,36(5):661-682

  相似文献   

On the estimation of hysteretic energy demands for SDOF systems   总被引：1，自引：0，他引：1  

Danny Arroyo  Mario Ordaz 《地震工程与结构动力学》2007,36(15):2365-2382

Based on a statistical study of the dynamic response of single degree of freedom (SDOF) systems subjected to earthquake ground motions, a rule to estimate hysteretic energy demands is proposed. Expressions for elastic–perfectly plastic, stiffness degrading and pinching SDOF systems were obtained. The proposed rule does not explicitly depend on the period of the system; instead, it depends on the elastic pseudo‐acceleration and elastic velocity spectra. It is shown that the proposed rule can be applied to compute hysteretic energy demands for systems located at different soil conditions. In addition, information about scatter and bias of the proposed rule is also presented. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献