Seismic response of self‐centring hysteretic SDOF systems     

Constantin Christopoulos  Andr Filiatrault  Bryan Folz 《地震工程与结构动力学》2002,31(5):1131-1150

The seismic response of single‐degree‐of‐freedom (SDOF) systems incorporating flag‐shaped hysteretic structural behaviour, with self‐centring capability, is investigated numerically. For a SDOF system with a given initial period and strength level, the flag‐shaped hysteretic behaviour is fully defined by a post‐yielding stiffness parameter and an energy‐dissipation parameter. A comprehensive parametric study was conducted to determine the influence of these parameters on SDOF structural response, in terms of displacement ductility, absolute acceleration and absorbed energy. This parametric study was conducted using an ensemble of 20 historical earthquake records corresponding to ordinary ground motions having a probability of exceedence of 10% in 50 years, in California. The responses of the flag‐shaped hysteretic SDOF systems are compared against the responses of similar bilinear elasto‐plastic hysteretic SDOF systems. In this study the elasto‐plastic hysteretic SDOF systems are assigned parameters representative of steel moment resisting frames (MRFs) with post‐Northridge welded beam‐to‐column connections. In turn, the flag‐shaped hysteretic SDOF systems are representative of steel MRFs with newly proposed post‐tensioned energy‐dissipating connections. Building structures with initial periods ranging from 0.1 to 2.0s and having various strength levels are considered. It is shown that a flag‐shaped hysteretic SDOF system of equal or lesser strength can always be found to match or better the response of an elasto‐plastic hysteretic SDOF system in terms of displacement ductility and without incurring any residual drift from the seismic event. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Multi‐objective optimal design of FLC driven hybrid mass damper for seismically excited structures     

A. S. Ahlawat  A. Ramaswamy 《地震工程与结构动力学》2002,31(7):1459-1479

Structural vibration control using active or passive control strategy is a viable technology for enhancing structural functionality and safety against natural hazards such as strong earthquakes and high wind gusts. Both the active and passive control systems have their limitations. The passive control system has limited capability to control the structural response whereas the active control system depends on external power. The power requirement for active control of civil engineering structures is usually quite high. Thus, a hybrid control system is a viable solution to alleviate some of the limitations. In this paper a multi‐objective optimal design of a hybrid control system for seismically excited building structures has been proposed. A tuned mass damper (TMD) and an active mass driver (AMD) have been used as the passive and active control components of the hybrid control system, respectively. A fuzzy logic controller (FLC) has been used to drive the AMD as the FLC has inherent robustness and ability to handle the non‐linearities and uncertainties. The genetic algorithm has been used for the optimization of the control system. Peak acceleration and displacement responses non‐dimensionalized with respect to the uncontrolled peak acceleration and displacement responses, respectively, have been used as the two objectives of the multi‐objective optimization problem. The proposed design approach for an optimum hybrid mass damper (HMD) system, driven by FLC has been demonstrated with the help of a numerical example. It is shown that the optimum values of the design parameters of the hybrid control system can be determined without specifying the modes to be controlled. The proposed FLC driven HMD has been found to be very effective for vibration control of seismically excited buildings in comparison with the available results for the same example structure but with a different optimal absorber. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

A response‐based decoupling criterion for multiply‐supported secondary systems     

Samit Ray Chaudhuri  Vinay K. Gupta 《地震工程与结构动力学》2002,31(8):1541-1562

It is often infeasible to carry out coupled analyses of multiply‐supported secondary systems for earthquake excitations. ‘Approximate’ decoupled analyses are then resorted to, unless the response errors due to those are significantly high. This study proposes a decoupling criterion to identify such cases where these errors are likely to be larger than an acceptable level. The proposed criterion is based on the errors in the primary system response due to decoupling and has been obtained by assuming (i) the input excitation to be an ideal white noise process, (ii) cross‐modal correlation to be negligible, and (iii) the combined system to be classically damped. It uses the modal properties of the undamped combined system, and therefore, a perturbation approach has been formulated to determine the combined system properties in case of light to moderately heavy secondary systems. A numerical study has been carried out to illustrate the accuracy achieved with the proposed perturbation formulation. The proposed decoupling criterion has been validated with the help of two example primary‐secondary systems and four example excitation processes. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Towards a direct collapse–load method of design for concrete frames subjected to severe ground motions     

M. C. Griffith  A. Kawano  R. F. Warner 《地震工程与结构动力学》2002,31(10):1879-1888

Most current methods of design for concrete structures under earthquake loads rely on highly idealized ‘equivalent’ static representations of the seismic loads and linear‐elastic methods of structural analysis. With the continuing development of non‐linear methods of dynamic analysis for the overload behaviour and collapse of complete concrete structures, a more direct and more accurate design procedure becomes possible which considers conditions at system collapse. This paper describes an evaluation procedure that uses non‐linear dynamic collapse–load analysis together with global safety coefficients. A back‐calibration procedure for evaluating the global safety coefficients is also described. The aim of this paper is to open up discussion of alternative methods of design with improved accuracy which are necessary to move towards a direct collapse–load method of design. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

全谱直读等离子发射光谱法直接测定天然矿泉水中的SO2-4   总被引：2，自引：0，他引：2  

查立新  刘洪青  马玲  戴先蓉 《安徽地质》2002,12(1):75-77

采用全谱直读等离子发射光谱(ICP-AES)直接测定天然矿泉水中SO2-4的方法在优化工作条件下SO42-的测定下限为0.09mgL-1,方法简便,快速,适用于批量生产.  相似文献   

利用卫星影像和航空影像更新基础地理信息方法研究     

狄沙力 《安徽地质》2002,12(3):204-207

基础地理信息的更新,是保证地理信息系统现势性的充要条件.卫星遥感影像数据具有周期短、信息丰富、现势性强等特征.利用卫星影像数据来更新基础地理信息数据是一种行之有效的方法.如何利用遥感数据融合技术,将多传感器获取的各种影像数据中所含的信息优势有机地结合起来,更是成为目前研究的热点.利用航空影像和Landsat多光谱波段影像进行数据融合,能够有效地提高影像空间分辨率,以获取更高质量的信息.  相似文献   

不同参考椭球体的GIS数据转换探讨     

杨友长 《安徽地质》2002,12(3):225-229

通过一项工程和不同参考椭球转换软件的实现过程,探讨了不同参考椭球GIS数据的转换问题.首先介绍了转换的数学模型和软件的实现过程.其次介绍了几种转换方法,并通过一个工程实例介绍了具体的操作步骤.最后对这个工程实例进行了可行性分析.  相似文献   

公路边坡工程监测技术评价与分析   总被引：1，自引：0，他引：1  

梁世华 《安徽地质》2002,12(4):245-247,251

结合公路工程、建筑工程等土木工程建设中经常涉及到的边坡工程,评价与分析边坡工程监测的作用、内容和方法,提出了边坡工程应该在工程项目开展的开始阶段就应进行和边坡工程监测的项目,选择原则,测点布置原则、监测周期等,对边坡工程建设具有重要的意义.  相似文献   

高速公路桥梁灌注桩工程成本价值分析     

张辉  秦玉斌 《安徽地质》2002,12(4):293-297

本文以桥目标成本管理等现代化管理方法,系统地指出了降低灌注桩工程成本的途径.对于桥梁灌注桩以外的企业的经营活动同样具有重要的指导意义.  相似文献   

基于栅格空间信息定量化的湖南西部地区生态环境综合评价   总被引：18，自引：0，他引：18  

谢炳庚  李晓青  吕辉红  贺曲夫 《冰川冻土》2002,24(4):438-443

以湖南西部地区为研究区域,采用遥感影像作为主要数据源,针对区域主要生态问题,利用栅格数据结构为主的数字环境模型,建立了生态环境质量综合评价模型. 对区域生态环境质量的空间分异格局进行了研究,通过将评价结果与数字高程模型迭加分析,研究了生态环境质量的垂直地带性分布规律,探索适合以山高坡陡为主要地貌特征的山区生态评价方法,结果显示,湖南西部地区生态环境综合指数呈正态分布,大部分地区环境质量属一般. 总体环境状况东南部好于西北部,河谷盆地优于山地. 研究表明,利用遥感和地理信息系统技术进行区域生态环境评价,具有数据采集快速、客观,评价和制图自动化,评价结果空间定位精度高,直观性与实用性强等优点.  相似文献