底部加强型工字形钢管混凝土柱抗震性能研究

提出了工字型截面钢管混凝土柱,同时提出了一种在柱底部区域翼缘贴焊钢板的底部加强型工字形截面钢管混凝土柱。进行了3个不同构造的工字形钢管混凝土柱模型的低周反复荷载试验,模型1为普通工字形钢管混凝土柱,模型2为工字形截面两翼缘外侧贴焊钢板的钢管混凝土柱,模型3为工字形截面两翼缘周边均贴焊钢板的钢管混凝土柱。分析了各模型的破坏特征、承载力、刚度及退化过程、延性和滞回耗能特性。给出了工字形钢管混凝土柱正截面及斜截面承载力计算公式,计算结果与实测符合较好。研究表明:所提出的底部加强型工字形钢管混凝土柱与普通工字形钢管混凝土柱相比,承载力明显提高,延性和抗震耗能能力显著提高。     

加劲T形钢管约束混凝土柱滞回性能研究

异形柱框架结构较传统框架结构能有效地改善建筑内部的使用空间,但目前应用较多的钢筋混凝土异形柱结构在抗震性能方面限制较严,制约了其进一步的推广和应用。加劲钢管约束混凝土异形柱可有效提高核心混凝土的约束作用,改善其滞回性能。为研究加劲T形钢管约束混凝土柱的滞回性能,进行了2个T形组合柱的压弯滞回性能试验研究。试验结果表明:外包钢管越长,试件的承载力和延性也相应越高;相比T形钢筋混凝土柱,T形钢管约束混凝土柱的刚度、承载力以及耗能性能均明显提高;对拉钢筋加劲肋能有效限制钢管局部屈曲和阴角处钢管与混凝土脱开。提出了适合T形钢管约束混凝土柱的数值分析程序并将数值程序计算所得的水平荷载-位移曲线与试验曲线对比,吻合较好。     

内约束方钢管混凝土柱抗震性能研究

由于方钢管对混凝土约束作用较弱,地震作用下方钢管混凝土柱底部钢管易出现屈曲,因此本文提出一种新型内约束方钢管混凝土柱。基于ABAQUS有限元软件,本文采用合理的材料本构模型建立内约束方钢管混凝土柱三维实体精细有限元模型,该模型能准确反应钢管、混凝土以及拉筋之间的相互作用,又能反应拟静力作用下混凝土的塑性损伤和钢材的循环硬化规律。有限元结果与试验结果吻合良好。首先,在此基础上笔选出最佳内约束形式,对拉箍筋方钢管混凝土柱的抗震性能明显优于圆环箍筋;其次,提出在不同轴压比下内约束方钢管混凝土柱的焊接拉筋最佳布置长度和合理体积配箍率;再次,探讨不同参数对内约束方钢管混凝土柱滞回性能的影响,结果表明:提高截面含钢率和长细比能有效改善组合柱的极限承载力,而轴压比在一定范围内有利于能提高柱的承载力;最后,讨论了约束措施对内约束方钢管混凝土柱耗能性能的影响。     

钢管混凝土斜折柱抗震性能试验研究

为解决实际工程中遇到的钢管混凝土斜折柱抗震性能的问题,进行了3个1/3缩尺的钢管混凝土斜折柱低周反复荷载试验.在试验基础上,研究了各钢管混凝土柱的承载力、刚度、延性、滞回特性及破坏特征,建立了钢管混凝土斜折柱承载力简化计算方法.研究表明:钢管混凝土斜折柱,经合理设计可以满足抗震要求.     

核心钢管混凝土短柱轴压受力机理及设计方法研究

为研究核心钢管混凝土(CSTRC)短柱轴压受力机理及设计方法,完成了7个CSTRC柱和2个RC柱的轴压试验,采用有限元软件ABAQUS对CSTRC柱轴压全过程进行数值仿真。在试验验证的基础上,利用有限元模型研究了CSTRC柱的轴压机理和轴力分配规律。研究表明,核心钢管混凝土柱试件中,钢管对内部混凝土的约束作用明显,钢管外部混凝土对钢管的约束作用可以忽略,其承载力可按RC部分与钢管混凝土柱部分承载力进行线性叠加。根据有限元分析结果,提出了CSTRC柱中钢管混凝土部分的承载力发挥系数。本文成果可为CSTRC结构的设计和应用提供参考。     

底部加强型矩形钢管混凝土柱抗震性能试验与分析

提出了一种底部加强型矩形钢管混凝土柱,采取在柱底部区域钢板外侧贴焊钢板的构造措施,以提高其抗震耗能能力.进行了3个不同构造的矩形钢管混凝土柱模型的低周反复加载试验,模型1为普通矩形钢管混凝土柱,模型2为矩形截面底部垂直加载方向钢板外侧贴焊钢板的钢管混凝土柱,模型3为矩形截面底部双向外侧钢板均贴焊钢板的钢管混凝土柱.模型按1/5缩尺.分析了各模型的承载力、刚度及退化过程、延性、滞回耗能特性和破坏特征.给出了底部加强型矩形钢管混凝土柱正截面及斜截面承载力的计算公式,计算与实测结果符合较好.研究表明:所提出的底部加强型矩形钢管混凝土柱与普通矩形钢管混凝土柱相比,其承载力明显提高,延性和抗震耗能能力显著提高.     

钢管高强混凝土柱抗震性能的试验研究

本文对钢管高强混凝土柱进行低周反复水平荷载作用的试验,得到了不同轴压比情况下的滞回曲线及骨架曲线,讨论了钢管高强混凝土柱压弯承载力计算公式的适用性。结果表明,钢管高强混凝土柱具有很高的承载力及良好的抗震性能。     

圆截面钢管混凝土柱的局部屈曲性能研究

在地震力作用下,钢管混凝土柱在塑性区域发生的局部屈曲会引起承载力下降并使钢管发生塑性形变,通过研究钢管混凝土柱的局部屈曲性能,使用能量法推出了屈曲应力的计算公式。分析结果表明:屈曲应力受钢管弹性模量的影响较大。对42根钢管混凝土柱进行了轴压试验,考虑了长细比、径厚比以及核心混凝土强度3个影响因素,通过将试验结果与计算结果进行对比,得到了钢管在塑性区域内发生屈曲时刻的切线模量。     

薄壁方钢管混凝土柱劲化设计及轴压性能探讨

对于薄壁方形钢管混凝土柱,有效且经济地提高柱的承载力、刚度和延性,增强其抵抗局部屈曲的能力是目前的一项重要研究课题。据此,进行8个薄壁方形钢管混凝土轴压试件的研究,比较普通薄壁钢管混凝土柱与劲化薄壁钢管混凝土柱的轴压极限承载力、延性性能、局部屈曲模态及相应耗钢量,研究表明:劲化设置在增加较少用钢量的情况下,使钢管壁对核心混凝土的约束作用相对于普通钢管混凝土柱和单纯加设约束拉杆的钢管混凝土柱更趋均匀,提高了整体约束效应,混凝土强度得以提高,本构关系明显改善。从而增加了钢管混凝土柱的轴压承载力和延性,改变了钢管的局部屈曲变形状态,其实用效益与经济效益极其可观,具有良好推广价值。     

钢管混凝土构件轴向受拉机理和承载力研究

采用有限元软件ABAQUS建立了钢管混凝土柱的有限元模型,对10个钢管混凝土柱试件在轴向拉力作用下的受力行为进行了数值模拟,并通过与试验结果对比验证了模型的适用性和有效性。使用经验证的模型分析了轴向拉力作用下钢管混凝土构件的受力过程、破坏机理以及钢管和混凝土之间的相互作用,并根据分析结果提出了钢管混凝土构件受拉承载力简化计算公式。研究表明:钢管混凝土柱在轴向拉力作用下,钢管承担大部分拉力,最终的破坏形态为构件端部或者中部的钢管破坏;含钢率和钢材强度对钢管混凝土柱的抗拉承载力影响较大,而核心混凝土强度对抗拉承载力影响很小。     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Earthquake Engineering and Engineering Vibration Aims And Scope

正This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and     

Foreword

Destructive earthquakes have caused great damage in China and the United States and collapsing buildings havecaused many deaths and injuries. The field of earthquake engineering studies earthquake hazards, the occurrence ofearthquakes of various magnitudes, the nature of the ground shaking during an earthquake, the vibration of structuresduring earthquakes, the strengthening of existing structures and the design of new structures to be earthquake resistant,and finally, how to cope with earthquake damage and restore a city to normal functioning. Such efforts are in progressin both countries, but unfortunately, the language barrier interferes with the free flow of information between China andthe Untied States. It would be mutually beneficial if some means could be developed to promote the exchangeof information across the Pacific Ocean. This new journal has been established for this purpose and its success willbe an important step in promoting earthquake engineering in China and the United States.     

WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)

正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study     

Enhancing remote sensing research on global change to improve our understanding on Earth system processes

正Global Change includes climate change and other environmental changes caused by the joint interaction among various layers of Earth. From the positive side, global change provides new opportunities to human and other living forms on Earth. In the meantime, it creates tremendous challenges and negative impact. At present, the negative impacts have reached all primary processes of the global ecosystem and every aspect of human society, especially causing degradation of the ecosystem. For instance, intensive deforestation causes decline of biodiversity; global warming causes sea level rise and increases