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Seismic response control with density-variable tuned liquid dampers

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Earthquake Engineering and Engineering Vibration 2009年第4期8卷 537-546页

作者： Yuxiang Xin genda chen Lou Menglin HNTB Corporation. 1330 Broadway. Oakland CA 94612 USA Centerfir Infrastructure Engineering Studies Misxouri University of Science and Technology Rolla M.O 65409 USA State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai China

In this paper, the seismic effectiveness of a density-variable tuned liquid damper （DVTLD） with a sloping bottom is experimentally investigated through a series of shake table tests on a 1/4-scale, 3-story frame structure and numerically simulated by a new semi-analytical model. Special attention was given to reducing the first peak and maximum response under near- and far-field ground motions, and the robustness of a density-variable control system consisting of multiple DVTLDs with closely-spaced frequencies. Adaptable to earthquake excitations, the density-variable control system has been demonstrated to be more effective and more robust than its corresponding traditional tuned liquid damper in suppressing story drift and floor acceleration of the structure. Numerical simulations of the DVTLD-controlled structure agreed very well in phase with experimental results but somewhat overestimated the amplitude of the structural response.

关键词： tuned liquid damper density-variable tuned liquid damper seismic response seismic effectivenessrobustness

Innovative hybrid reinforcement constituting conventional longitudinal steel and FRP stirrups for improved seismic strength and ductility of RC structures

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Frontiers of Structural and Civil Engineering 2016年第1期10卷 44-62页

作者： Mostafa FAKHARIFAR Ahmad DALVAND Mohammad K. SHARBATDAI~ genda chen Lesley SNEED Department of Civil Architectural and Environmental Engineering Missouri University of Science and Technology 209 PineBuilding 1304 N. Pine Street Rolla MO 65409 USA 'Department of Engineering Lorestan University Khorramabad Iran Department of Civil Engineering Semnan University Semnan Iran

The use of fiber reinforced polymer （FRP） reinforcement is becoming increasingly attractive in construction of new structures. However, the inherent linear elastic behavior of FRP materials up to rupture is considered as a major drawback under seismic attacks when significant material inelasticity is required to dissipate the input energy through hysteretic cycles. Besides, cost considerations, including FRP material and construction of pre-fabricated FRP configurations, especially for stirrups, and probable damage to epoxy coated fibers when transported to the field are noticeable issues. The current research has proposed a novel economical hybrid reinforcement scheme for the next generation of infrastructures implementing on-site fabricated FRP stirrups comprised of FRP sheets. The hybrid reinforcement consists of conventional longitudinal steel reinforcement and FRP stirrups. The key feature of the proposed hybrid reinforcement is the enhanced strength and ductility owing to the considerable confining pressure provided by the FRP stirrups to the longitudinal steel reinforcement and core concrete. Reinforced concrete beam specimens and beam- column joint specimens were tested implementing the proposed hybrid reinforcement. The proposed hybrid reinforcement, when compared with conventional steel stirrups, is found to have higher strength, stiffness, and energy dissipation. Design methods, structural behavior, and applicability of the proposed hybrid reinforcement are discussed in detail in this paper.

关键词： FRP ductility confinement seismic shear

Corrosion Resistance of Transmission Pipeline Steel Coated with Five Types of Enamels

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 390-398页

作者： Liang Fan Fujian Tang Signo T. Reis genda chen Michael L. Koenigstein Department of Civil Architectural and EnvironmentalEngineering Missouri University of Science andTechnology Rolla MO 65409-0030 USA Pro-Perma Engineered Coatings Roesch Inc. Belleville IL62226 USA

Corrosion is one of the main causes of incidents occurred in hazardous liquid and gas transmission pipelines in the USA, resulting in a loss of over $12 billion per year. In this study, the corrosion resistance of pipeline steel coated with five types of enamel was investigated in 3.5 wt% NaCl solution with linear polarization resistance and electrochemical impedance spectroscopy tests. Steel coupons were cut from API 5L X65 pipeline steel and coated with five types of enamels using the wet process. The microstructures of all enamel samples were examined by scanning electron microscopy. Experimental results indicate that all enamel coatings increase the corrosion resistance of pipeline steel, and pure enamel PE2, mixed enamels ME1 and ME2 have higher corrosion resistances than pure enamel PE1 and mixed enamel ME3.

关键词： Steel pipe Enamel coating Scanning electron microscopy (SEM) Electrochemical impedance spectroscopy (EIS)

Lessons in bridge damage learned from the Wenchuan earthquake

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Earthquake Engineering and Engineering Vibration 2009年第2期8卷 275-285页

作者： W. Phillip Yen genda chen Mark Yashinski Youssef Hashash Curtis Holu Wang Kehai GuoXiaodong Turner-Fairbank Highway Research Center of Federal Highway Administration （FWHA） Center for Transportation Infrastructure and Safety （CTIS） a National University Transportation Center at Missouri University of Science and Technology California Department of Transportation Representing the Earthquake Engineering Research Institute （EERI） University of Illinois at Urbana Champaign and Representing Geo-Engineering Earthquake Reconnaissance （GEER） Mid-America Earthquake Center （MAE） University of Illinois at Urbana Champaign Research Institute of Highway the Ministry of Communication of China Sichuan Province Highway Planning Survey Design and Research Institute China

A strong earthquake occurred in Wenchuan County, Sichuan Province, China, on May 12, 2008. Shortly after the earthquake, the Turner-Fairbank Highway Research Center of the Federal Highway Administration, in partnership with the Research Institute of Highways, the Ministry of Communication of China, led a reconnaissance team to conduct a post-earthquake bridge performance investigation of the transportation system in the earthquake affected areas. The U.S. transportation system reconnaissance team visited the area during July 20 24, 2008. This paper presents the findings and lessons learned by the team.

关键词： earthquake engineering bridge engineering post earthquake investigation

Porosity,Pore Size Distribution and Chloride Permeability of Shotcrete Modified with Nano Particles at Early Age

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Journal of Wuhan University of Technology(Materials Science) 2016年第3期31卷 582-589页

作者：李贺东闫东明 chen genda XU Shilang LIU Jintao HU Yanjia Department of Civil Engineering Zhejiang-UniversityHangzhou 310027China Dep-artment of Civil Architecture&Environment EngineeringMissouri University of Science and TechnologyRollaMissouri65401USA

Nano particles have been found to be effective in enhancing many properties of regular concretes. However, there is little information on the effect of nano particles on shotcrete. In fact, if similar positive effect of nano particles can also appear in shotcrete, they will greatly benefit the wide application of shotcrete in more and more repair and strengthening of structures in civil engineering, especially in corrosive environments. In this study, through experiments on 70 specimens, the effects of nano SiO2, CaCO3 and Al2O3 particles on the early-age porosity, pore size distribution, compressive strength and chloride permeability of shotcrete were *** results indicated that nano SiO2 particles significantly increased the compressive strength and chloride penetration resistance; nano Al2O3 and CaCO3 particles had slight enhancing effect on the compressive strength; nano CaCO3 particles were most effective in promoting the chloride penetration resistance of shotcrete. As a conclusion, nano SiO2 particles were recommended when both early age compressive strength and chloride penetration resistance were crucial, and nano CaCO3 particles were recommended when only chloride penetration resistance was concerned for their high cost-effectiveness.

关键词： shotcrete nanoparticles chloride penetration resistance compressive strength porosity

多次各向异性散射模式对S波能量密度包络曲线的影响

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地球物理学报 2012年第6期55卷 1993-2003页

作者：景月岭 Yuehua Zeng 林皋 genda chen 李建波大连理工大学海岸与近海工程国家重点实验室辽宁大连116024 大连理工大学建设工程学部工程抗震研究所辽宁大连116024 U. S. Geological Survey Golden CO 80401 USA Department of Civil Architectural and Environmental Engineering MisSouri University of Science and Technology MO 65409 USA

在多次各向异性散射理论的基础上,本文重新推导了方向性散射系数的球函数展开式.引入特征时间的概念,来定义震源处初始地震波脉冲宽度,并在地震波能量密度积分方程中引入任意给定频率的初始脉冲能量谱密度的解析表达.通过离散波数方法... 详细信息

在多次各向异性散射理论的基础上,本文重新推导了方向性散射系数的球函数展开式.引入特征时间的概念,来定义震源处初始地震波脉冲宽度,并在地震波能量密度积分方程中引入任意给定频率的初始脉冲能量谱密度的解析表达.通过离散波数方法求解了修正的地震波能量密度积分方程.基于积分方程的数值解,研究了不同散射模式对S波能量密度包络曲线的影响.计算结果表明:随着震源距的增加,在S波到时之后,多次各向异性散射模式与多次各向同性散射模式合成的能量密度包络差异逐渐增大.其中通过多次前散射模式,我们可以得到不同震源距的尾波能量密度包络的同一衰减趋势,以及S波能量密度包络随着震源距的增加而出现的展宽现象.最后,利用美国内华达州Wells地震余震的台站记录验证了多次前散射模式的实用性与有效性.

关键词：多次各向异性散射 S波能量密度包络方向性散射系数包络展宽尾波同一衰减能量传输理论

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活学活用两自由度动力系统基本理论

金属世界 2011年第3期 20-23页

作者：潘旦光 genda chen 北京科技大学土木与环境工程学院 Department of Civil Architectural and Environmental EngineeringMissouri University of Science and TechnologyMO65409USA

结构动力学涉及很多抽象的力学模型和概念,数学理论要求较高,特别是多自由度体系。文章总结了如何针对工程实际问题,通过理解问题、分析问题和解决问题,提高结构动力学学习效果。为使抽象力学模型的物理意义及其工程应用更为直观,将两... 详细信息

结构动力学涉及很多抽象的力学模型和概念,数学理论要求较高,特别是多自由度体系。文章总结了如何针对工程实际问题,通过理解问题、分析问题和解决问题,提高结构动力学学习效果。为使抽象力学模型的物理意义及其工程应用更为直观,将两类重要的工程问题:动力测量和桥梁减震简化为两自由度体系。讨论多自由度体系中刚度和阻尼的作用。详细讨论了动力测量中的增加刚度和减震中降低刚度以及阻尼对减震的影响的全局和局部效应。

关键词：两自由度动力系统多自由度体系结构动力学工程问题力学模型动力测量低刚度

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TLD控制的钢结构振动台模型试验研究

地震工程与工程振动 2006年第1期26卷 145-151页

作者：楼梦麟牛伟星宗刚陈根达同济大学土木工程防灾国家重点实验室上海200092

本文通过钢结构的振动台模型试验,研究了在刚性地基条件下矩形调谐流体阻尼器(TLD)对结构地震反应的减震机理和减震效果,为进一步研究土-结构相互作用对结构TLD减震控制效率影响的振动台模型试验提供对比数据。试验结果表明,在水箱中设... 详细信息

本文通过钢结构的振动台模型试验,研究了在刚性地基条件下矩形调谐流体阻尼器(TLD)对结构地震反应的减震机理和减震效果,为进一步研究土-结构相互作用对结构TLD减震控制效率影响的振动台模型试验提供对比数据。试验结果表明,在水箱中设置铁丝网有助于提高TLD的减震效率,地震动的频谱特性和峰值加速度大小对TLD的减震效率有重要影响。

关键词：调谐流体阻尼器钢结构振动台模型试验减震

土-桩-钢结构-TLD系统振动台模型试验研究

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地震工程与工程振动 2006年第6期26卷 172-177页

作者：楼梦麟宗刚牛伟星陈根达同济大学土木工程防灾国家重点实验室上海200092

通过系列振动台模型试验,研究土-结构相互作用对结构TLD减震控制影响。文中首先提出试验模型设计中应考虑的几个主要问题及解决方法,然后介绍土-桩基础-钢结构-TLD相互作用体系的试验成果,分析TLD的减震效果,最后与刚性地基上钢结构TLD... 详细信息

通过系列振动台模型试验,研究土-结构相互作用对结构TLD减震控制影响。文中首先提出试验模型设计中应考虑的几个主要问题及解决方法,然后介绍土-桩基础-钢结构-TLD相互作用体系的试验成果,分析TLD的减震效果,最后与刚性地基上钢结构TLD减震试验结果相比较,揭示土-结构相互作用对TLD减震效率的影响特点。试验结果表明:土-结构相互作用使得TLD减震效率降低,这一削减作用受到输入地震动的频谱特性和强度的影响。因此,对于建在土层场地上的结构进行TLD减震设计时,应充分重视工程场地条件和地震动特性等实际情况。

关键词：土-结构相互作用 TLD减震控制钢结构振动台模型试验