An Improved Displacement-Based Adaptive Pushover Procedure for the Analysis of Frame Buildings

The main purpose of this article is to develop an alternative adaptive pushover method in which multiple inelastic response spectra proportional to the instantaneous ductility ratio of the structure are employed to reflect the actual energy dissipation characteristic of the structure at a given deformation level. Based on the proposed methodology, two load patterns are independently applied to the structure and the envelope of the demand values is computed. The obtained results demonstrate that the proposed method provides improved predictions of the peak interstory and total drift profiles of the structure.     

明万历援朝将士与韩国姓氏

万历年间 ,明廷援朝抗倭将士立下赫赫战功。战后许多将士落籍朝鲜 ,亦有许多将士的子孙东渡定居。明朝将士落籍及援朝将士子孙东渡使朝鲜的姓氏结构发生了变化 ,增加了韩国历史上从未有过的姓氏 4个 ,本贯 14个。这些华裔在朝鲜朝廷和地方都受到重用 ,在军事、经济、文化等各个领域都做出了贡献。     

Practical Application of Digital Photogrammetry for Fieldwork in the American Midwest: An Example from the Middle Ohio Valley

The use of close-range digital photogrammetry for field documentation has been steadily increasing in the past half decade in several parts of the world. However, this technology has not been widely utilized in archaeological contexts in the American Midwest. We explore the utility of close-range photogrammetry in this region with examples from the Guard site (12D29), a Fort Ancient village located in southeastern Indiana. This article outlines the methods utilized for production of georeferenced 3-D models of several units excavated during the 2016 field season. These models as well as plan and profile orthophotos derived from them act as important supplements to standard photographs and drawings made in the field and easily integrate with the site GIS. Overall, we found close-range digital photogrammetry to be very useful to better document excavation details, doing so for limited cost and time expenditure.     

中国农村工业结构变化的省际差异分析

本文应用结构变化指数和专业化指数,定量分析了全国各省、市、区1986至1991年农村工业结构变化的差异、专业化差异及两者关系的差异,并根据各地专业化部门的变化趋势,对农村工业结构政策提出若干建议。     

Optimal Control of Structures under Earthquakes Including Soil-Structure Interaction

It is well known that the soil-structure interaction (SSI) changes the dynamic response of a structure supported on flexible soil. The analysis of optimally controlled SSI systems has certain difficulties due to the nature of the SSI and the optimal control problem. In this paper, a two-step iteration-based numerical algorithm is proposed to handle optimally controlled SSI systems under earthquakes. First, the optimal control forces are obtained by using a fixed-base system. Then, the optimal control forces are converted to the frequency domain by the Fourier transform technique to be used in the equations of the SSI system. The lateral displacement and the rocking of the foundation are obtained from the equations of the SSI system containing the optimal control forces in the frequency domain. The lateral displacement and rocking of the foundation are then converted to the time domain by the inverse Fourier transform technique, and the lateral accelerations and the rocking accelerations of the foundation are obtained by the forward finite difference method. During the second step, the optimal control forces are calculated again by using the lateral acceleration and the rocking acceleration of the foundation along with the earthquake ground motion. Using the method explained above, the optimal control forces obtained in the time domain are used in the equations of the soil-structure system from which the behavior of foundation and structure is obtained. In the final section of the paper, a numerical study is conducted for a controlled structure supported on flexible soil.     

Estimation of the Displacement of Viscously Damped Pinching Hysteretic Structures Subjected to Near-fault Ground Motions

To fulfill a displacement-based design or response prediction for nonlinear structures, the concept of equivalent linearization is usually applied, and the key issue is to derive the equivalent parameters considering the characteristics of hysteretic model, ductility level, and input ground motions. Pinching hysteretic structures subjected to dynamic loading exhibit hysteresis with degraded stiffness and strength and thus reduced energy dissipation. In case of excitation of near-fault earthquake ground motions, the energy dissipation is further limited due to the short duration of vibration. In order to improve the energy dissipation capability, viscous-type dampers have been advantageously incorporated into these types of structures. Against the viscously damped pinching hysteretic structure under the excitation of near-fault ground motions, this study aims to develop a seismic response estimation method using an equivalent linearization technique. The energy dissipation of various hysteretic cycles, including stationary hysteretic cycle, amplitude expansion cycle, and amplitude reduction cycle, is investigated, and empirical formulas for the equivalent damping ratio is proposed. A damping modification factor that accounts for the near-fault effect is introduced and expanded to ensure its applicability to structures with damping ratios less than 5%. An approach for estimating the maximum displacement of a viscously damped pinching hysteretic structure, in which the pinching hysteretic effect of a structure and the near-fault effect of ground motions are considered, is developed. A time history analysis of an extensive range of structural parameters is performed. The results confirm that the proposed approach can be applied to estimate the maximum displacement of a viscously damped pinching hysteretic structure that is subjected to near-fault ground motions.     

篇章结构:谋篇之形,结构之象

本文通过对篇章结构理论的解读,诠释了篇章结构理论作用下的谋篇之形和结构之象;讨论了谋篇之形是文章实现主题的设计蓝图;剖析了结构之象的具体组合形态及其对结构理论的意义;研究了篇章结构的延承发展和组合法则。指出它们的构象组合是一个完美的统一的整体,是谋篇布局的思维成果,是写作过程中对材料组织安排的思维轨迹的实现。     

不同方法加固古建筑榫卯构架抗震试验

为保护古建筑,采用试验方法,研究了不同方法加固榫卯节点后木构架的抗震性能。基于故宫太和殿某开间梁柱节点的具体尺寸,制作了1:8比例的4梁4柱木结构空间框架模型,其中梁和柱考虑为燕尾榫形式连接。采用人工加载方式,进行了低周反复加载试验,研究了马口铁、CFRP布和钢构件加固榫卯节点后对木构架抗震性能的影响。基于试验结果,获得了加固前后构架的力-侧移滞回曲线和骨架曲线,分析了构架耗能能力、刚度退化规律及变形能力,对不同方法加固木构架的抗震效果进行了对比,对其工程应用提出了建议。     

区域旅游:空间结构及其研究进展

区域旅游的空间结构涉及内容复杂。文章在对国内外研究进行综述的基础上,首先导入了区域旅游的概念,从旅游空间要素的识别与分析入手,接受了Pearce Douglas的观点,认为区域旅游供给的五大空间影响要素:吸引物、交通、住宿、支持设施和基础设施。从旅游规划、基本距离、旅游地区位等角度对旅游空间结构及其研究进展进行了阐释。指出由于缺乏范式的指引,国内外对区域旅游规划的研究体系较为松散,绝大多数研究者被实践性问题或者潮流牵着走。对区域旅游活动发生地的区位进行考查,显示出对城市这一空间经济实体的极大依赖。同时,指出旅游地宏观区位因子和可进入性是衡量旅游地发展潜力的主要因素。运用TDD理论对西安旅游目的地区域的空间结构进行了解释。     

重庆城市体系的结构研究

本文讨论了重庆城市建设发展的总特征,分析了城市体系发展中规模结构工业职能的空间结构所存在的主要问题,提出了进一步推动重庆城市体系建设发展的战略研究。