钢筋混凝土扁梁柱节点抗震设计方法

为考虑扁梁柱节点内、外核心区的相互作用,对扁梁柱节点的内、外核心区进行了重新划分,认为内、外核心区有一个重叠的区域,给出了地震作用在扁梁柱节点内外核心区的分配方法,采用压杆模型和软化桁架模型,提出扁梁柱节点的设计方法。该方法可以考虑节点核心区钢纤维和扁梁中无粘结预应力对扁梁柱节点抗剪极限承载力的作用。该设计方法的可靠性得到四个钢筋混凝土扁梁柱节点试验数据的验证。     

The relationships between tropical Atlantic sea level variability and major climate indices

Relationships were examined between variability in tropical Atlantic sea level and major climate indices with the use of TOPEX/POSEIDON altimeter and island tide gauge data with the aim of learning more about the external influences on the variability of the tropical Atlantic ocean. Possible important connections were found between indices related to the El Niño–Southern Oscillation (ENSO) and the sea levels in all three tropical regions (north, equatorial, and south), although the existence of only one major ENSO event within the decade of available altimetry means that a more complete investigation of the ENSO-dependence of Atlantic sea level changes has to await for the compilation of longer data sets. An additional link was found with the Indian Ocean Dipole (IOD) in the equatorial region, this perhaps surprising observation is probably an artifact of the similarity between IOD and ENSO time series in the 1990s. No evidence was obtained for significant correlations between tropical Atlantic sea level and North Atlantic Oscillation or Antarctic Oscillation Index. The most intriguing relationship observed was between the Quasi-Biennial Oscillation and sea level in a band centered approximately on 10°S. A plausible explanation for the relationship is lacking, but possibilities for further research are suggested.     

Notes

Abstract

J. N. L. Baker. The History of Geography. Barnes &; Noble, Inc., 105 Fifth Ave., New York 3, N.Y., 1963. xxviii and 266 pages with table of contents and index. $7.50.

R. J. Harrison Church. Environment and Policies in West Africa. D. Van Nostrand Co. Inc., 120 Alexander St., Princeton, N.J., 1963. 135 pages with table of contents, maps, diagrams and general index. $1.45.

Richard M. Highsmith, and J. Granville Jensen. Geography of Commodity Production, Second Edition. J. B. Lippincott Co., East Washington Sq., Philadelphia 5, Pa., 1963. 515 pages with table of contents, maps, photographs, graphs and index. $7.95.

Oliver H. Heintzelman and Richaid M. High-smith, Jr., World Regional Geography. Prentice-Hall, Inc., Englewood Cliffs, N.J., 1963, 2nd edition. 391 pages with table of contents, pictures, maps, diagrams, and index. $7.95.

Gerd Fraenkel with Lindley J. Stiles. Today's World in Focus: Israel. Ginn and Co., Statler Building, Boston 17, Mass., 1963. 122 pages with table of contents with black and white photographs with colored illustrations, appendices and bibliography. $1.40.

Thomas Sterling. Exploration of Africa. Horizon Caravel Books, 551 Fifth Ave., New York 17, N.Y., 1963. 153 pages with table of contents, maps, color and black and white illustrations and index. $3.95.

C. W. Harrison. Conservationists and What They Do. Franklin Watts, Inc., 575 Lexington Ave., New York 22, N.Y., 1963. 170 pages with table of contents and index. $3.95.

William Trout Chambers and Lorrin Kennamer, Jr. Texans And Their Land. The Steck Co., P.O. Box 16, Austin, Tex., 1963. 232 pages with table of contents, black and white pictures, colored maps, appendix, bibliography and index. $4.88.

Olive Burt. The First Book of Utah. Franklin Watts, Inc., 575 Lexington Ave., New York 22, N.Y., 1963. 66 pages with table of contents, general map of Utah, photographs and an index. $2.50.

Bernt Lloyd Wills. North Dakota: The Northern Prairie State. B. L. Wills, University of North Dakota, Grand Forks, N.D., 1963. 318 pages with table of contents, black and white pictures and black and white illustrations and index. $4.80.

Mary Foley Horkheimer and John W. Differ, (compilors and editors). Educators Guide to Free Filmstrips. Educators Progress Service, Randolph, Wis., 1963. 15th Annual Edition with 159 pages, table of contents and indices. $6.00.

Patricia Horkheimer Suttles, (editor). Educators Guide to Free Social Studies Materials. Educators Progress Service, Randolph, Wis., 1963. 402 pages with XV pages editorial comment and table of contents. $6.75.

C. B. Hitchcock and O. M. Miller. Nine Glacier Maps, Northwestern North America with Text. Special Publication No. 34. American Geographical Society, 156th St. and Broadway, New York 32, N.Y., 1960. 22 pages with table of contents, three appendices, one table, one locational text map, 15 photographs and nine separate topographic maps. $3.00.

Harry M. Caudill. Night Comes To The Cumberlands. Little, Brown &; Co., 128 Oliver St., Paterson 1, N.J., 1963. 394 pages with table of contents and black and white photographs. $6.75.     

带双腹板顶底角钢连接初始刚度研究

初始连接刚度在节点刚度分类和钢结构地震分析中占有很重要的地位,因此研究连接的初始刚度很有现实意义。主要研究带双腹板顶底角钢连接初始刚度的确定方法以及影响其性能的主要因素。     

TESTING OF ENERGY DISSIPATING CLADDING CONNECTIONS

Properly designed precast concrete cladding could potentially provide lateral stiffness, ductility, and energy dissipation for an overall building structure, especially during earthquakes. This paper describes a set of advanced connections that take advantage of the interaction between facade panels and structure (mainly due to horizontal interstorey drift) to dissipate energy, thereby reducing the response of the main structure. The results of an experimental program to characterize the hysteretic behaviour of advanced connections are presented. Design equations for the advanced connections are then calibrated against the test results, and the corresponding design charts are presented. It is anticipated that this research will lead to innovative ways of viewing the entire cladding system of a building.     

Effect of gravity framing on the overstrength and collapse capacity of steel frame buildings with perimeter special moment frames

This paper investigates the effect of the gravity framing system on the overstrength and collapse risk of steel frame buildings with perimeter special moment frames (SMFs) designed in North America. A nonlinear analytical model that simulates the pinched hysteretic response of typical shear tab connections is calibrated with past experimental data. The proposed modeling approach is implemented into nonlinear analytical models of archetype steel buildings with different heights. It is found that when the gravity framing is considered as part of the analytical model, the overall base shear strength of steel frame buildings with perimeter SMFs could be 50% larger than that of the bare SMFs. This is attributed to the gravity framing as well as the composite action provided by the concrete slab. The same analytical models (i) achieve a static overstrength factor, Ω_s larger than 3.0 and (ii) pass the collapse risk evaluation criteria by FEMA P695 regardless of the assigned total system uncertainty. However, when more precise collapse metrics are considered for collapse risk assessment of steel frame buildings with perimeter SMFs, a tolerable probability of collapse is only achieved in a return period of 50 years when the perimeter SMFs of mid‐rise steel buildings are designed with a strong‐column/weak‐beam ratio larger than 1.5. The concept of the dynamic overstrength, Ω_d is introduced that captures the inelastic force redistribution due to dynamic loading. Steel frame buildings with perimeter SMFs achieve a Ω_d > 3 regardless if the gravity framing is considered as part of the nonlinear analytical model representation. Copyright © 2014 John Wiley & Sons, Ltd.     

Out‐of‐plane stability of buckling‐restrained braces including moment transfer capacity

Buckling‐restrained braces (BRBs) are widely used as ductile seismic‐resistant and energy‐dissipating structural members in seismic regions. Although BRBs are expected to exhibit stable hysteresis under cyclic axial loading, one of the key limit states is global flexural buckling, which can produce an undesirable response. Many prior studies have indicated the possibility of global buckling of a BRB before its core yields owing to connection failure. In this paper, BRB stability concepts are presented, including their bending‐moment transfer capacity at restrainer ends for various connection stiffness values with initial out‐of‐plane drifts, and a unified simple equation set for ensuring BRB stability is proposed. Moreover, a series of cyclic loading tests with initial out‐of‐plane drifts are conducted, and the results are compared with those of the proposed equations. © 2013 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.     

基于信息流的长三角城市群中心性及影响因子研究

信息流作为流空间的一种重要表现形式,为城市群网络研究提供了新视角。但目前利用信息流对城市群的研究多侧重于描述城市间的层级关系或网络结构的外部特征,对网络结构及其时空演变规律缺乏从点到面的系统分析,且较少考虑距离因素。该文提出假设:信息流会在远距离影响城市间的交互,据此利用2011年、2015年、2019年信息流研究长三角城市群地理中心性随距离的变化情况,并对城市间关联的影响机制进行分析。研究表明,长三角城市群网络的主体结构由以上海为核心向四周辐射的格局转换为以上海、苏州、南京、杭州4个城市构成的多核心结构;城市群内部各城市发展呈现由东向西递减趋势,短距离尺度上,距离增长导致城市间交互强度逐渐减弱,长距离尺度上,城市属性成为城市间交互的主导因素;选取的影响因子与信息流的相关性日益增长,其中距离因子与信息流强度呈负相关,表明流空间一定程度上减弱了距离因素对城市间关联强度的影响。     

钢框架后张抗震梁柱节点的非线性分析

推导了后张顶底角钢梁柱节点的初始刚度及极限承载力的一般公式,并利用ANSYS建立了其三维有限元模型,模拟该节点在地震荷载下的受力特征.分析表明,后张顶底梁柱节点具有与传统焊接刚性节点相近的刚度,能够充分发挥各个组成构件的性能,且残余变形较小.对比证明,角钢厚度和后张力大小是影响节点性能的主要因素.最后针对后张节点的薄弱环节提出了适合应用的改进形式.     

Returning home: migrant connections and visions for local development in rural Nepal

Migration to domestic and international destinations has become an emblematic feature of Nepal’s societal changes. Part of this development is education migration from rural to urban areas within the borders of Nepal, an often overlooked but increasingly important aspect of contemporary migration flows. By focusing on these educational migrants, this paper explores how they connect to their rural homes. Guided by a critical reading of the migration-development scholarship, the paper examines how migrants and their relatives make sense of educational migrants’ remitting and returning practices, and by comparing three groups of educational migrants, the migrants’ reasons for staying connected and sending remittances are scrutinized. The paper finds that although educational migrants do not generate extensive economic remittances for local development in Nepal, they stay connected to their rural homes and partake in important social remittance practices that represent a vision for impacting local development.