回顾与展望:社会史视野下的中国蝗灾史研究

近二十多年来,社会史新颖的视角使史学研究趋向丰富和深入,但这并未引起蝗灾史研究者的重视。本文以蝗灾与社会的互动关系为线索,在梳理蝗灾史研究的发展脉络的基础上,对目前的研究不足提出几点看法,并就蝗灾史研究中应该引入新的视角和方法、挖掘新的历史资料等方面做出展望。     

区域产业结构演变的城市化响应机理研究

区域产业结构演变城市化响应的研究作为地理学新的研究领域,已经越来越成为理论界和学术界研究的热点。本文对产业结构演变城市化响应的内涵进行了界定,从产业结构演变城市化响应过程、强度、形态、机制以及变化趋势等几个方面系统分析了区域产业结构演变的城市化响应机理,并建立起理论体系,以期为区域产业结构与城市化的研究开拓新的研究视角。     

我国能源效率对产业结构演变响应的区域差异研究

通过分析我国30省(市、自治区)产业结构和能源效率演变特征,建立向量自回归模型,揭示能源效率对产业结构演变的响应机理及区域差异。结果显示:东部地区产业结构演变高度大于中西部和东北地区,我国能源效率总体呈自东南向西北递减态势,同时,两者在地区内部均存在较大差异;北京、上海第二产业对能源效率提高的抑制效应已经显著显现,天津、辽宁和黑龙江初步显现,其他省份尚未显现;东部、中部与东北、西部地区产业结构演变对能源效率提高总体分别呈正向推动、负向抑制和前期正向推动后期负向抑制效应。     

馆藏浮放陶瓷文物地震摇晃响应振动台试验

为保护可移动文物,采取试验方法研究了地震作用下馆藏浮放文物的摇晃响应.以故宫某展柜为原型,制作了1∶1比例的模型,并在展柜内放置了一陶瓷文物,进行了振动台试验.通过白噪声激励,获得了展柜的基频;通过输入不同类型、不同强度的地震波,研究了展柜和文物的地震响应;通过数值模拟,从理论上对模型地震响应进行了进一步论证.结果表明:对展柜而言,其基频在29～35 Hz之间,与地震波卓越频率相差较大,因而在地震作用下摇晃不明显;对文物而言,在地震波强度较小时能保持稳定振动状态,而在地震波强度较大时,文物容易产生明显摇晃并导致倾覆.此外,数值模拟结果与振动台试验结果吻合,证明了试验方法的有效性.在实际工程中,对高宽比较大的文物,应采取适当的加固措施,以减轻其摇晃震害.     

强风作用下木拱廊桥的风振响应分析——以文兴桥为例

中国传统木拱廊桥采用较短的木材构件,形成了较大的桥梁跨度,其整体造型优美,结构巧妙,构造特殊,具有重要的历史价值、艺术价值和科学价值。我国现存的传统木拱廊桥仅有百余座,集中分布于我国浙南和闽北地区,大多建于明清至民国时期,是我国木构桥梁建造技术和古代人民智慧的体现,而近些年来由于台风洪水等自然灾害导致的传统木拱廊桥破坏甚至损毁的事件时有发生。现有的对于传统木拱廊桥的研究大多着眼于其历史艺术价值和建造技术工艺等方面,鲜有对于其结构性能的研究,尤其缺乏强风作用下木拱廊桥的风振响应性能的深入研究。本工作为研究中国传统木拱廊桥在强风作用下的风振响应性能,以典型传统木拱廊桥——浙江泰顺的文兴桥为例,基于几何尺寸的精确测绘,采用SAP2000建立有限元模型进行了木拱廊桥的动力特性分析。研究内容包括以下几方面:首先,采用线性滤波法,基于自回归(AR)法模拟风场,利用MATLAB软件编写脉动风速时程。此后,由于我国现行的规范没有给出适用于木拱廊桥这一结构类型的风压体型系数,本工作通过CFD软件FLUENT风洞数值模拟得到适用于文兴桥的风压体型系数。最后,将模拟编译得到的时程风压作用于文兴桥的有限元模型得到其风振响应。计算结果表明:结构主振型为第一阶横向水平振动;风荷载对三节苗和五节苗两边最外侧的斜苗影响较大,对五节苗平苗的影响较大;下部剪刀撑的最大拉、压应力超过抗拉、抗压强度;剪刀撑脱榫将使下部斜撑的轴压力突增从而导致整体结构抗侧能力大幅降低;强风作用下传统木拱廊桥的时程计算风振系数为1.43～1.75,由此可见木拱廊桥风动力效应不容忽视。本研究成果反映了我国传统木拱廊桥在风荷载作用下结构构件的受力规律和整体结构的动力特性,并为我国传统木拱廊桥的风振性能评估和抗风保护提供理论依据,更科学地保护这一宝贵的建筑遗产类型。     

DUCTILITY REDUCTION FACTOR OF MDOF SHEAR-BUILDING STRUCTURES

In this paper, the results of recent studies on inelastic seismic response of MDOF shear-building structures are presented. In the last few decades, the concept of response modification factor R has been introduced and developed to account for inelastic nonlinear behaviour of structures under earthquakes. In this paper, an attempt has been made to adjust and extend this concept through introducing a modifying factor R _T . This factor is used for dynamic analysis of MDOF structures, including the calculation of inelastic response spectra. Sensitivity analysis was carried out to identify the parameters that have influence on R _T . It has been demonstrated that R _T is predominantly a function of number of stories, and accordingly a relationship has been suggested. Finally, an approximate approach has been developed for evaluating the seismic strength and ductility demands of MDOF structures.     

THREE DIMENSIONAL NONLINEAR BUILDING POUNDING WITH FRICTION DURING EARTHQUAKES

The three dimensional pounding phenomenon of two adjacent buildings during earthquakes with aligned rigid horizontal diaphragms is investigated for the linear and nonlinear structural response. The developed formulation takes into account three dimensional dynamic contact conditions for the velocities and accelerations based on the impulse-momentum relationship, using the coefficient of restitution e and the ratio μ, of tangential to normal impulses, which corresponds to the coefficient of friction under certain conditions. The contact points are determined geometrically from the displacements of the diaphragms' centre of mass. The results of the proposed formulation are compared with those obtained with the Lagrange multipliers approach. Test results are performed for two sets of multi-storey adjacent buildings subjected to real earth-quake motions with elastic and inelastic structural response.     

SEISMIC TORSIONAL EFFECTS ON DUCTILE STRUCTURAL WALL SYSTEMS

With a distinct design rather than analysis-oriented approach, some torsional phenomena, arising during the elasto-plastic seismic response of building structures, are addressed. It is postulated that existing code recommendations, expressed only in terms of the properties of elastic structures, are largely irrelevant when the design needs to be based on ductile system behaviour. Torsional restraint provided by elastic elements of a system, is claimed to be the desirable property controlling the amplification of inelastic translatory deformations of critical elements by storey twist. With the identification of the sources of inelastic element deformations, a simple behaviour-based design strategy is proposed. This should ensure that the displacement ductility demand, expected to be imposed on the system, does not result in deformations that, as a consequence of storey twist, may exceed the displacement ductility capacity of critical elements.     

Responding not Believing: Political Theology and Post-Secular Societyzxht

Abstract

In the past decade social theorists and Continental philosophers have returned again to an engagement with Christianity and the legacy of Christian belief. This is framed in the context of a Europe seen in transition to a post-secular identity and, often implicitly, against what is seen as an encroaching Islamic presence within Europe. This move has often brought together Marxist, post-Marxist, and Catholic-legacy philosophers, together with philosophical Protestants in an attempt to recover what I term a political theology of response. Response, in opposition to belief, signals an alternative post-secular turn of attempted inclusion out of a perceived shared cultural legacy. This essay asks if, in such a cultural-philosophical turn, the alternative post-secular turn of a political theology of response signals that belief remains within the private sphere as we seek to engage in a public conversation of non-believing "response"?     

Intensive hunting during the Iron Age of Southern Africa

Domestic faunal samples from farming sites from southern Africa dating from the Early (～AD 200–900) and Middle (～AD 900–1300) Iron Ages with large faunal samples are typically dominated by sheep/goats (both number of identified specimens and minimum number of individuals for large samples). However, four exceptions to this general pattern from these time periods are Bosutswe, Nqoma (both in Botswana), KwaGandaganda and Mamba (both in KwaZulu-Natal). At these sites, cattle outnumber sheep/goats, which have previously been measured using a Cattle Index. Intensive hunting is investigated at one of these sites, Bosutswe. Using various lines of evidence, including measuring high- vs. low-ranked prey, economic activities, as well as grease extraction and ageing from the most common taxon, plains zebra (Equus quagga), it is suggested that resource depression of wild game likely occurred. This would fit the expectation, based on human behavioural ecology, that as high-ranked game resource diminished over time, more emphasis was placed on cattle herding. The greater emphasis could have influenced descent patterns of people at Bosutswe. By the Late Iron Age (～AD 1300–1820s), cattle dominate most faunal assemblages in southern Africa with large sample sizes, and ethnographic and historical information confirm the central role these animals played in the social, political and economic lives of these farmers.