Seismic Performance Assessment of Slender T-Shaped Reinforced Concrete Walls

T-shaped slender reinforced concrete (RC) structural walls are commonly used in medium-rise and high-rise buildings as part of lateral force resisting system. Compared to its popularity, experimental results on seismic performance of these walls are relatively sparse, especially for data regarding these walls in the non-principal bending directions. This article aims at providing additional experimental evidence on seismic performance of T-shaped RC structural walls. Experimental results of six T-shaped RC walls were presented. These walls resemble the structural walls found in existing buildings in Singapore and possess slightly inferior details compared to the requirements of modern design codes. The test variables were the loading direction and the axial load ratio. The experimental results were discussed in terms of the failure mechanisms, cracking patterns, hysteretic responses, curvature distributions, displacement components, and strain profiles. In addition, the experimental results were compared with methods commonly adopted in current design practice including the nonlinear section analyses, shear strength models and effective width of the tension flange. The experimental data illustrate that the shear lag effect not only was not accurately accounted for by the effective width method but also significantly affected the strength and stiffness of the tested specimens.     

明代延绥镇长城的修筑及其地理意义

本文对明代延绥镇长城的"二边"和"大边"的修筑时间、地点、修筑者等问题进行了系统研究,指出"二边"长城为余子俊督修,时间为成化九年(1473年)三、四月至次年的三、四月之间;"大边"长城则为文贵主持修建,时间在弘治十七年(1504年)九月至正德二年(1507年)四月之间。"二边"长度为2013里(明里)195步,约合1183.4公里;"大边"长度为1087里(明里),约合639.2公里。延绥镇长城的修筑过程与明代西北边防方略的发展过程密切关联,也间接反映了边地卫所土地屯垦的变化,对研究历史时期陕北长城沿线环境变迁具有重要意义。     

Seismic Overstrength of Shear Walls in Parking Structures with Flexible Diaphragms

The objective in current design practice for parking structures is that energy is dissipated through the formation of plastic hinges at the base of shear walls while floor diaphragms remain elastic and are vertically supported by a combination of shear walls and gravity resisting columns. Unfortunately, this objective is not always achieved due to inaccuracies in current methods for calculating demands on shear walls and in calculating the capacity of shear walls (IBC 2003 International Building Code. International Conference of Building Officials. Whittier, CA.  [Google Scholar], ACI code). When demands are overestimated and capacity underestimated, then diaphragm can fail prior to flexural yield of shear walls as was observed in several parking structures in the 1994 Northridge earthquake.

Eigenvalue and inelastic dynamic response analyses were performed in order to investigate the effects of diaphragm flexibility on wall responses and of wall overstrength on diaphragm responses. The elongated periods of parking structures due to diaphragm flexibility were found to significantly decrease seismic force demand on shear walls relative to what is calculated using codes of practice in which diaphragms are assumed to be rigid. This leads to the over design of shear walls, which further compounds the problem by preventing the flexural yielding of these walls and thereby driving inelastic response to diaphragms. Various degrees of diaphragm flexibility, shear wall layout, seismic zone, and the number of stories were considered in these analyses.

Inelastic static pushover analyses were preformed to investigate the design and capacity evaluation of shear walls. The results illustrate that the shear capacity of walls may be close to twice that calculated by codes of practice. The largest overstrengths were observed in shear walls with low height-to-length ratios in which a significant portion of the lateral load was taken by direct strut action to the foundation and without placing demands on the longitudinal tension reinforcement in the shear walls. The article concludes that methods in codes of practice for calculating shear wall demands and capacities need to be improved if good seismic performance of parking structures is to be achieved.     

Experimental Evaluation of Seismic Performance of Squat RC Structural Walls with Limited Ductility Reinforcing Details

This article describes an experimental study carried out on of reinforced concrete (RC) walls of less confining reinforcement than that recommended by ACI 318. A total of eight RC walls with boundary elements comprising of five walls with aspect ratio of 1.125 and three walls with aspect ratio of 1.625 were tested by subjecting them to low levels of axial compression loading and simulated seismic loading, to examine the structural performance of the walls with limited transverse reinforcement. Conclusions are reached concerning the failure mode, drift capacity, strength capacity, components of top deformation, and energy dissipation characteristics of walls on the seismic behavior with limited transverse reinforcement. The influences of axial loading, transverse reinforcement in the wall boundary elements, and the presence of construction joints at the wall base on the seismic behavior of walls are also studied in this paper. Lastly, reasonable strut-and-tie models are developed to help in understanding the force transfer mechanism in the walls tested.     

Cattle mobility in prehistoric Britain: strontium isotope analysis of cattle teeth from Durrington Walls (Wiltshire,Britain)

An important role has been envisaged for cattle during the Neolithic period in Britain based on their prominence within the faunal assemblages of the period as a whole. The relative ease with which cattle can be moved over long distances and the requirement to provide ample pastureland leads almost inescapably to the consideration of prehistoric cattle movement. This paper presents the results of an investigation into the mobility of Late Neolithic cattle at the well-known site of Durrington Walls, Wiltshire. ⁸⁷Sr/⁸⁶Sr values from cattle (Bos taurus) teeth were compared to local vegetation samples, well established values from archaeological material and to known geological conditions in order to determine whether individual animals were raised in areas with similar geological conditions as those found at the site (i.e. chalkland), and therefore whether the animals were of allochthonous or autochthonous origin. In total, 13 mandibular molars from Durrington Walls were analysed. Two of the animals included in the study were certainly raised under conditions similar to those found in the vicinity of Durrington Walls, but the other 11 provided signatures so distinct from that found locally that they could not have been raised on chalkland. From the results it is suggested that cattle were brought to the site from a variety of grazing areas in different parts of Britain. The implication of these findings is that the movement of cattle was undertaken during the Late Neolithic, and that in a number of cases substantial distances must have been traversed in order for animals to reach the site. In addition, the study provided valuable information for the interpretation of the site, which attracted people from a variety of regions, probably for ceremonial reasons.     

Seismic Behavior Prediction of Flanged Unreinforced Masonry (FURM) Walls

In most available studies, unreinforced masonry (URM) walls are idealized as rectangular sections, while in reality walls have effective sectional shapes such as C, I, T, and L. In this article, the results of experimental and analytical assessment of flange effects on the behavior of I- and C-shaped URM walls are reported. Four clay brick walls at half scale were tested. Two specimens were designed with I- and C-shaped sections, and for comparison, two additional specimens were designed without flanges. The tests showed that under constant axial load the strength of the I-shaped wall increases, but that of the C-shaped wall decreases, because of out-of-plane distortion effects. Despite the loss of strength, both flanged walls indicated almost similar initial stiffness, deformation capacity, and mode of failure in comparison with walls without flanges. A mixed-mode analytical model is proposed to predict the lateral force displacement curve of flanged URM (FURM) walls. The proposed analytical model is based on section analysis of the walls and shows good agreement with previous experimental results.     

“山东定陶王墓地（王陵）M2汉墓保护工程”设计研究

山东定陶王墓地（王陵）M2汉墓为目前我国已发掘规模最大的“黄肠题凑”汉墓,201 3年被公布第七批全国重点文物保护单位.20 14年,中国文化遗产研究院组织编制的“山东定陶王墓地（王陵）M2汉墓保护工程方案”获国家文物局审批通过.本文概述了“山东定陶王墓地（王陵）M2汉墓保护工程”的项目背景、项目设计、任务分解及各个子项目工作的开展情况.     

Contested Identities: The Dissonant Heritage of European Town Walls and Walled Towns

Town walls have always played a critical role in shaping the identities and images of the communities they embrace. Today, the surviving fabric of urban defences is a feature of heritage holding great potential as a cultural resource but in management terms one that poses substantial challenges, both practical and philosophical. Town walls can be conceptualised as a ‘dissonant’ form of heritage whose value is contested between different interest groups and whose meanings are not static but can be rewritten. Evidence is gathered from walled towns across Europe, including member towns of the WTFC (Walled Towns Friendship Circle) and inscribed UNESCO World Heritage Sites, to explore the cyclical biographies of town walls in their transformation from civic monuments, through phases of neglect, decay and destruction to their current status as cherished cultural resources. To explore this area of interface between archaeology and tourism studies, the varying attitudes of populations and heritage agencies to walled heritage are reviewed through examination of policies of conservation, preservation, presentation and restoration. Areas of commonality and contrast are thus identified.     

文化遗产保护中的风险评估——以“台州府城墙”洪灾为例

文化遗产风险管理是近十年国际、国内文化遗产保护领域越来越引起重视的课题之一,而风险评估是风险管理的重要环节。本文以ICCROM-CCI-ICN三家研究机构制定的"风险管理"体系为主要依据,以"台州府城墙"洪灾研究为实例,介绍风险管理基本概念,探讨文化遗产"风险评估"的研究方法,并结合台州府城墙保护实践思考遗产风险评估对文化遗产保护的影响。     

Hard to miss,easy to blame? Peacelines,interfaces and political deaths in Belfast during the Troubles

As Northern Ireland moves further from the period of conflict known as the ‘Troubles’, attention has increasingly focussed on the social and material vestiges of that conflict; Northern Ireland is still a deeply-divided society in terms of residential segregation between Catholic nationalists and Protestant unionists, and urban areas are still, indeed increasingly, characterised by large defensive walls, known as ‘peacelines’, which demark many of the dividing lines between the two communities. In recent years a body of literature has emerged which has highlighted the spatial association between patterns of conflict fatality and proximity to peacelines. This paper assesses that relationship, arguing that previous analyses have failed to fully take account of the ethnic complexity of inner-city Belfast in their calculations. When this is considered, patterns of fatality were more intense within the cores or ‘sanctuaries’ of highly segregated Catholic and Protestant communities rather than at the fracture zones or ‘interfaces’ between them where peacelines have always been constructed. Using census data at a high spatial resolution, this paper also provides the first attempt to provide a definition of the ‘interface’ in clear geographic terms, a spatial concept that has hitherto appeared amorphous in academic studies and media coverage of Belfast during and since the Troubles. In doing so it embodies both the material and demographic aspects of social division in Northern Ireland, and suggests an urgent need to reappraise the true role of these forms of social boundary in influencing patterns of violent conflict.