Modeling the Seismic Response of Modern URM Buildings Retrofitted by Adding RC Walls

Modern unreinforced masonry buildings with reinforced concrete slabs are often retrofitted by inserting reinforced concrete walls. The main advantages of this technique are the increase in strength and displacement capacity with respect to masonry structures. This article presents two modeling approaches for evaluating such structures: a shell-element model and a macro-element one. The objective is to formulate practical recommendations for setting up a macro-element model using as input the geometry of the structure and results from standard material tests. Structural configurations of masonry buildings, in which the insertion of reinforced concrete walls is an efficient retrofit technique, are also investigated.     

汉代的城郭

从先秦至两汉的中国古代社会 ,城市构成为人类文明活动的主要基盘。以这一时期的都城为中心的大城市的研究 ,近数十年来成果颇丰 1。而被视为封建王朝地方统治据点的众多郡县城市的构造尚未完全解明。本稿尝试着利用近年来不断出现的考古发掘资料 ,并与有限的文献史料相结合 ,通过对构成中国古代城市的基本要素——城郭的研究 ,尽可能地描绘出包括郡县城市在内的汉帝国城市的全景图。自中国古代城市产生之日起 ,城郭即作为其重要标志而存在。从文献记载的“黄帝筑邑 ,造五城”2 、“鲧作城郭”3到考古发现的长江流域的城头山 4 、石家河 5和…     

中国明清城墙

8处明清城墙位于中国6省8市,它们完整构建了中国南方与北方、都城与王城、府城与县城的逻辑体系,代表着长达500多年时间范围内的不同城市级别、不同地域范围却具有内在关联性的中国城市制度体系,最大限度地代表了组成该遗产的完整的文化背景、观念及技术体系。     

Observations on the Ancient City Walls of Rochester

Abstract

A recent survey of the floor-tiles of Cleeve Abbey has revealed a much larger range of designs and fabric groups than had previously been assumed. The style of the earliest pavements derive from those laid at Clarendon Palace in the first half of the 13th century, and may have been made on site. In the late 13th century tiles of high quality were imported from the Gloucester region to pave the frater. The next group of tiles came from a Somerset tilery operating at the same time or just after the Gloucestershire tilery. By c. 1330 the entire church was paved along with the sacristy and chapterhouse, using tiles made by a local industry. There was no revival of tile-making after the mid-14th century.     

城墙下的古戏班

大约二十来年前,西安城墙四周的护城河沿岸突然聚集了许多唱秦腔拉京胡演豫剧的古戏班子.初到西安的人,还未进城,就会被锣鼓家什所吸引.一声秦腔,一曲京胡,一段豫剧,历史长河似乎没有带走千古帝王的业绩,它们留在了古城子民的日常生活中.     

三城三河相套而成的古城典型--江苏武进春秋淹城个案探析

江苏武进春秋晚期的淹城,是我国目前同时期古城遗址中保存最为完整的一座。它从里向外,由子城、子城河,内城、内城河,外城、外城河即三城三河相套组成。这种城市的筑造形制,在我国古代城池遗存中可以说是绝无仅有。为此,通过淹城个案的探析,我们可以清楚地看到,古淹城的三城三河相套的建筑形制以及城市水上交通、水门的建设等都明显具有南方特点。     

药王·道童·雨师——宋耀州窑雨师赤松子瓷塑考辨

北京故宫藏有一件耀州窑瓷塑，被命名为“宋药王庙供像”。瓷塑为青年男子形象，赤足，双髻系蝴蝶结，弯眉圆目，面庞饱满。服饰自肩至膝下皆为草叶编缀而成，腰部系带，衣带打蝴蝶结，左手捧一葫芦形瓶，右手于胸前持一弯曲枝条。     

Capacity Design of Coupled RC Walls

Capacity design aims to ensure controlled ductile response of structures when subjected to earthquakes. This article investigates the performance of existing capacity design equations for reinforced concrete coupled walls and then proposes a new simplified capacity design method based on state-of-the-art knowledge. The new method is verified through a case study in which a set of 15 coupled walls are subject to nonlinear time-history analyses. The article includes examination of the maximum shear force in individual walls in relation to the total maximum shear force in the coupled wall system, and subsequently provides recommendations for design.     

Estimating the Size of Social Networks

It is notoriously difficult to define and estimate the size of individuals' social networks. Methods are suggested for estimating the size of such networks, using known rates of mobility together with survey data on the number of acquaintances of individuals who have recently moved. Special attention is given to the likely correlation between mobility rates and network size. Estimates are found to be consistent with previous estimates in the literature. The relation of this approach to multiplicity sampling and to “the small-world problem” is also discussed.     

飘洒在古诗中的春雨

雨,本是大自然的客观物象,当其成为人们的审美对象之后,便频频见诸诗人笔端。特别是对春雨,可谓情有独钟。观赏古典诗歌中有关春雨的篇章,或曲尽其态,摹尽自然精灵,或境生象外,开拓精神蕴涵,使人为之反复咏叹,含英咀华、陶冶性灵,获得审美的愉悦。我们不妨从浩瀚的诗海中,撷取一些名篇佳句,品赏诗人是如何将自在之物的春雨诗化为自我之物,将其自然美升华为艺术美的!“沾衣欲湿杏花雨,吹面不寒杨柳风”,这是僧志安的名句。“欲湿”二字,令人叫绝。说起春雨,人们总爱说“濛濛雨”、“毛毛雨”,诗人却说“沾衣欲湿杏花雨”?河辏惺毕溉缗C…     

原始沙捞越 赤道上的“隐秘天堂”

<正>"旅游圣经"《Lonely Planet》,对沙捞越热带雨林有这样的描述:"如果你一直对婆罗洲魂牵梦萦——梦见乘坐大船顺着浑浊的江河漂流,梦见像野人一样穿越茂密的大丛林,梦见炊烟袅袅的长屋和酒醉后狂放的舞步,梦见奇怪的生物和隐蔽的洞穴,梦见吹箭筒和猎取人头的蛮人……那么,现在你终于可以得偿所愿了。沙捞越就是婆罗洲最经典的代表,提到冒险和刺激,没有什么地方可以与之相媲美。"     

雪地自驾：穿越南太行

郭亮,与南坪、罗姐寨在海拔1700米的太行山深处,组成了一道靓丽的风景线。它最初闻名是出于谢晋导演的一部电影《清凉寺的钟声》,后来郭达、潘长江在这里拍摄了中国版＂虎口脱险＂——《举起手来》。但对于我们来说,它的诱惑可不止这些,开凿在万仞峭壁上的挂壁公路,是对驾车族的巨大诱惑,而一场意料之外的大雪,更让我们体会了雪地自驾的惊险与乐趣。     

Simple Homogenization-Topology Optimization Approach for the Pushover Analysis of Masonry Walls

ABSTRACT

A topology optimized rigid triangular FE macro-model with non-linear homogenized interfaces for the pushover analysis of in plane loaded masonry is presented. The shape of the mesh and the position of the interfaces is evaluated through a topology optimization approach that detects the main compressive stress fluxes in the structure. Different values of the horizontal action are considered to derive an adaptive mesh or an optimal discretization that is suitable for multiple loads. Masonry properties are calibrated by means of a homogenization approach in the nonlinear range. To tackle elastic and inelastic deformations, interfaces are assumed to behave as elasto-plastic with softening in both tension and compression, with orthotropic behavior. The two-step procedure competes favorably with classic equivalent frame approaches because it does not require a-priori assumptions on the mesh and on the length of the rigid offsets. An example of technical relevance is discussed, relying into a multi-story masonry wall loaded up to failure.     

江南烟雨里宿眠

暮春的时候,,心血来潮决定给自己放个小假。想着,也体会一下绿遍山原白满川,子规声里雨如烟的美丽。背上行囊,伴着耳机中的音乐,就这么一路前行,恍然之间发现自己已身在江南,住进了江南的烟雨朦胧之中……宿在那个有着南朝四百八十寺的烟雨江南里,演绎着属于自己的情调。     

Estimating the Higher-Mode Response of Ductile Structures

While the importance of higher-mode actions is appreciated within the engineering community, the affect that ductile nonlinear response has on higher-mode characteristics and the subsequent implications this has for design has received little attention. In this article, the manner in which the higher-mode response of frame-wall structures is affected by inelastic behavior is closely examined and a means of accounting for this in design is proposed. The work focuses firstly on the characteristics of the higher modes present at the development of peak response and then considers how these characteristics would affect the total forces in the building. The study utilizes a series of nonlinear time-history analyses of two different groups of RC frame-wall structures subject to a suite of real records. It is shown that a new modal analysis approach that incorporates transitory inelastic modal characteristics gives significantly improved predictions of peak base shear in frame-wall structures than more traditional modal analysis methods which use elastic higher-mode characteristics. The issues associated with the use of transitory inelastic modal characteristics are discussed and various challenges that would need addressing for the prediction of other response parameters and structural types are identified.     

The Influence of Masonry Infill Walls in the Framework of the Performance-Based Design

In this article, a performance-based seismic design (PBD) methodology is proposed for the design of reinforced concrete buildings, taking into account the influence of infill walls. Two variants of the PBD framework are examined: The first is based on the non-linear static analysis procedure (NSP) while the second relies on the non-linear dynamic analysis procedure (NDP). Both design approaches are compared in the context of structural optimization with reference to the best possible design achieved for each case examined. Life-cycle cost analysis is considered a reliable tool for assessing the performance of structural systems and it is employed in this study for assessing the optimum designs obtained. The optimization part of the problem is performed with an Evolutionary Algorithm while three performance objectives are implemented in all formulations of the design procedures. The two most important findings can be summarized as follows: (i) if structural realization follows the design assumptions, then total expected life-cycle cost of the three type of structures, bare, fully infilled and open ground story, is almost the same and (ii) if an open ground story building is designed as bare or as fully infilled frame, real performance will be much worse than anticipated at the design stage.