MODIFICATION OF SITE RESPONSE IN PRESENCE OF LOCALISED SOFT LAYER

Experimental and numerical simulations are performed to evaluate the modification of ground response resulting from either the presence of soft layers or occurrence of partial liquefaction. Results from two densely instrumented dynamic centrifuge tests are presented to show the ambiguous role played by the presence of a soft layer. It was found that the lateral extent of the soft layer has significant influence on the overall response of the layered strata and any structure founded on it. The experimental observations are supported by simplified numerical analysis. The amplification or deamplification of the input motion is found to be a function of the ratio of the width of soft layer to the wave length. Based on the numerical analysis, a general function describing the site amplification is presented which may be used as a guide in seismic design of foundations in such layered strata.     

COMPLEX MODE SUPERPOSITION ALGORITHM FOR SEISMIC RESPONSES OF NON-CLASSICALLY DAMPED LINEAR MDOF SYSTEM

This paper deals with a complex mode superposition method for the seismic responses of general multiple degrees of freedom (MDOF) discrete system with complex eigenvectors and eigenvalues. A delicate general solution, completely in real value form, for calculat-ing seismic time history response of the MDOF system which cannot be uncoupled by normal modes, is deduced based on the algorithms of the complex superposition method. This solution comprises of two parts which are in relation to the Duhamel integration to sine and cosine function respectively. The related term of the Duhamel integration to sine function is actually the displacement response of the oscillator with corresponding modal frequency and the damping ratio. The other can be transferred into a combina-tion of the displacement and velocity responses of the same oscillator. In order to meet the practical needs of seismic design based on code design spectra for various kinds of structures equipped by viscous dampers, the complex complete quadratic combination (CCQC) method is deduced following similar procedures such as the well-known CQC method, in which a new modal velocity correlation coefficient, together with a new modal displacement-velocity correlation coefficient are involved besides the modal displacement correlation coefficient in normal CQC formula. The new algorithm of CCQC is not only as concise as that of the normal CQC but also has explicit physical meaning. The results obtained from complex mode superposition approaches are discussed and verified in some examples through step by step integration computation under a prescribed earth-quake motion input. From these examplary analyses, it may be pointed that the CCQC algorithm normally yields conservative outcome and that the forced mode uncoupling approach has good approximation even the discussed examplary structures are strongly non-proportional.     

国内外旅游解说研究进展

旅游解说是旅游景区服务设施的重要组成部分,但相关研究滞后于实践发展。基于国内外关于旅游解说文献资料的整理分析,认为现有的研究集中于概念辨析、解说媒介、案例规划设计、解说系统评估、新兴旅游方式解说、多学科理论引入等方面。同时从研究内容、研究理论、数据来源、分析方法方面对比了国内外旅游解说研究的异同。最后提出国内旅游解说未来重点的研究内容,以及在研究方法上可借鉴国际研究,采用更多定量定性方法结合使研究成果更加丰富。     

基于细分类型的南京市创意产业空间演化特征与差异

运用核密度分析的方法,对南京市创意产业总体和细分类型的空间分布演化特征和差异进行研究。研究表明,南京市创意产业总体上呈现集聚态势,集聚重心主要位于城市商业和商务中心,并沿城市商务业主轴中山北路和中山路向外扩散,与外围地区的小型据点呈连绵粘合之势。然而,各类创意产业的空间格局与演化又呈现出一定的差异,主要表现在分布模式、演化态势、集聚强度、集聚速度等方面。这些差异主要与各类创意产业的行业关联特征、所有制结构、企业规模结构、行业发展阶段与增长趋势的差异相关。     

SHAPE MEMORY ALLOYS IN SEISMIC RESISTANT DESIGN AND RETROFIT: A CRITICAL REVIEW OF THEIR POTENTIAL AND LIMITATIONS

Shape memory alloys (SMAs) are a class of materials that have unique properties, including Young's modulus-temperature relations, shape memory effects, superelastic effects, and high damping characteristics. These unique properties, which have led to numerous applications in the biomedical and aerospace industries, are currently being evaluated for applications in the area of seismic resistant design and retrofit. This paper provides a critical review of the state-of-the-art in the use of shape memory alloys for applications in seismic resistant design. The paper reviews the general characteristics of shape memory alloys and highlights the factors affecting their properties. A review of current studies show that the superelastic and high-damping characteristics of SMAs result in applications in bridges and buildings that show significant promise. The barriers to the expanded use of SMAs include the high cost, lack of clear understanding of thermo-mechanical processing, dependency of properties on temperature, and difficulty in machining.     

SEISMIC DESIGN OF BASE-ISOLATED STRUCTURES USING CONSTANT STRENGTH SPECTRA

This paper presents the concept of constant strength design spectra for the design of base-isolated structures; particularly those structures using isolators with a bilinear hys-teretic behaviour when subjected to dynamic loading. The constant strength design spectra relate peak accelerations, velocities, displacements and effective isolated natural periods for bilinear systems with a given yield strength and post yield stiffness. Constant strength design spectra could be useful for the design of base isolators with bilinear hysteretic behaviour, as these devices can be designed for fixed yield strength and post yield stiffness. The concept of constant strength design spectra and its application for the design of base isolated structures is illustrated with case studies of specific structures.     

EFFECT OF SOIL-STRUCTURE INTERACTION ON SEISMICALLY ISOLATED BRIDGES

The objective of this study is two-fold: first, to assess the effects of soil-structure interaction (SSI) on the response of seismically isolated bridge piers and, second, to develop a method that considers SSI and can be easily applied to the preliminary design of bridges. Emphasis is given on pier behaviour, because piers together with the abutments are the most critical components of a bridge with a high potential for concentration of ductility demands during earthquakes. The relative importance that several parameters of the bridge-isolators-soil system play on design is examined. Conclusions and suggestions that can lead to safer and more economical isolated pier design are also presented. Cases in which SSI needs to be incorporated in seismically isolated bridge design are identified and ways to take advantage of SSI in order to enhance safety level and reduce design costs are recommended.     

网络社会视角下的城市意象理论辨析与规划应用

在信息技术深度融合的网络社会进阶中，移动互联网支撑城市环境的即时共享与未来愿景，非在地的空间感知生成元宇宙类现实/虚拟的城市意象，网络媒介叠加于建成环境主/客观作用的传统经验感知，形成感知拼贴、地方再构、时间重叙、认知分异的意象特征。研究通过梳理互联网语境下的城市意象研究，揭示网络社会背景下城市意象的先验式建构过程，发现了意象节点偏离于城市社会经济活动峰值区域的一般规律，并归纳了互联网环境下城市意象研究的图片、文本和轨迹等应用素材，以丰富人本主义城市设计理论。     

DEFORMATION-CONTROLLED EARTHQUAKE-RESISTANT DESIGN OF RC BUILDINGS

A procedure for deformation-controlled, or displacement-based, seismic design of multistorey RC buildings is proposed, implemented and applied for the full design of a four-storey RC structure. It is integrated into the overall structural design, along with the design for the non-seismic actions and consists of a ULS verification against the conventional strain limits for a frequent “serviceability” earthquake and of proportioning the compression reinforcement and the transverse reinforcement of critical regions of members to meet the member peak inelastic chord rotation demands under the “life-safety” seismic action. Quantitative rules and expressions are proposed for the estimation of (a) mean and upper-characteristic peak inelastic chord rotation demands, through appropriate linear-elastic analyses, and (b) mean and lower-characteristic values of member ultimate chord rotations, in terms of member geometric and material data.     

INFLUENCE OF CAPACITY DESIGN METHOD ON THE SEISMIC RESPONSE OF R/C COLUMNS

Abstract

This paper aims at assessing the influence of the design procedure followed in designing the columns of a reinforced concrete (R/C) building on the performance of the columns, aa well as of the structure as a whole, when subjected to seismic loading; to identify potential weaknesses in currently adopted procedures; and to present a new procedure which is based on currently-available, powerful analytical tools, and results in increased reliability with regard to seismic loading. Two case studies are presented, involving multistorey reinforced concrete buildings with frame and dual structural systems subjected to various appropriately-scaled input accelerograms. The results obtained indicate that capacity design of columns results in adequate safety margins against failure, even when the adopted overstrength factors are quite low, but hinging in columns is not avoided unless very high overstrength factors are used. The suggested novel technique of capacity design led to very satisfactory seismic performance, and offers the possibility of cost reduction by achieving an appropriate balance between provided flexural strength and corresponding confinement.     

中部地区城乡收入两极分化程度分析及其时空特征变化

ER型指数测算表明,中部地区88个地市(州)城乡居民收入两极分化程度存在明显的时空变化和地区分异;根据2000年、2009年各地市ER指数值,分别将88个地市分为四大类型区,根据2000-2009年各地市ER指数值的变化情况,将88个地市又分为三类地市,综合分析2000-2009年中部地区城乡收入两极分化程度的时空特征变化。分析结果显示:2000-2009年,中部地区城乡收入两极分化程度越来越严重,绝大多数地市的城乡收入极化程度变化呈现出加速上升或一般化上升趋势,各省城乡居民收入两极分化程度也有很大差别;城乡收入极化程度各类型区的空间分布情况发生了明显的变化,各省收入极化程度变化不同类型区的分布存在明显的差异。     

COMPETITIVE LOCATION UNDER UNCERTAINTY OF COSTS

ABSTRACT. In this paper, we study the centroid problem from competitive location theory for a linear market with uniform demand, assuming that the leader has imperfect information about the follower's fixed and marginal costs. It is shown that the general version of this problem can be formulated as a nonlinear programming problem and the exact solution can be obtained analytically in a special case. A simple strategy is also given for the general problem, and it is proven that this strategy has a guaranteed error bound. It is demonstrated that uncertainty of costs might lead to market failure in the centroid problem, but this disappears if the game is repeated and the firms learn from observing each other's moves. It is also shown that it is possible for the leader to obtain optimal expected profit at a low perceived risk, with only sufficient, and not necessarily perfect, information. These two observations lead to our primary conclusion from the study that although cost uncertainty is a realistic feature of most competitive location models, there are very effective ways of dealing with it.     

CALIBRATION OF FORCE REDUCTION FACTORS OF RC BUILDINGS

A comprehensive study is undertaken to assess and calibrate the force reduction factors (R) adopted in modern seismic codes. Refined expressions are employed to calculate the R factors “supply” for 12 buildings of various characteristics represent a wide range of medium-rise RC buildings. The “supply” values are then compared with the “design” and “demand” recommended in the literature. A comprehensive range of response criteria at the member and storey levels, including shear as a failure criterion, alongside a detailed modelling approach and an extensively verified analytical tool are utilised. A rigorous technique is employed to evaluate R factors, including inelastic pushover and incremental dynamic collapse analyses employing eight natural and artificial records. In the light of the information obtained from more than 1500 inelastic analyses, it is concluded that including shear and vertical motion in assessment and calculations of R factors is necessary. Force reduction factors adopted by the design code (Eurocode 8) are over-conservative and can be safely increased, particularly for regular frame structures designed to lower PGA and higher ductility levels.     

DESIGN SPACES: AGGLOMERATION AND CREATIVITY IN BRITISH DESIGN AGENCIES

Although there is a growing body of research into the cultural and creative industries, little work has focused specifically upon on the geography of design and its role in regional economies. The relative neglect of the geography of the UK design industry is surprising given recent assertions about the sector's role in national economic competitiveness; its contribution to product innovation; and its importance as an urban regeneration resource. This paper explicitly considers the extent to which existing conceptualizations of agglomeration and creativity provide insights into the realm of design. Our discussion reflects upon recent surveys of the design sector and analyses current design organization membership data, both of which reveal an overwhelming concentration of design activities in London and the South East. Our analysis of the strategies, organization and practices of agencies in London reveals that a number of the key features associated with cultural industries in general are significantly less discernible within design.     

SEISMIC DESIGN AND RESPONSE OF BARE AND MASONRY-INFILLED REINFORCED CONCRETE BUILDINGS. PART II: INFILLED STRUCTURES

The effects of masonry infills on the global seismic response of reinforced concrete structures is studied through numerical analyses. Response spectra of elastic SDOF frames with nonlinear infills show that, despite their apparent stiffening effect on the system, infills reduce spectral displacements and forces mainly through their high damping in the first large post-cracking excursion. Parametric analyses on a large variety of multi-storey infilled reinforced concrete structures show that, due to the hysteretic energy dissipation in the infills, if the infilling is uniform in all storeys, drifts and structural damage are dramatically reduced, without an increase in the seismic force demands. Soft-storey effects due to the absence of infills in the bottom storey are not so important for seismic motions at the design intensity, but may be very large at higher motion intensities, if the ultimate strength of the infills amounts to a large percentage of the building weight. The Eurocode 8 provisions for designing the weak storey elements against the effects of infill irregularity are found to be quite effective, in general, for the columns, but unnecessary and often counterproductive for the beams.     

基于交通网络中心性的长春市大型综合医院空间可达性研究

交通网络中心性是测度交通网络及社会经济活动可达性的有效手段。从交通网络中心性视角,结合可达时间研究长春市中心城区大型综合医院空间可达性。大型综合医院邻近度和中间性与距离(到人民广场路网距离)均呈负相关,在距人民广场最近处二者大致相等且最高,随着距离的增加,邻近度超过中间性。距人民广场4740-5799米处中间性超过邻近度并形成高值分布区,7862-8400米处二者均降到最低。约33.3%的大型综合医院空间可达性最好,其集中分布于以人民广场为中心的城市中心。空间可达性最差的大型综合医院约占总数的24.1%,多分布于城市边缘。空间可达性较差的大型综合医院为数不多,且多分布于城市周边。但高邻近度、高中间性、可达时间较长的大型综合医院主要分布于安达街沿线。高邻近度、低中间性,可达时间较短的大型综合医院则多分布于火车站前与新民大街沿线等城市中心位置。     

AUTOMATIC MINIMIZATION OF THE RIGIDITY ECCENTRICITY OF 3D REINFORCED CONCRETE BUILDINGS

The objective of this paper is to obtain the optimum design of 3D reinforced concrete buildings in terms of their performance under earthquake loading. This goal is achieved by considering the minimisation of the eccentricity between the mass centre and the rigidity centre of each storey layout as the optimisation objective in order to produce torsionally balanced structures. This problem is considered as a combined topology and sizing optimisation problem. The location and the size of the columns and the shear walls of the structure of each storey layout constitute the design variables. Apart from the constraints imposed by the seismic and reinforced concrete structure design codes, architectural restrictions are also taken into account. The test examples showed that a reduction in the structural cost of the building is achieved by minimising the eccentricity between the mass centre and the rigidity centre of each storey layout. Evolutionary optimisation algorithms and in particular a specially tailored algorithm based on Evolution Strategies is implemented for the solution of this type of structural optimisation problems.     

Analysis of Dynamic Spatial Interaction Models by Means of Optimal Control

This paper deals with the design of general classes of dynamic spatial interaction models. On the basis of a general (well-behaved) multiperiod objective function and of a dynamic model representing the evolution of a spatial interaction system, an optimal control model is constructed. Particular attention is given to the equilibrium and stability conditions. It turns out that it is possible to identify steady-state solutions for a dynamic spatial interaction model. Furthermore, it can also be demonstrated that the entropy model is a specific case of this spatial interaction system. A simple illustration for urban dynamics is given as well.     

CONCEPTUAL DESIGN OF ISOLATION SYSTEMS FOR BRIDGE STRUCTURES

Abstract

In the first part of this paper the objectives of an isolation system for a bridge structure are discussed, in relation to modelling options and modification of the traditional capacity design principles. A displacement-based design approach is then presented, using a linear equivalent single degree-of-freedom model. The preliminary design of an isolation system for existing bridges is based on the definition of a “structure regularity” which allows the estimation of whether the response of the real structure will be similar to that predicted in the preliminary design phase. The efficiency of the approach is shown in designing the isolation system for a highly irregular bridge.     

THE EMPIRE OF THE FUTURE

This rich collection analyzes science in the archives over the past several thousand years. The chapters work together to tell stories of ambitious attempts to provide timeless data for science, which will be used for generations to come—ranging from ancient astronomy to geology to life‐logging and the development of web search. They also demonstrate convincingly that archives are powerful forces across the sciences—every science discussed has an archival base—which partly determine what kind of general knowledge claims can be made by future generations: it is hard to read an archive askance. The collection works best as a series of individual chapters, though some work is done to indicate where they speak to one another. It is a pity that there was not more input from archivists themselves in the project: their noninclusion means that some archival issues (especially what goes on with data after it gets into the archive—how it gets cleaned up, changed, reorganized) are treated somewhat lightly. The collection does provide a very useful set of tools for thinking about scientific archives. It is also an excellent introduction to the peculiarities of scientific archives—one that reflects back on the use of archives in history in general.