The progressive salination of groundwater in Beirut,Lebanon

The degradation in groundwater quality in Greater Beirut, the subject of several investigations in the past two decades, is attributable to seawater infiltration into the coastal aquifer induced by the excessive and uncontrolled groundwater utilization. The present study elucidates the increasing trend in seawater infiltration from 1971 to 1985. The brackish groundwater, generally used domestically for washing and flushing, is now creating extensive corrosion and scale‐formation problems that have to be faced by the users. At this critical stage, effective measures must be instituted that include the provision of adequate public water supplies to facilitate the control of groundwater utilization.     

星巴克的中国之路 国际品牌的本土化

星巴克设计师胡德介绍了一系列中国大陆地区的咖啡连锁店设计,阐释了国际品牌的本土化策略。     

CIM、BIM应用中坐标转换技术研究

城市信息模型（CIM）的建设,需要解决各类数据在统一坐标系下的转换问题。本文梳理了常用坐标系统,分析了不同坐标系统之间的转换原理,介绍了CGCS2000投影坐标系和南京地方投影坐标系下BIM模型转换过程的应用案例,提出了一套在异构坐标体系下集成BIM模型到CIM平台的解决方法。     

Freshwater biodiversity: a review of local and global threats

The total freshwater biodiversity is not fully known. In particular, freshwater invertebrates and microbes are poorly studied groups, and in tropical latitudes, that support most of the species of the world, the information is lacking. Although almost a hundred thousand of species live in fresh water, the species losses continue at the high rate and the probability of preserving much of the remaining biodiversity in fresh water seems to be very low. Freshwater ecosystems are increasingly influenced by multiple stressors that lead to loss of sensitive species and an overall reduction in diversity. Environmental change threatens freshwater biodiversity. This paper reports an extensive review of work that evaluates the current main threats for freshwater biodiversity, on a local and global scale.     

Cellular buckling in I-section struts

An analytical model that describes the interactive buckling of a thin-walled I-section strut under pure compression based on variational principles is presented. A formulation combining the Rayleigh–Ritz method and continuous displacement functions is used to derive a system of differential and integral equilibrium equations for the structural component. Numerical continuation reveals progressive cellular buckling (or snaking) arising from the nonlinear interaction between the weakly stable global buckling mode and the strongly stable local buckling mode. The resulting behaviour is highly unstable and when the model is extended to include geometric imperfections it compares excellently with some recently published experiments.     

冷弯薄壁梁的屈曲及优化设计综述

介绍了冷弯薄壁梁的整体-局部屈曲和优化,包括:简化分析与计算、数值分析及试验。详细阐述了薄壁梁翼缘和腹板的屈曲问题。采用质量检测方法,对不同横截面薄壁梁进行比较。     

黎首都贝鲁特国际机场遭以军导弹袭击，引发大火

（本刊讯）黎巴嫩安全官员称，7月16日晚，以色列海军从军舰上向黎巴嫩首都贝鲁特发射了4枚导弹，击中了位于贝鲁特南部地区的拉菲克-哈裹裹国际机场，并导致其中的一座储油罐发生大火。这是以色列军方第二次对贝鲁特国际机场发动袭击。在此前的一次空袭中，贝鲁特国际机场的数条跑道被完全摧毁，导致附近的多个储油罐发生大火。     

The local and global instability and vibration of systems subjected to non-conservative loading

The paper presents the results of theoretical and numerical studies on the slender, geometrically nonlinear system supported at the loaded end by a spring of a linear characteristic and subjected to non-conservative (generalized Beck's) loading. The boundary problem was formulated based on the Hamilton principle and then solved using, due to the nonlinearity, the small parameter method. The bifurcation force depending on system parameters and local and global instability regions has been determined in the study, and the characteristic curves have been plotted in the load-free vibration plane.     

Response of a circular metallic hollow beam to an impulsive loading

A model of the dynamic response of a relatively long circular hollow section beam to a uniform blast modeled as an impulsive loading is developed in order to reveal the characteristic features of deformation and energy absorption of hollow section beams under such loading. A two-phase analytical model is proposed for a circular metallic hollow beam made of a strain-rate insensitive material. Both local and global deformations build up simultaneously during the first phase, and then only global bending occurs during the second phase. Because mainly large plastic deformations develop in the hollow section, the elastic deformations are neglected and a rigid-plastic method of analysis is applied. The responses of circular hollow beams with lengths between 600 and 1000 mm are analyzed for beam radii varying between 50 and 70 mm and wall thicknesses between 1.2 and 1.6 mm. The model predictions are verified by numerical simulations and reasonable agreement is observed with respect to the characteristic displacements and deformed section shape. The energy partitioning during the deformation process is briefly discussed.     

Experimental study of fire-resistant steel H-columns at elevated temperature

This paper presents the experimental studies of axially loaded fire-resistant steel columns under elevated temperature. With the advancement of metal production, fire-resistant steel with enhanced mechanical properties at elevated temperatures has been developed recently. However, extensive research work is needed in order for the application of fire-resistant steel in building structures. In this study, a series of fire-resistant steel columns was loaded to their ultimate states at specified temperature. The effects of width-thickness ratios, slenderness ratios and residual stress on the performance of fire-resistant steel H-columns are examined. Based on this study, it is found that the section property of fire-resistant H-columns should be at least a non-compact section in order to prevent local buckling. Column strength is sensitive to slenderness ratio at elevated temperature. The strength of a slender column decreased sharply especially for temperatures above 600 ^°C. It is also found that the failure mode of steel columns changed from inelastic global buckling at room temperature to local buckling at elevated temperature, due to the release of residual stress in fire. An analytical model is proposed which is able to predict the behavior of fire-resistant steel H-columns under elevated temperature. Design guidelines are also proposed for the design of fire-resistant steel columns in fire conditions.     

新世纪摩天楼的发展趋势

文章对21世纪摩天楼的全球化／地域主义倾向,高技倾向,独石式倾向,动力学倾向,图像学倾向,媒介化倾向,生态倾向等发展趋势进行了介绍。     

The crisis of cultural identity in rehabilitating historic Beirut-downtown

The dilemma of devising a theme that can convincingly and collectively express the cultural identity of a nation usually surfaces at the time of planning for the reconstruction and rehabilitation of devastated sites of significance. Particularly following civil wars, both the planning phase and procedures for rehabilitation often exhibit an extension of the civil conflict over the issues of identity and cultural ideology. The 15-year Lebanese civil war (1975-1991) left Beirut severely damaged. After almost two decades after the end of the war, the city center rehabilitation is in its final stages and presents an explicit paradigm of urban governance and management in a severely damaged urban setting claimed by a community of multilayered culture stratums. The construction and reconstruction effort has aspired to resurrect the pre-war cosmopolitan Beirut, and has represented not only the rehabilitation of the infrastructure and devastated structures, but equally, an attempt to reinterpret Lebanon’s tumultuous past and to create a new collective memory for the nation. For many, most of this effort was in vain for multiple reasons, but more notably, it fueled an endless cultural conflict in the historical city overlooking the sea. The objective of this article is to develop a better understanding of the specific socio-political dynamics and attributes influencing the rehabilitation process of the historic Beirut city center. The article examines the capacity of the chosen rehabilitation approach which was meant to crystallize the intangible meanings of Lebanese cultural identity. In addition to the site visits and observation which took place upon settling in Beirut for the last 6 years, the conclusion is underpinned by a review of culturally-diverse literature and interviews with multiple stakeholders, in particular urban officials, local professionals, visitors, and affected residents of the city center, and represents the groundwork for similar rehabilitation initiatives.     

酒店、高级住宅及商业综合楼,贝鲁特(黎巴嫩)

设计任务:一个酒店、高级住宅及商业综合楼. 　　结合了一个综合住宅楼的Rotana酒店项目,坐落在黎巴嫩首都贝鲁特市中心十分特殊的位置:沿海景观散布大道的起点.同时他显著的地理位置及周围良好的视野使得人们在市中心的主干道上也可清晰地看到这幢建筑物.……     

Performance of steel H columns loaded under uniform temperature

This paper presents the experimental results for a series of H steel columns under fire load. The width-to-thickness ratio of steel plates and the slenderness ratios of steel columns are two dominating factors linked to local buckling and global buckling of columns, respectively. To evaluate the influence of these two factors on the structural behavior of steel columns in fire conditions, a series of H steel columns were loaded to their limit states at specified temperature levels. The steady state method has been adopted in order to derive the structural behavior of steel columns at specified temperatures directly.On the basis of the experimental results, it has been found that steel columns with non-compact section are able to reach yield strength at elevated temperature. That is, the width-to-thickness ratio, designed in accordance with current ambient temperature specifications, is capable of preventing brittle failure of steel columns in fire conditions. Depending on the slenderness ratio, the failure of steel columns may change from global buckling at ambient temperature to local buckling at elevated temperature. For plastic section columns with a slenderness ratio greater than 50, column strength drops dramatically to 40% of its strength at ambient temperature. At temperature levels of 500 ^°C, the column retains more than 70% of its ambient temperature strength if the slenderness ratio of the column is less than 50. However, in the case of temperature levels exceeding 500 ^°C, or when the slenderness ratio is greater than 50, column strength drops significantly. On the basis of this study, it is tentatively suggested that 500 ^°C be adopted as the critical temperature for steel members subjected to compression in order to ensure that the column strength keeps higher than 2/3 of the ambient temperature yield strength. The slenderness ratio of steel columns should be limited to 50, so as to prevent brittle failure of steel columns under fire attack.     

Finite strip elastic buckling solutions for thin-walled metal columns with perforation patterns

Approximate finite strip eigen-buckling solutions are introduced for local, distortional, flexural, and flexural-torsional elastic buckling of a thin-walled metal column with perforation patterns. These methods are developed to support a calculation-based strength prediction approach for steel pallet rack columns employing the American Iron and Steel Institute׳s Direct Strength Method, however they are generally posed and could also be useful in structural studies of thin-walled thermal or acoustical members made of steel, aluminum, or other metals. The critical elastic global buckling load including perforations is calculated by reducing the finite strip buckling load of the cross-section without perforations using the weighted average of the net and gross cross-sectional moment of inertia along the length of the member for flexural (Euler) buckling, and for flexural-torsional buckling, using the weighted average of both the torsional warping and St. Venant torsional constants. For local buckling, a Rayleigh–Ritz energy solution leads to a reduced thickness stiffened element equation that simulates the influence of decreased longitudinal and transverse plate bending stiffness caused by perforation patterns. The cross-section with these reduced thicknesses is input into a finite strip analysis program to calculate the critical elastic local buckling load. Local buckling at a perforation is also treated with a net section finite strip analysis. For distortional buckling, a reduced thickness equation is derived for the web of an open cross-section to simulate the reduction in its transverse bending stiffness caused by perforation patterns. The approximate elastic buckling methods are validated with a database of 1282 thin shell finite element eigen-buckling models considering five common pallet rack cross-sections featuring web perforations that include 36 perforation dimension combinations and twelve perforation spacing combinations.     

转型与城市发展

转型是人类社会中直存在的普遍现象。学们对社会转型和经济转型进行了长期和深入地研究,其学术成果有助于从新的角度研究和认识城市转型与发展的问题,探求城市特别是在社会、经济转型时期的发展、变化规律。     

Buckling analysis of thin-walled cold-formed steel structural members using complex finite strip method

In this paper, a generalised complex finite strip method is proposed for buckling analysis of thin-walled cold-formed steel structures. The main advantage of this method over the ordinary finite strip method is that it can handle the shear effects due to the use of complex functions. In addition, distortional buckling as well as all other buckling modes of cold-formed steel sections like local and global modes can be investigated by the suggested complex finite strip method. A combination of general loading including bending, compression, shear and transverse compression forces is considered in the analytical model. For validation purposes, the results are compared with those obtained by the Generalized Beam Theory analysis. In order to illustrate the capabilities of complex finite strip method in modelling the buckling behavior of cold-formed steel structures, a number of case studies with different applications are presented. The studies are on both stiffened and unstiffened cold-formed steel members.     

Architecture,values and perception: Between rhetoric and reality

Throughout history, design values have always underlined a given architectural style. The manner architects and architectural critics distinguish between them varies from that of the public. In fact a style well perceived by civil society was read as pathological by architectural academia. This paper examines the values and perceptions of contemporary architecture by architects and civil society. Through qualitative methodology, a project by each of the following leading contemporary architects-Renzo Piano, Norman Foster and Rem Koolhaas-was analyzed. The selected designs, all commissioned not more than a decade ago, vary in locations from Malta to Lebanon to India. The study concludes that design values and perceptions of architecture as read by members of the architectural profession do not tally with those of the public. The emphasis by architects is on the aesthetic whilst non-architects focus on the utilitarian dimension. Furthermore, the rhetorical language which architects use is not read as such by the public. The assessment of the public is based on the existential reality which they experience. The perception of civil society matters; it is at the core of architectural design values.     

A time-series analysis of mortality and air temperature in Greater Beirut

The literature on the association between health and weather in the temperate to semi-arid cities of the Eastern Mediterranean is scarce. The quantification of the relationship between temperature and daily mortality can be useful for developing policy interventions such as heat-warning systems. A time-series analysis of total daily mortality and weather data for the city of Beirut was carried out. The study covered the period between 1997 and 1999. Poisson auto-regressive models were constructed, with mean daily temperature and mean daily humidity as explanatory variables. Delayed effects, up to 2 weeks, were accounted for. The regression models were used next to assess the effect of an average increase in temperature on yearly mortality. The association between temperature and mortality was found to be significant. A relatively high minimum-mortality temperature (TMM) of 27.5 degrees C was calculated. A 1 degrees C rise in temperature yielded a 12.3% increase (95% confidence interval: 5.7-19.4%) and 2.9% decrease (95% confidence interval: 2-3.7%) in mortality, above and below TMM, respectively. Lag temperature variables were found to be significant below TMM but not above it. Where the temperature change was less than 0.5 degrees C, annual above-TMM losses were offset by below-TMM gains, within a 95% confidence interval. TMM for Beirut fell within the range usually associated with warm climates. However, the mild below-TMM and steep above-TMM slopes were more typical of cities with temperate to cold climates. Our findings suggest that heat-related mortality at moderately high temperatures can be a significant public health issue in countries with warm climates. Moreover, at the projected climate change over the next 50 years, heat-related losses are unlikely to be offset by cold-related gains.