The impact of urban street layout on local atmospheric environment

The investigation was carried out to reveal the impact of urban street layout on local atmospheric environment through computational fluid dynamics (CFD) numerical simulations using standard k$k$–ε$\epsilon$ turbulence model. Different street canyon configurations are considered and the flow regimes summarized according to the aspect ratio of the leeward building height and the street width H1/W$H1/W$ and the aspect ratio of the leeward building height and the windward building height H1/H2$H1/H2$. Three regimes are defined to denote the vortices and characteristics of pollutant dispersion in street canyons according to the parameters H1/W$H1/W$ and H1/H2$H1/H2$. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. The study indicated that there is a strong influence of the street layout on the wind field and the pollutant dispersion in the street canyon mainly depends on the vortex structure in the canyon. The results are validated against an extensive wind tunnel experimental (Meroney and Rafailidis) [Journal of Wind Engineering and Industrial Aerodynamics, 1996;62:37–56; http://www.mi.uni-hamburg.de] and the simulated results concluded by Sini [Atmospheric Environment 1996;30:2659–77] and Sang [Atmospheric Environment 2002;36:1137–45].     

当代建筑结构体系中的技术表现分析

建筑技术的发展一直伴随着建筑艺术的发展,当代建筑结构技术也成为了建筑表现的重要因素之一,其在满足建筑形式和功能要求的同时,开始更多地关注哲学思想、人文情感和环境意识的表达.该文分析和总结了当代建筑结构技术在建筑表现中的运用和发展趋势,希望这样的分析与归纳对建筑实践有一定的参考意义.     

Local buckling of steel plates in concrete-filled thin-walled steel tubular beam-columns

The availability of high strength steels and concrete leads to the use of thin steel plates in concrete-filled steel tubular beam-columns. However, the use of thin steel plates in composite beam-columns gives a rise to local buckling that would appreciably reduce the strength and ductility performance of the members. This paper studies the critical local and post-local buckling behavior of steel plates in concrete-filled thin-walled steel tubular beam-columns by using the finite element analysis method. Geometric and material nonlinear analyses are performed to investigate the critical local and post-local buckling strengths of steel plates under compression and in-plane bending. Initial geometric imperfections and residual stresses presented in steel plates, material yielding and strain hardening are taken into account in the nonlinear analysis. Based on the results obtained from the nonlinear finite element analyses, a set of design formulas are proposed for determining the critical local buckling and ultimate strengths of steel plates in concrete-filled steel tubular beam-columns. In addition, effective width formulas are developed for the ultimate strength design of clamped steel plates under non-uniform compression. The accuracy of the proposed design formulas is established by comparisons with available solutions. The proposed design formulas can be used directly in the design of composite beam-columns and adopted in the advanced analysis of concrete-filled thin-walled steel tubular beam-columns to account for local buckling effects.     

全球气候变化与河口城市气候脆弱性生态区划研究——以上海为例

在分析全球气候变化影响及世界主要河口城市应对策略的基础上,提出了建设资源节约型与环境友好型城市的概念、内涵、运行模式以及河口城市上海在全球变化影响下的气候脆弱性生态区划及适应性对策。     

Application of the Direct Strength Method to local buckling resistance of thin-walled steel members with non-uniform elevated temperatures under axial compression

This paper assesses the applicability of the Direct Strength Method (DSM) to calculating the local buckling ultimate strength of cold-formed thin-walled (CF-TW) steel members with non-uniform elevated temperature distributions in the cross-section. The assessment was carried out by checking the DSM calculation results with numerical simulation results using the general finite element software ABAQUS which was validated against ambient and uniform elevated temperature tests on short lipped channel sections. The validated numerical model was used to generate an extensive database (372 models) of numerical results of load carry capacity of CF-TW members with different uniform and non-uniform temperature distributions in the cross-sections, under different boundary and loading conditions and with different dimensions and lengths. It was concluded that the DSM local buckling curve was directly applicable for columns with uniform temperature distributions in the cross-section. For columns with non-uniform temperature distributions, a modification to the local buckling curve was necessary and this paper has proposed a new curve.     

Preliminary investigation of a vapor-open envelope tailored for subtropical climate

Concerning global warming and resource depletion, the impact of buildings in subtropical regions is becoming even greater due to a high growth rate of urbanized areas. From the viewpoint of building physics, the main problem concerning subtropical climate is the high level of humidity in combination with high temperature. In this study, a flexible building envelope consisting of wood and clay components was developed so that the materials and the assemblies can be easily tailored to comply with local climatic conditions. The movement and accumulation of moisture in the wall was of prime concern. This has been investigated by means of testing full scale walls in a climate chamber and the corresponding one dimensional transient heat and transfer simulation. In order to achieve a consistency between calculation and measurement, the individual materials were tested for their hygric and thermal properties. Based on these findings attempts were made to calculate the behavior of an optimized wall assembly under real climatic conditions of central Japan. As a result, it was shown that the hygrothermal behavior of the envelope is predictable by means of the models and the simulation program used, and that no risk of interstitial condensation and mold growth was predicted under the real climatic conditions of Kyoto.     

Development of new indices to assess the contribution of moisture sources to indoor humidity and application to optimization design: Proposal of CRI(H) and a transient simulation for the prediction of indoor humidity

Many indoor and outdoor factors (e.g., the presence of occupants, hot-water supply equipment, the use of hygroscopic materials, and ventilation) contribute to indoor humidity. It is important to investigate and understand the contribution of each factor to indoor humidity and to establish an effective method for the design and control of indoor humidity. In this study, indoor humidity was treated as a linear summation of the contribution of various factors, all of which can cause an increase or decrease in indoor humidity. New indices for assessing the contribution of factors to the humidity distribution in a room are proposed as Contribution Ratios of Humidity (CRI_(H)) 1, 2, and 3 which can be calculated based on Computational Fluid Dynamics (CFD) simulations. Furthermore, a transient simulation based on CRI_(H)1 and the Contribution Ratio of Indoor Climate (CRI_(C)) was developed to predict the indoor humidity distribution. A 100-day transient analysis was performed in a living room in which moisture-buffering materials were used. The simulation results were compared with those from a well-mixed zonal model and a CFD transient analysis to confirm the effectiveness of the approach. The analysis provided the three-dimensional spatial distribution of indoor humidity and temperature with good prediction accuracy. The calculation time was approximately equal to that of the well-mixed zonal model and much faster than that of the CFD transient analysis.     

寓意于形,创作有生命的建筑--杭州天辰国际广场建筑设计后感

当今的中国,短期内房地产开发的巨大利润促使开发商们形成了强烈的“拿来主义”思想。因此建筑师在做房地产项目时经常会面临着一种仅为画图工具的尴尬。杭州萧山天辰国际广场项目设计却与此不同。建筑师与业主齐心协力,一起在“破”与“立”上做文章,通过寓意于形及多重性空间的塑造,试图赋予建筑以一种生命的语言。     

局部地区城市化及其与经济发展关系研究——以美国49个州为例

本文选取高度城市化国家美国为研究对象，对美国及其国内49个州的经济及城市化发展过程以及两者在发展过程中的相关关系进行分析，发现地区城市化发展特征差异明显，经济发展影响着城市化发展，相对的经济位置决定城市化水平的高低；但经济水平不是决定城市化发展的唯一因素，且经济发展对城市化的影响存在不同的阶段，传统的城市化理论已经在局部地区城市化发展中不再适用。     

Ultimate strength of dented steel plates under edge shear loads

The aims of this paper are to investigate the ultimate shear strength reduction characteristics of steel plates due to local impacts, and also to develop the ultimate shear strength design formulae of dented steel plates. The ANSYS nonlinear finite element code is used to investigate the effects of shape, size (depth, diameter), and location of the denting on the ultimate strength behavior of simply supported steel plates under edge shear loads. A closed-form expression for predicting the ultimate shear strength of dented steel plates is derived by the regression analysis based on the computed results. The results and insights developed from the present study will be very useful for damage tolerant design of steel plated structures with local denting.