Non-linear finite element analysis of axially restrained steel beams at elevated temperatures in a fire

A method is presented for the analysis of the non-linear structural behavior of axially restrained steel beams at elevated temperatures, which employs the axis arc-length and section rotation of the deformed beam as basic variables. The novelty of the proposed formulation is an inclusion of a balance function that measures the error of the equilibrium between the internal- and external-forces in a cross-section of the beam. This strategy can easily deal with the geometric non-linearity and elasto-plasticity of steel at elevated temperatures. Each node for representing the section of the beam has two degrees of freedom in the proposed method. It is more computationally economical than the traditional beam element, which has three degrees of freedom. An example beam is studied to verify the proposed method. Parameters including the load ratio, axial restraint stiffness ratio, transversal and longitudinal temperature gradient, are studied. The middle-span’s deflection, axial force and moment, along with the strain and stress distributions across the section, are calculated at elevated temperatures. The comparison with results from the finite element method employing shell elements shows that the method presented here is precise.     

高梯度氧化锌电阻片的研制

使用高梯度氧化锌电阻片可以使避雷器小型化。在一定范围内增加Bi2O3、Sb2O3等添加剂的用量及掺加0.4%￣0.6%的Y2O3,有助于提高氧化锌电阻片电位梯度。严格控制原料的松装密度、粒度分布及水分等,如:Co2O3松装密度提高到0.6 g/cm3左右,使用效果良好。使用新型高效混磨设备,循环处理流量可达到5.4m3/h,效率比原来提高了30%以上,改善了电阻片微观均匀性。氧化锌电阻片电位梯度可达350V/mm,长持续时间电流冲击耐受800A。     

不同受载方式下桩侧阻的渗水力模型试验研究

利用ｎ·ｇ渗水力土工模型试验对垂直受载桩在桩顶压桩，桩顶拔桩及桩底托桩等受载方式下的桩侧摩阻力的发展规律进行了试验研究，得到了侧阻与位移的关系、侧阻强度沿桩身的分布以及侧阻强度和相应截面位移之间的关系，试验成果在一定程度上揭示了侧阻发展的机理。     

影响我国房地产价格变化因素分析

近年来．我国房地产价格持续上涨。为了平抑房价。国家采取了调控措施．房地产价格上涨速度虽然减缓．但价格仍居高位。文章从宏观调控下我国房地产投资的特点出发。通过对影响我周房地产价格变化因素进行分析，力图探明住房价格持续上涨问题的根源，并提出相应的政策建议。     

珠江压咸补淡跨地区应急调水的政策探讨

为了避免咸潮对珠江三角洲及港澳地区供水安全的潜在威胁,2005年珠江流域管理机构组织实施了珠江压咸补淡跨地区应急调水.笔者把珠江压咸补淡应急调水界定为水行政部门组织实施的一项公共政策,运用公共政策理论对此次应急调水所隐含的政策选择依据与价值取向进行了剖析.立足一般公共政策所应该遵循的效率与公平原则,阐述了在今后调水政策设计过程中开展成本效益分析和引入水权交易机制的必要性.     

地板供冷/置换通风复合空调系统的可行性探讨

随着地板辐射供暖的迅速推广，地板辐射供冷的可行性备受关注，本文探讨了地板辐射系统和置换通风系统相结合用于夏季供冷的可行性。     

Housing Theory,Housing Research and Housing Policy

Abstract

Jim Kemeny in 1992 criticized existing housing research for neglecting social theory and being overly positivist and policy focused. The result has been a strengthening of the conceptual basis of housing research in general, but also a growing schism between researchers who focus on policy relevancy and those that pursue more theoretical work. This paper challenges this schism and argues for theoretically based and policy-relevant research. First, the paper argues that the policy-making process is complex and can vary between different countries, situations and over time. Therefore, it is argued that many styles of research can influence policy in the right circumstances. Second, the paper challenges the idea that there can be theoretically free housing research arguing that all research has a theoretical foundation even though in many studies it is not explicit. Finally, the paper engages with the debate about where theory for housing research should come from and what it would look like.     

Towards more Social Cohesion in Large Post-Second World War Housing Estates? A Case Study in Utrecht,the Netherlands1

The last few years have seen many studies of large post-Second World War housing estates. At present they are often the most deprived areas of European cities. The turnover of the population on these estates is characteristically rapid, leading to considerable socio-economic and socio-cultural changes and a multi-ethnic neighbourhood. Such areas often have to contend with severe physical, social and economic problems and the consequent dissatisfaction of the residents. This combination of rapid and selective population turnover and increasing numbers of problems may well affect aspects of social cohesion within these neighbourhoods, particularly the social networks. This process is regrettable, because social cohesion is regarded in a positive light, something that enhances the quality of life. Stimulating social cohesion is therefore an important objective of many policies that focus on large post-Second World War housing estates. The authors have found it interesting to discover how important social cohesion is in the opinions and the lives of the inhabitants rather than the policy makers. In their opinion, urban policies focus on social cohesion while the inhabitants' views of its relevance are unknown. On the basis of this paper, certain aspects of social cohesion in large post-Second World War housing estates appear to be valued, but housing market behaviour, such as residential moves, is hardly affected by aspects of social cohesion. Other aspects, such as moving to a better house, are much more relevant. The results may put into doubt the stress placed in urban policies on social cohesion.     

Mortgage interest deductibility and homeownership in the Netherlands

This paper considers the growing amount of mortgage interest paid in the Netherlands against the background of its full fiscal deductibility, increasing homeownership rates, innovation in the mortgage market, and changes in the Dutch income tax system. Its main conclusion is that arguments in favor of fiscal deductibility are weak. Since the deductibility puts pressure on the income tax base, it is likely that sooner or later the facility must be limited or abandoned.

SARS门诊病房楼通风空调设计探讨

结合工程实例分析了SARS门诊病房楼的特点，对此类建筑的空调系统、通风系统设计进行了探讨，给出了其通风空调设计原则。