钢筋混凝土筒中筒结构内力分析与模型试验

取消筒中筒结构传统的等效连续化计算假定，按照外框筒自然的梁、柱结构状态，提出了筒中筒结构内力和位移分析的层模型计算方法，并考虑外框筒翼缘框架对抗剪刚度的贡献，层模型每层仅3个自由度，计算工作量小，计算方法简单。同时，完成了比例为1／10的筒中筒结构模型的静力试验，理论计算与实测结果吻合较好。     

城市污水再生回用潜力的优化分析

为了较合理地确定再生水水量和水质的优化分配问题,以使用再生水的净效益为目标函数,建立了能反映再生水在不同水质要求的用户之间进行水量分配的非线性规划(NLP)模型,并以西安市为例,采用该模型进行了污水再生回用系统的优化计算。结果显示,西安市在近期和中期对再生水的需求潜力较大,污水再生回用工程规模的增长率可达10%,且以集中处理回用为主,城市生态建设对再生水的最大需求量约25×104m3/d;水价对再生水在生态方面的使用影响较大,合理地调整水价可有效刺激对再生水的需求。     

太阳辐射引起建筑群温升的探讨

介绍了建筑群温度变化的数学模型，模拟了济南某小区在四种不同工况下太阳辐射引起的建筑群的温升情况，比较了建筑密度、下垫面材料、风速对建筑群温升的影响，结果表明，改变下垫面材料和增强自然通风可改善城市热岛效应。     

Application of cross validation techniques for modelling construction costs during the very early design stage

Building client/owners need estimates of likely construction costs for budgeting purposes early in the procurement process when little detailed design information is available beyond the type, size and location of the facility. One of the more sophisticated techniques available for this purpose is the storey enclosure method, developed by James in 1954. This uses the basic physical measurements of the building envelope, together with an arbitrary set of multipliers, or weights, to forecast tender/bid prices. Although seldom used in practice, James succeeded in showing his method to be capable of significantly outperforming alternative approaches.

The research reported in this paper aimed firstly to reassess James’ claims with new data and secondly to advance his method by using regression techniques to obtain the weights involved. Based on data from 138 completed Hong Kong projects for four types of building, two types of regression models were developed. This involved the use of sophisticated features such as leave-one-out cross validation to simulate the way in which forecasts are produced in practice and a dual stepwise selection strategy that enhances the chance of identifying the best model. An algorithm was also designed to select the appropriate parametric and non-parametric tests for objective and rigorous model evaluation against alternatives.

The results indicate that, contrary to James’ claim, both his original method and the two regression-based alternatives are not significantly better or worse than other models. Surprisingly, the widely used floor area model was found to under-perform in terms of consistency for offices and private housing. For private housing in particular, it was felt that the storey enclosure method was likely to offer good prospects of improvement on those methods currently in use in practice.     

钢筋砼结构的比拟桁架及其设计

桁架比拟法能直观地显示钢筋硷结构复杂区域开裂后的传力体系．本文阐述了构造桁架的方法，并简述了砼节点和压杆及钢筋拉杆的设计方法．     

Method for detecting moment connection fracture using high-frequency transients in recorded accelerations

The 1994 Northridge earthquake caused brittle fractures in steel moment frame building connections, despite causing little visible building damage in most cases. Future strong earthquakes are likely to cause similar damage to the many un-retrofitted pre-Northridge buildings in the western US and elsewhere. Without obvious permanent building deformation, costly intrusive inspections are currently the only way to determine if major fracture damage that compromises building safety has occurred. Building instrumentation has the potential to provide engineers and owners with timely information on fracture occurrence. Structural dynamics theory predicts and scale model experiments have demonstrated that sudden, large changes in structure properties caused by moment connection fractures will cause transient dynamic response. A method is proposed for detecting the building-wide level of connection fracture damage, based on observing high-frequency, fracture-induced transient dynamic responses in strong motion accelerograms. High-frequency transients are short (<1 s), sudden-onset waveforms with frequency content above 25 Hz that are visually apparent in recorded accelerations. Strong motion data and damage information from intrusive inspections collected from 24 sparsely instrumented buildings following the 1994 Northridge earthquake are used to evaluate the proposed method. The method’s overall success rate for this data set is 67%, but this rate varies significantly with damage level. The method performs reasonably well in detecting significant fracture damage and in identifying cases with no damage, but fails in cases with few fractures. Combining the method with other damage indicators and removing records with excessive noise improves the ability to detect the level of damage.     

Kinetic model of 4-CP degradation by Fenton/O2 system

A kinetic model of the degradation of 4-CP by Fenton/O(2) system was established, in which particular attention was paid to the role of oxygen in the process because many former researches suggested that the presence of oxygen could decrease the input of H(2)O(2). The proposed model well predicted 4-CP degradation and H(2)O(2) consumption by Fenton/O(2) and Fenton/N(2) systems at varying levels of Fe(2+), H(2)O(2), and 4-CP input. Most correlation coefficients between experimental and predicted data of 4-CP and H(2)O(2) concentration were above 0.95. The model could predict the enhancement of 4-CP degradation by oxygen and the difference in the evolution of aromatic intermediates between Fenton/O(2) and Fenton/N(2) system. The predicted and experimental data both showed the degree of benzene ring cleavage in Fenton/O(2) system was higher than that in Fenton/N(2) system. Understanding the role of oxygen is very important to improve the decomposition performance.     

基于实时数据的网状城市快速路行驶时间预测方法研究

基于城市快速路实时管理和控制的思路,利用观测断面的数据,给出动态预测网状城市快速路上的交通状态和任意两点间行驶时间的方法。具体做法是,依据时序列数据、状态空间模型和自回归模型进行模型参数自拟合,并且预测出将来几个时段的交通状态,然后计算出行驶时间。最后,给出应用于城市快速路网的实例计算结果。结果表明,提出的方法可以用于预测路网上的交通状态和行驶时间,并为城市快速路的信息服务和交通诱导提供一种方法。     

混凝土损伤本构模型研究评述

现有混凝土本构关系主要是基于成熟的经典弹塑性模型所建立的,弹塑性模型在数学上较严格,但是与混凝土材料破坏机理不协调,各国学者针对混凝土这类特殊多相复合材料提出了很多基于不可逆热力学理论的损伤本构模型。系统综述了混凝土损伤本构研究的成果,在分析了各个有代表意义的混凝土损伤本构模型基础之上,对比研究了各个模型的特点及各自适用范围,通过总结前人成果,为损伤本构模型研究提供了思路。     

Modeling thermal behaviors of window flame ejected from a fire compartment

A series of reduced-scale experiments were carried out in order to investigate thermal behaviors of window flame, which exposes the upper floors as well as the adjacent buildings to potential risks of fire spread. A stainless pan filled with alcohol was used as the fire source and was placed inside a cubic compartment of 900 mm side. Temperatures and velocities at various points inside and outside of the compartment were measured. The compartment was pressurized during the experiment by mechanically supplying air at several mass inflow rates through an inlet duct set at the bottom part of the compartment. This was for simulating fire conditions under the effect of external wind pressure. On the basis of the experimental observation, line (i.e., two-dimensional) heat source assumption was adopted for developing a model of window flame behavior. A dimensionless parameter Q^′*${Q^{\prime }}^{*}$ was derived from the governing differential equations in order to generalize the measurement results. Expressions for temperature rise along the trajectory ΔT_m and characteristic flame width b_T were developed incorporating the parameter Q^′*${Q^{\prime }}^{*}$.