结构保温板的制备及热工性能分析

结构保温板（Structural Insulated Panel/SIP）一般由两块木基面板和一块泡沫芯材复合而成。文章介绍了一种结构保温板的制备过程并对其进行了热工性能分析,推导了结构保温板外墙相对于非节能墙体的节能费用公式和结构保温板最佳芯层厚度的公式,文章推导的公式可以为结构保温板在设计使用时提供指导和参考。     

自然火灾下M8.8级螺栓的性能研究:试验与模拟

近期钢结构和组合结构的足尺试验表明:在火灾冷却阶段,轴向约束梁产生的拉力会导致螺栓破坏。为了更好理解这种破坏形式,合理设计并避免发生此种破坏,必须对螺栓等各组件在受热和冷却阶段时的材料属性进行深入研究。介绍了在意大利Centro Sviluppo Materiali研究中心进行的受热-冷却循环工况下M8.8级螺栓的拉伸和剪切试验结果。为确定受热和冷却阶段M8.8级螺栓的力学性能,定义了材料准则,考虑了M8.8级螺栓力学属性的不可逆性。     

路堤荷载下现浇X形桩复合地基承载特性数值分析

以江苏省南京长江第四大桥北接线工程N1标段现浇X形桩软基加固段为工程背景,建立了路堤荷载作用下现浇X形桩复合地基数值分析模型,开展了现浇X形桩复合地基承载机理的分析,并采用现场实测沉降曲线验证了分析方法的合理性.就填土期和运营期地基土固结对现浇X形桩桩身轴力和桩侧摩阻力的影响进行分析,探讨了褥垫层模量、褥垫层厚度、桩体模量、桩端土模量对桩身轴力、桩侧摩阻力和桩土应力比的影响.结果表明:随着路堤的填筑和地基土的固结,桩土应力比先快速后缓慢增加并逐渐趋于稳定,中性点逐渐下移;褥垫层模量和厚度的增加对调节现浇X形桩桩土应力分配有明显的作用;由于现浇X形桩为摩擦刚性桩,桩顶荷载主要由桩侧摩阻力承担,桩端土模量和桩体模量对桩身轴力和中性点位置的影响较小;路堤荷载下现浇X形桩的桩土应力比可在30左右,褥垫层模量建议取为20～50 MPa,厚度为30～50 cm.     

轴向压缩荷载下双层中空钢管混凝土短柱的试验和数值研究

使用试验和数值方法研究轴向压缩荷载下双层中空钢管混凝土柱的性能。对一个外层为八边形钢管﹑内层为环形PVC-U管﹑且在两层间填充高强混凝土的双层中空钢管混凝土柱进行研究。测试混凝土强度﹑径厚比﹑空心率﹑长细比对双层钢管混凝土柱的极限轴压承载力的影响。经测试发现:双层中空钢管混凝土柱的极限轴压承载力随着混凝土强度的增加而增加,但随着径厚比或空心率的增加而减少。根据试验结果,提出一个能预测双层中空钢管混凝土柱极限轴压承载力的设计公式。     

Numerical Modeling of Heat and Moisture Through Wet Cotton Fabric Using the Method of Chemical Thermodynamic Law Under Simulated Fire

The paper deals with numerical modeling of heat and moisture transfer behavior of a fabric slab during combined drying and pyrolysis. The model incorporates the heat-induced changes in fabric thermo physical properties and the drying process is described by a one-step chemical reaction in the model. The new model has been validated by experimental data from modified Radiant Protective Performance (RPP) tests of fabrics. Comparisons with experimental data show that the predictions of mass loss rates, temperature profiles within the charring material and skin simulant, and the required time to 2nd skin burn are in reasonably good agreement with the experiments. It is concluded that moisture increases the time to 2nd degree skin burn for fabrics exposed to low intensity heat flux of 21 kW/m², but under high heat flux exposures, such as 42 kW/m², moisture tend to increase heat transfer through the thermal protective fabric system and the tolerance time of the same fabrics will reduce. The model can find applications not only in thermal protective clothing design, but also in other scientific and engineering fields involving heat transfer in porous media.     

Fire Performance of External Thermal Insulation Composite System (ETICS) Facades with Expanded Polystyrene (EPS) Insulation and Thin Rendering

External Thermal Insulation Composite System (ETICS) facades with expanded polystyrene (EPS) insulation and thin rendering are applied frequently in buildings. Considering high combustibility of EPS, with these facades concerns also arise regarding spread of a possible fire between neighbouring compartments of high-rise buildings. Fire tests of two large-scale facades were performed to study two parameters presumably influencing significantly the fires of such facades in real-life settings, i.e. incident heat flux upon the facade’s surface (IHFFS) and damage of the facade’s render (the latter being a consequence of poor or unfinished construction work, ageing or fire-induced thermal strain). The first facade was rendered fully and was exposed to moderately-fast increasing IHFFS. In the second (partially unrendered) facade case the IHFFS progressed faster. The facade flame body (temperatures and shape) was monitored by thermocouples, photo and video cameras. For detection of melting of EPS and internal burning, thermocameras were used within the facades areas outside the visible plume. In the plume zone, however, a group of thermocouples was embedded inside EPS and the shapes (plateaus and slopes) of the collected time-temperature graphs were observed for these purposes. The IHFFS imposed on the facades during fire testing were estimated by numerical calculations. In both cases the first pronounced render crack was evolved at the estimated average between-windows IHFFS of around 30 kW/m\(^2\) and was followed by internal burning of EPS. While the latter did not seem to spread across the facade for the fully-rendered facade, a fast fire spread was detected for the second specimen.     

Experimental and Numerical Study of Window Glass Breakage with Varying Shaded Widths under Thermal Loading

To investigate the effect of shaded width on the breaking behavior of window glass, a series of experiments was carried out on float glass with dimension of 600 mm × 600 mm × 6 mm in an enclosed compartment under radiant heat. The shaded width of glass pane ranged from 10 mm to 50 mm with an interval of 10 mm. Experimental results showed that crack patterns of the glass pane were influenced little by the shaded width, while the average value of the first breaking time of the glass pane decreased firstly and then increased with an increase in the shaded width. The average time to the first crack with the shaded width of 20 mm was shortest in experiments and the corresponding time was 572.5 s. In addition, the finite element method was also used to simulate the process of crack initiation and single crack propagation. Temperatures measured by thermocouples in experiments were employed as thermal loads for the problem of glass breakage. The first breaking time obtained by the program was in good agreement with experimental data.     

桩-网复合地基承载及变形的数值分析

采用有限元程序,对不同荷载水平下复合地基中单桩荷载传递特性、桩间土的沉降、桩间土上的应力及桩土应力比进行了分析;同时分析了复合褥垫层的变形模量以及地基中第一层土的物性参数对桩土应力比和复合地基表面沉降及差异沉降的影响。     

全受压和局部边缘受压下有裂纹薄板屈曲的试验和数值研究

受压下薄钢板经常发生屈曲失效,尤其当薄钢板存在一些如开口和裂纹等缺陷时。这种失效模式先于强度失效。给出了轴压下有裂纹板的屈曲荷载的试验结果和数值结果。为此,采用1200A铝合金制作成矩形板,且板的中心有斜裂缝。在试验和数值研究中,分析了裂缝的长度和方向、板的厚度和长宽比的影响。对两种不同的支撑形式和荷载条件(如:局部边缘荷载和支撑)的影响进行研究。最后,将试验结果与数值结果进行对比。     

新型轻钢复合墙体承重抗火试验及其墙柱热翼缘温升简化计算研究

提出以蒸压加气混凝土(ALC)板与玻特(CS)板作为覆板组合、以钢蒙皮和钢带作为墙板拼缝保护措施的新型轻钢复合墙体构造,开展了ALC板-CS板覆面的新型构造轻钢复合墙体足尺模型承重抗火试验。将轻钢复合墙体受火侧由不同覆板组合而成的防火构造简化为一层均质防护层,提出均质防护层的等效热物理参数(包括厚度、比热容、密度和导热系数)简化计算方法。根据能量守恒原理以及有限差分方法,提出ALC板-CS板覆面轻钢复合墙体的墙柱热翼缘受火温升简化增量表达式。结果表明:ALC板-CS板覆面轻钢复合墙体在0.27荷载比率条件下发生高温承载力失效的耐火极限达到197 min,表现出优异的耐火性能; 提出的温升简化增量表达式预测结果与有限元模拟结果吻合良好,可以用于确定轻钢复合墙体的耐火极限。     

四川汶川大地震中玻璃窗和玻璃幕墙抗震性能的初步分析

2008年5月12日汶川8.0级大地震中建筑物遭受巨大损失，震害调查表明：玻璃固定窗破损与主体结构破坏具有明显的相关性。玻璃幕墙则基本完好，目前尚未发现幕墙受到震害的事例。     

Development of Ignition Time and Mass Loss Rate Prediction Models for Rigid Polyurethane Foam with Multi-Step Thermal Degradation Under Various External Heat Flux Conditions

Fire Technology - To predict the ignition time and mass loss rate of rigid polyurethane foam (RPU) under various radiative conditions, numerical models with a multi-step thermal degradation process...     

Partnering 模式下的伙伴选择与项目绩效:合作关系的中介效应

Partnering 模式是改善项目绩效的一种有效方式,不同的伙伴选择会对项目绩效产生不同的影响。根据已有的研究将伙伴选择划分为信任程度、有效沟通、共赢态度和技术水平 4 个维度,引入合作关系作为中介变量,实证研究了伙伴选择对项目绩效的作用机制以及合作关系的中介效应。研究发现,合作关系在技术水平对项目绩效影响的中介效应并不显著,在有效沟通和共赢态度对项目绩效的影响中起着部分中介作用,在信任程度对项目绩效的影响中起着完全中介作用。研究结果对于 Partnering 模式下项目绩效的改善以及 Partnering 模式在我国的进一步发展与应用有着借鉴意义。     

Validation of Heat Transfer,Thermal Decomposition,and Container Pressurization of Polyurethane Foam Using Mean Value and Latin Hypercube Sampling Approaches

Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. It can be advantageous to surround objects of interest, such as electronics, with foams in a hermetically sealed container in order to protect them from hostile environments or from accidents such as fire. In fire environments, gas pressure from thermal decomposition of foams can cause mechanical failure of sealed systems. In this work, a detailed uncertainty quantification study of polymeric methylene diisocyanate (PMDI)-polyether-polyol based polyurethane foam is presented and compared to experimental results to assess the validity of a 3-D finite element model of the heat transfer and degradation processes. In this series of experiments, 320 kg/m³ PMDI foam in a 0.2 L sealed steel container is heated to 1,073 K at a rate of 150 K/min. The experiment ends when the can breaches due to the buildup of pressure. The temperature at key location is monitored as well as the internal pressure of the can. Both experimental uncertainty and computational uncertainty are examined and compared. The mean value method (MV) and Latin hypercube sampling (LHS) approach are used to propagate the uncertainty through the model. The results of the both the MV method and the LHS approach show that while the model generally can predict the temperature at given locations in the system, it is less successful at predicting the pressure response. Also, these two approaches for propagating uncertainty agree with each other, the importance of each input parameter on the simulation results is also investigated, showing that for the temperature response the conductivity of the steel container and the effective conductivity of the foam, are the most important parameters. For the pressure response, the activation energy, effective conductivity, and specific heat are most important. The comparison to experiments and the identification of the drivers of uncertainty allow for targeted development of the computational model and for definition of the experiments necessary to improve accuracy.     

"资源紧约束"条件下两规的有序衔接——基于上海"两规合一"工作的探索和实践

从探索上海城市总体规划和土地利用总体规划相互衔接的实践出发,从理论综合和实践分析的角度,总结城市总体规划和土地利用总体规划的目标、特征和实施途径、工作效果,.对探索当前资源约束条件下特大城市"两规合一"的工作方法作了研究.     

Using Numerical Simulations and Engineering Reasoning under Uncertainty: Studying the Collapse of WTC‐1

Abstract: A series of numerical aircraft crash simulations and thermal behavior analyses were made at Purdue University to study the response of the World Trade Center Tower 1 (WTC‐1) on September 11, 2001. The process included accuracy verification for the computational tools using available experiment data. Numerical models for the Boeing 767–200ER aircraft and the structural system for the top 20 stories of WTC‐1 were developed for the simulations. A second aircraft model, simpler yet comparable in effect, was developed and used for a parametric sensitivity analysis. Results from these simulations and published by other researchers indicate that while the observed impact damage to tower exterior framing can be estimated accurately, the unseen impact damage to the core structure of the tower could not be estimated with high confidence. Although the computational tools helped in developing an understanding as to what might have happened as the aircraft penetrated and disintegrated into the structure, they were not able to reduce the uncertainty in the core damage estimate. However, reflecting insight from the behavior of the Pentagon building under the impact loads it received on the same day and studying the effects of elevated temperature on mechanical properties of steel in light of experimental data, the uncertainty in the core structural damage estimate was found to be of negligible importance with regards to the ultimate fate of the tower. It is demonstrated that through use of numerical simulations and engineering reasoning, a dominant factor in the collapse of the tower could be proposed with confidence. It was the loss of fire‐proofing in the tower core during aircraft impact that left the core vulnerable to ensuing thermal loads and resulted in the eventual collapse of the tower.     

Evaluation of Fire Models by Using Local and Global Metrics and Experimental Uncertainty Estimates: Application to OECD/NEA Prisme Door Tests

Fire Technology - The use of numerical methods in fire safety investigations for civil buildings and nuclear facilities has received enormous attention in recent years. To evaluate...     

Toward the Characterization of Building Occupancies for Fire Safety Engineering: Prevalence, Type, and Mobility of Disabled People

This paper is the first in a series of four that collectively provide a substantial body of knowledge on the egress capabilities of disabled people who frequent public-assembly buildings. Here, the results are given of an analysis of survey data estimating the numbers and types of disabled people who are mobile beyond their own homes, the degree of assistance they require, the percentage of the total mobile population they constitute, and the extent to which they are involved in sports and leisure pursuits. This information can be used to derive working estimates of the prevalence and nature of disability among building populations when characterizing building occupancies, a prerequisite to fire engineering.