预应力混凝土结构抗火设计构造措施分析

预应力混凝土结构在火灾下的抗火性能可以通过理论计算得到保证，但是如果预应力混凝土结构的构造措施不合理，也将大大降低结构的抗火性能，甚至引起预应力失效。通过非线性有限元计算讨论了保护层厚度和防火涂料对结构抗火性能的作用，并对规范要求的保护层厚度进行了分析，最后对锚固区的耐火设计提出了建议。     

两类常用森林火灾蔓延模型的比较

简要介绍了两类常用的森林火灾蔓延模型--邻接单元模型和波动传播模型的原理和实现方法.对作为离散模型的邻接单元模型和作为连续模型的波动传播模型的优、缺点作了系统的总结,并分析了它们对系统精度、实时性、复杂性、全局适应性、计算可靠性和整个模拟系统结构性能的影响.通过对比发现,两类模型在性能上的优势和局限有很强的互补性.因此,为了提高蔓延模型的性能,并使其不受火行为和地理要素复杂性的限制,有必要取长补短,通过现有的计算机技术将两者结合起来.     

混凝土简支梁设计基准期内的可靠度

根据统计资料对不同类型建筑在不同防火措施下发生火灾的概率研究,得出了各类建筑达到轰燃的概率.基于蒙特卡罗随机有限元方法,引入材料高温本构关系、截面尺寸和计算模型系数等的变异性,按照ISO标准升温曲线升温,给出了单构件轰燃下的失效概率计算方法.最后,将设计基准期内建筑物达到轰燃的概率与单构件轰燃下的失效概率组合,给出了设计基准期内建筑构件在火灾下的失效概率公式.     

基于系统动力学模型的影剧院人员疏散策略

随着社会的发展,人们对生命的重视程度日益增强,大型公共场所临灾情况下人员疏散问题的研究也越来越有实际意义.分析以往影剧院火灾事故可以发现,不正确的疏散逃生行为所引起的通道堵塞,是导致人员大量伤亡的一个主要原因.根据系统动力学原理,应用STELLA系统软件,建立了基于粗网络模型的人员疏散模型.以影剧院发生火灾为例,分析了采取不同疏散策略所产生的避难效果差异,找出了最佳的疏散策略.所提研究方法和建立的模型,对于合理设计疏散路线和优化建筑物的出口与通道结构具有一定的实用价值.     

西部复杂性地貌地区消防规划评估与建设研究 ——以凉山州区域为例

城市消防规划作为城市消防安全体系建设的重要依据,是助力城市现代化进程、推动城市综合安全智慧网络形成的重要基石。通过对凉山州各地貌地区消防现状存在问题的分析,结合凉山州的实际情况及全州建设发展多种形式综合性消防应急救援队伍的需要,提出了能满足全州消防安全需求且能够有效指导城市消防建设的相应对策。     

火灾科学需深入研究的课题探讨

火灾科学是系统的科学,它涉及多个技术领域。从科学发展和现实角度,提出当前的火灾科学在城市消防规划、高大空间建筑防火设计综合方法、多层地下交通枢纽防火研究、安全疏散心理和机理研究、火灾自动报警系统的关联研究、建筑防排烟技术研究、建筑结构耐火性能研究等10个技术领域需深入研究的课程,以最终实现基础理论、实用方法、先进技术和科学管理一体化。     

城乡接合部居民楼火灾风险评价及防控对策研究

为了准确探究城乡接合部居民楼火灾事故致因机理,预防与控制城乡接合部日常生产与生活过程中引发火灾事故的有效途径,建立信息面更全、实际性更强的火灾风险评估模型是目前行之有效的手段。基于湖南省某地发生火灾事故的实际情况,根据事故树分析法,以城乡接合部居民楼火灾事故为顶事件构建事故树,计算得到事故树的最小割集、最小径集和结构重要度,研究城乡接合部居民楼火灾事故的发生模式、致因因素及影响程度,为改善城乡接合部居民楼火灾安全提供重要的理论依据,并提出相应的防控措施及对策。     

煤矿火灾烟气流动传播过程仿真研究

煤矿发生火灾后会生成大量有毒气体并产生火风压,烟气在火灾动力的影响下出现状态紊乱,研究煤矿火灾烟气流动传播过程对控制火情有着重要意义。基于国内外研究现状,对燃烧及风流特点进行分析,建立了煤矿火灾烟气流动数学模型,并利用CFD软件进行仿真。研究表明:无通风工况下的烟气为对称流动;随着风速增加,出口处温度降低,烟气向风流入口处的流速减小。     

Understanding Interaction Effects of Climate Change and Fire Management on Bird Distributions through Combined Process and Habitat Models

Abstract: Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process‐based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf‐area index values were lower in shrubland. This high probability of occurrence likely is related to the species’ use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes.     

Ecosystem restoration in fire-managed savanna woodlands: Effects on biodiversity,local livelihoods and fire intensity

Ethiopia aims to restore 15 million ha degraded forests and woodlands, but effects on the potentially contrasting goals of long-term carbon storage, biodiversity and sustainable livelihoods are unknown. To quantify the effects of grazing exclusion on vegetation and fire behaviour, we established six 30 × 30 m fenced exclosures with grazed controls, in a mesic wooded savanna. Experimental burns were done after 1.5 years. Tree seedlings were few but more common inside fences. Field layer cover and biomass increased inside fences, and grass species increased in numbers and cover. Fire intensity was higher inside fences, killing shrubs and saplings but not mature trees. Interviews confirmed that overgrazing has resulted in “cool fires”, causing shrub encroachment. High-intensity fires occurred in the 1980s after a zoonotic disease killed most livestock. Short-term increase in carbon storage through fire and grazing exclusion may lead to loss of pasture, and in the long-term increased wildfire risk.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01343-7) contains supplementary material, which is available to authorized users.