共查询到16条相似文献，搜索用时 500 毫秒
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文中介绍了一种新型工程竹产品——正交胶合竹（CLB）。已有试验对CLB墙体在稳态传热过程下的保温性能进行了探究，为进一步研究CLB墙体在室外综合温度周期性变化作用下的传热过程并探究采用CLB墙体的竹结构房屋的能耗情况，通过建立在稳态传热过程下CLB墙体的有限元模型并与已有试验结果对比验证了其有效性，从而进一步建立了受到室外综合温度作用下的5种墙体模型，以此分析CLB墙体在非稳态传热条件下的保温性能以及不同保温方式对于CLB墙体保温性能的影响，最后通过DeST对CLB墙体房屋进行能耗分析。结果表明：研究建筑墙体受到的温度作用时，太阳辐射引起的当量温度不应忽视；CLB墙体拥有优越的保温性能，采用CLB墙体的建筑室内热环境稳定；无论夏季或冬季，保温层最合理的位置在CLB墙体的外侧；围护墙体采用CLB墙体的竹结构能够达到江苏省居住建筑节能率65%的水平。 相似文献
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木质复合材料与现有墙体材料传热物理性能的比较 总被引：1，自引：0，他引：1
采用热脉冲法测定木质复合材料的传热物理特性,并将其与现有墙体材料比较。分析可知：木质复合材料的热导率远小于现有墙体材料,是一种优良的保温材料。 相似文献
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为了强化轻型木结构墙体热工性能的研究工作,笔者采用建筑围护传热系数现场测试法,对内置两种材质的玻璃保温棉在同一轻型木结构房外墙围护结构进行现场传热系数测定,以此比较墙体保温系数的测试值与理论值,并优选保温棉填充材料。结果表明,墙体内填充材料为玻璃保温棉A的墙体的隔热保温性能优于玻璃保温棉B。对轻型木结构墙体进行传热数值计算,得到各组成材料温度的计算值与测试值具有同向可对比性,因此可用复合材料理论预测木结构热学性能。有助于提高我国轻型木结构房屋墙体结构的传热现场测试技术水平,为轻型木结构房屋的墙体结构的节能保温等优化设计工作提供借鉴。 相似文献
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轻型木结构墙体的热工性能对建筑节能至关重要,其稳态传热性能是节能效率评估指标之一。工程调研发现,轻型木结构墙体墙骨柱热传递过程易产生冷热桥,改善墙体保温构造并通过试验测试,对得到不同构造的墙体传热系数等指标进行分析研究,有利于设计人员优选墙体设计参数、研发墙体新型保温材料。试验采用标定热箱法与热流计法相结合的试验方法——控温箱-热流计法对改善保温措施的墙体进行试验,分析了12种墙体试件的热流密度、传热系数、热阻以及日传热量参数,并与理论计算结果进行比较验证,试验结果与理论计算结果吻合性较好。研究发现:气凝胶毡放置在墙骨柱位置能够有效降低平均传热系数3.8%~15.0%,随厚度增加可逐渐减弱或消除墙骨柱冷热桥效应;聚苯乙烯保温板可有效降低传热系数32.4%~35.1%,墙体蓄热能力较好;纳米纤维保温材料可有效降低传热系数5.9%~8.7%,提高墙体冷热面温差,平衡室内温度。选取的3种保温材料中,聚苯乙烯保温板相比气凝胶毡和纳米纤维保温材料,对墙体整体热工性能的提升更为显著。 相似文献
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第六讲 林火蔓延 总被引：1，自引：0，他引：1
森林在着火之后,火就会向四周和上下不断地扩展和蔓延,使大片森林发生火灾,这就是星星之火可以燎原的原因。火在森林中所以能自由蔓延,无限制地进行扩展,这与热的传播方式有着密切关系。热的传播方式总的来说有三种,即热对流,热辐射和热传导,前两种热的传播,主要是将热能传送到可燃物的表面,即可燃物之间的外部传热方式,而后一种则是可燃物在其内部的传热方式,这三种热的传播对林火的蔓延都起到一定的作用。热对流:众所周知,热空气比冷空气轻,在强风作用下,使对流热转为平流热,产生使火能过大江的现象,例如:1979年在大兴安岭林区春防期间的一次火灾,在15米/秒的大风影响下,林火越过三百米宽的嫩 相似文献
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The load-carrying capacity of a timber structure is highly dependent on the strength of its connections. Very limited information exists on the thermal degradation, or the properties at elevated temperatures, of such connections. This insufficient information is one of the major impediments for modeling elevated temperature performance for wood-frame structures. The objective of this study was to characterize thermal degradation of yield load capacity of single-shear nailed connections between wood and oriented strand board (OSB) as a function of time and temperature. The mechanism of degradation was explained using first order kinetics. Using the principles of time–temperature superposition (TTS), predictive models for connection capacity degradation were developed. A total of 450 wood-to-OSB connections were tested laterally after exposure to nine different elevated temperature regimes. The degradation of yield load strength over time occurred at a constant linear rate. Temperature dependence of this rate was modeled using the Arrhenius activation energy theory. Using Arrhenius activation energy theory and principles of TTS, a master curve was developed to predict the performance of connections after exposure to a temperature of 150°C. The predictions matched well with independent experimental observations. The master curve developed using TTS provides predictive estimates of residual capacity in a connection as well as its failure times. 相似文献
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【目的】为探明胶合木-钢夹板螺栓连接的动力性能和抗震性能,确保连接件在车辆、机械振动等动力荷载下的可靠性。【方法】针对胶合木-钢夹板螺栓连接的构造特点,考虑胶合木厚度和螺栓直径之比(厚径比)、螺栓顺纹间距、螺栓并列和错列布置方式等参数的影响,设计制作了4类13组共39个胶合木-钢夹板螺栓连接件,在低周反复荷载作用下进行滞回性能试验。【结果】试验结果表明:在单螺栓连接中,连接部位的破坏模式逐渐由"螺栓刚直"向"双铰"转化,胶合木销槽破坏模式逐渐由销槽整体承压破坏向两端部挤压破坏转变,试件滞回曲线基本都呈现饱满的弓形和棱形,具有良好的耗能能力和抗震性能,但其承载能力较低。在多螺栓连接中,螺栓和胶合木的破坏模式分别以"双铰"破坏和销槽端部挤压破坏为主,试件滞回曲线均呈现饱满棱形,该类试件在承载能力、抗震性能和耗能能力上均有大幅提升;随着螺栓顺纹间距的增大,试件的承载能力不断增大,但螺栓顺纹间距在200 mm时,极限荷载增幅趋于平缓,初始刚度增涨大幅放缓,且整体刚度退化与螺栓顺纹间距为250 mm时基本相同;螺栓并列布置滞回曲线饱满程度好于错列布置;螺栓双排布置承载能力比单排布置的承载能力更高,刚度退化更小。【结论】胶合木-钢夹板螺栓连接具有较好的耗能能力、抗震性能及延性性能;螺栓顺纹间距在200 mm时,抗震性能最佳;螺栓错列布置的抗震性能比并列要好,螺栓双排布置的抗震性能更优越。 相似文献
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This survey was conducted from 2005 to 2008 regarding the thermal environment of three types of experimental houses—a wood and mud composite wall type (Type WM), a mud wall type (Type M), and an insulated wall type (Type I). To reveal the influence of the wall composition of wooden houses on the indoor thermal environment, each experimental house was constructed on the same site. As a result, under natural indoor air temperatures, the monthly average indoor air temperature level and the time ratio of indoor air temperature surpassing the outdoor air temperature were in the following order: Type I > Type WM > Type M. Type WM exhibited the highest phase shift of air temperature, indicating that the insulation performance and heat capacity affect the phase shift of air temperature. The equalization of indoor air temperature through the suppression of the increase in the indoor air temperature of Type M is likely caused by low insulation performance and large thermal capacity. The time fluctuations in electric consumption by air conditioning and indoor–outdoor air temperature differences of each experimental house over 1 day indicated that a building’s thermal load and the thermal capacity are related. 相似文献
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FEI Benhua ZHAO Yong** REN Haiqing CHEN Enling Research Institute of Wood Industry Chinese Academy of Forestry Beijing P.R.China 《中国林业科技(英文版)》2006,5(3):1-5
INTRODUCTION China has a long history of wood framed construction. But, due to the increasing of population and lack of timber, wood framed construction is limited in the market, its research and development is relatively scarce. The modern wood framed construction has been developed and widely applied in the North American area and other countries for several decades. Recently, with the rapid development of economy and the requirement of society, especially energy saving, the wood frame… 相似文献
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A three-dimensional finite solid element model for Japanese traditional post-and-beam connections was developed using the
wood foundation method, which employed the concept of a beam on a nonlinear foundation. The wood foundation in the model was
a three-dimensionally prescribed zone surrounding a nail shank in order to address the intricate wood crushing behavior induced
by nail slip. Material models for the wood members and the foundation were developed based on the transversely isotropic plasticity
from the software package ANSYS. The Japanese post-and-beam connection modeled was a ten-nail multiple connection with a mortise
and tenon joint and is called the CPT (Corner Plate, T-shaped) connection. Details of the model development are presented.
As a feasibility study, blind predictions of the model were compared with available connection test data and showed good results
for predicting the progress of the load-deformation relations in three dimensions. However, the limitation of the model was
found in simulating fracture failures such as wood splitting or nail tear-out from the wood. Model applications and the need
for model improvement are discussed. 相似文献