共查询到20条相似文献,搜索用时 250 毫秒
1.
插头插座在不同接触电阻下火灾危险性研究 总被引:1,自引:0,他引:1
分析了接触电阻过大引起插头插座温度变化的规律,为火灾调查提供依据。在实验中选用了额定电流分别为10A和16A的插头插座,研究在不同的接触电阻条件下以及在相同的接触电阻下通过不同过负荷电流时插头的升温情况,分析影响插头插座温度升高的因素,总结出不同条件下的插头插座的火灾危险性。 相似文献
2.
实验了五种插头插座在不同过负荷电流条件下温度上升的情况,测出了不同过负荷电流条件下插头插座接触处的最大温升,并对过负荷情况下插头插座的火灾危险性进行了分析。 相似文献
3.
《消防技术与产品信息》2017,(2)
研究了铜铝导线在违规搭接状态下的火灾危险性,选用常见的线径为2.5 mm2的铜铝导线,模拟出在实际生活中可能出现的铜铝导线违规搭接状态。具体阐述了实验仪器、材料和过程。实验结果表明:铜铝导线的违规搭接会在接点处形成较大的接触电阻,在电流作用下接触点温度上升,进一步增大接触电阻,形成恶性循环,具有较大的火灾危险性。 相似文献
4.
5.
6.
接触电阻对导电混凝土电热特性的影响 总被引:4,自引:0,他引:4
从理论和实验两方面讨论了接触电阻对导电混凝土测试电阻和电热效应的影响。研究结果表明,不同材料和不同布孚形式的电极与导电混凝土之间的接触电阻不同,在相同的外部电热功率作用下,导电混凝土板的升温速率和升温幅度不同,板内温度分布规律也不同;采用在混凝土中预埋带有孔洞的不锈钢板电极可以有效地减小接触电阻,从而获得良好的电热效应。 相似文献
7.
据有关部门统计,插头插座产品质量不高是近年来引发火灾的原因之一,在笔所调查过的火灾中,也曾有数次是因插头插座使用不当引起的。 相似文献
8.
9.
10.
《新安全 东方消防》2002,(9):74-75
插头插座产品虽小,其质量却直接关系到千家万户的安全。据有关部门统计,插头插座产品质量不高是近年来引发电器火灾的原因之一。针对这种状况,2002年第2季度,国家质量监督检验检疫总局对家庭及类似用途插头插座(含转换器)(以下简称插头插座)产品质量进行了国家监督抽查。 相似文献
11.
幕墙防火封堵安全性分析及解决方案 总被引:1,自引:0,他引:1
常用的幕墙封堵方法为在幕墙与每层楼板、隔墙处的缝隙处采用非燃性材料填充.主要填充材料岩棉在高温下碳化会失去阻火作用.新解决方案为用电缆防火板作支架,靠板大孔隙用防火包填实,幕墙玻璃接触面用有机防火堵料填实.优点为:高温强度好;膨胀率为20%以上,能有效填充空隙. 相似文献
12.
采用有限元法,考虑接触热阻,对组合楼板温度场进行模拟,得到的结果与试验数据进行了比较;分析了热阻大小对温度场的影响。结果表明:由于接触热阻的阻力作用,在热源附近,热阻越大,热量传递越困难,构件在该处的温度升高越快;在其他地方,热阻越大,传递过来的热量越少,温度升高越慢;热阻使接触界面两侧产生温差,造成温度分布不连续;热阻越大,界面两侧温差越大,对结构抗火越有利。 相似文献
13.
14.
Suriyah Thongmunee Tatsunori Matsumoto Shun-Ichi Kobayashi Pastsakorn Kitiyodom Ken Kurosawa 《Soils and Foundations》2011,51(5):959-974
This paper focuses on the bearing capacity of soil plugs (internal shaft resistance) through fundamental research on the bearing mechanism of dry silica sand plugs. Push-up load tests on the dry silica sand plugs inside a model pipe pile and DEM simulations were carried out to investigate the plugging behaviour. The influences of the packing state of the soil plugs (the relative density), and the height of the plugs on the bearing capacity were investigated. Prior to the push-up load tests, element tests on the silica sand and DEM analyses were performed to characterise the silica sand and to determine suitable DEM analysis parameters. The experimental and DEM results clearly show that the push-up force increases significantly with the increase in the aspect ratio of the soil plug, H/D, and with the relative density of the soil plug. The DEM analyses show a good agreement with the experimental results when the push-up force is small. Furthermore, the DEM results reveal that only the density of the soil plug in the lower portion, adjacent to the pile tip, increases gradually with the increase in the push-up displacement as well as the increase in H/D. Hence, it is the lower portion of the soil plug that mainly controls the capacity of the soil plug. 相似文献
15.
Segmental joints present a weak link in the tunnel lining both structurally (due to its low stiffness) and non-structurally (high risk of water leakage); therefore the behaviour of the lining joints has a significant effect on the performance of the shield TBM tunnel lining. Segmental joints are thus a particular concern when the tunnel lining is exposed to high temperature in the case of a tunnel fire. This paper presents an experimental study on the behaviour of TBM tunnel joints in fire under different mechanical loading and boundary conditions, and with both the normal reinforced concrete (RC) segments and hybrid fibre reinforced concrete (HFRC) segments. Totally thirteen jointed specimens were constructed at a scale of 1:3 and tested. Eleven specimens were exposed to a HC (Hydrocarbon) curve and mechanically loaded to failure either under-fire or post-fire, while two specimens were tested in ambient temperature to provide benchmark data. The results demonstrate that the initial loading conditions have a significant effect on the jointed segments during and after fire, and this is closely related to different rate of degradation of concrete in different stress state under high temperature. In general, the resistance capacity of both RC and HFRC joints increased with axial force. The use of HFRC material provided good spalling resistance. 相似文献
16.
17.
使用损伤与高温耦合作用下钢筋混凝土梁火灾试验研究与数值分析 总被引:1,自引:0,他引:1
为研究不同裂缝宽度对钢筋混凝土梁抗火性能的影响,以混凝土裂缝最大宽度wmax为损伤指标,制作7个钢筋混凝土梁试件,加静载使其产生最大宽度为0.05 mm、0.10 mm、0.15 mm、0.20 mm、0.25 mm、0.30 mm的裂缝,模拟其正常使用时受力状态,并对其进行火灾试验。试验结果表明:不同试件相同位置测点升温大致相同,但截面历经最高温度相差较大,最大温差达到150℃;裂缝宽度越大,试件最终破坏时历经最高温度越小,挠度增长越快。采用ANSYS有限元软件分析梁截面的温度场分布,结果表明:由于初始损伤的存在,相同截面高度处,不同截面沿跨度方向的温度曲线出现波动,裂缝处尤为明显;同一截面,沿截面高度方向的温度曲线出现平台,且裂缝越宽,平台越长,使得截面高温承载力显著退化。提出了考虑裂缝影响的高温作用下混凝土梁承载力简化计算模型,较未考虑裂缝影响的高温作用下混凝土梁承载力的计算精度提高显著。 相似文献
18.
火灾产生的高温可使建筑结构严重破坏甚至倒塌,为了保证建筑结构具有足够的抗火能力,必须进行建筑结构的抗火分析和设计。总结了目前国内外钢筋砼结构抗火性能研究的现状,包括国内外抗火试验研究现状、温度场计算、构件承载力计算以及建筑结构抗火性能应用软件研究等,并对今后的研究方向进行了展望。 相似文献
19.
摘 要:根据通风安全理论与基于组分输运模型的CFD方法,探讨圆形煤仓通风安全特性及合适的性能评价指标。以100 m直径圆形煤仓为例,研究环形通风口开口方式、位置及几何尺寸等因素对煤粉尘和气体分布和运移特性及去除效率的影响规律,得到最优的通风口设计参数。研究结果表明:单环形开口情况下,通风口由水平改为侧向,可改善内部环境,提高煤粉尘和有害气体的去除效率,推荐侧向环形通风口高度为2 m;在穹顶中部增设环形开口,能够有效减少煤仓上方30~35 m高度处的悬浮污染物量;双环形开口最优位置分别为15,31 m,可使煤仓内部大部分区域粉尘质量浓度低于10 mg/m3,CO2气体质量浓度低于30 mg/m3;排污效率最高均接近80%。研究成果可为超大空间圆形煤仓通风安全设计提供参考。 相似文献
20.
An approach for evaluating the fire resistance of reinforced concrete (RC) beams is presented in this paper. A macroscopic finite element model is applied to study the influence of various parameters on the fire resistance of RC beams. Data from parametric studies is utilized to develop a simplified expression for evaluating the fire resistance of an RC beam as a function of influencing parameters. The validity of the proposed approach is established by comparing the fire resistance predictions with those obtained from finite element studies as well as from fire resistance tests. Predictions from the proposed equation are also compared with fire resistance estimates from current codes of practice. The applicability of the approach to design situations is illustrated through a numerical example. The proposed rational approach expresses fire resistance in terms of conventional structural and material design parameters, and thus facilitates easy evaluation of fire resistance. The proposed approach provides better estimates than those from current codes of practice and thus can be used to evaluate the fire resistance of RC beams with an accuracy that is adequate for design purposes. 相似文献