钢框架结构中钢筋混凝土双向板火灾下的声发射特性

Research on Acoustics Emission Characteristics of the Concrete slabs in a Steel-frames Building in Fire

利用自行研制的火灾试验炉,对1栋3层3×3跨足尺钢框架结构中的钢筋混凝土双向板进行火灾试验,开展了将声发射技术用于火灾下整体结构中钢筋混凝土双向板的破坏监测研究。考察了火灾作用下板的声发射事件数、能量率和b值的变化,分析了各参数与板的裂缝开展、炉温及竖向位移等的关系。结果表明:利用事件数、能量率、b值等参数可以准确区分火灾下钢筋混凝土双向板的裂缝早期开展阶段、裂缝集中出现阶段以及裂缝缓慢扩展阶段;火灾下板的声发射参数产生突变时,如能量率突然升高、b值突然下降等,表征结构可能出现破坏,在建筑结构的消防安全指导方面应给予足够关注。

The specially designed furnaces were used, and two full--scale fire test was conducted on the concrete slab in a three--storey steel--framed building. Acoustic emission technique was used for monito- ring the failure of two--way RC slab in a whole structure under fire conditions. The changes of parameters of event, energy rate and b value are investigated. The relationship between these parameters and the cracking of slab, furnace temperatures and the vertical deflections are analyzed. The results indicate that the early stage of cracking, the stage of extensive cracks occurring and the stage of cracks propagating slowly could be distinguished accurately by analyzing these parameters. When these parameters change ab- ruptly, such as the sudden rise of energy rate and sudden decrease of b value, some structural failure may occur, and these moments should be highly concerned in fire.