火灾下门式钢刚架倒塌试验与雷达位移测试系统有效性研究

Collapse test of steel portal frame under fire and effective analysis of radar-based displacement measuring system

近年来火灾下钢结构倒塌造成消防官兵伤亡的事故频繁发生,亟需开展建筑火灾倒塌预警研究。现有研究已表明:可以通过测量门式钢刚架柱顶和屋脊处的微变形来预测火灾下结构的倒塌,但由于高温和热烟气的存在,火灾下位移的实时测量问题尚需研究。该文通过试验方法研究雷达在实际火场位移测量中的可行性,首先设计一个缩尺单跨门式钢刚架的火灾试验,得到结构的升温特点和位移变化规律;采用雷达位移测试系统对门式钢刚架火灾试验的关键点位移进行了测量,并与传统拉线位移测试系统的测量结果进行对比,验证雷达位移测试系统用于火灾条件下的结构位移实时测量的有效性与准确性;采用有限元软件ABAQUS模拟火灾下刚架的倒塌过程,数值模拟发现:考虑了次要构件约束作用的三维结构分析模型,可以较准确地模拟火灾下门式钢刚架的倒塌过程。

The accidents of firefighter casualties caused by the fire-induced collapse of steel structures are frequent in recent years. It is urgent to carry out research on the early-warning method for building collapse under fire. Studies have shown that the collapse prediction of steel portal frames under fire can be achieved by measuring the micro deformation of the eaves and apex of the frame. However,the measurement technology of displacement under real fire still needs to be explored due to high temperature and hot smoke. This paper investigated the feasibility of In SAR Radar technology in the displacement measurement under fire through a test. A fire test was conducted on a scaled steel portal frame structure model,and the thermal and displacement responses of key points of the frame were measured by the Radar-based displacement measuring system. By comparing with the results of traditional guyed displacement meter,the effectiveness and veracity of the radar-based displacement measuring system for structural displacement test in fire were verified. A numerical model was established to simulate the fire performance of the test frame in ABAQUS. The analysis results indicate that the three-dimensional model considering the actions of secondary members can accurately simulate the collapse process of the steel portal frame in fire.