Acoustic emission characteristic of steelconcretecomposite floor during fire
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2018年06期
- Page:
- 69-78
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Acoustic emission characteristic of steelconcretecomposite floor during fire
- Author(s):
- ZHANG Dashan; ZHANG Jianchun; DONG Yuli; LU Xin
- （College of Civil Engineering, Huaqiao University, Xiamen 361021, Fujian, China）
- Keywords:
- structural engineering; acoustic emission; monitoring; steelconcrete composite floor; fire
- PACS:
- -
- DOI:
- -
- Abstract:
- To study the acoustic emission (AE) characteristics of a steelconcrete composite floor during a fire, a MicroⅡ multichannel digital AE instrument was used to conduct AE nondestructive monitoring during a fire on a fullscale composite floor，which had a secondary frame beam arranged along the short spans in the middle of long spans. The simulated fire environment was based on the ISO 834 international standard curve. AE signal data of measuring points were collected for filtering analysis at critical locations，such as the positions of corner, perimeter, and midspan in the composite floor. Through analyzing typical AE characteristic parameters, such as ringing count, cumulative count, amplitude, and energy, and combining them with the experimental phenomena during the tests, the loadtransferring mechanism and damage process in the composite floor during fire were examined. The results show that the AE parameters of a steelconcrete composite floor during a fire show different characteristics as the temperature along the slab depth changes nonlinearly, and the characteristics are in accordance with the crack stages of the slab. The phenomenon is considered to be caused by the mechanical behaviors of the material and structures. During the tests, the signal of the AE sources at early stage is most active, and it is in accordance with the inflection points in the curve of the ringing count and cumulative count with time and also the progress, distributed area, and intensity of the cracks on the slab surface. The variation of distribution characteristics for AE events in space is an important indicator of structural instability and inner damage, and its intensity (amplitude, energy, etc.) should receive more attention. During the cooling period, a certain amount of movement appeared between the steel beam and concrete slabs because of the difference coefficient of thermal expansion. Accordingly, the AE signal is still active at this stage. For this reason, AE characteristics during the cooling period should be considered sufficiently when a collapse warning system for building structures during fires is developed. 7 figs, 25 refs.
Last Update: 2018-12-18