Acoustics Emission Characteristics Of Beams Of The Overall Structure Under Fire

The traditional fire design method, which is absolutely based on the single element fire resistance behavior, is unscientific and uneconomical. Because the structural integrity will cause the different fire resistance performance, the design method would lead to dangerous or uneconomical results. In order to obtain the real reaction of components of the overall structure under fire and provide effective recommendations for fire resistant design,fire resistance tests of a single-span beam and a two-span continuous beam of a full-scale overall structure, which is a 3-floor steel frame building (3x3bays) with floor and wall, have been carried out in this thesis. At the same time, the acoustic emission is monitored.Experiment on fire performance of signal-span steel beam and two-span steel beam under a static load is completed. The temperature of the steel beam and concrete slab, the deformation of the steel column and the vertical deformation of the beam were measured. Then, the deformation-temperature curve and deformation-time curve are obtained by analyzing the steel beam's temperature and displacement variation. The results show that: the temperature of the steel beam with different constrains is almost the same, but the displacement of the steel is very different from each other. The middle-span beam vibration goes down first and then goes up, while the side-span beam vibration goes down great and goes up little.At the same time, the signals of acoustics emission were collected. By analyzing the characteristic parameters of Acoustics Emission(AE),we find that:the number of cracks increases when the peaks of the energy rate appears; the amplitude of the acoustic emission signals is different when the beam is in the process of ascending and descending; these signals whose amplitude is between 75db to 85db appear when the beam is ascending.The data and conclusions of the test is valuable for the researchers to verify their results of the numerical simulation and theoretical analysis. This paper can offer effective recommendations for the fire resistance design and provide the basis for developing the software of the acoustic emission monitoring.