Researches Of Structural Random Damping In Shaking Table Test Of High Building

With increasing of construction span and height and anti-disaster capability, the structure damping seemed more important in engineering, but there is a problem about how to estimate value of damping. Combined with a shaking table test conducted, this paper designed a program by means of Matlab language and its signal toolbox function based on experimental modal analysis theory. With the program, the structural damping ratio of prototype is calculated and used to modify experience-formula. The main contributions of this paper are as follows.1) The history of structural damping is summarized, each damping theory and its present research status in the world are introduced, the problems during the present research are put forward, the significance on the research is discussed, the research contents and technical route in the paper are established.2) Each factor that has effected on the structural damping is analyzed. The authentic measured data from the factual structures and mathematic method is applied, and the effect of different measuring method on structural damping is also discussed.3)A 1:25 micro concrete scale model, which is a high-rise building of frame-shear wall structure with high transfer floor, keeping model similar to prototype in loading behavior, is used in a shaking table test. Three seismic waves are selected in 51 operating modes. The acceleration, displacement responses and strain of the model are measured and the appearance and development of the crack are observed.4) Combined with a shaking table test conducted, this paper designed a program by means of Matlab language and its signal toolbox function. With the program, the transfer functions of model were obtained from the acceleration data of white-noise seismic wave inputting after shaking. Then frequency and damping ratio of model were estimated based on the frequency-magnitude curves.5) The other damping ratios about model in shaking were calculated according to an experience-formula and max -displacements integrated from acceleration data. The curves of damping ratio were drawn and analyzed with structural model varying from elastic stage to elastic-plastic stage. It can be practiced on other analogical high-building structures design for reference of dumping ratio.6) A modified experience-formula is derived from the old based on comparing modal damping ratio data with experience damping ratio.7) In the end, all research in the paper is summarized, and the problems that may be further studied are put up.