Research On The Foundamental Theory Of Smart Stability Control In The Steel Structure

Steel possesses a good ability of high strength and ductility, and is easy for processing and convenient for building; however, the stability of the skeleton steel structure becomes conspicuous. Moreover, once the stability break of the structure or its member occurs, the whole structure collapses instantly and incurs disastrous engineering accident. It follows therefore that the stability of the steel structure has been the research focus in civil engineering.Smart material structures, with such functions as self-diagnose, self-tuning, self-recovery, self-repair and smart drive, enjoy wide application in civil engineering. For example, owing to its special positive and negative piezoelectric effects, the piezoelectric material can be developed into piezoelectric smart feeler unit and driver with high efficiency and reliance, thus achieving such functions as smart quiver control, smart stability control, smart monitoring, etc in civil engineering. This is a new research field, so at present, many problems are still in their initial stage.This thesis advances a new method of embedding piezoelectric piles to the common steel structure to form the smart active control element in the structure, that is, the pivot element bar. And this element can check as well as drive, so it can actively control the stability in the steel structure or its member.Based on the above considerations, first of all, the stability equation of the pivot element bar with piezoelectric piles embedded is deduced in both cases of static forces and dynamic forces, with both cases of non-mechanic-electric couple and mechanic-electric couple taken into considerations. Besides, the effect on the stability of the pivot element bar by the length and supply of the piezoelectric pile is demonstrated with calculations. Then, through the same procedures, the analysis of the stability of the pivot element bar is performed, and Mathieu-Hill Equation-the equation of dynamic stability break under the simple harmonic load is reached. Secondly, with the model as the example, theoretical analysis and calculation by finite element software are used to reach the proper mass of the model node and to find the proper site of the pivot element bar. Through the analysis of the four methods of embedding piezoelectric piles to the pivot element bar, the most appropriately embedding position is found and the most appropriate length of the pile is also reached, thus supplying the theoretical basis in employing piezoelectric materials properly and economically.At last, the dynamic time history analysis of the model is proceeded with the finite element analysis software. By analyzing and computing the dynamic time history response of the structure without piezoelectric piles embedded, the maximum displacement of the structure and the time curve of typical nodes are reached under various earthquake summits. And likewise, the dynamic time history response is analyzed and computed with piezoelectric piles embedded. And B-R guideline is used in judging the stability of structure. Then by comparing the results of the two cases, the thesis arrives at a natural conclusion that embedding the pivot element bar can delay the stability of the structure. Thus this thesis supplies the theoretical basis for specific jarring table experiments.