The Research on the Anti-seismic Performances of the Multi-layered Steel Frame Structure Workshop with Top Layer for Gabled Frame
|Keywords||Steel frame Prtal frame Seismic design Dynamic property Elastic time-history analysis Elastic-plastic time-history analysis Deformation control|
In recent year, the multi-layered steel frame structure workshop with top layerfor gabled frame is getting more and more attention because of its good characters.Although such structure combines the advantages of structural system of steel frameand portal frame, it has many shortcomings, such as uneven distribution of mass andstiffness and the dynamic characteristics which are easily affected by the processequipments. At present, studies on seismic performance of the multi-layered steelframe structure workshop with top layer for gabled frame are not enough. Therefore,further research on seismic performance of such structure has practical significancebecause of the importance of seismic design. Taking a multi-layered steel framestructure workshop with top layer for gabled frame that locates in the city of GeErmuin province QingHai as a practical example, the studies reported in this dissertationare summarized as follows:(1)The basic theory and analysis methods of seismic design are introduceddetailedly, which include the principles of seismic fortification, motion equations andsolving, etc. The basic principles of seismic fortification summary are as follows:avoiding soft ground; sizing uniform neat; ensuring the strength and stiffness andductility of the structure and components; designing according to the approximatedegree of safety; installing multichannel seismic lines; preventing brittleness andinstability of damage.(2)Combined with practical engineering, the topology is discussed from the angleof seismic design of structure type selection and layout of the structure. Results showthat the framework type of door rigid frame structure is conducive to coordinationwith the major process equipment layout, formed under the firm on the soft isadvantageous to the aseismic structure system. For this kind of structure, steelaseismic structure is better than reinforced concrete aseismic system because of itslight weight and high strength, as well as convenient arrangement for largeequipments. To improve seismic performance of structure on structural arrangement,the structure of mass, stiffness distribution uniformity and the rationality of theprocess equipment layout should be paid special attention.(3)According to the seismic deformation control parameters from differentspecifications and taking the typical case of framework as an example, the researchermade different aseismic designs. Based on the finite element software, the seismicperformance of the multi-layered steel frame structure workshop with top layer for gabled frame, including elastic time-history analysis and elastic-plastic time-historyanalysis,is investigated by3-D solid finite element simulation model analysis. Resultsshow that the scheme i, in which the top horizontal displacement limit value and theinterlayer displacement angle limit both referred to specification for design of steelstructure of multi-layer steel framework as H/500and1/400, met the requirements ofspecification of earthquake structure deformation, but the efficiency is not high. Thescheme ii, in which the top horizontal displacement limit value and the interlayerdisplacement angle limit of1~3layers referred to H/500and1/400, and the interlayerdisplacement angle limit of1~3layers referred to1/180, showed good performanceunder frequent earthquakes, as well as high efficiency, but did not met therequirements of structure deformation under rare earthquakes. The last one, in whichthe top horizontal displacement limit value referred to H/500and the interlayerdisplacement angle limit referred to1/250, not only met the requirements ofspecification of earthquake deformation under both frequent earthquakes and rareearthquakes, but also had good economic benefit. In a word, for the type of the doorframe steel structure factory building in seismic design, the choice on the tophorizontal displacement limit value of H/500and the interlayer displacement anglelimit of1/250is the most reasonable.