The Study On The Effect Of The Kind Of Vertical Irregular Structure With Flexible Upper Stories And Rigid Bottoms' Property

The mixed structure, a kind of vertical irregular structure with flexible upper stories and rigid bottom is formed due to the big differences in stiffness of multi-layer concrete frame upper gabled frame and the quality of upper and lower parts. At present, there are not perfect codes for the flexible upper and rigid bottom structure used in the anti-seismic building design in China.But only some clauses mentioned in the Technical specification for steel structure of light-weight buildings with gabled frames(CECS102:2002),the1.0.2,which describes as:When the top floor of building is designed by means of the steel structure of light-weight buildings with gabled frame, the rule can be applied to the building design,operation and installation.At the same time, substructure influence on the displacement of the top floor should be taken into consideration according to the specific situation of the substructure.In practice, the layers added and reconstruction of buildings for multi-layer concrete frame, especially for the upper gabled frame, is usually calculated and analysed separately.This paper aims to discuss the feasibility of separate calculation for the portal frame of the multi-layer concrete frame upper gabled frame.In this paper, the finite-element method is adopted to analyze separate gabled frames and multi-layer concrete frame upper gabled frame and discuss their dynamic property. Stepl, the natural vibration period, interlaminar shear force, inter-story displacement angle and steel moment of separate gabled frame and multi-layer concrete frame upper gabled frame have been studied. Step2, under seismic condition, the contrast and analysis of inter-story displacement angle and steel moment between the separate gabled frame and the portal frame of the multi-layer concrete frame upper gabled frame have been carried out.The last, Though comparison,the conclusion can be drawn that separate gabled frame method is infeasible.At the same time, the Technical Specification for Steel Structure of Light-weight Buildings with Gabled Frames(CECS102:2002), the1.0.2clause is inaccurate in structural dynamic condition.The study results obtained in this paper will provide reference value for engineering design in further improvement of multi-layer concrete frame upper gabled frames'structural dynamic property.