| The composite frames are widely used much in tall structures, which are composed of steel columns and composite beams. The modern building is taller and its span is longer than before. The stability will become a crucial factor. However, The experimentation and theoretical research of stability about composite frames are scanty in China and overseas. The composite frame still adopts the design method of steel frame without thinking the composite action of floor slab. Therefore, The study of stability about composite frames can offer theory for planner. It is significant for optimizing structure, improving economical efficiency and consummating relevant criterions and rules for composite structure.The stability and practical design approach for composite frames were studied, main research work are as follows:(1) Based on stiffness of composite beams. In which the inter slip is take into account. The flexuosity characteristic equation of composite frame was established. The influence of composite action on ultimate bearing resistance of composite frames was analysed.(2) The modified method of computational length about composite frames' column was established and its applicability was discussed. Especially considering the influence of various beam end and column end constrains. The effect of composite action and semi rigid joint on computational length also were studied. The difference between the modified method and traditional steel frame' method.(3) The second-order analytical approach of composite frame was established, which mostly considered the influence of second-order action and semi rigid joint on internal force and displacement of composite frame.(4) In terms of redistribution of steel-concrete composite continuous beams'internal force and non-linear joint performance of composite connections. The abbreviated stability design method was established, the economical efficiency and suitability were discussed. |
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