The Elementary Research On A Practical Drift Analysis Approach And The Drift Limits Establishing Of Steel Frame Considering 2-orer Effect

Lateral displacement analysis is one of the most important items for steel frame design. First-order lateral displacement analysis and second-order later displacement analysis are different approaches for drift analysis, and they need different drift limits to be adapted. Code for Design of Steel Structure GB50017-2003, the being employed code in China, has codified the basic theory about second-order analysis, but there is no criteria about second-order drift, and the drift limits in the code can be only used in first-order lateral displacements analysis. Therefore, it is urgently that researches are needed on second-order drift analysis and on how to establish the new limits for second-order drift.It's a practical problem that researching how to establish second-order drift limits, and some conditions relative practical engineering are required to be taken into account. And before second-order drift limits have been established, the equations about second-order drift calculation which can be used in practice are required to be set down first.Many scholars have bring forward various principles and equations for second-order drift calculation. But the principles and equations are all on the ground of theoretic analysis, and they don't satisfy the needs of engineering practice. Based on these principles and equations, this paper attempts to give a prepositional equation for simplified analysis for second-order drift.Through the elementary research on second-order drift limits, this paper gives a second-order drift limit to one-bay-one-story steel frames, a second-order total building drift limit and a inter-story drift limit to multi-stories steel frames. This paper also contrasts the results of design examples calculated by the equation given in this paper and the accurate approach's. The contrasted results indicate the equation given in this paper has a good precision.