Push-over Analysis Of Reinforced Frame Structure With Consideration Of P-△ Effect

With the development of high buildings, the influence of gravity second-order effect (gravity P-â–³ effect) is attached more and more importance to, especially the areas in which the wind load or earthquake action is very great. The P-A effect caused by gravity load makes internal force and displacement of structure larger, even instable. As have been shown by a serial of massive earthquake at home and abroad. Among of the elastoplastic analysis, the time-history analysis has been proved to be the most reliable method. But the method is constrained in the application to the earthquake engineering because technology is complicate, amount of work is big, and calculation time is long. Based on the background, to search a simple method to make it understand the elastoplastic performance in the strong earthquake action, which will have application value.So the static elastoplastic (Push-over) analysis is put forward in succession by different researches in variant countries in order to check the aseismic ability of structure. In itsessence, Push-over analysis is a kind of static calculation method. In brief, one of simulating lateral inertia forces is put on the analyzing model and is enlarged step and step till the structure gets into a predetermined state. During the procedure, the yielding elements are then relaxed to form plastic hinges and incremental lateral loading until a nonlinear static capacity curve is created.The author has mainly done the following work: establishing the structure and element calculation model of RC frame structures; achieving the section moment-curvature cure; judging the place and the appearance order of the yielding elastoplastic hinges and the limiting elastoplastic hinges; discussing the target displacement and the distribution pattern of lateral force; making the Push-over analysis program considering P-â–³ effect, based on established model; contrasting the consideration of P-â–³ effect to non. In this article, the author made a Fortran Language program, analyzed a real case through Push-over and checked its usefulness. The results showed that: (1) The estimating method based on the code is useful and can be practiced; (2) The Push-over analysis program made by the author can analyze the behavior of structure and judge structural weak place; (3) In judging the aseismic ability of structure, it is advisable to combine the Push-over curve with the displacement of different story and the distribution of plastic hinges.