Ductility Design And Pushover Analysis Of Large-span Prestressed Concrete Frame Structure

Elimating oxygen and coal storehouse of thermal power plant is under heavy vertical loads, which is of long-span. As a result, the sectional dimension of beams and columns are heavy .But at the present time , this kind of structure system has been hardly applied in the central workshops of thermal power plants which are abuilding or built. When this kind of prestressed concrete structure system is applied in thermal power plants, the sectional dimension of members will be decreased evidently, steel will be saved, the earthquake reaction will be weaken, and social and economical benefits will be obviously obtained. Therefore, great theoretical and application value could be obtained when studies are conducted from the respects of its anti-seismic capacity and design approach. The main researches in this paper are shown as follows:First, the design method for creating excellent seismic performance of prestressed concrete frames is discussed: This method is developed from passively verifying the crack resisting coefficient to forwardly satisfying the bearing capacity according to performance. With this method, structures could be designed according to the degree of prestress, and the area of prestressing reinforcement could be determined. Then the area of regular reinforcement could be calculated with the equation of ultimate bending capacity on head-on cross-sections and structures in detail. This method makes design more simple, reasonable and economical.Second, the theory of Push-over analysis is introduced in detail and according to the characters of the thermal power plants namely "strong beam and weak column", Push-over analysis is conducted for this prestressed frame structures to obtain the deformation curves, the position and development of plastic hinges. Then an evaluation of the anti-seismic capacity is given in this paper by the method of capacity spectrum.Third, based on the pseudo-static test of 1/8 scale model of prestressed concrete frame the development regularity of cracks, ductility ,stiffness deterioration and the failure mechanism of building model , as well as the capacity for dissipation of energy are studied. Finally this paper provides some suggestions for anti-seismic design.The experimental study and theory analysis show that the structure failure mode is column side way system and the structural dissipating behavior is not excellent enough. But the displacement ductility factor of the test structure is more than 4; the prototype can meet the demand of seismic design in 7 intensity zones.