Research On Displacement-Based Design Method Of Reinforced Concrete Frame Structures

Displacement-based seismic design is one of the important methods on performance-based seismic design, it have such advantages that the performance level is more straightforward and the method is easy to use as it will represent the development tendency of seismic design in this century.The displacement-based seismic design of reinforced concrete structure includes the contents of two respects mainly. One is determination of the base shear by target displacement and design the bearing capacity of member section; the other is estimate of the curvature ductility of the member section by target displacement ductility to design the deformation ability of member section.It is generally a characteristic that, for multi-story frame, the stiffness of the reinforced concrete frame structure is not constant over the height of the structure. Applying the inverted triangular distribution of lateral force to cantilever column with varying section, and the displaced shape of it is regarded as initial displacement mode. On the basis of the theory, the multi-degree-of-freedom system is transformed into single-degree-of-freedom system, thus the corresponding equivalent parameter can be calculated. And then design the bearing capacity of member section. In the paper the structure is analyzed with pushover method. Compared with the lateral displacement mode of identical section, this method is more rational.For the purpose of mastering the seismic performance of the structure accurately, it is very important to study the yielding position, yielding process and the failure mechanism of the structure under earthquake. A method of yielding-ratio is put forward and it makes the structure designer judge the plastic hinge distribution more easily, so the performance after the structure has entered the non-linear state can be understood thoroughly.In order to guarantee the brittle failure wouldn't take place in the structure, the design of deformation capacity of member section plays a key role in the ultimate state of the structure. For different demands of displacement ductility and the different failure modes, the demand of curvature ductility can be deduced and, for frame column and beam, the formulation of confining reinforcement characteristic value is established based on the relationship of confined concrete and the outer confining.