Seismic Capacity Comparative Study Of Prestressed And Non-prestressed Frame Designed Based On The Code

Although the seismic capability of prestressed concrete structure(PC) shown in the previous earthquake is satisfactory, but there is still some controversy on the usage of it in highly seismic region at home and abroad engineering.The idea that the seismic capacity of PC structures is poor than nonprestressed concrete(RC) structure, recommends some codes and norms of a number of countries to have different restrictions on the use of PC structures in the earthquake zone.Yet another contrasted view is that the seismic capacity of PC structures is not less than RC structures.The compound seismic capability of structure will be dependent on the method adopted to design.In order to better contrast the seismic capacity of PC frame with RC, designed according to our country's specifications, analyze their differences, study the deficiencies that may exist in PC frame, this article in accordance with the present stage of the existing concrete structures, a train of elastoplastic seismic time-history analysis is conducted on 16 specimens in 8 groups of PC and RC frame with different fortification intensity and aseismic grade under rare earthquake by Opensees.The specimens are designed in accordance with the current national norms and regulations including"Code for design of concrete structures", "Code for seismic design of buildings" and "Specification for seismic design of PC structures" in the same engineering condition(the same total span, overall height and story height on the same site).Then the comparative studies are carried on the seismic capacity of PC and RC frame based on the results of nonlinear dynamic time-history analysis.The main conclusions are:1.The results of nonlinear dynamic analysis demonstrate that: the PC and RC frames with seismic-resistance level 1, 2 and 3 individually which are designed according to our country's norms and regulations in operation on the zone of fortification intensity 7, 8 are able to avoid the overall and partial failure and therefore achieve the earthquake fortification target, "No Collapsing under Strong Earthquake";2.With anti-seismic grade 2 of seismic intensity 8 and anti-seismic grade 3 of seismic intensity 7 for the housing is less than 24m in height the PC frame is prone to a poor hinge pattern that plastic hinges are emerged at every end of every ground floor column at the same time under the rare earthquake, and with the fortification earthquake acceleration decline, this situation is particularly prominent. 3.PC frame with anti-seismic grade 1,2 and RC frame are be able to form mixed energy dissipation mechanism with beam hinge mainly, and achieve strong column and weak beam seismic design goals of the code requirements.But that is difficult thing for PC frame with anti-seismic grade 3 of seismic intensity 7.And the level of strong -column-and-weak-beam of RC frame is higher than that of PC frame as a whole.At seismic intensity 8 area, with the reduce of the seismic grade requirements and acceleration, the structures will be shown by a decline of level of strong-column-and -weak-beam , which is more prominent in PC frame.4.Under the rare earthquake, the maximum rotation angles of beam and column in two kinds of frames are far less than the limitations, and The needs of rotation ductility are all in reasonable level.