The Verification Of The Seismic Measures For Frame-Tube Structure And The Anti-Shear Design Method For Joints

So far, the seismic measures of Code for Seismic Design of Buildings and Code for Design of Concrete Structure are established by referring to the code of some other countries on the basis of experience of seismic disasters,seismic behavior experiments of structures and members and experience of structural design, and have not been verified by nonlinear dynamic response analysis with multi-waves input. Our research group has compiled the computer programs of nonlinear dynamic response analysis since 1998 in order to make these verifications possible. So far, the compiling and test of fake three-dimensional program TS-EPA have been completed which can be used in nonlinear dynamic response analysis of frameworks,frame-wall structures and frame-tube structures. Our research group has completed a series of nonlinear dynamic response analysis of various typical multi-storey and multi-span frameworks in various intensity-category by this program. With the support of special doctoral fund projects of the ministry of education, the following research works have been completed in this paper: 1. a 15-storey frame-tube structure and a 20-storey frame-tube structure have been designed strictly according to the design measures in intensity-category 9 of the code of our country. On the basis of the fake three-dimensional nonlinear dynamic response analysis of the designed frame-tube structures in the rare earthquake with six waves (five natural waves and one artificial wave) input for each structure, the response of every component of these structures has been meticulously analyzed, and the availability of corresponding seismic design methods and seismic measures has been verified; 2. The demand of displacement ductility of joint-beam-column combinations of some typical multi-storey and multi-span frame structures selected from the former analysis results in the rare earthquake has been identified. At the same time, the displacement ductility supply of beam-column combinations designed by the anti-shear design methods of seismic RC frame joints in the code of our country has been testify on the basis of the results of gathered tests in the world. And the demand of displacement ductility in the rare earthquake and supply of displacement ductility which is offered by the design formula have been compared. The following conclusion can be drawn from the above analysis and compute: 1. The couple beam is the important component which yields first and exhausts the earthquake energy by inelastic deformation in turns in these two typical frame-tube structures in the rare earthquake of intensity-category 9, so it need certain ductility ability. Thus, the seismic anti-shear performance and ductility ability of couple beam should be guaranteed by more effective design methods. 2. Currently, ductility ability of couple beam may be increased because the method which reduces the stiffness of couple beam in advance or anti-bent ability in the design of couple beam have to be done as result of the design method to control the upper limit of shear in order to guarantee basic ductility ability of couple beam in our country design field. 3. In these two typical structures which are analyzed in this paper, the wall of tube has not yielded for some other reasons although its amount of reinforcement is decided by compute, which results in that a few beam and none of column of the framework joined with and paralleled to the tube yield. It is clear that the seismic grade of framework can be degraded in the frame-tube structure which is similarity to these typical structures in this paper in intensity-category 9. And it should be tested by further nonlinear dynamic response analysis whether the framework can exert its seismic ability as the second line of defense or not after the wall yielded. 4. From the verification of the availability of the anti-shear design methods of seismic framework joints in current Code for Seismic Design of Buildings and Code for Design of Concrete Structure, it is clear that the joints which are designed according to the articles of seismic joints in intensity-category 9 in current code can offer enough anti-shear ability to guarantee that the joints are not shear failure in advance in rare earthquake. The corresponding measures are looser in intensity-category 8 and are necessary to be enhanced moderately.