|M.Sc Student||Alwely Fisal|
|Subject||Seismic Behavior of Ductile Wall-Frame Structural Systems|
|Department||Department of Civil and Environmental Engineering||Supervisors||Professor Emeritus Avigdor Rutenberg|
|Professor Robert Levy|
In this study the seismic base shear demand on multistory structures comprising shear walls and ductile frames - dual systems - is examined. The amplification of shear force demand on the walls due to the higher vibration modes, before and after the formation of plastic hinges, is studied as it is affected by the following three parameters: (1) fundamental vibration period of the structure; (2) strength reduction factor; (3) horizontal interaction between the walls and frames, which is represented here, as in the conventional continuum approach, by the relative stiffness parameter aH.
The linear and non-linear behavior of dual systems with distributed stiffness and strength per the continuum approach, assuming elastic-plastic moment-curvature relationship in the plastic hinges - confined to the walls' and columns' bases and to the ends of the frame beams - is studied. A computer program, written as part of this study, adapted to perform regular and cyclic pushover, carried out the analysis. The solution algorithm was based on solving the different differential equations governing the respective responses in the elastic and yielding regions of the wall-frame structure.
It is shown that the amplification of base shear depends strongly on the flexural strength at the base, i.e., the strength reduction factor (K in IS 413, R or q in foreign seismic codes), the fundamental natural period and the relative stiffness parameter between wall and frame aH. The shear amplification factor is found to be much larger than specified by seismic codes: the New Zealand (1982) and the Israeli SI 413 (1995).