EVALUATION OF THE ADDED FORCE IN THE SEISMIC DESIGN OF STEEL MOMENT FRAMES IN DIFFERENT SITES OF TEHRAN DUE TO THE INCREASE OF FLOORS
Keywords:
Moment frame, periodicity, design spectrum, added force, construction site, tall buildingsAbstract
Moment frames are one of the most widely used structural steel systems, especially for residential use. In the design of such structures, lateral seismic loads and different gravitational loads play a role which according to most design regulations about such structures for the convenience of designers, seismic design spectra and the amount of gravitational loads are determined. Since the forces in the model play an essential role in the design of sections and optimization of materials, especially for high-rise Buildings, in this study using the Site Special design Spectra for 6 different sites in Tehran with Different seismicity and soil types are obtained and using the periodic intervals intended for them, spectral acceleration and final base shear are calculated and according to the loading combinations, the final force is obtained for adding each floor to the model. The results show that the total force of the model increases linearly with the increase of each floor with very high accuracy and the total base shear acts as 2 ascending lines with the increase of the floors, but the force from per added floor for models up to 13 is ascending classes, 4 to 10 descending classes and from 11 to 66 floors is almost constant.