SEISMIC BEHAVIOUR AND MODIFICATION FACTOR OF STEEL INDUSTRIAL MILL STRUCTURES

According to developments in construction of industrial buildings in developing countries, more concentration and studies on seismic behavior of these types of structures are required. Noting that, no modification factors are proposed for this types of structures in seismic codes , current research is carried out on a special type of above mentionedbuildings, which is composed of a moment resisting steel structure with wide spans, containing heavy machinary on both floors of the building. These types of structures are used in various types of factories specially in cement plants. In this research, first thecomputational method for modification factor determination and related effective parameters are briefly described. Then the three dimensional finite element model of Abyek cement plant’s mill structure (which is computed and designed by the authors ofthe current paper some 10 years ago) is studied. Using accelerograms recorded on soil types 1,2, 3 & 4 ( due to Iranian 2800 code), after scaling them to Sa=0.3g, a total of 80 linear and Nonlinear Time History analyses are carried out on above mentioned 3D model using Sap2000 finite element analysis software. By performing a Modal Push-over Analysis and using achieved results of above mentioned analyses, the ductility and over strength reduction factors are computed for each related record. Finally the modification factors are calculated for both Ultimate state and Working stress design methods respectively.

کلیدواژه ها:

Accelerogram ، Nonlinear Analysis ، Modification Factor ، Overstrength Reduction Factor ، Industrial Building