SOIL CATEGORY EFFECTS ON THE PERFORMANCE POINT OF STEEL FRAMED TUBE TALL STRUCTURES EQUIPPED WITH TRUSS BELTS AND ADDITIONAL ISOLATED UPPER FLOORS (AIUF)

Current research is carried out on Steel Framed Tube Tall Structures with Truss Belts, consisting welded connections. The main aim is to illustrate the effects of soil categories on the Performance Point of such structures, when using Seismic Base Isolation System under the top stories. For this purpose, 5 three dimensional 40 similar to 60 stories Framed Tube Structures, equipped with belt trusses are modeled, analyzed and designed according to ASCE 7-10 code, based on 3 soil categories of Rock (800<V-s<1200m/s), Dense Soil (360<V-s< 800m/s) and Loose Soil (180<V-s< 360m/s) respectively, according to spectral acceleration level of S-a=0.40g. Then, all designed models are equipped with Additional Isolated Upper Floor (AIUF), which behaves as a Soft Story on the top of the structure. After tuning the frequency and damping ratios for these secondary systems, a Modal Pushover Analysis is carried out on each secondary model. Finally by the means of FEMA356/440 guideline, Capacity Spectrum and Performance Point characteristics due to related soil categories are computed for each model, using USB97 pseudo-acceleration spectrums.