Vertical Load Carrying System | Concrete slab supported on a pan-joist floor system and concrete encased steel frame with riveted connections. After seismic retrofit, the building is supported on isolation bearings. |
Lateral Force Resisting System | Original system consists of perforated unreinforced masony (URM) infill walls, lightly reinforced concrete walls, and steel frames with wind bracing. The building was retrofitted by using a hybrid system consisting of 526 base isolators and sliders at the base and supplemental dampers at the base (52 viscous dampers) and top of the building (12 dampers), and new concrete shear walls in the superstructure. |
Foundation Type | Steel columns of the tower are supported by concrete mat foundation; other columns are supported by isolated spread footings. The spread footings were enlarged and tied by new grade beams during the retrofit. |
Remarks | The building was seismically strengthened in 1997. |