National Bank Building is a 26-story structure with 3 basement floors, 6 atrium floors, 17 office, and mechanical floors, and on top of these a steel construction executive floor. Story heights are in general 4 meters. Basement floors are bigger in the plan area than the upper levels and with the rigid sheer walls all around, serve as rigid support to building for the earthquake loads.
The structural system is composed of tube-like shear walls to carry earthquake loads and gravity loads, and interior columns to carry gravity loads. The sheer walls and columns are connected with beams. The thickness of the shear walls is decreased on the upper floors to obtain a lighter structure. For the atrium and the roof floor of the conference hall steel structural system will be used. According to the preliminary design analysis, the structural displacements are at a reasonable level.
Due to the weak soil conditions, a deep foundation system will be used. Piles will carry both gravity loads and earthquake loads. 100cm diameter piles with 250 tons of carrying capacity will be used. Preliminary analysis shows that 340 piles will be enough to support the structure.
26-storey bank building, over 26,000m2, is in the most severe seismic zone. It has survived a terrorist attack in 1999 without incurring any structural damage.