Octagonal Framed Tube Office Building: A Case History

This paper documents the structural design and analysis as it evolved in the planning of the new Capital Bank Plaza in Houston, Texas. The 1,375,000 sq ft $\left(127\text{,}900m^2\right)$ office tower consists of 50 levels above grade and 2 levels below grade. Wind resistance for the tower, an irregular shaped octagon in plan, facilitated the “framed tube” concept. Two‐story high prefabricated “tree column” modules were located at 10 ft (3 m) on center at the building perimeter. The structure is supported by a foundation mat with a basic thickness of 8 ft (2.4 m). Shortly after steel erection had commenced on the structure originally planned as a speculative office development, a Houston bank initiated plans to move their banking operations into the tower. To accommodate the bank's space planning requirements, the lower levels were redesigned to accommodate expansive open atrium banking and executive office areas with elevated walkways crossing the atrium spaces at various levels.