Steel should be used as the primary structural material with special emphasis placed on innovation in steel design. Structural steel offers a number of strengths in building design including high resiliency and performance under harsh and difficult conditions, (e.g., earthquakes and hurricanes) and offers the ability to span great distances with slenderness and grace. Steel can be shaped to achieve curved forms and can be erected quickly to meet tough construction schedules under almost any weather condition. Steel can be easily modified to satisfy the life cycle of a building including changing occupant requirements. Steel is the most recycled material in the world. Today structural steel is 97% recycled with the primary source of material being automobiles. It is the environmentally sound choice for a building material. Architects have praised the natural beauty of steel and are excited about exposing it in the design of their structures to emphasize grace, slenderness, strength and transparency of frame.