Building a high-rise or any multi-level building demands the use of lightweight yet strong materials. Steel, by its high strength to weight ratio, enables large spans and lightweight construction. Steel structures can have a variety of structural forms like braced frames and moment-resistant frames suitable to meet the specific requirements of higher buildings or high-rise buildings. Taller buildings also face higher wind loads, and hence steel being flexible, allows the building to move and deflect with the wind forces, rather than making it rigid like concrete.