Editing Skyscraper (section)

===Steel frame===
By 1895, [[steel]] had replaced [[cast iron]] as skyscrapers' structural material. Its malleability allowed it to be formed into a variety of shapes, and it could be riveted, ensuring strong connections.<ref>{{cite journal |title=Built Like Bridges: Iron, Steel, and Rivets in the Nineteenth-century Skyscraper|author1-link=Thomas Leslie (architect) |first=Thomas |last=Leslie |journal=Journal of the Society of Architectural Historians|volume=69 |issue=2 |date=June 2010|pages=234–261 |jstor=10.1525/jsah.2010.69.2.234|doi=10.1525/jsah.2010.69.2.234 }} Abstract only.</ref> The simplicity of a steel frame eliminated the inefficient part of a shear wall, the central portion, and consolidated support members in a much stronger fashion by allowing both horizontal and vertical supports throughout. Among steel's drawbacks is that as more material must be supported as height increases, the distance between supporting members must decrease, which in turn increases the amount of material that must be supported. This becomes inefficient and uneconomic for buildings above 40 stories tall as usable floor spaces are reduced for supporting column and due to more usage of steel.<ref name="lehigh.edu"/>