Description

In 1995, an archival paper presented to the Wire Association International described four cast-iron girders discovered inside an old Philadelphia bank building in 1981. Each of the girders had been post-tensioned with two wire cables. Although the girders were traced to 1854, no one could explain how such previously undocumented technology was used so early. This paper gives an overview of the research by cast-iron construction expert Dr. Sara Wermeil, who discovered the girders were created by obscure American innovator Benjamin Severson.