The firm was founded in 1974 in Louisville, Kentucky by Thangam "Sam" Rangaswamy and Calvin Hatfield as Rangaswamy, Hatfield & Associates.  In 1982 the firm began practicing as Rangaswamy, Yost, & Associates with Michael Yost joining Mr. Rangaswamy as a partner.  In 1983 the firm was officially incorporated.  In 1987, the firm was reorganized as Rangaswamy & Associates, Inc. (RAI) with Mr. Rangaswamy being the  sole owner.  Under Sam's leadership the company was certified as a Minority Business Enterprise (MBE).  In 2001 a branch office was established in Chennai, India.  The Chennai office relocated to Coimbatore, India in 2010.

After a career spanning over 52 years, Mr. Rangaswamy decided to retire in 2016.  Long time employee Anthony Ehlers, along with his wife Celia, purchased the firm from Sam, with Celia being the majority & controlling partner.  In 2017 the firm was certified as a Women Business Enterprise (WBE) by the Louisville and Jefferson County Metro Human Relations Commission.

In 2018 the firm began operating under the shortened moniker of RAI Engineering, rebranding to both reflect the change in ownership while also maintaining our identity and continuing the legacy of excellence in structural engineering that has been established over the last 45 years.