This document summarizes research on pre-engineered steel structures (PES). It begins by defining PES as steel structures designed and prefabricated in a factory. The document then reviews 12 previous studies on PES that analyzed topics like the behavior of PES under different conditions, seismic analysis of PES using software, and comparisons of PES to conventional steel buildings. The studies found that PES can be more cost effective and use less steel than conventional structures. However, the document notes that a firm conclusion cannot be drawn. It concludes that while PES offer advantages over conventional structures, both approaches have merits depending on the situation.