Abstract In this paper, an experimental programme of six steel plate girders subjected to patch loading as well as results of forty eight numerically-tested prototypes are presented. Results of ultimate load capacity as well as structural responses from these girders are provided. In addition, experimental and numerical values of ultimate load capacity are compared with those predicted by EN1993-1–5. With such results, the response of transversally stiffened steel plate girders is discussed throughout the paper. Particular emphasis is given to the influence of the transverse stiffening on the ultimate load capacity of the girders. It is observed that girders with largely spaced transverse stiffeners present a considerably different response from girders with closely spaced transverse stiffeners. The structural response for the former case has been thoroughly studied in the last decades whereas little attention has been paid for the latter. Further analysis of this particular topic is provided in a companion paper.