Ultimate behaviors of mechanically fastened shear type connections of thin stainless steel plates were investigated on the basis of quasi-static tensile test of 90 specimens. The specimens were formed from SUS 304 flat plates of 1.5mm and 3.0mm thickness and an SUS304 angle section of 3.0mm thickness, the connections of which were fastened by SUS 304 ordinary strength bolts of M12 and M16,and SUS 630 high-strength bolts of M12. Major observations are : four fracture modes, i.e., net section fracture, end opening fracture, block shear fracture, and fastener shear fracture were observed ; current design method has a difficulty in predicting the fracture mode which should take place among the four modes ; and current design formulae tend to overestimate the ultimate strength. From these facts, modified formulae for calculating the ultimate strength were proposed, which were found to provide a satisfactory prediction for failure mode and ultimate strength.
