Criteria for Designing Bearing-Type Bolted Joints

The current (1965) criteria for proportioning bearing-type bolted joints are reviewed. The concepts of balanced design are examined and existing test results of bolted A7 and A440 steel connections fastened with A325 bolts are analyzed and compared with theoretical results. The examination of the currently used design concept showed that: (1) The concept of balanced design leads to inconsistent allowable bolt stresses for different plate materials; (2) the high-strength bolt behaves similarly under shear in a compact joint regardless of the type of connected material; and (3) the balanced design concept has no meaning in long joints because the bolts unbutton before the plate material can attain its full strength. A more logical design philosophy is suggested and possible design guides are outlined. The criterion is based on the shear strength of the bolt in various steel joints and is applicable to both the A325 and A490 high-strength bolts.