This report presents details of the testing of various two bolt connections, some with plain holes and some incorporating a single kidney shaped slot. Based on the results of the tests, it is recommended that the connection capacity be taken as the capacity of a single bolt in a plain hole multiplied by a factor of 1.6. It was found that the displacement at working load is not significantly greater than connections with two plain holes, and should not preclude the use of such details in orthodox structures.
The recommendations apply to bracing connections in orthodox buildings with two bolts, and where the end and edge distances of the connection detail comply with certain limitations. For strut design, connections incorporating a kidney shaped slot should not be assumed to provide directional restraint.