Eccentric rivet connection problem

The concentric rivet connection does not bear the action of moment, and the rivet is evenly loaded, that is, the load is evenly distributed to each rivet. This is very close to the actual situation. Even if the rivets are distributed on the same line, the end rivets (or the first fastener) will not be overloaded as much as imagined. All connection elements are checked according to the following: the shear strength of the fastener; the compression strength of the fastener to the connecting plate.

For fastener groups whose fasteners need to withstand bending moment and shear force, it is necessary to check whether they can withstand the combined load. Assuming that the load on each fastener is proportional to its distance to the centroid, the calculation of the load distribution of a group of fasteners under the action of torque becomes quite easy. Of course, this assumption is correct only if the size of each fastener is the same (also assuming the same material). (Guide: Features and uses of stainless steel self-drilling screws)

Assuming that there are 5 rivets of the same size on a symmetrically arranged joint, the shear load is 10000lbf and the torque is 12000lbfin. In this case, the centroid position of the connecting rivet (the center of the moment action) is based on No. 5 rivet to make sure. The central rivet cannot bear any moment because it is at the centroid position and has no moment arm. The distances from the outer three rivets to the centroid are the same, and the loads caused by the moments are the same. The magnitude and direction of the resultant force on all rivets are different. The resultant force of the rivet is composed of the vertical concentrated load and the load caused by the moment. In this case, No. 1 and No. 4 rivets bear the largest and most critical load. The No. 5 rivet falls exactly at the centroid position of the group, so the load caused by the No. 5 rivet is not affected by the moment.

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