Will the Rivets Hold?

A riveted lap or splice joint usually fails by shearing the rivets across the plane between the plates. The capacity is straightforward: each rivet resists its cross-sectional area times the material’s shear strength, multiplied by how many shear planes cut through it, summed over every rivet — then divided by a factor of safety to give a working allowable.

Compare that allowable to the load the joint carries. If the load is lower you pass; the ratio of capacity to load is your real factor of safety.

Single vs Double Shear

In a simple lap joint the rivet is cut on one plane — single shear. In a butt joint with two cover plates the same rivet is cut on two planes at once, so it carries roughly twice the load for the same diameter. Switching a marginal joint from single to double shear is often the cheapest way to pass without adding rivets.

What Else Can Fail

Shear is only one of several failure modes. The plate can crush where the rivet bears on it (bearing), tear out to the edge if the rivet sits too close (tear-out / edge distance), or fail across the reduced net section in tension. A joint is only as strong as its weakest mode, so check all of them — rivet shear frequently is not the governing one.