Static and dynamic tests on steel joints equipped with novel structural details for progressive collapse mitigation

This paper presents static and dynamic tests on nominally-pinned steel joints equipped with novel structural details for progressive collapse mitigation. The proposed structural details utilise the exceptional ductility and strength of stainless steel pins to enhance both the tie force and the rotational capacity of a vulnerable steel joint. The stainless steel pins along with additional supporting elements are installed in the joint region without interfering with the design for gravity loads, and they can be used for both new designs and to retrofit existing steel buildings. A static test on a vulnerable industry-standard steel fin-plate connection is first presented followed by two static tests on the same connection retrofitted with the proposed structural details. The retrofitted connections were subsequently tested under dynamic conditions with increasing imposed loading using a test setup that simulates a sudden column loss scenario. The test results showed that nominally-pinned joints equipped with the proposed structural details can achieve the required tie force capacity while undergoing rotations larger than 0.2 rad. Analytical equations based on simple joint equilibrium are used to validate the results of the static tests. An analytical method based on the energy conservation principle is also proposed and comparison with the dynamic tests shows very good predictive capability when the assumed loss of energy is 22%.