Cyclic testing of existing and retrofitted riveted stiffened seat angle connections

A typical riveted stiffened seat angle connection taken from an 83-year-old building was tested to investigate its actual hysteretic behavior and potential moment resistance. Results show that such existing connections can develop a considerable moment resistance, but pinched hysteretic curves indicate they have a relatively low energy dissipation capability. Analytical models for prediction of the moment capacity of these connections are also developed and predicted results based on these models are found to be in good agreement with the test results. Then, two retrofitting schemes are proposed to improve the connection's hysteretic behavior, and the adequacy of the suggested retrofits is verified experimentally. First, the addition of ductile knee-braces is investigated. A 'selective welding' approach is developed as a second retrofitting technique. The design philosophy of each retrofitting scheme is explained, and analytical procedures to predict the moment capacity of retrofitted connections are presented. Experimentally obtained hysteretic curves are presented, improvements in the behavior of connections are noted, and comparison with analytical predictions are made.