Experimental Study on Seismic Performance of Flexural-shear Replaceable Energy Dissipators in the Beam-column Joint

A high-strength steel beam-column joint with flexural-shear type replaceable components is proposed to solve the problems of damper buckling under compression and unstable energy dissipation capacity under certain practical working conditions. This joint offers the advantages of minimal plastic residual deformation, stable energy dissipation capacity, and convenient repair after an earthquake. Five specimens are designed based on the mechanical characteristics of the flexural-shear energy dissipators in the joint. The energy dissipators’ collaborative working mechanism and failure modes are investigated through quasi-static tests. The influences of various design parameters on the bearing capacity, stiffness degradation, and energy dissipation capacity were analyzed. In addition, the applicability of calculation equations for bearing capacity and stiffness is discussed, leading to the proposal of appropriate design advice. Test results indicated that the flexural-shear energy dissipators exhibited superior synergistic performance between the struts. Damage is primarily concentrated at the ends of the energy-dissipating struts, where cracks develop from the interior toward the surface, causing fractures. Then, seismic energy is dissipated. The hysteretic curves of the specimens are relatively full and demonstrate good energy dissipation capacity. Increasing the height-width ratio or the width-thickness ratio of the struts results in decreased initial stiffness and bearing capacity of the energy dissipators. The trend toward out-of-plane deformation becomes evident, reducing the equivalent viscous damping coefficient and worsening the energy dissipation capacity. The strength equation, which considers the effects of flexure and shear strength, accurately predicts the yield and ultimate load of the energy dissipators. The average error between the predicted and test results is less than 5%. However, when the struts’ height-width ratio (H_T·<italic>B</italic>^–1) exceeds 5, the predicted results from the stiffness equation are too high, indicating that the softening effect of flexural deformation should be considered at this stage. After a comprehensive comparison of the seismic performance indicators of each specimen, it is recommended that the value of H_T·<italic>B</italic>^–1 be approximately 3.5, <italic>B</italic>·<italic>t</italic>^–1 be 1.5, and <italic>n</italic> be 10.