Static performance and energy-dissipation mechanism of a rockburst-resistant joint for U-shaped steel roadway supports

Maintaining load-bearing capacity while accommodating deformation and absorbing energy remains a challenge for metallic roadway supports in rockburst-prone coal mines. To address this need at the connection level, an energy-absorption joint (EAJ) incorporating patterned steel blades is proposed for U-shaped steel supports. Its static response is investigated through laboratory tests and finite element (FE) analysis. The experiments examine the effects of patterned material area and blade configuration, while the numerical study evaluates four configurations with blade thicknesses of 3–6 mm. Relative movement between the connected steel members induces blade stretching and plastic deformation, accompanied by inward bending of the cover plates. Experimental blade fracture is associated with an abrupt load reduction near the peak. The FE model reproduces the principal deformation pattern and peak-load ranking. Absolute errors in peak load and absorbed energy are 2.97–14.55% and 2.32–17.72%, respectively, whereas failure displacement is overpredicted by 12.73–32.34%, indicating greater uncertainty in deformation-capacity prediction. Across the numerical cases, peak load, absorbed energy, and mean crushing load range from 187.90 to 695.13 kN, 6.38 to 23.84 kJ, and 85.24 to 317.37 kN, respectively. ED-2 achieves the highest values of these indices at each investigated thickness. Stress contours suggest load transfer through multiple ligament branches in ED-2, although the evolution of local plastic deformation requires further verification. Increasing blade thickness raises peak load, absorbed energy, and mean crushing load, with comparatively limited variation in predicted failure displacement. These results support considering blade configuration together with thickness in joint design and provide a static performance basis for further development. Resistance to rockburst impact requires subsequent dynamic validation. Highlights Patterned steel blades enable energy absorption at U-shaped steel support joints.Blade stretching is accompanied by inward bending of the cover plates.Blade topology influences load-transfer paths and fracture locations.The lattice-like blade configuration provides higher static resistance and absorption.Thicker blades increase predicted resistance and energy absorption.