Abstract: The lateral bending loading test of the T-joint made of I-core sandwich plates with base metal of low-alloy CCS-B steel was performed by using the lateral bending loading test device.Tracking shooting T-joint lateral bending deformation and failure process was investigated by the macro camera technology,the entire loading dynamic response process was recorded by the material testing machine,and the bending process of T-joint was simulated.The joint fracture was investigated by SEM.The results show that the yield strength and ultimate strength of the T-joint are 337 MPa and 501 MPa,respectively.The initiation crack is located outside of the gap at the weld connection in the upper of the neutral axis of the core plate and the crack extends to the center of the weld in the wake of loading.When the width of yield zone at the junction exceeds 1/3 of the width of the core panel,the joint reaches the yield strength;when the width of yield zone exceeds 1/2,the joint reaches the maximum bearing capacity and fast failures.