It is found that mechanism which improves seismic performance of steel bridge pier: Inner cruciform plates changes local deformation mode of tubular column and improves strength and ductility.

• 明确了十字形钢板改善桥墩抗震性能的机理：十字形钢板的设置改变了钢管局部变形的模态，从而提高了结构的延性和承载力。