The steel坝, also known as the bottom shaft-driven flap gate, is widely used and belongs to a special type of gate, playing a crucial role in water ecosystem management and environmental preservation. The steel坝 is a two-way water-blocking structure that has gained popularity in recent years. Its scenic features, such as creating artificial waterfalls by passing water over the top of the gate, concealed structure, flood discharge through a lying gate, and infinitely adjustable opening, have led to its extensive application in urban river management. This gate structure, which controls the opening and closing of the gate by driving the bottom shaft, primarily consists of the gate leaf structure, bottom shaft, support pivot, arm structure, water seal structure, locking structure, and sediment flushing system.

The structural connections of the steel dam are primarily焊接, with local bolted connections as a supplement; the structural types can be divided into a multi-span statically determinate structure composed of a bottom shaft and hinge support, and a cantilever structure with the bottom shaft as the fixed end and the main longitudinal beam of the gate leaf as the free end, both being planar structures. The working principle involves a hydraulic actuator driving a lever arm, creating torque at both ends of the shaft, which drives the bottom shaft and the gate to rotate around the axis.