Abstract: A multi-piece pre-assembled raft foundation is provided and includes pre-assemble bottom layer rebars of foundation slab, foundation steel columns, upper layer rebars of the foundation slab, and foundation rebars. The pre-assembled raft foundation is transported to a construction site for final assembly. A construction method of the multi-piece pre-assembled raft foundation is also provided.

Abstract: A pre-embedded piece includes a reinforcing steel bar and a screw rod. The reinforcing steel bar includes a body and an embossed portion formed on an outer periphery of the body. An end of the screw rod is connected to an end of the reinforcing steel bar. A method for producing a pre-embedded piece includes preparing a reinforcing steel bar and a screw rod. The reinforcing steel bar includes a body and an embossed portion formed on an outer periphery of the body. The reinforcing steel bar and the screw rod are placed end to end and fused together. A reinforcing steel structure of an embodiment includes a plurality of main bars, a plurality of hooped columns, and a plurality of pre-embedded pieces. A reinforcing steel structure of another embodiment includes a plurality of hooped columns and a plurality of pre-embedded pieces.