Steel rebars contribute to the seismic performance of a structure by enhancing its strength and ductility. When embedded in concrete, rebars act as reinforcement, providing tensile strength to resist the forces generated during an earthquake. This reinforcement helps prevent cracking and failure in the concrete, allowing the structure to better absorb and dissipate seismic energy. Additionally, the flexibility and high yield strength of steel rebars enable them to deform and absorb seismic forces, reducing the likelihood of structural collapse during an earthquake.