Long-Term Mechanical Properties of Steel–Concrete Connectors Subjected to Corrosion and Load Coupling

Steel–concrete composite structures are widely used in modern buildings and bridges for their great rigidity, light weight, and simple construction. However, the mechanical behaviors of steel–concrete composite structures degrade over time because of environmental corrosion and long-term load. The existing research on structural durability has often focused on concrete or steel structures. Few studies have been conducted on steel–concrete composite structures, especially on structures under the coupled impact of corrosion and load. To investigate the coupled impact of corrosion and load on the performance of steel–concrete composite structures, a long-term test of 200 days was carried out on eight connectors. The corrosion of the studs was accelerated by DC current, and the test connectors were submerged in a salt solution with a concentration of 5% NaCl. Deformations including the concrete strain and relative slippage between the concrete slab and the steel beam were measured in the long-term test. The experimental results showed that at the end of the long-term test, the deformations induced by shrinkage were about three times larger than those induced by creep for the steel–concrete composite structures. Notably, the stiffness of the connectors degraded substantially with the aggravation of the corrosion of the studs, whereas the concrete strain was only slightly affected by the studs’ corrosion. The measured deformations were also obviously larger than those calculated by the current specifications. As a reference, a suitable formula for the long-term elastic modulus is proposed to enhance the applicability of specifications.