Experimental and numerical study of the flexural behavior of SCS beams with two-end welding C-shape connectors and reactive powder concrete core

The steel-concrete-steel (SCS) sandwich structure consists of a concrete core and two steel face plates connected by mechanical shear connectors. Channels, or C-shaped shear connectors, are commonly used. However, a research gap is the difficulty of constraining the ends of the channels to the steel face plates. In this research, it is proposed to use a complete weld at one end and a slot weld at the other end to ensure two-end welding of channels to the steel face plates. To study the flexural behavior of SCS beams with the proposed structure, eight experimental SCS beam samples were created. These included one sample with a conventional concrete core and seven samples with a Reactive Powder Concrete (RPC) core, incorporating different contents of steel fiber and polypropylene (PP) fibers. The samples underwent a four-point bending test. Additionally, to evaluate the impact of geometric parameters, the numerical model was validated using experimental results. The results showed that slot welding can be a suitable alternative to constrain the inaccessible end of channel shear connectors. This method effectively maintains the integrity of the layers and significantly reduces the likelihood of failure at the weld points. Observations also indicated that incorporating 1 % steel fibers or polypropylene fibers into RPC provides the best performance in controlling shear cracks, enhancing maximum strength, and improving energy absorption. Additionally, the results demonstrated that an improper arrangement of shear connectors can significantly lower the load-displacement diagram level.