Mechanical properties of the composite sandwich structures with cold formed profiled steel plate and balsa wood core

Fiber reinforced plastic (FRP) sandwich structure are increasingly used in construction areas recently for its high strength, light weight and corrosion resistance performance. This paper proposed an innovative composite sandwich structure incorporating GFRP skins, a cold formed profiled steel plate and a light weight balsa wood core. The interaction between the different components was connected by stainless steel core rivets. Three-point bending tests were conducted on eleven specimens to investigate the parameters (shear span to depth (a/d) ratio, thickness of cold formed profiled steel plate and spacing of the stainless steel core rivets) effect on the performance (deflection, ultimate load bearing capacity, and failure modes) of the new proposed structure. The test findings indicate that a reduction in ultimate load-bearing capacity ranging from 13% to 41%, accompanied by an escalation in deflection between 1.7 and 13.9 times, as the a/d ratio ranges from 1 to 6. All beams experienced failure at deflections ranging from span/114 to span/50. Specifically, specimens displayed core shear failure for a/d ratios ≤ 4, transitioning to top skin compression failure at an a/d ratio of 6. Compared to specimens without cold formed profiled steel plate reinforcement, the load bearing capacity of the new proposed composite structure at serviceability limit states and ultimate limit states was increased by 68%−194% and 53%−83%, respectively. Moreover, the reinforcement of the stainless steel core rivets can ensure the coordinated working of different components, and the smaller the spacing, the better the working effect. Finally, an analytical model was developed to account for the impact of cold-formed profiled steel plates on specimen stiffness and load-bearing capacity. This model was subsequently validated through experimental results. Both the experimental and theoretical analysis verified the favorable performance of the proposed new composite structure.