Experimental and numerical investigation of biomimetic Serpenoid geometry for deformation control and stiffness regulation in reinforced concrete frames

Biomimetic Serpenoid geometry is a curvature-based structural configuration inspired by the lateral undulation of snakes, in which continuous sinusoidal curvature enables deformation through geometric straightening and uncoiling. Such geometry provides a basis for developing structural elements that regulate deformation and load transfer through geometry-driven mechanisms. However, the application of Serpenoid geometry as an externally connected deformable component in reinforced concrete frames remains insufficiently investigated, particularly with respect to its influence on structural deformation, stiffness response, strain-energy behaviour, and load-transfer characteristics. The Serpenoid geometry was initially investigated at a winding angle of α = 30°, followed by a parametric finite-element investigation over the range of α = 5°–60°. A critical transition region was identified between α = 35° and 40°, and the α = 36° configuration was subsequently selected for frame-level investigation. The selected Serpenoid configuration was fabricated using Fe550D reinforcement and externally integrated with an M30 reinforced concrete frame having overall dimensions of 600 mm × 1090 mm. Numerical and experimental investigations were subsequently performed on conventional bare and Serpenoid-integrated RC frames. At a common numerical load of 20 kN, the vertical deformation and strain-energy responses of the two configurations differed by only 0.225% and 0.159%, respectively. Experimentally, at a common load level of 8 kN, the Serpenoid-integrated frame exhibited a 13.21% reduction in vertical deformation compared with the bare frame, while the experimentally calculated energy absorption was 5.51% lower. The Serpenoid-integrated frame also exhibited a 120.6% increase in horizontal deformation capacity, higher absolute secant stiffness over the investigated load range, and a more distributed crack-development pattern. The results indicate that the proposed Serpenoid configuration primarily contributes to deformation control, stiffness regulation, and increased lateral deformation capacity rather than an increase in global energy absorption within the investigated experimental loading range.