Free Vibration Analysis of Arches with Partially Hybrid-Material Confinement

This study analytically investigates the effects of partial hybrid-material confinement on the free vibration characteristics of arch structures. A confinement layer composed of different materials was arranged over a specified segment along the arch axis. The stiffness parameters associated with the free vibration of the confined cross-section, such as axial rigidity, flexural rigidity, mass per unit length, and mass moment of inertia, were explicitly formulated. By using these stiffness parameters, the governing differential equations were derived based on the Euler–Bernoulli beam theory, including the effect of rotary inertia couple. The resulting changes in natural frequencies and mode shapes were analyzed. In addition, a parametric study was conducted to examine variations in dynamic characteristics with respect to the confinement thickness, confinement length, confinement location, and material combination. The results provide effective strategies for the optimal placement of confinement layers in structural reinforcement design.