Study on dynamic impact performance of double U-shaped buffer device based on synchronous / asynchronous yield

In response to the urgent need for protection against rockfall impacts in mountainous road and bridge engineering, this paper focuses on a novel double-U-shaped energy-dissipating bearing and systematically investigates its mechanical performance and energy-dissipation mechanism under impact loads. Currently, there is a lack of protective devices that combine high energy dissipation efficiency with reusability. To address this, this study uses elastic-plastic theory to determine the geometric dimensions required for simultaneous yielding of the device. Based on Abaqus finite element simulations, it reveals the influence of radius, thickness, and straight-section coefficient on energy dissipation performance, and verifies the mechanical response under various operating conditions through static pressure tests and dynamic impact tests. The results indicate that the base group of the synchronous yielding design achieves a relative energy dissipation efficiency of 68.1%, exhibiting the characteristic of “large geometric deformation with small material strain”; the group with a thicker lower section achieves a maximum energy dissipation of 594.694 J and a buffering delay time of 40.9%, making it suitable for scenarios sensitive to dynamic responses; the group with a larger lower diameter has an effective stroke of 160 mm, capable of withstanding high-speed rockfall impacts. The double-U-shaped bearing achieves efficient energy dissipation through the elastic-plastic deformation of its core components and can be reused after mechanical stretching, providing critical data support and design references for rockfall protection projects in mountainous areas.