Influence of rebar configuration and steel liner detailing on the local impact response of reinforced concrete panels

Abstract

Despite growing interest in impact-resistant structures, including those used in nuclear power plants (NPPs), previous studies are limited in number and are often conducted under experimental conditions that deviate from actual construction practices. Although NPP structures typically incorporate dense steel reinforcement, the role of reinforcing steel in enhancing impact resistance has often been overlooked. The combined influence of rebar detailing and welded steel liner systems—both integral to real-world NPP construction—has not been systematically investigated, leaving a critical gap in understanding their combined contribution under impact loading. To address this gap, this study presents a comprehensive experimental and numerical investigation of the impact resistance of reinforced concrete panels with varying rebar detailing and rear steel liners. High-velocity impact tests were conducted to simulate hard projectile impacts representative of aircraft collisions against NPP structures. Complementary finite element analyses were performed to examine two key design parameters: steel liner thickness and angle stiffeners spacing. The results demonstrated that wider rebar spacing (180 mm vs. 130 mm) led to reduced impact resistance. Incorporating a rear steel liner significantly enhanced impact resistance, effectively preventing perforation when the liner thickness was approximately 2 % of the panel thickness. Beyond this threshold, additional increases in thickness yielded only marginal improvements. Similarly, reducing stiffener spacing improved resistance, though the improvement plateaued below 160 mm.