Impact-resistant capacity and failure behavior of unbonded bi-directional PSC panels

• Evaluation of impact resistant-capacities of unbonded bi-directional PSC panels.
• Verification of impact energy absorption efficiency of unbonded PSC panels.
• Deflection of impacted PSC panels controlled by concrete/rebar interfaces.
• Verification of superior impact residual strength capacities of PSC panels.

Prestressed concrete (PSC) constructions are widely used to build civil infrastructures such as nuclear containment vessels, super-span bridges, and mega-height high-rise buildings due to their excellent load and crack-resisting capacities. However, extreme loading scenarios such as blast and impact on prestressed concrete (PSC) members have yet to be sufficiently studied, due to the difficulties associated with analysis of high strain rate conditions in concrete structures. Therefore, to further elucidate the impact-resistant capacity, and protective performance of PSC structures, we detail the results from impact tests carried out on reinforced concrete (RC), PSC without rebars (PS), and PSC with rebar (PSR) panels with dimensions of 1400 × 1000 × 300 mm. Using a facility in Korea, impact tests were performed using a 14 kN impactor with drop heights of 10 m, 5 m, and 4 m for preliminary tests, and 3.5 m for the main tests. From the preliminary tests, the procedure, layout, and measurement system of the main impact tests were established. The impact-resistant capacity was measured using crack patterns and damage rates, while displacement, acceleration, and residual flexural strength were also measured. From these results, it was determined that unbonded, bi-directional PSR specimens show a high-impact energy absorption capacity, well-dispersed crack pattern, and outstanding residual flexural strength capacity. Also, the test results showed that the unbonded, prestressed concrete construction method can be used to protect critical infrastructures and structures against impact loading. These results advance fundamental understanding in this area, and aid in the advancement of similar research such as protective design and numerical structural impact simulation.