Unbonded Pre-Stressed Concrete Blast Test
Given the large number of existing post-tensioned concrete structures and the number of new post-tensioned structures anticipated in the U.S. and worldwide, there is a critical need to evaluate blast performance and develop practical design provisions for blast resistance of these structures. Currently, there is a lack of data on the blast performance of post-tensioned structures. As a result, end users and designers are typically conservative in their assumptions and tend to underestimate the blast resistance of structural components with unbonded post-tensioned reinforcement subjected to blast loading. Information on the blast behavior of these structures and structural components would be beneficial for vendors, designers, regulators, and standards development organizations worldwide.
VSL Unbonded Pre-Stressed Slab Specimen Post-blast Test
Stone Security Engineering and Stone-OBL has lead an investigative effort in conjunction with Structural Technologies/ VSL to conduct open-air blast testing on an unbonded Post-tensioned slab reinforced with Structural Technologies’ proprietary systems. The slab was specifically detailed by Structural Technologies to withstand blast loading was tested at Stone-OBL blast testing site outside of Bend, Oregon. The 16-ft by 16-ft by 8- inch thick concrete slab was attached to the concrete reaction structure at the Stone-OBL test facility using a stiffened steel frame and was subjected to two blast tests using two different weights of ammonium nitrate/fuel oil (ANFO). The slab was tested using different standoff for each test. The behavior of the slab during these tests was recorded using sensors and high speed cameras. The measured responses out-performed initial predictions and exceeded current blast response criteria for unbonded pre-stressed systems. The remarkable results obtained during these tests warrants further investigation and research to define parameters that affect the performance of these structures and to develop practical design provisions for unbonded pre-stressed concrete elements.