Impact Response of RC Beams Coated with Polyurea Layers

Abstract

During the service life of reinforced concrete beams (RC beams), they may experience impact loadings induced by various falling objects, such as falling rocks and fragments of upper floors. Therefore, the RC beam’s impact resistance is important to its application in structures. This paper investigated the impact mitigation performance of polyurea coatings on RC beams by drop weight impact tests with different impact velocities and hammer shapes. According to the test results, the polyurea coatings can significantly reduce the RC beams’ local damage and midspan displacement. Moreover, it was found that the RC beams’ plateau impact forces were notably increased by the polyurea coatings. Besides, comparisons between impact tests with different impact loads indicated that the polyurea coatings’ protection effect was not noticeably influenced by the hammer shape or impact velocity. Based on the test results, a numerical model was established and validated, and the model was used to study the mechanism and the parameter influence of polyurea coatings. By simulating the response of upper- and lower-side coated beams, it was revealed that the polyurea coating reduced the RC beam’s overall damage by reducing its local damage and increasing its bending moment. Parametric studies showed that the mitigation effect increased with coating thickness and the increase rate decreased with the thickness. In addition, the effect of longitudinal coating length was also studied via numerical simulation, and it was found that the mitigation effect increased with coating length, and it became nearly identical to that of the fully coated beam when the coating length exceeded 60[Formula: see text]cm.