An experimental study of autoclaved aerated concrete lintels strengthened with externally bonded glass FRP

摘要

This article presents the experimental data obtained from four-point loading of AAC lintels and compares the measured failure loads with capacities predicted using the conventional strength-design method. Fiber-reinforced polymer (FRP) fabrics are used to strengthen existing concrete structures as an alternative to externally bonded steel plates. Design approaches have been developed for application of FRP on conventional concrete surfaces, but there are other types of concrete materials that have not been sufficiently studied for FRP application. Autoclaved aerated concrete (AAC) is one such material introduced in the US market in the mid 1990s. There is an interest in evaluating the feasibility of application of FRP to retrofit existing structures or components made of AAC (e.g., AAC lintels, floor panels, wall panels, etc.). The specimens used in this study include AAC lintels without FRP and with two alternative schemes of FRP applied to the external lintel surfaces for flexural and shear strengthening. Specimens of conventional reinforced concrete were also tested for comparison with AAC when both are strengthened with FRP. The measured test data provide a basis for evaluating the accuracy of existing strength-design equations to predict the capacity of such specimens. Test results show that the application of FRP at the bottom of the lintels, in combination with U-wrap at the ends of the lintels, increases the load and deflection capacities. Comparison of test results and calculated strengths shows that the existing guidelines such as ACI 440.2R and ACI S23.4R give safe estimates of shear and flexural strength for FRP-enhanced AAC lintels.