Seismic damage and evaluation analysis of joints in enhanced-performance recycled aggregate concrete frame

Abstract

Through the low cycle loading test of three full-scale enhanced- performance recycled aggregate concrete frame joints, the damage evolution and accumulation are analyzed according to the traditional ductile damage model (single parameter) and the improved Park-Ang damage model (double parameters): when the characteristic displacement of each specimen equals 20 mm, the specimen has been damaged, but the calculated results are negative according to ductile damage model; when the characteristic displacement exceeds 100 mm, the calculated results of the improved Park-Ang damage model show that all the specimens have been completely destroyed and cannot continue to bear load, but the actual results of the specimens still show certain bearing capacity and energy dissipation capacity. Therefore, it is necessary to modify the aforementioned damage model to make it suitable for enhanced-performance recycled aggregate concrete structures. Based on the foregoing test results, the fiber coefficient a, displacement coefficient α, and correction coefficient of energy coefficient k were proposed and fitted for the improved Park-Ang damage model. In addition, a corresponding modified Park-Ang damage model was established. Finally, using the proposed damage model, the error analysis of damage index was carried out with the example of HF-RAC2. The results show that the average error is within 6%, so the proposed two-parameter damage model can be applied to the analysis of seismic damage assessment of EC-RAC frame joints.