Guided wave-based damage assessment on bolt in precast beam-to-column joints

This paper deals with theoretical, numerical, and experimental investigations of guided wavebased damage assessment on bolts in the precast joints under cyclic loads. The mechanical behavior of precast bolted joints is analyzed, and the relationship between the force and drift ratio of the energy-dissipating (ED) bolt is derived. The propagation characteristic of guided wave in ED bolt is revealed through finite element simulation. The influence of tensile damage and looseness damage on the received signals is further studied, and two indexes are developed for evaluating the health status of ED bolts. Cyclic loading tests were carried out on four precast bolted beam-column joints with different precast beams, and the guided wave signals of ED bolts under each level of loading were monitored by arranging lead zirconate titanate (PZT) sensors. The bolt yield drift ratios were obtained by skeleton curves and FBG strain detectors respectively. The relationships between the two damage indexes and the drift ratio are obtained, and the two developed damage index trends were very well reproduced by analytical expressions. The health state assessment of ED bolts and precast bolted structures is realized by the proposed damage limit method, whether in daily maintenance or after the earthquake.