Evaluation of dynamic characteristics of spliced PSC hollow box girder

초록

The main objective of the paper is to evaluate the dynamic characteristics of a prestressed concrete (PSC) girder that has been spliced with precast box segments. A 20 m full-scale spliced PSC girder is fabricated and tested to compare its dynamic properties against a monolithically fabricated girder. The monolithic girder has the same geometric and material properties with respect to the spliced girder. The experimental program involves two phases. First, a series of dynamic test is conducted to identify modal parameters of the girder including the natural frequencies and damping ratios. Finite element model is also developed to predict modal parameters of the test girder. The second phase is to study the effect of cracks in PSC girder on changes in dynamic, modal parameters. Experimental modal tests are conducted after test girders are loaded up to failure. It is found that the spliced girder provides 4% lower natural frequency and 5% larger damping ratio compared to the monolithic girder in the elastic range. The spliced girder is found to dissipate more energy through the splicing joints than the monolithic girder. In the damage state, the natural frequencies of both girders decrease compared to in the elastic state: 3.5% decrease for the spliced girder and 1.7% decrease for the monolithic girder. The accuracy of the predicted natural frequencies against the experimental ones is also presented.