Comparison of dynamic properties of spliced and monolithic prestressed concrete box railway girders

Longitudinal splicing of precast prestressed concrete (PSC) girders has recently gained increasing support as an effective method to accelerate bridge construction. The presence of the joints in the spliced girder may alter the dynamic properties of the system. In this study, a 20 m long full-scale spliced PSC girder was fabricated and tested to identify its dynamic characteristics against a monolithically fabricated girder (monolithic girder) with the same dimensions. The experimental program involved two phases. First, the dynamic properties of the test girders were identified from a modal test. Numerical modal analyses based on three-dimensional finite element models were also performed, and the calculated modal parameters were compared with the test results. The second phase involved a characteristic decrease of the natural frequency due to the damage to each girder after the load test. This study shows that the spliced girder provides a dynamic performance comparable to that of a monolithic girder in both the uncracked and cracked states.