Abstract: According to the characteristics of the PC composite box girder with corrugated steel webs，a formula calculating the torsional vibration frequency of the composite box girder is proposed based onthe Hamilton theory， which considers the shear deformation of the composite box girder． Then，a 5. 2 m experimental box girder model with corrugated steel webs is taken as the objective to conduct a modal experiment，and a modal analysis is performed by adopting the finite element analysis software ANSYS to construct a finite element model of PC composite box girders with corrugated steel webs． By comparing the measured value，the theoretical value and the finite element analysis results，both the correctness of the proposed formula and the applicability of the finite element model are verified． Analytical results show that the shear deformation has a great influence on the torsional vibration performance of the composite box girder with corrugated steel webs． Finally，through the parameter analysis，the influences of the thickness and folded angle of corrugated steel webs on the torsional vibration frequency of the composite box girder are analyzed． The results show that the torsional vibration frequency of the composite box girder with corrugated steel webs increases with the thickness of corrugated steel webs，while it decreases with the increase of the folded angle of corrugated steel webs．

Key words: corrugated steel web, composite girder, torsional vibration, shear deformation, modal experiment