Abstract：A large number of expansion joints on bridge decks of simplysupported beam bridges may lead to driving uncomfortable，so that the measures of continuous decks for multispan simply-supported beam bridges have been widely used. The Hainan Puqian sea-crossing bridge is located in the seismic zone. To improve driving comfort and to achieve the purpose of protecting the main structure of the box girder under strong earthquake，a continuous structure of steel-STC lightweight composite simply-supported beam bridges with excellent performance and easy to repair was proposed. To explore the bending resistance of the continuous bridge deck of simplysupported beam bridge，two schemes were proposed for the full-scale model test of negative bending moment. Test results showed that in the scheme 2，the cracks focused on the bolt connection area，but in the scheme 1，rare cracks occurred at the bolt connection area.From the failure mode，it was observed that in the scheme 1，U ribs yielded under compression and the bolts didn’t fail under shearing. While in the scheme 2，U ribs didn’t yield and the bolts failed under shearing. That means that under seismic loads the continuous deck structure was destroyed firstly to protect the main structure of the box girder. Finite element software was used to simulate the experiments，and the results agreed well with the test results. On this basis，the finite element calculations of real bridge for the two schemes of continuous decks of Hainan Puqian sea-crossing bridge were carried out. The results disclose that both schemes can meet the requirements of serviceability limit state. However，the factor of safety against cracking of the STC layer in scheme 2 (21.4 MPa/19.7 MPa=1.09) is higher than scheme 1(22.4 MPa/22.0 MPa=1.02). By calculating the design moment of the two schemes and comparing with the ultimate flexural capacity obtained from the test，the bearing capacity coefficients of scheme 1 and scheme 2 are 1.1 and 1.8 respectively，and that of scheme 2 is higher than that of scheme 1. In addition，the angular stiffness calculated from the two schemes is basically equal，which is higher than that calculated from the original scheme of simple-supported beam. From a comprehensive view，scheme 2 is better than scheme 1. Consequently，scheme 2 has been applied to the approach bridge project of the Hainan Puqian sea-crossing bridge.
