# Study of a Layered Plate Grider Element of Composite Materials and Its Applications
## 4 Engineering Application  
A model test is performed to study the behavior of the steel-concrete composite decks. The correctness of the LPGE method is proven. An arch model for a three-truss bridge with six panels is constructed according to the scale ratio 1:6 of the real bridge structure, as shown in Figure 5. The length of the joint is 2 m, the height of the truss 2.77 m, and the rise-span ratio 1/4.8. The deck adopts the concrete bridge ballast deck. The whole steel deck adopts a multi-girder system with one main transverse girder and three small transverse girders arranged in every panel along the bridge direction. The main transverse girder is connected to the main truss at the main truss node, and the small transverse girder is welded to the lower chord element of the main truss. In the cross direction of the steel deck, two inverted T-shaped longitudinal girders are welded under every track. The concrete ballast trough is arranged above the steel deck with a thickness of 100 mm. In the test, the jack loading method is used. In this method, the load is imposed on the deck and joints separately so as to accurately simulate the stress state of the real bridge under the action of dead load and live load (see Figure 5d). The LPGE is introduced into the general software after improvements to analyze and compute the test model. The computation results, the results obtained by ANSYS in the plate beam model, and the measured result for the model test are compared as shown in Figures 6-13. The deck is simulated by the ANSYS general plate element, while the longitudinal and transverse girders and the stiffeners of the deck are simulated by the beam element, and the main trusses are simulated by the beam element (hereinafter referred to as the ANSYS plate beam model). The number of longitudinal and transverse girders is shown in Figure 5c. As seen from Figures 6-9, the difference in the stress between point 1 and point 2 on the transverse girders is not significant. It indicates that the load caused by the bending moment outside the transverse girder surface is less prominent. This is attributed to the fact that the composite deck connects the upper flange of the longitudinal girders, transverse girders, and lower chord members, reducing the transverse deformation of the transverse girders and improving the stress of the transverse girders. Thus, the expansion of the longitudinal girders that are arranged to reduce the lateral deformation of the transverse girders is avoided, and the driving conditions on high-speed roads are greatly improved. It is seen from Figures 10-13 that the difference in the stress of the longitudinal girders between the panels is not prominent and the stress is distributed relatively uniformly. The concrete ballast slab bears a greater tensile stress above the transverse girders, where broken seams in the concrete ballast slab are arranged to improve the concrete stress. For the ANSYS method, modeling for the plate element and the beam element needs to be conducted separately. The coupling displacement between the plate elements and the beam elements is used to simulate their combined action. The modeling process is complex with low computation efficiency. Moreover, the deformation coordination between the plate elements and the beam elements cannot be guaranteed since the displacement patterns of the plate elements and the beam elements are different, and the accuracy of the computation is low. From the above results, it is observed that the computation results produced using the ANSYS method are larger than those obtained using the LPGE method. This is attributed to the uncoordinated deformation between the plate elements and beam elements in the ANSYS model. The LPGE method combines the plate element  
Figure 4: Other types of LPGE. and the girder element into one element to conveniently construct the model with high efficiency. The displacement pattern of the LPGE adopts the independent interpolation of the displacement and rotation angle.