| Assembly hollow slab bridge is the main structure of middle and small span bridges in China. Taking Shanxi province for an example, hollow slab bridge accounts for81.8%of middle and small span bridges in the area. A large number of assembly hollow slab bridges exhibit some similar diseases along with time. The hinge joint cracking and reduce of the lateral integrity are the most prominent ones and some of them may even affect the safe operation of the bridges. Therefore, it is necessary to study typical diseases after fully understanding the current situation of using assembly hollow slab bridges.Firstly, the survey data of2510serving hollow slab bridges in Shanxi province are analyzed. After mastering the classictypical diseases, current strengthening methods and the relationship among design load, bridge span and the structure type, it is clear that the hinge joint disease is one of the main factors that influence the safe operation of the bridges. Secondly, the linear elastic model of common assembly hollow slab bridge (L=10m) is established using Abaqus finite element software. What’s more, the stress inside the hinge joints and the contact surfaces with plate-girder are analyzed along with the varying force patterns both in longitudinal and horizontal directions. The nonlinear model of hinge joint of the assembly hollow slab bridge (L=10m) is also established and loaded in the most unfavorable place (1/2and1/8length of bridge) until the structure is broken. Besides, the development law of stress pattern of hinge joint with or without deck pavement is calculated along with the load pattern. Four methods, transformation of deck pavement, transverse prestressed strengthening under slabs, bonded and anchored steel beams under slabs and glue injection in hinge joints, are applied in the reinforced concrete bridge (L=10m) and prestressed concrete bridges (L=13m and L=16m). After comparing and analyzing the data, the feasibility of the4enforcement methods is checked with Midas finite element software.According to the linear elastic analysis, the control position of longitudinal shear stress τ1lies in the inside of hinge joints which is close to1/8length and the vertical shear stress τ2of internal hinge joints and contact surfaces are similar. Moreover, the most unfavorable loading position of both normal stress σn and τ2lies in the middle of the span, which is close to the hinge joints. Based on the nonlinear elastic analysis, we found that the bottom side of hinge joints is the most vulnerable place wich is most likely to have normal bond failure. The upper position of hinge joints is prone to being destroyed by longitudinal shear stress and the middle side of hinge joints is the main stress-transfer position in hinge joint structure. We also found out that the load-transfer is undertaken by vertical shear strength, normal bonding strength and deck pavement in the middle of hinge joints. By comparing the four strengthening methods we can know that the transfer of deck pavement is a common way to improve the lateral wholeness of the structure and the thickness of deck pavement varies in different spans of bridges. The results of the loading tests show that the transfer of deck pavement proposed in this paper could improve the transverse integrity of assembly hollow slab bridges effectively. |
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