Design and Construction of a Self-Balancing Composite Shoring System for Rigid-Frame Bridge with V-Shaped Piers
The Meishan Waterway Embankment-Crossing portion of Liuheng Highway Bridge at Zhoushan Port,Ningbo is a rigid-frame bridge with a main span of 100 m and two side spans of 60 m.The superstructure consists of prestressed concrete box girders supported on V-shaped piers.During the construction of the bridge,a self-balanced composite shoring system composed of a temporary shoring system and a tie-rod system was developed specially for the erection of V-shaped piers and pier-top girder segments.The temporary shoring system includes the falsework installed around the V-shaped piers and the falsework installed in the center of the pier-top girder segment.Tie rods were arranged at three elevations along the vertical direction of the pier,five ones at each elevation.The numerical modelling indicated that the load bearing performance of the shoring system during the construction of the V-shaped piers and pier-top girder segments meet the requirements.The falsework around the V-shaped piers and tie rods connected to the piers can be dismantled after the closure of the superstructure,while the falsework in the center of the pier-top girder segment after the implementation of the prestress in the girder segment No.4.After the construction of the pile caps,the falsework around the V-shaped piers and tie rods were installed,the piers took shape by one-off cast with the aid of chutes,and the tie rods were tensioned at three stages.After the construction of the V-shaped piers,the central falsework for the pier-top girder segment was installed,and the pier-top girder segment was cast at two times using the mobile pumps.The tie rods were tensioned four times.After the casting of the pier-top girder segment,the cantilever casting of the remaining girder segments using the form travelers began.The shoring system was dismantled according to the numerical simulation.After the completion the main girders,the piers were in good alignment,no cracks were observed in the surfaces and bottom of piers,and pier-top segment as well.
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