Application of Hydraulic-Walking Incremental Launching to Steel Arch Girder Construction of Shen′an Huanghe River Bridge in Lanzhou

The main bridge of Shen′an Huanghe River Bridge in Lanzhou is designed as a bowstring steel arch composite girder bridge with a main span of 156 m.The two arch ribs splay outward like a butterfly.The main girder is the steel-concrete composite girder with constant cross section.The main bridges characterized by its heavy weight and long spans,weighs about 4000 t after all the components are installed.The main bridge construction is likely to impose impact on the navigation channel and the transportation.Due to these reasons,the steel arch girder is designed to be constructed by the hydraulic-walking incremental launching scheme and by way of multiple-point simultaneous incre mental launching.The specialist hydraulic-walking incremental launching equipment was used to carry out the overall incremental launching construction of the main bridge.During the incremental launching construction,the truss support structure made of steel tubes was added so as to ensure that the load bearing capacity of the bridge in the incremental launching process could meet the requirements.During the construction,the technique of incremental launching along varying vertical curve was adopted,the elevation of the temporary piers was optimized and determined by optimizing the preliminary elevation and improving the equipment.The construction technique was made better by placing the launching nose on the piers and enhancing applicability of the positioning equipment,achieving the goal of reducing cost and improving safety.The engineering experience proves that the incremental launching technique ensured the safety of the construction process and the geometrical shape of the completed bridge meets the requirements.