Construction Control of Long Span Steel Box Girder Cable-Stayed Bridge

To ensure that the internal force and geometric shape of the completed north main bridge (a semi-floating system steel box girder cable-stayed bridge with double pylons,double cable planes and with a min span 780 m) of the Xiazhang Sea-Crossing Bridge could meet the design requirements,the construction control of the bridge was carried out,using the control method based on the unstressed state method theory,the parameter identification and adjustment calculation that considered the structural nonlinearity and also the rational completed bridge and construction stage state determined according to the structural characteristics of the bridge. In the construction control,the unstressed included angles were used to determine the site installation locations of the steel box girder blocks,the pull-out amount of the cable length was used to rapidly determine the tensioned cable forces and in regard of the structural characteristics and temperature changes,the scheme of pushing the steel box girder towards one side mainly and cutting the girder auxiliarily for closure of the central span was utilized and the purpose of effective control of the risk of the closure was achieved. Through the all-round and stringent construction control, the north main bridge was eventually closed smoothly with high precision and the geometric shape and internal force of the bridge could all satisfy the design requirements.