Cable Clamp Slip Control for Oujiang River North Estuary Bridge in Wenzhou During Construction
The Oujiang River North Estuary Bridge in Wenzhou is a steel truss girder suspension bridge with three pylons that create two main spans of 800 m.The steel trusses in the two main spans were divided into large segments to be erected by the 1 000 t-capacity lifting cranes mounted on the main cables.The cable clamps were prone to slip during construction due to the large imposed forces on cable clamps and the loss of the tightening forces of cable clamp bolts.Based on the formulas to calculate slip coefficients of cable clamps given in Specifications for Design of Highway Suspension Bridge(J TG/T D65-05-2015),methods to calculate the slip coefficients of cable clamps of long-span suspension bridge during the construction process are proposed,taking into account the diameter shrinkage of main cables caused by temporary loads on cable clamps and the increase of main cable axial forces as well as the loss of tightening forces of cable clamp bolts induced by the rearrangement of steel strands of main cables and the time-varying effect of cable clamp bolts.In addition,the influence of main parameters on the slip coefficients of cable clamps during construction was analyzed,the slip risk was predicted,and the measures to control slip of cable clamps were proposed.As per the analysis,it is proper to use the cable clamp inclination angles at an exact construction stage to calculate their slip coefficient,considering that the inclination angles of cable clamps would undergo big change during the erection of steel truss segments.The increase of axial forces of main cables would induce shrinkage of the main cable diameter,and in turn trigger slip of cable clamps.Apart from the midspan cable clamps of the main spans,the slip coefficients of the remaining cable clamps did not meet the requirements.In accordance with the slip risk prediction,the bolts of cable clamps were tightened for slip control.And the tightening times and timing were worked out.After taking control measures,no cable clamp slip was observed during construction.
万方数据
维普
