NONLINEAR STABILITY ANALYSIS OF LONG-SPAN CONTINUOUS RIGID FRAME BRIDGE WITH DOUBLE THIN-WALL HIGH PIERS AT ITS CANTILEVER STATE

Both geometrical and material nonlinear stability of high piers at the cantilever state are studied for the case of Longtan River Bridge. The effects of the wall thickness and concrete strength on the ultimate loading capacity are analyzed. It is concluded that the nonlinear stability number obtained in this paper is 60% of the one considering only the geometrical nonlinearity. The high piers with tapered sections fail at the locations of 1/3 pier height away from the pier bottom other than the bottom part as observed in the high piers with regular sections. At the maximum cantilever, the transversal static wind load has the great effect on the structural stability. When the basic wind velocity increases to 18m/s or 25.3m/s, the ultimate loading capacity of high piers decreases by 14.06% and 28.2% respectively. The concrete strength and wall thickness have significant impacts on the structural stability. Nonlinear stability analysis considering all effects is of great importance in practices.