Special-shaped Steel Box Arch Pylon Geometry Control During Construction Based on Stress-free State Method
To provide the reference for prefabricated steel box arch pylon installation,this study took the double limbs non-uniform inclined arch bridge pylon used in the special-shaped cable-stayed bridge as engineering case.Considering the influence of support on the structural alignment,the bridge pylon geometry variation during construction was analyzed.To address the issues of complex and irregular variations in internal plates of steel box bridge pylons and the inefficiency of traditional modeling methods,the coordinates were generated by using the interpolation principle and matched to node logical numbers,which inherently included element information.This formed the fast modeling method for complex steel box structures.Additionally,the traditional forward iterative methods often cause non-convergence when calculating closure structures due to element distortion.This study explained the failure principle of traditional methods,and proposed the unstressed forward method ( USFM ) combining with the stress-free method with the forward method.By using this method,3 alignment schemes in the construction process of ring-closure structures on supports were analyzed.For precise closure,the three-dimensional geometry of main pylon structure during construction was accurately calculated.The maximum deformation along bridge direction,across the bridge direction,and vertical value are 16,2,9 cm respectively.The three-dimensional geometry deviations between limbs are 5.0,3.5,5.0 cm respectively.The installation alignment of pylon sections is also calculated,serving as the crucial positioning basis for the actual construction and installation of bridge pylon.The maximum vector displacement of installation alignment is 2.8 cm,ensuring that the final segments installation alignment falls precisely at the zero position,enabling zero-deviation installation of the closure segment.The application of stress-free state method in the geometry control of special-shaped steel box arch pylons demonstrates its advantages in ensuring construction precision and efficiency,providing the essential benchmark for pylon installation.
bridge engineeringconstruction process simulationgeometry analysisstress-free state methodring-closure structurequick modeling
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