Ground-anchor to Self-anchor System Transformation Analysis for Self-anchored Suspension Bridge
To study the structural stress and deformation characteristics of self-anchored suspension bridge when using temporary ground-anchor during the cable erection before girder construction,the Shatian Bridge in Dongguan was taken as the case study to establish a finite element model for the transformation from ground-anchor to self-anchor.The stress and deformation of cables,beams,and pylons were analyzed during three transition processes:temporary cables synchronous release,alternately release from both banks,and cyclic release.The variation rules of saddle anti-slip safety factors during system transformation were compared.The result indicates that when the asynchronous release is employed,the pylon top displacement fluctuates significantly.The tensile stress appears at the root of central pylon column during cyclic release.The maximum stresses at the upper and lower edges of stiffening beam by using alternately release are notably greater than those by using synchronous release and cyclic release.During the temporary cable force releasing,the stiffening beam compresses,and the main cable anchor point shifts towards the mid-span.That leads to the reduced cable forces in the synchronous,alternate,and cyclic release schemes when the transition is completed.Only the cable force variation rules during system transformation are different.The non-synchronous release of temporary cables increases the difference of main cable forces on both sides of saddle,and reduce the anti-slip safety factor.The minimum anti-slip safety factor of alternately released saddle is 1.98,which does not meet the relevant regulation requirements.The influence of three releasing schemes on the radial deviation from sling outer side to anchorage pipe orifice is little.For self-anchored suspension bridges,utilizing temporary anchorage for cable erection before girder construction,it is supposed to adopt the synchronous release scheme whenever possible.If the synchronization cannot be achieved,the system transformation can be realized by increasing the number of stages of temporary cable release and reducing the unbalanced force of each stage of temporary cable release.
bridge engineeringsystem transformationcable erection before girder constructionself-anchored suspension bridgefinite element method
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