Stay Cable Anchor Displacement for Bridge Catenary Alignment
Solution Overview
Problem
Cable supported bridges face a significant challenge due to permanent angle breaks in stay cables, which occur due to manufacturing tolerances, changes in stay cable weight, or changes in bridge deck height, leading to excessive bending moments and reduced service life.
Innovation Solution
A method is introduced to transform a cable supported bridge by adjusting the catenary of stay cables, involving the provision of additional anchorages and displacement of anchor units to align with the new catenary, thereby avoiding permanent angle breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the stay cable is replaced by a lighter cable during renovation, then the bridge structure becomes more efficient, but a permanent angle break occurs at the recess pipe exit due to catenary mismatch
Solution Approach 1:
The method performs preliminary adjustment of the anchor unit position before the angle break problem becomes critical. By calculating the new catenary curve of the lighter stay cable and pre-positioning the anchor unit accordingly, the system prevents the development of harmful bending moments at the recess pipe exit, thereby maintaining cable reliability while achieving weight reduction
Solution Approach 2:
The invention changes the position parameter of the anchor unit along the bridge deck to match the new catenary configuration. By adjusting the anchor unit's location, the system adapts the cable's geometric parameters to eliminate angle breaks caused by weight changes, resolving the contradiction between cable lightness and structural reliability
2Ease of manufacture
If manufacturing tolerances are exceeded during fastening unit positioning, then installation becomes more flexible, but a permanent angle break occurs at the recess pipe exit
Solution Approach 1:
The method introduces dynamic adjustability to the anchor unit position, allowing it to be relocated along the bridge deck. This dynamic positioning capability compensates for manufacturing tolerances and alignment deviations, enabling the system to achieve proper catenary alignment even when initial positioning exceeds specified tolerances, thus preventing angle breaks
Solution Approach 2:
The invention separates the anchor unit from the fastening unit, allowing independent positioning and adjustment. This segmentation enables the anchor unit to be relocated to the optimal position that matches the catenary curve, independent of the fastening unit's fixed position, thereby accommodating manufacturing tolerances while preventing angle breaks
3Length of moving object
If the bridge deck is raised to increase clearance, then navigation capability improves, but the stay cable catenary changes causing a permanent angle break
Solution Approach 1:
The method performs preliminary recalculation and repositioning of the anchor unit before the bridge deck raising is completed. By anticipating the new catenary configuration resulting from increased bridge deck height, the system pre-adjusts the anchor unit position to match the upcoming geometric changes, preventing angle breaks that would otherwise occur during or after the elevation process
Solution Approach 2:
The invention changes the position parameter of the anchor unit in response to changes in bridge deck elevation. By adjusting the anchor unit's location along the bridge deck to match the new catenary curve resulting from increased clearance, the system maintains proper cable alignment and prevents angle breaks despite the changed geometric conditions
Data Source
AI summary
The invention relates to a method for transforming a cable supported bridge from a first bridge state in which at least one of said stay cables extends according to a first catenary to a second bridge state in which said at least one stay cable or at least one new stay cable replacing said at least one stay cable extends according to a second catenary, comprising at least one of the steps ofa) providing at a predetermined position of said bridge deck a further anchorage for an end of said at least one stay cable previously received and held by said bridge deck side anchorage or for an end of at least one new stay cable, andb) displacing an anchor unit of said bridge deck side anchorage or said further anchorage relative to an allocated fastening unit of said bridge deck side anchorage or said further anchorage to said predetermined position,said predetermined position being located closer to or further away from a support structure od said cable supported bridge than said bridge deck side anchorage or said anchor unit of said bridge deck side anchorage or said further anchorage, respectively, and being determined such that a tangent to the second catenary of said at least one stay cable or said at least one new stay cable at an entrance to said anchor unit of a support structure side anchorage is substantially parallel to an axis of a recess pipe of said anchor unit of said support structure side anchorage.