Cable Bending Limiter With Annular Gap for Anchorage Stress Control
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Solution Overview
Problem
Cable stay systems in structures like bridges experience excessive bending stress at anchorage points due to lateral movements, leading to potential damage, and existing solutions like damping devices and cable guide constructions either fail to effectively manage stress or result in increased costs and unsightly installations.
Innovation Solution
A cable bending limiting arrangement featuring a device with a predetermined annular gap inside a recess pipe, which limits bending by creating a second bending location and distributing stress, combined with a damping device to manage lateral movements, and a curved surface to reduce pressure on strands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If damping devices are attached to the cable to reduce lateral movements, then the bending stress is reduced, but the bending angle may still exceed critical values requiring increased steel cross-section
Solution Approach 1:
A cable guide construction is introduced as an intermediary element between the cable and the anchorage. This guide construction with a curved surface redirects the cable path, creating a geometric constraint that limits the bending angle to below critical values. The intermediary structure works in conjunction with damping devices to achieve both stress reduction and bending angle control without requiring increased steel cross-section
Solution Approach 2:
The cable guide construction features a curved surface that guides the cable through a controlled bending path. This curvature is specifically designed to limit the bending angle to below critical values, preventing excessive stress concentration at the anchorage while maintaining the cable's structural integrity
2Shape
If cable guide constructions are arranged at certain distance from anchorage to avoid excessive bending angles, then bending angle is controlled, but damping devices must be placed far away increasing their size and costs
Solution Approach 1:
The cable guide construction and damping device are merged into a single integrated assembly. The cable guide construction serves dual functions: it acts as a structural element that limits bending angles through its curved geometry, and simultaneously serves as the mounting structure for damping devices. This integration allows damping devices to be positioned closer to the anchorage, reducing their required size and cost while maintaining both bending angle control and vibration damping effectiveness
3Shape
If damping devices are placed far from anchorage to be effective with cable guide constructions, then bending angle control is achieved, but appearance and costs deteriorate
Solution Approach 1:
The cable guide construction and damping device are merged into a single integrated assembly. The cable guide construction serves dual functions: it acts as a structural element that limits bending angles through its curved geometry, and simultaneously serves as the mounting structure for damping devices. This integration allows damping devices to be positioned closer to the anchorage, reducing their required size and cost while maintaining both bending angle control and vibration damping effectiveness
Solution Approach 2:
The cable guide construction is designed with locally optimized properties: the curved surface geometry is specifically tailored to limit bending angles to below critical values, while the same structure provides optimized mounting positions for damping devices. This local quality optimization ensures effective bending control and damping performance in a compact configuration that is more cost-effective and aesthetically pleasing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively limits bending stress on cable strands, preventing damage and reducing the need for increased steel cross-sections, while maintaining a compact and aesthetically pleasing design by distributing stress and using a damping device to manage extreme movements.
Implementation Method 1
the bending of the cable strands at the anchorage is stopped, and a second bending location is created at a distance from the anchorage resulting in a local distribution of the bending stress
Implementation Method 2
In order to reduce the amplitude of dynamic lateral movements, i.e. the bending angle of the strands, and thus the bending stress acting on the cables, it has been suggested to laterally attach a damping device to the cable
Implementation Method 3
the radius R of the predetermined curvature may amount to at least 2 m, preferably to at least 3.5 m, even more preferably to at least 4.3 m
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a cable bending limiting arrangement for a anchoring unit comprising an anchorage(106), a cable(102)including a plurality of wires and/or strands (108) extending in a tensioned manner from the anchorage(106), a compacting clamp unit (118) adapted and intended for compacting the wires and/or strands (108) to a side-by-side arrangement and located at a predetermined distance(d)from the anchorage(106), and a recess pipe (120) surrounding the cable(102)in at least a portion of the predetermined distance,wherein said cable bending limiting arrangement comprises a cable bending limiting device(130)adapted and intended for being located axially inside the recess pipe (120) and radially between an outer surface of the cable (102)and an inner surface of the recess pipe (120) leaving an annular gap (132) of a predetermined radial width if the longitudinal axis (A) of the cable (102) extends substantially parallel to the longitudinal axis (B) of the anchorage(106).