Prestressing Unit for Earth-Anchored Cable-Stayed Bridges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cable-stayed bridges face significant economical inefficiencies due to increased compressive stress on main-span deck segments as the span length increases, requiring larger cross-sectional areas or high-strength steel, which can lead to local buckling and complex construction processes.
Innovation Solution
A method using a main-span prestressing unit to apply tensile stress to deck segments at the mid-span, reducing maximum compressive stress and utilizing anchor units and prestressing members to control tensile stress, thereby reducing the cross-sectional area and simplifying construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the main span length is increased to cross wide rivers and seas, then the bridge capability is improved, but the compressive stress on deck segments increases significantly
Solution Approach 1:
The patent changes the stress state parameter of the deck segments from purely compressive to a combination of compressive and tensile stresses. By installing prestressing units that apply tensile stress to the deck segments, the net compressive stress is reduced, allowing for longer main spans without proportionally increasing the compressive stress on the deck segments.
2Strength
If high-strength steel is used to resist increased compressive stress, then the strength is improved, but local buckling occurs and construction complexity increases
Solution Approach 1:
The patent changes the stress distribution parameter by introducing tensile stress through prestressing units. This reduces the net compressive stress on the deck segments, thereby reducing the risk of local buckling and the need for high-strength steel and dense stiffeners, which simplifies the construction process.
3Strength
If the cross-sectional area of deck segments is increased to cope with compressive stress, then the strength is improved, but the dead load increases leading to larger cables and towers
Solution Approach 1:
The patent changes the stress state parameter from purely compressive to a combination of compressive and tensile stresses. By applying tensile stress through prestressing units, the net compressive stress is reduced, allowing for smaller cross-sectional areas and reduced dead load, which in turn allows for smaller cables and towers.
4Stability of the object's composition
If stiffeners are densely disposed to prevent local buckling, then the stability is improved, but the dead load increases and the working process becomes complicated
Solution Approach 1:
The patent changes the stress distribution parameter by introducing tensile stress through prestressing units. This reduces the net compressive stress on the deck segments, thereby reducing the need for dense stiffeners to prevent local buckling, which simplifies the construction process and reduces the dead load.
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
This approach reduces the magnitude of compressive stress on deck segments, decreases the amount of required structural steel, enhances economical efficiency, and simplifies the construction process by acting as a windproof mechanism without obstructing ship passage.
Implementation Method 1
mounting a prestressing member including a steel stranded cable between the first and second anchor units so as to cause the first and second main-span deck segments separated in the axial direction of the bridge at the main span to be connected in the axial direction of the bridge, and prestressing and anchoring the prestressing member to cause a tensile stress to be applied to the first and second main-span deck segments
Data Source
AI summary
Provided are partially and fully earth-anchored cable-stayed bridges, each of which uses a prestressing unit including anchor units and a prestressing member from deck segments installed at its main span such that the prestressing unit serves as a conventional windproof cable and can simultaneously introduce a tensile stress. Thereby, a magnitude of the maximum compressive stress acting on a cross section of each main-span deck segment is reduced, so that it is possible to reduce a cross-sectional area of each main-span deck segment and thus to ensure economical construction. All or part of the compressive stress generated at the main span can be offset by the tensile stress caused by the prestressing member.