Rectangular Mandrel Expansion Joint with Concrete Fill
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Solution Overview
Problem
Existing expansion joint construction elements with round heavy-duty mandrels experience punctiform support issues leading to cold welds and premature failure, while those with solid steel mandrels are overly rigid and prone to sudden fracture without warning, and hollow mandrels filled with sound insulation materials cause excessive deformation and concrete destruction.
Innovation Solution
An expansion joint construction element featuring a heavy-duty mandrel with a rectangular cross-section filled with ultra-high-strength concrete and equipped with double-headed bolts on vertically aligned side walls, allowing for greater deformation before fracture and early detection of maximum load limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If round heavy-duty mandrels are used, then installation is easier, but punctiform support causes cold welds and premature failure
Solution Approach 1:
The patent applies the opposite principle by using a rectangular cross-section instead of a round one. The rectangular shape distributes support over a larger area at the outlet, eliminating punctiform contact and preventing cold weld formation while maintaining ease of installation.
Solution Approach 2:
The patent incorporates double-headed bolts that are pre-installed on the heavy-duty mandrel before concrete filling. These bolts create predetermined support points that distribute loads evenly, preventing cold welds before they can form during operation.
2Strength
If solid steel mandrels are used, then strength is high, but rigidity causes sudden fracture without warning
Solution Approach 1:
The patent uses a composite structure combining steel heavy-duty mandrel with ultra-high-strength concrete filling. This composite material provides both the strength of steel and the ductility of concrete, allowing the system to maintain high load-bearing capacity while exhibiting visible deformation before failure.
Solution Approach 2:
The patent changes the material parameter by filling the hollow mandrel with ultra-high-strength concrete instead of leaving it empty or using solid steel. This material substitution fundamentally alters the deformation characteristics, enabling gradual deformation that serves as a warning before complete fracture.
3Object-affected harmful factors
If hollow mandrels filled with sound insulation materials are used, then punctiform support is avoided, but excessive deformation occurs and concrete is destroyed
Solution Approach 1:
The patent changes the material parameter by using ultra-high-strength concrete with compressive strength exceeding 150 MPa instead of conventional sound insulation materials. This dramatically increases the filling's ability to resist deformation while still maintaining the distributed support that prevents cold welds.
Solution Approach 2:
The patent pre-installs double-headed bolts that create controlled support points within the concrete filling. These bolts prevent the excessive deformation that would otherwise occur in hollow mandrels, distributing stresses evenly and protecting the surrounding concrete structure from destruction.
4Reliability
If heavy-duty mandrels are oversized for safety, then reliability increases, but deformation detection capability decreases
Solution Approach 1:
The patent changes the material composition to ultra-high-strength concrete, which has different deformation characteristics compared to solid steel. This allows the mandrel to achieve the required safety margin while still exhibiting measurable deformation under load, improving detectability without sacrificing reliability.
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
The solution provides increased safety by allowing significant deformation up to complete fracture, enabling early detection of load limits and preventing sudden failure, while maintaining similar deformation to solid steel under normal loads.
Implementation Method 1
The heavy-duty mandrel is filled with ultra-high-strength concrete
Implementation Method 2
allows a significantly greater deformation path up to complete fracture
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
The element (1) has a heavy load arbor (10) designed as a filled hollow arbor. A bearing sleeve (20) runs in an inserted state with an exit surface with an expansion joint-side outer surface of a component (B2) in which the bearing sleeve is installed in a flushed manner while the heavy load arbor is installed in a concreted component (B1) with the bearing sleeve. Double side bolts are directly or indirectly attached at two opposite side walls aligned vertically in a final installation position. The hollow arbor is filled with ultrahigh-fixed concrete.