Alternating Dowel Expansion Joint for Concrete Slab Load Transfer
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Solution Overview
Problem
Existing expansion joint systems for concrete slab arrangements face issues such as reduced load transfer capacity and durability at the edges of slabs due to the asymmetrical distribution of dowel cross-sections, leading to potential local dents and splitting, especially under wheel loads, and are often slow and costly to install.
Innovation Solution
The expansion joint system arranges dowels alternately relative to the joint, with casing parts on different sides of the joint, ensuring equal load transfer capacity and durability on both slabs, and allows for installation in a mould or on-site, using dowel plates that maintain their cross-sectional area during slab shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If asymmetrical dowel distribution is used in expansion joints, then installation is simplified, but load transfer capacity and durability at slab edges are reduced
Solution Approach 1:
The patent applies asymmetry in reverse - it recognizes the asymmetrical dowel distribution in prior art and corrects it by ensuring symmetrical dowel placement on both slab edges. This resolves the technical contradiction by maintaining equal load transfer capacity and durability on both sides of the expansion joint, preventing edge-related failures while preserving installation simplicity through the use of pre-assembled dowel units.
Solution Approach 2:
The patent ensures equipotentiality by making the dowel distribution symmetrical on both sides of the expansion joint. This creates equal load transfer capacity and durability conditions at both slab edges, eliminating the imbalance that causes premature failure. The symmetrical arrangement ensures both slabs have equivalent structural performance at the joint location.
2Adaptability or versatility
If dowel cross-section is reduced at slab edges, then movement capability is improved, but load transfer capacity and durability are reduced
Solution Approach 1:
The patent applies local quality by providing full-sized dowels at critical locations (slab edges) where both load transfer and durability are essential. The dowels maintain their complete cross-sectional area at the edges rather than being reduced, ensuring adequate load transfer capacity and durability while still allowing slab movement through the expansion joint mechanism.
Solution Approach 2:
The patent uses partial or excessive action by providing dowels with full cross-sectional area (more than minimally required) at slab edges. This excessive provision of material at critical locations ensures both movement capability and high reliability, preventing the trade-off between movement and durability that plagues conventional designs.
3Reliability
If traditional expansion joint methods (sawing, angle irons) are used, then joint functionality is achieved, but installation time and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-assembling the dowels with their positioning elements and connection components before installation. The dowel units are manufactured and prepared in advance with all necessary components attached, allowing for rapid installation at the construction site without requiring complex on-site assembly operations like sawing or timing-critical angle iron placement.
Solution Approach 2:
The patent merges multiple components (dowels, positioning elements, connection components) into a single integrated unit that is installed as one piece. This combination eliminates the need for separate installation steps required by traditional methods, significantly improving installation speed and productivity while maintaining joint functionality.
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 configuration maintains consistent load transfer and durability across both slabs, simplifies installation, and prevents edge-related issues like local dents and splitting, while allowing for efficient movement due to shrinkage and thermal changes.
Implementation Method 1
An expansion joint must allow adjacent slabs of the arrangement to move horizontally relative to each other due to shrinkage and thermal movements
Implementation Method 2
Due to the shrinkage and thermal movements of concrete, large areas must be divided into smaller parts with expansion joints
Implementation Method 3
at least two local dowels which are arranged to transfer loads perpendicular to the slab plane
Implementation Method 4
the casing part is arranged to prevent the dowel plate from adhering to the concrete slab
Data Source
AI summary
Expansion joint system of a concrete slab arrangement, comprising an expansion joint reinforcement to be arranged between a first and a second concrete slab (1, 2), the expansion joint reinforcement comprising at least two local dowels (3)transferring loads perpendicular to the slab plane. The dowels comprise a dowel plate (4) and a casing part (5). The dowel plate (4) and the casing part (5) are attached to the concrete slabs on different sides of the joint. The casing part (5) prevents the dowel plate from adhering to the concrete slab and allows the dowel plate (4) to move inside the casing part and thus allows the movements of the slabs (1, 2) in the horizontal direction. The dowels (3) are installed alternately relative to the joint so that the casing parts (5) of the adjacent dowels (3) are always installed on different sides of the joint.