Moulded Expanded Polystyrene Shuttering for Slab Support
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Solution Overview
Problem
Traditional shuttering methods for casting slabs or beams over substrates prone to upward movement, such as heaving clay, face issues like premature destruction from moisture and non-uniform load-bearing characteristics due to varying density in expanded polystyrene support structures, leading to increased costs and excavation requirements.
Innovation Solution
A hollow support structure made from moulded expanded plastics with a first supporting condition depth (D) and a second collapsed condition depth (d) where d is less than 0.38D, allowing for reduced excavation needs and cost-effective manufacturing, featuring thin walls and recessed intersections to facilitate even collapse and uniform performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shuttering is used with expanded polystyrene support structures made by cutting blocks, then the shuttering can accommodate upward substrate movement, but the support structures have non-uniform density and inconsistent load-bearing characteristics
Solution Approach 1:
The patent changes the manufacturing method from cutting pre-expanded blocks to moulding expanded polystyrene beads in a controlled mould. This parameter change in the manufacturing process ensures uniform density distribution and consistent cell structure throughout the support structure, eliminating the non-uniformity inherent in the cutting method
Solution Approach 2:
The patent uses color-coded indicators (such as colored strips or markers) on the mould to ensure proper alignment and positioning during assembly. This visual feedback mechanism ensures that multiple support structures are assembled with consistent orientation and positioning, maintaining uniform load-bearing characteristics across the entire shuttering system
2Manufacturing precision
If moulded expanded polystyrene support structures are used, then manufacturing consistency improves, but the depth of excavation required increases
Solution Approach 1:
The patent designs the support structure with a dynamic collapse mechanism where the vertical walls are configured to buckle inward at predetermined points when subjected to excessive upward force. This dynamic response allows the structure to accommodate substrate movement by collapsing to a reduced depth, thereby reducing the initial excavation depth required while maintaining safety through controlled failure modes
Solution Approach 2:
The support structure is divided into multiple cellular compartments with vertical walls that can collapse independently. This segmentation allows different portions of the structure to fail at different stages, providing a progressive collapse mechanism that reduces overall depth while maintaining load-bearing capacity up to the design limit
3Reliability
If the support structure is designed with high Safe Load capacity, then structural integrity is maintained, but the Fail Load is much higher creating a large safety margin that increases cost
Solution Approach 1:
The patent carefully controls the density and structural parameters of the moulded expanded polystyrene to achieve a specific Safe Load capacity. By optimizing these parameters during moulding, the structure is designed so that the Fail Load is only slightly higher than the Safe Load, creating a narrow safety margin that reduces material usage and manufacturing cost while maintaining adequate structural integrity
Solution Approach 2:
The patent uses composite construction with a combination of expanded polystyrene beads bound together in a moulded matrix structure. This composite approach allows precise control over the load-bearing characteristics, enabling the design to achieve the desired Safe Load while limiting the Fail Load to a minimal margin above, thereby optimizing cost efficiency
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 reduces the depth of the support structure upon failure, minimizing excavation costs and ensuring consistent load-bearing capabilities while accommodating upward substrate movement, with adaptable Safe and Fail Loads and improved moulding processes for uniform density and performance.
Implementation Method 1
a first supporting condition in which the depth of the support structure is D and a second collapsed condition in which the depth of the support structure is d, wherein d is less than 0.38D
Data Source
Figure 1~2
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AI summary
Shuttering for use in casting a slab/beam over a substrate comprises a hollow support structure defining a multiplicity of four-sided cells (8, 9) bounded by a first set of walls (6) extending across the structure in a first direction and a second set of walls (7) extending across the structure in a second direction transverse to the first direction. The support structure is able to be placed on the substrate to support the slab/beam during casting. The support structure is formed with its spaced apart walls (6, 7) by a moulding process and is moulded from expanded plastics material. The structure has a first supporting condition in which the depth of the support structure is D and a second collapsed condition in which the depth of the support structure is d, wherein d is less than 0.38D.