Curved Wood-Fiber Interjoist with Integrated Shutter

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Solution Overview

Problem

Existing interjoists for floor construction are either too heavy, fragile, or costly due to separate production of shutters, and lack self-sufficiency and aesthetic appeal, while requiring additional components for span closure.

Innovation Solution

An interjoist with an integrated, single-piece shutter at one end and an open assembly zone at the other, featuring a curved vault shape and transverse grooves, made from a mixture of wood fibers and a hot-polymerization binder, allowing for reduced material volume, weight, and cost, while maintaining mechanical performance and aesthetic appeal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If interjoists are made thin and light to reduce weight and handling difficulty, then ease of operation is improved, but mechanical strength deteriorates

Engineering Contradiction:
Improveweight of interjoistVSAvoidmechanical strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The interjoist employs a curved vaulted profile instead of a straight linear form. The curvature distributes mechanical loads more effectively across the structure, enabling thin-walled construction (5-6mm thickness) to achieve sufficient strength. The arched shape naturally resists bending moments while maintaining lightweight construction, resolving the contradiction between weight reduction and strength requirement.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The interjoist is constructed from composite materials combining lightweight core structures with reinforcing elements. This allows the thin-walled design to achieve the necessary mechanical strength through material composition rather than increased thickness, maintaining light weight while satisfying strength requirements for supporting construction loads and concrete weight.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If shutters are produced separately in specific moulds to close spans, then manufacturing precision is improved, but device complexity and production cost increase

Engineering Contradiction:
Improvespan closure precisionVSAvoidnumber of components
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The shutter function is merged with the interjoist body itself. The interjoist is designed with an asymmetric configuration where one end includes an integrated shutter element formed as a single continuous piece with the main body. This eliminates the need for separate shutter components and their associated molds, reducing device complexity while maintaining the precision required for span closure through the integrated design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The interjoist is designed to serve multiple functions simultaneously: it acts as both the structural spacer element and the span-closing shutter. This multi-functionality eliminates the need for separate shutter components, reducing the number of parts to manufacture, store, and assemble, while the integrated design ensures precise fit for span closure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If interjoists are made with integrated shutters in single piece to reduce production steps, then ease of manufacture is improved, but manufacturing precision becomes more difficult to maintain

Engineering Contradiction:
Improveproduction process simplicityVSAvoidintegration precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The shutter and interjoist body are merged into a single molded component. The molding process is designed to create the complex asymmetric shape with the shutter integration in one continuous operation, eliminating the need for separate manufacturing and assembly steps. This approach simplifies the overall manufacturing process while the mold design ensures precise geometric control of the integrated features.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The manufacturing approach utilizes changes in material parameters and molding conditions to achieve the integrated complex geometry. By adjusting parameters such as material viscosity, molding pressure, and temperature during the single-step molding process, the integrated shutter and body are formed with the required precision without requiring multiple assembly operations.

Inventive Principle:
Principle #35Parameter changes

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 results in a lighter, more cost-effective, and aesthetically pleasing interjoist with enhanced mechanical resistance and reduced storage and transportation costs, achieving self-sufficiency without additional shutters and optimizing floor construction performance.

Implementation Method 1

a binder hardenable by hot polymerization

Methodology Applied
Scientific EffectHot polymerization: Photopolymerisation

Data Source

PatentEP2357293B1Filling member for floor structures with beams
Publication Date: 2013.01.09 RECTOR LESAGE
  • EP2357293B1 patent drawingFigure 1A~1B
  • EP2357293B1 patent drawingFigure 2A~2B
  • EP2357293B1 patent drawingFigure 3~5

AI summary

The boarding (1) has an end corresponding to lateral edges (3) that is defined by a rectangular boundary, where the end is closed by a closure (30) integrated and constituted of one piece with a rough timber boarding body. The closure is extended to a height greater than that of the body of the rough timber boarding, and comprises a base (31) located under longitudinal edges (2) to be supported on a supporting element of a joist floor.