Angled GFRP Shear Connectors for Composite Building Panels

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Solution Overview

Problem

Existing precast sandwich panels face challenges in achieving high shear stiffness and minimizing thermal leakage due to the use of thermally conductive connectors, which compromise the panel's insulating properties and strength, especially with the need for increased insulation thickness to meet new energy codes.

Innovation Solution

The use of glass-fibre reinforced polymer (GFRP) shear connectors oriented at angles and in a modified Pratt truss-like pattern, which are non-thermally conductive, extend through the insulation layer to bridge its thickness, providing enhanced strength and bonding between concrete layers while maintaining low thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermally conductive materials are utilized as connectors, then the connection strength and shear stiffness are improved, but the thermal insulation properties deteriorate due to thermal draws

Engineering Contradiction:

Improveconnection strengthVSAvoidthermal draw

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The patent changes the material parameter of the connector from thermally conductive (steel) to thermally insulating (GFRP), while adjusting the connector dimensions (increasing length and diameter) to compensate for the lower strength-to-weight ratio, thereby maintaining connection strength while eliminating thermal draws

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses glass-fibre reinforced polymer (GFRP) as a composite material for the connector, combining the strength benefits of reinforced materials with the thermal insulation properties of polymers, creating a connector that provides both mechanical strength and thermal insulation

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If the insulation layer thickness is increased to meet energy codes, then the effective R-value is improved, but the connector length requirement increases making manufacturing more complex

Engineering Contradiction:

Improveeffective R-valueVSAvoidconnector length variation

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent establishes a direct relationship between insulation thickness and connector dimensions, specifying that connector length shall be 1.5 times the insulation thickness and diameter shall be 0.5 times the insulation thickness, providing a systematic approach to sizing connectors for different insulation thicknesses without manual calculation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent incorporates the connector length and diameter calculations into the manufacturing specification before production, allowing factories to pre-determine connector dimensions based on the insulation thickness specification, thereby simplifying the manufacturing process despite varying insulation thicknesses

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If conventional narrow connectors are used, then the manufacturing process is simple, but the bending stiffness and shear resistance are insufficient

Engineering Contradiction:

Improveconnector fabricationVSAvoidbending stiffness

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the dimensional parameters of the connector by increasing both the diameter and length beyond conventional narrow connectors, specifying a diameter of 0.5 times the insulation thickness and length of 1.5 times the insulation thickness, thereby achieving sufficient bending stiffness and shear resistance while maintaining relative simplicity in manufacturing

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

This solution significantly improves the effective R-value of the panels, maintains design flexibility, and reduces shearing, allowing for customizable panel dimensions and insulation thicknesses without thermal draws, while ensuring structural integrity and efficient manufacturing.

Implementation Method 1

the connectors are made of non-thermally conductive material... significantly lower thermal conductivity than steel... no thermal draws

Methodology Applied

Scientific EffectThermal Insulation: Thermal Insulation

Implementation Method 2

achieves high shear stiffness and limit differential slip... provide sufficient strength to the panel for lifting and reduced shearing

Methodology Applied

Scientific EffectShear Stress: Shear Stress

Data Source

PatentUS9534384B2Concrete and insulation composite structural building panels including angled shear connectors

Publication Date: 2017.01.03 HOMENKO BUILDERS INC

AI summary

A composite structural building panel has a first concrete layer and a second concrete layer in spaced apart relationship with one another so as to receive an insulation layer spanning between the first concrete layer and the second concrete layer. A plurality of shear connectors are individually supported to extend through respective bores in the insulation layer between opposing first and second ends of the shear connector which are entirely embedded in the first and second concrete layers respectively. At least some of the shear connectors are oriented at an inclination to a normal axis of the insulating layer.