Expansion Joint Seal with Spring Centering and Segmented Ribs
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Solution Overview
Problem
Current expansion joint seal systems fail to provide durable, flexible, and fire-resistant solutions for surfaces subject to temperature expansion, mechanical shear, and impact, often leading to premature failure due to inadequate resiliency, seismic movement, and inability to address vertical shifts and coefficient of linear expansion differences between cover plates and substrates.
Innovation Solution
An expansion joint system comprising a cover plate, a plurality of ribs, an elastically-compressible core, and a flexible member, where the ribs pierce the core and are rotatable relative to the cover plate, with a force transfer plate providing additional support and shock absorption, allowing for multi-axis movement and improved attachment to substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid extruded rubber or polymer glands are used to support transfer loads, then load-bearing capacity is improved, but resiliency and seismic movement capability deteriorate
Solution Approach 1:
The expansion joint seal system is divided into multiple independent components: a cover plate, a force transfer plate, an elastically-compressible core, and a rib assembly. This segmentation allows each component to perform its specific function - the force transfer plate handles load transfer while the elastically-compressible core provides resiliency and seismic movement capability, resolving the contradiction between rigidity and flexibility.
Solution Approach 2:
The system combines different materials with complementary properties: a rigid cover plate for structural integrity, an elastically-compressible core (such as foam or rubber) for resiliency and seismic movement, and a force transfer plate for load distribution. This composite approach allows the system to simultaneously achieve load-bearing capacity and adaptability to seismic movements.
2Reliability
If elastically-compressible core systems with a continuous spine are used, then sealing capability is improved, but resistance to lateral forces from single direction deteriorates due to compression set
Solution Approach 1:
The continuous spine is replaced with a rib assembly consisting of multiple discrete ribs spaced apart and attached to the force transfer plate. This segmentation prevents the compression set that propagates along a continuous spine, as each rib can independently deflect and recover from lateral forces without affecting the entire length of the expansion joint seal system.
Solution Approach 2:
The rib assembly is designed to be flexible and rotatable relative to the cover plate, allowing dynamic response to lateral forces. The ribs can deflect under load and return to their original position, providing resistance to lateral forces from single direction while maintaining sealing capability through the elastically-compressible core.
3Strength
If cover plates are mechanically attached by drilling into the deck or joint substrate, then attachment strength is improved, but system complexity and installation difficulty increase
Solution Approach 1:
The mechanical attachment requirement is extracted and replaced with an adhesive bonding system. The force transfer plate is designed with a bottom surface that can be adhesively bonded to the joint substrate, eliminating the need for drilling and mechanical fasteners. This reduces installation complexity while maintaining attachment strength through proper adhesive selection and application.
4Reliability
If the expansion joint seal system extends above the adjacent substrates, then fire protection and waterproofing are improved, but tripping hazard and contamination risk increase
Solution Approach 1:
The system provides fire protection and waterproofing primarily through the vertical dimension (the height of the cover plate and elastically-compressible core filling the joint), while minimizing protrusion into the horizontal walking surface. The force transfer plate and rib assembly are positioned within the joint or slightly below the substrate surface, providing the necessary sealing and protection functions without creating tripping hazards or contamination risks.
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 system enhances durability and fire resistance, maintaining a usable surface under varying conditions, reducing damage from impact and ensuring long-term functionality by accommodating thermal and seismic movements while preventing water penetration and tripping hazards.
Implementation Method 1
an elastically-compressible core, such as of foam
Implementation Method 2
to allow for independent movement, such in response to ambient temperature variations
Implementation Method 3
a spring providing a centering force
Implementation Method 4
a shock absorber positioned at a bottom of the cover plate
Data Source
AI summary
A system which creates a durable seal between adjacent horizontal panels, including those that may be curved or subject to temperature expansion and contraction or mechanical shear. The durable seal system incorporates a plurality of ribs, a flexible member between the cover plate and the ribs and may incorporate a load transfer plate to provide support to the rib from below, and/or cores of differing compressibilities.