Expansion-Joint Bridging Plate With Hinged Strap Joints to Reduce Fatigue
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Solution Overview
Problem
Existing expansion-joint bridging devices face challenges in achieving low manufacturing, installation, and maintenance costs while ensuring high functional safety, reliability, and long useful life, with significant impairment of traffic during installation and maintenance.
Innovation Solution
The bridging device consists of two plate portions joined flush with one another by a strap, allowing pivot joints with rotational freedom, eliminating the need for welding and reducing dynamic stress, and incorporating anti-lifting safeguards and sealing members to enhance stability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to join plate portions at butt joints, then strength and rigidity are improved, but manufacturing complexity and installation time increase, and reliability decreases due to environmental factors
Solution Approach 1:
The patent replaces the welding process (thermal/chemical joining) with a mechanical strap joining system. The strap is fastened to plate portions using fasteners (screws, bolts, or clips), creating a purely mechanical connection that eliminates the need for welding equipment, skill, and environmental controls while maintaining sufficient joint strength for the application.
Solution Approach 2:
The joining system is segmented into discrete components: the strap element and separate fasteners. This segmentation allows for modular assembly, enabling workers to attach the strap to each plate portion independently using standard fastening mechanisms, thereby simplifying the manufacturing and installation process compared to continuous welding operations.
2Reliability
If welding is used to join plate portions, then joint strength is improved, but installation time increases and reliability decreases
Solution Approach 1:
The mechanical strap joining system with fasteners is significantly faster to install than welding, as it eliminates the need for pre-heating, welding, post-heating, and cooling periods. The strap can be quickly attached to each plate portion using hand tools or power tools, dramatically reducing installation time while maintaining reliable joints that are less susceptible to environmental defects.
Solution Approach 2:
The strap and fastener system uses simpler, more replaceable components compared to permanent welded joints. If damage or failure occurs, the strap and fasteners can be easily removed and replaced without affecting the structural integrity of the plate portions themselves, thereby maintaining reliability while enabling rapid replacement if needed.
3Strength
If welding is used to join plate portions, then joint strength is improved, but functional safety decreases due to fatigue fractures from dynamic loads
Solution Approach 1:
The strap joining system allows for slight movements and adjustments in the connection between plate portions, creating a more dynamic and adaptable joint that can accommodate thermal expansion, contraction, and dynamic loading without creating stress concentration points. This flexibility prevents the fatigue fractures that occur in rigid welded joints subjected to repeated dynamic loads.
Solution Approach 2:
The mechanical fastening system distributes loads more evenly across the joint compared to welding, as the strap and fasteners create multiple load paths that prevent stress concentration at any single point. This distribution mechanism significantly reduces the risk of fatigue fractures while maintaining sufficient joint strength for the application.
Data Source
AI summary
An expansion joint bridging device in the form of a plate-type roadway joint which bridges an expansion joint between two building components. The expansion joint is spanned by crossbeams which are braced in a load-bearing relationship on both building components. Supported on the crossbeams is at least one plate disposed above the crossbeams, the plate having two plate portions which lie flush with one another and are interconnected in a force-transmitting relationship. The plate portions are connected in situ by means of at least one cover plate which bridges the joint between the plate portions and connects the two plate portions in a force-transmitting relationship. At least one of the connections between the cover plate and the plate portions is hinged, having a rotational degree of freedom about an axis extending horizontally transversely to the orientation of the relevant plate.