Mono-pile Steel Pile Sleeve Connection via Projection Plates
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Solution Overview
Problem
The mono-pile type foundation structure for wind and tidal power generation facilities experiences reduced fatigue performance and shear capacity due to reliance on surface friction and weld connections, which are prone to fatigue and residual stress issues from welding heat input.
Innovation Solution
A connection structure using steel plates with projections that are formed during hot rolling and installed on the steel pipe pile and sleeve without direct welding, reducing residual stress and enhancing shear capacity by distributing load longitudinally and improving torsional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If weld connections are used to attach steel plates to steel pipe pile and sleeve, then structural integrity is improved, but fatigue performance deteriorates due to residual stress from welding heat input
Solution Approach 1:
The invention extracts the harmful welding process from the connection method. Instead of welding steel plates to the steel pipe pile and sleeve, the patent uses mechanical attachment methods (bolts, rivets, or clamps) to fix the steel plates, thereby eliminating residual stress and heat-affected zones that cause fatigue while maintaining structural integrity.
Solution Approach 2:
The invention introduces an intermediary mechanical fastening system between the steel plates and the steel pipe pile/sleeve. This intermediary attachment method transfers the connection function from direct welding to a mediated mechanical connection, reducing stress concentration and improving fatigue resistance while maintaining load transfer capability.
2Device complexity
If grout connection without shear key is used, then device complexity is reduced, but shear capacity deteriorates due to reliance on surface friction only
Solution Approach 1:
The invention applies local quality enhancement by adding steel plates with projections at specific locations on the steel pipe pile and sleeve. These localized projections create mechanical interlocking zones within the grout connection, providing shear resistance only where needed rather than requiring a shear key throughout the entire connection, thus maintaining simplicity while improving shear capacity.
3Force
If shear key is installed in grout connection, then shear capacity is improved, but device complexity increases and fatigue performance worsens due to additional steel material with projections
Solution Approach 1:
The invention merges the functions of the steel plates and the projections into a single integrated component. Instead of adding separate shear keys with their own attachments, the projections are formed as integral parts of the steel plates, eliminating additional fastening hardware and reducing overall connection complexity while maintaining enhanced shear capacity through mechanical interlocking.
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 significantly improves fatigue performance and shear capacity, reducing the risk of fatigue cracks and corrosion, while maintaining structural integrity under repeated loads and torsional torque.
Implementation Method 1
As a function thereof, it is necessary to transmit a load which is transmitted from a superstructure, from a sleeve pipe to a steel pipe pile through grout
Implementation Method 2
This connection structure is a structure which depends on the surface friction of a steel material and has a low shear capacity
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
This connection structure is a connection structure between a steel pipe pile and a steel sleeve pipe disposed outside the steel pipe pile with a gap therebetween and includes a steel plate with outward projections having a plurality of outward projections and fixed to an outer peripheral surface of the steel pipe pile by a first weld portion; a steel plate with inward projections having a plurality of inward projections and fixed to an inner peripheral surface of the steel sleeve pipe by a second weld portion; and grout filled in the gap so as to bury at least the steel plate with outward projections and the steel plate with inward projections, wherein the plurality of outward projections is disposed at intervals in a vertical direction with respect to one another and extends over a circumferential direction of the steel pipe pile, and the plurality of inward projections is disposed at intervals in a vertical direction with respect to one another and extends over a circumferential direction of the steel sleeve pipe.