Double Coating Expansion Anchor for Seismic Friction Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional expansion anchors face a dilemma in designing coefficients of friction, where high friction is beneficial for static loads but detrimental in dynamic situations, particularly in cracked concrete during earthquakes, leading to potential damage from stuck expansion bodies.
Innovation Solution
A double coating system is applied to one of the elements in contact, with a high-friction outer layer for static loads and a low-friction inner layer for dynamic situations, allowing the expansion body to move freely and prevent substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high coefficient of friction is provided between the expansion body and the anchor body, then static extraction loads are improved and premature failure is avoided, but the expansion body cannot slide back and forth in cracked concrete during seismic events, resulting in damage to the surrounding concrete
Solution Approach 1:
The coating on the expansion body is divided into two distinct layers: an outer layer with high friction coefficient and an inner layer with low friction coefficient. This segmentation allows each layer to serve different functions - the outer layer provides high friction for static load resistance, while the inner layer enables low friction for dynamic movement in cracked concrete.
Solution Approach 2:
Different regions of the coating have different friction properties. The outer layer has high friction coefficient for static conditions, while the inner layer has low friction coefficient for dynamic conditions. This local quality variation allows the same component to adapt to different operational states.
2Adaptability or versatility
If a low coefficient of friction is provided between the expansion body and the anchor body, then the expansion body can slide freely in cracked concrete during earthquakes, but static extraction loads are reduced and premature failure occurs
Solution Approach 1:
The coating is segmented into two layers with different friction characteristics. The outer layer compensates for the low friction of the inner layer by providing high friction for static load resistance, while the inner layer enables free sliding for dynamic conditions.
Solution Approach 2:
The coating system is a composite structure combining two materials with different friction properties. This composite coating allows the expansion body to exhibit both high-friction and low-friction behaviors depending on the operational state.
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 configuration achieves excellent static performance in both uncracked and cracked concrete, while ensuring robustness during seismic events by adapting friction levels based on the situation, preventing premature failure and substrate damage.
Implementation Method 1
the outer layer having a coefficient of friction μ2 with respect to the other element that is greater than a coefficient of friction μ1 of the inner layer with respect to the other element
Data Source
AI summary
An expansion anchor, including at least one anchor body as a first element and at least one bolt as a second element, wherein the bolt has an expansion body, which pushes the anchor body radially outward when the expansion body is moved in an extraction direction in relation to the anchor body is provided. A double coating having an inner layer and an outer layer covering the inner layer is provided on one of the two elements in an area of contact with the other element, wherein the outer layer has a coefficient of friction with respect to the other element that is greater than a coefficient of friction of the inner layer with respect to the other element.