Buckling-Restrained Brace Core for Residual Drift Reduction
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Solution Overview
Problem
Buckling-restrained braces in building and bridge structures face challenges in reducing residual drift after plastic axial deformation due to earthquakes, which can render structures unusable, and there is a need to secure the strength of these braces during seismic events.
Innovation Solution
A buckling-restrained brace design incorporating a core with three steel plates of different yield points, where the first steel plate has a lower axial strength in its center segment and longer length, and the second and third steel plates have lower yield points with shorter lengths, allowing for controlled yielding and reduced residual drift while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the core is designed to yield and deform to absorb seismic energy, then the energy dissipation performance is improved, but the residual drift increases making continuous use of the structure impossible
Solution Approach 1:
The core is divided into three steel plates with different yield points, allowing segmented yielding behavior. The first steel plate yields at a lower stress level to absorb energy, while the second and third steel plates maintain higher strength to limit residual drift, achieving both energy dissipation and post-earthquake usability
Solution Approach 2:
Different segments of the core (different steel plates) are given different local qualities in terms of yield point and axial strength. This allows the core to exhibit multi-stage yielding behavior where some segments yield while others remain elastic, balancing energy absorption with residual drift control
2Loss of energy
If the core uses steel plates with different yield points to absorb seismic energy of different magnitudes, then the energy absorption efficiency is improved, but the structural strength may be compromised
Solution Approach 1:
The core is constructed as a composite of three steel plates with different yield characteristics. This composite structure allows the buckling-restrained brace to utilize the full range of seismic energy from small to large earthquakes while maintaining overall structural strength through the contribution of all three steel plates
3Reliability
If the first steel plate has a longer yielding segment to increase the ratio of steel plate yield deformations, then the residual drift reduction is improved, but the axial strength of the core may be reduced
Solution Approach 1:
The first steel plate is given a longer yielding segment length compared to the other steel plates, creating a local quality difference that increases the ratio of steel plate yield deformations. This localized design enhancement improves residual drift control without significantly compromising the overall core axial strength due to the contribution of the other steel plates
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 design effectively reduces residual drift and secures the strength of the buckling-restrained brace by ensuring that the steel plates with higher yield points remain elastic during axial deformation, enhancing the seismic resistance and energy dissipation capabilities of the structure.
Implementation Method 1
the first steel plate includes a first yielding segment provided in a center segment of the first steel plate in the axial direction and having an axial strength smaller than an axial strength of both end segments of the first steel plate
Implementation Method 2
the steel plate having a relatively high yield point remains elastic, and therefore the tangent stiffness of the entire buckling-restrained brace is high
Data Source
AI summary
A buckling-restrained brace includes a core and a restrainer, the core includes a first steel plate having a first yield point, a second steel plate having a second yield point different from the first yield point, and a third steel plate having a third yield point different from the first yield point, the first steel plate is sandwiched between the second steel plate and the third steel plate, and a length of a first yielding segment of the first steel plate in the axial direction is different from a length of the second yielding segment of the second steel plate in the axial direction, and is different from a length of the third yielding segment of the third steel plate in the axial direction.