Composite Hold-Downs for Reinforced Concrete Stem Wall Repair
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Solution Overview
Problem
Existing structural repair methods for reinforced concrete structures often fail to address the underlying issues of corroded rebar and anchors, leading to premature failure and costly, time-intensive repairs, as they either cover up the problems or use ineffective remedies like epoxy coatings and cathodic protection systems that are not cost-effective for residential applications.
Innovation Solution
A method involving the use of a non-ferrous jack and hold-downs made of composite materials, which are inserted into the damaged stem wall to support and reinforce the structure with a horizontal composite bar, while filling the space with cementitious material to create a durable repair that resists pull tests and minimizes further corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy coatings or cathodic protection systems are used to protect corroded rebar, then the rebar is temporarily protected from corrosion, but the solution is not cost-effective for residential applications and does not address the root cause of structural failure
Solution Approach 1:
The patent removes the corroded rebar from the concrete structure and replaces it with composite reinforcement bars. This extraction approach eliminates the source of corrosion rather than attempting to protect the corroded material, providing a permanent solution that is cost-effective for residential applications.
Solution Approach 2:
The patent uses fiber-reinforced polymer (FRP) composite bars as replacements for traditional steel rebar. These composite materials provide the necessary tensile strength while being immune to corrosion and chloride ion penetration, resolving the contradiction between reliability and cost-effectiveness.
2Reliability
If concrete is removed to access and repair corroded rebar, then the degraded reinforcing material can be replaced, but extensive demolition is required which is time-consuming and costly
Solution Approach 1:
The patent employs drill-and-dowel techniques to access and replace corroded rebar at specific localized points rather than requiring extensive concrete removal. This localized approach maintains structural integrity while significantly reducing repair time and cost.
Solution Approach 2:
The repair process is divided into discrete, manageable segments: drilling access holes, inserting hold-downs, replacing individual rebar sections, and patching. This segmentation allows for efficient, targeted repairs without requiring complete demolition of affected areas.
3Strength
If traditional steel rebar is used in reinforced concrete, then the structure gains tensile strength, but the rebar is susceptible to corrosion from moisture and chloride ions leading to premature failure
Solution Approach 1:
The patent replaces traditional steel rebar with fiber-reinforced polymer (FRP) composite bars that provide equivalent or superior tensile strength while being inherently resistant to corrosion and chloride ion penetration, eliminating the harmful effects that plague steel reinforcement.
Solution Approach 2:
The composite reinforcement bars create an inert, non-corroding environment within the concrete structure. Unlike steel rebar that actively corrodes when exposed to moisture and chlorides, the composite materials remain chemically inert and do not degrade over time.
4Stability of the object's composition
If anchors are used to secure walls to the foundation, then the structure gains stability, but the anchors become degraded and corroded over time compromising the connection
Solution Approach 1:
The patent replaces traditional metal anchors with composite hold-down devices made from corrosion-resistant materials. These composite hold-downs maintain the critical wall-to-foundation connection while eliminating the corrosion mechanism that compromises anchor durability over time.
Data Source
AI summary
A method of reinforcing a structure comprising a wall built on a reinforced concrete stem wall may include removing concrete from the reinforced concrete stem wall at an exterior of the structure to expose the reinforcing material within the stem wall and create a space within the stem wall. A degraded portion of the of the reinforcing material may be removed. A hold-down may be partially disposed within the wall inserting, from below the wall, such that an upper portion of the hold-down is disposed within the wall and a lower portion of the hold-down extends into the space within the stem wall. A horizontal composite bar may be coupled to the exposed reinforcing material and to the lower portion of the hold-down. A cementitious material may be disposed in the space within the stem wall, around the lower portion of the hold-down, and around the horizontal composite bar.