Segmented Post-Tensioning Retrofit Assemblies for Structural Reinforcement
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Solution Overview
Problem
Existing retrofit systems for strengthening aging concrete structural members are complex, require special equipment, and involve extensive fieldwork, including cutting and welding, which is time-consuming and costly, and do not easily adapt to rectangular or circular columns with sharp corners.
Innovation Solution
A retrofit assembly comprising pre-fabricated segments with connecting rods, braces, and nuts that can be easily installed using standard tools, eliminating the need for special equipment and fieldwork, and includes force distributors and direct tension indicators to ensure effective pre-stressing without elongation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wedge and anchor system with hydraulic jack is used to tension strands around concrete columns, then pre-stresses are applied to strengthen structural members, but special equipment and extensive fieldwork are required making installation complex and costly
Solution Approach 1:
The retrofit assembly is divided into multiple discrete segments that can be independently installed around the structural member. Each segment contains its own tensioning mechanism with connecting rods and nuts, eliminating the need for a single complex hydraulic jack system. The segments are connected through overlap regions, allowing modular installation and removal without specialized equipment.
Solution Approach 2:
The retrofit assembly uses standard tools and materials that can be easily handled and installed by conventional construction equipment. The connecting rods with threaded ends and nuts provide a self-contained tensioning system that does not require external hydraulic equipment. The design enables installation and removal using basic hand tools or standard mechanical equipment.
2Strength
If multiple separate corner pieces and risers are used to wrap strands around rectangular columns, then the strands can be tensioned, but alignment and installation become more complex and time-consuming
Solution Approach 1:
Multiple corner pieces and risers are merged into integrated retrofit segments that combine the functions of corner brackets, risers, and tensioning mechanisms into single units. Each segment is pre-assembled with connecting rods and nuts, eliminating the need for separate alignment and installation of multiple components. The segments are designed to interconnect through overlap regions, simplifying the installation process.
3Strength
If pressure casing with corner pieces and splices is used to tension structural elements, then pre-stresses are applied, but field cutting and welding are required increasing cost and time
Solution Approach 1:
The retrofit segments are pre-assembled and pre-configured with all necessary connecting rods, nuts, and tensioning mechanisms before installation. The overlap regions are pre-designed to accommodate the connection of adjacent segments without requiring field cutting or welding. This preliminary preparation eliminates the need for complex fieldwork and allows for straightforward installation using standard equipment.
4Strength
If strands are highly tensioned to provide pre-stresses, then structural properties improve, but the strands require special hydraulic equipment for installation and removal
Solution Approach 1:
The complex hydraulic tensioning system is replaced with a simpler mechanical tensioning system using connecting rods with threaded ends and nuts. The mechanical advantage provided by the threaded connections allows for effective tensioning without requiring hydraulic jacks or special equipment. The design maintains the ability to apply high pre-stresses while using basic mechanical fastening principles that can be operated with standard tools.
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 allows for quick and efficient installation and removal of retrofit assemblies without specialized equipment, reducing costs and fieldwork, while providing consistent pre-stressing across structural members, including those with complex geometries.
Implementation Method 1
the second ends are each operatively threaded to engage with one of the nuts
Implementation Method 2
the braces each include a hole operatively sized to receive the second end of one of the connecting rods
Data Source
AI summary
A retrofit assembly for reinforcing a structural member including a plurality of retrofit segments including a first retrofit segment and a last retrofit segment, wherein the first retrofit segment connects to the last segment, and wherein each of the retrofit segments comprises a connecting rod, a brace, and a threaded nut, wherein the connecting rods each include a first end and a second end, wherein the first ends are each fixedly secured to one of the braces, and the second ends are each operatively threaded to engage with one of the nuts, and wherein the braces each include a hole operatively sized to receive the second end of one of the connecting rods.