Precast Segmented Annular Structure with Interlocking Hairpin Joints

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Solution Overview

Problem

Large annular structures, such as cylindrical manholes, face challenges in transportation and installation due to size constraints and structural weaknesses at joints when assembled from precast segments, which can be prone to moments and shear forces from external loads.

Innovation Solution

The design incorporates segments with interlocking hairpin bars and field closure casting using rebar and cement to form joints capable of transferring moments and shear forces, allowing for continuous force distribution around the structure, enhancing structural integrity while maintaining the benefits of precast segments like increased portability and reduced installation time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If annular structures are assembled from precast segments, then transportation and installation become easier due to smaller individual component sizes, but structural weaknesses develop at the joints between segments

Engineering Contradiction:

Improvetransportation and installationVSAvoidstructural integrity at joints

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The annular structure is divided into multiple precast segments that can be transported and installed separately. Each segment is cast as a discrete unit with standardized dimensions, allowing for easier handling and installation while maintaining the overall structural functionality of the complete annular form.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The joint system merges multiple segments into a unified structural assembly through interlocking hairpin bars that physically connect adjacent segments. The field closure casting then combines these interconnected segments into a monolithic appearance and structural behavior, eliminating weak points at the joints.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 3:

The joint system utilizes composite construction combining metal hairpin bars embedded in concrete segments with additional field closure casting material. This composite approach at the joint interface creates a stronger connection than either material alone, reinforcing the transition zone between segments.

Inventive Principle:

Principle #40Composite materials

2Productivity

If traditional joint methods are used between precast segments, then installation is simpler, but the joints cannot effectively transfer moments and shear forces from external loads

Engineering Contradiction:

Improveinstallation speedVSAvoidforce transfer capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The hairpin bars are pre-installed in the segments during manufacturing, positioned to optimally receive and transfer forces. This preliminary preparation eliminates the need for complex field operations while ensuring the joint is pre-configured for reliable force transfer from the outset.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The hairpin bars act as intermediary elements between adjacent segments, providing a mechanical bridge that transfers moments and shear forces across the joint interface. These bars embed into both segments and extend into the field closure casting, creating a continuous load path that reinforces the connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If segments are connected without interlocking mechanisms, then assembly is faster, but the structure cannot withstand significant external forces such as earth backfill and live loads

Engineering Contradiction:

Improveassembly complexityVSAvoidresistance to external loads

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The hairpin bars are nested within the segment structure during manufacturing, with portions embedded in the concrete and portions extending outward. This nested configuration allows the bars to be integrated into the segment without adding external complexity, while providing substantial force transfer capability when segments are assembled.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The hairpin bars feature curved or bent geometries that follow the contour of the annular structure. This curvature allows the bars to effectively resist radial and tangential forces from earth backfill and live loads, converting complex multi-directional stresses into compressive forces along the bar length that the concrete can effectively carry.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS10119633B2Precast segmented annular structure with structural joint

Publication Date: 2018.11.06 JENSEN ENTERPRISES

AI summary

A segment for an annular structure includes an arcuate body extending between a first end and a second end. The segment includes a first plurality of interlocking portions extending from the first end and a second plurality of interlocking portions extending from the second end. Each interlocking portion includes a first leg and a second leg partially embedded in the arcuate body and a connecting portion connecting the first leg and the second leg, the connecting portion external to the arcuate body. The segment also includes a flange proximal to the first end and the second end of the arcuate body. Each flange includes a first spacing portion that extends radially outward from the outside surface and a second extending portion that extends distally from the main body portion.