Pre-tensioned Bearing Structure for Concrete Beam Demolding

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Solution Overview

Problem

Current methods for manufacturing prestressed concrete beams face challenges such as excessive forces during demolding, risk of cracking, and limited load-bearing capacity due to tensile stresses, and are either complex and expensive or limited by the need for bulky tensioning machines.

Innovation Solution

A structural element with a second tensioner fixed at two distinct points to compress and flex the elongated body, allowing for deactivation of compression and flexing, which is implemented during molding and released as the element is loaded, enabling greater prestressing and reduced risk of cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If pre-tensioning is used to simplify manufacturing, then ease of manufacture is improved, but the beam bends excessively and cracks when tensioners are released

Engineering Contradiction:

Improveease of manufactureVSAvoidrisk of cracking

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by introducing a second tensioner that temporarily compensates for the bending caused by the first tensioner during the critical demolding phase. This second tensioner is activated beforehand to counterbalance the excessive bending forces, preventing cracks during demolding, and then deactivated after the beam has safely been removed from the mold.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the second tensioner's prestressing force adjustable and time-dependent. The second tensioner is activated during manufacturing to counteract bending, then deactivated after demolding when it is no longer needed. This dynamic adjustment allows the system to adapt to different stages of the manufacturing process.

Inventive Principle:

Principle #15Dynamics

2Strength

If prestress is increased to support higher loads, then load-bearing capacity is improved, but the beam bends too much and cracks under the prestress

Engineering Contradiction:

Improveload-bearing capacityVSAvoidrisk of cracking

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies the counterweight principle by using the second tensioner to counterbalance the bending effects of the first tensioner. The second tensioner creates an opposing bending moment that compensates for the excessive bending caused by high prestress from the first tensioner, allowing higher loads to be supported without cracking.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The second tensioner is activated in advance during the manufacturing process to prevent cracking before the beam is subjected to service loads. This preliminary action ensures that the beam can withstand the high prestress forces without cracking during the vulnerable demolding phase.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If demolding is delayed to avoid cracking, then reliability is improved, but productivity decreases due to longer manufacturing time

Engineering Contradiction:

Improveavoidance of crackingVSAvoidmanufacturing time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The second tensioner is activated beforehand during the manufacturing process to prevent cracking during demolding. This allows demolding to proceed at the optimal time without waiting for excessive concrete strength development, thereby maintaining productivity while ensuring reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dynamic activation and deactivation of the second tensioner allows the beam to be demolded at the appropriate time without unnecessary delays. The tensioner provides protection only when needed during demolding, then is deactivated to avoid unnecessary waiting time, thus maintaining high productivity.

Inventive Principle:

Principle #15Dynamics

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 approach allows for earlier demolding without cracking risks, increased load-bearing capacity, and reduced production costs, enabling the structural element to support heavier loads while minimizing bending and tensile stresses.

Implementation Method 1

there is provided at least a second tensioner which is fixed at two distinct points to said elongated body such that it compresses and flexes the elongated body

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

there is provided deactivation means for releasing the compression and flexing exerted on the body elongated by said second tensioner

Methodology Applied

Scientific EffectForce Release:

Data Source

PatentEP3175057B1A pre-tensioned bearing structure

Publication Date: 2023.12.13 SABBAH ALAIN

Figure 1A~3B
Figure 2A~2C
Figure 4A~5B

AI summary

The invention relates to a prefabricated structural element comprising an elongate body (11) and at least one first tensioner (1) that is attached in the elongate body such that it compresses the elongate body. According to the invention, the structural element comprises at least one second tensioner (2) that is attached at two separate points to said elongate body by two attachment means so that it compresses the elongate body. At least one of said attachment means is removable so as to make it possible to relax the compression exerted by the second tensioner on the elongate body.