Metal Restraint Strap for Structural Uplift Suppression

Solution Overview

Problem

In timber frame construction, metal hold-down brackets fixed to posts with nails or bolts face excessive shear forces during earthquakes or typhoons, leading to potential breakage and failure in suppressing uplift behavior between parallel structural bodies.

Innovation Solution

A metal restraint strap with an elongated base member and bolt members with external threads, connected using fasteners, is used to securely link parallel structural bodies, such as a concrete foundation and a beam, to prevent displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal hold-down brackets are fixed to posts with nails or bolts, then the uplift behavior can be suppressed, but excessive shear force may break the fasteners

Engineering Contradiction:

Improvesuppression of uplift behaviorVSAvoidshear force resistance of fasteners

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The restraint system is divided into multiple bolt members distributed along the elongated base member. Instead of relying on a single connection point, the shear force is segmented and distributed across multiple fasteners, reducing the load on each individual fastener while maintaining overall suppression of uplift behavior.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a compact hold-down bracket to an elongated restraint strap that extends along the post. This dimensional change allows the system to distribute fasteners over a longer distance, effectively spreading the shear force across multiple connection points rather than concentrating it at one location.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If metal hold-down brackets are used to suppress uplift behavior, then displacement between structural bodies can be reduced, but the fasteners may break due to excessive shear force

Engineering Contradiction:

Improvedisplacement suppression between structural bodiesVSAvoidfastener integrity under shear force

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The restraint system is divided into multiple bolt members distributed along the elongated base member. Instead of relying on a single connection point, the shear force is segmented and distributed across multiple fasteners, reducing the load on each individual fastener while maintaining overall suppression of uplift behavior.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameter of the restraint system by using an elongated base member instead of a compact bracket. This parameter change increases the distance between fasteners, allowing the system to maintain displacement suppression while reducing the shear force concentration on each fastener through optimized spacing.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If a compact hold-down bracket is used, then the structure is simpler, but it cannot effectively distribute shear force to prevent fastener breakage

Engineering Contradiction:

Improvesimplicity of restraint systemVSAvoidshear force distribution capability

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The invention transitions from a compact hold-down bracket to an elongated restraint strap that extends along the post. This dimensional change allows the system to distribute fasteners over a longer distance, effectively spreading the shear force across multiple connection points rather than concentrating it at one location.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11168473B2Metal restraint strap and structural body restraining method

Publication Date: 2021.11.09 SHERUTAA

AI summary

A metal restraint strap for suppressing a displacement between two parallel disposed structural bodies away from each other includes an elongated metal base member; metal bolt members extending outward in a longitudinal direction of the base member from opposite longitudinal ends of the base member, and each having an external thread at least on an outer periphery of an distal end portion of the bolt member; and fasteners adapted to be screwed onto the external threads of the bolt members.