Drywall-Spaced Joist Hanger for Fire-Rated Load Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing joist hangers struggle to securely attach joists to structural members while protecting them from fire damage, especially when drywall is used as a fire barrier, as drywall is susceptible to cracking and crushing under fasteners.
Innovation Solution
A joist hanger design that uses stand-off members to maintain a distance between the joist and the structural member, allowing drywall panels to be interposed, providing fire protection without requiring additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If drywall panels are used as fire barrier between joist and structural member, then fire protection is improved, but fastener holding strength deteriorates due to drywall's susceptibility to cracking and crushing
Solution Approach 1:
The patent introduces side walls extending from the joist hanger that protrude through the drywall panel to engage the structural member directly. These side walls act as intermediaries that transfer load from the joist through the drywall to the structural member, bypassing the weak dowel bearing interface. The side walls provide a strong mechanical connection path while allowing the drywall to maintain its fire barrier function without requiring fasteners to penetrate it.
Solution Approach 2:
The patent transitions from a single-plane fastening system to a three-dimensional connection system. Instead of relying solely on fasteners penetrating the drywall in one dimension, the side walls extend in another dimension (protruding through the drywall) to create engagement with the structural member, effectively adding a spatial dimension to the load transfer mechanism.
2Object-affected harmful factors
If stand-off members are used to maintain distance between joist and structural member for fire protection, then fire barrier effectiveness is improved, but connection complexity increases
Solution Approach 1:
The patent combines the stand-off function with the joist hanger structure itself. The side walls that are integral to the hanger serve dual purposes: they maintain the required distance between the joist end and structural member for fire protection, and simultaneously provide the load transfer mechanism to the structural member. This eliminates the need for separate stand-off components.
Solution Approach 2:
The side walls perform multiple functions simultaneously: they provide lateral support to the joist, maintain spacing for fire barrier installation, protrude through the drywall to engage the structural member, and transfer loads. This multi-functionality reduces overall connection complexity despite the added fire protection requirement.
3Object-affected harmful factors
If drywall panels are interposed between joist and structural member, then fire shielding is improved, but load transfer capability deteriorates due to negligible dowel bearing strength
Solution Approach 1:
The side walls act as intermediary load transfer elements that bridge the gap created by the drywall panel. Instead of relying on the drywall's weak dowel bearing strength, the side walls transfer loads through direct engagement with the structural member, with the drywall serving only as a fire barrier in between.
Solution Approach 2:
The connection system is segmented into distinct functional zones: the side walls handle load transfer, the drywall handles fire protection, and the drywall notches accommodate the side wall protrusions. This segmentation allows each component to optimize its specific function without compromising the others.
Data Source
AI summary
A connection utilizing a joist hanger to hang a joist or beam from a wood structural support member such as a top plate or header in cooperation with a first plurality of fasteners such as screws or nails and one or more substantially vertical fire-resistant panels such as drywall.