Rail Support Post Bracket for Stair Stringer Attachment
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Solution Overview
Problem
Existing methods for attaching rail support posts to stairways lack structural strength, particularly in transferring lateral forces to shear forces within the stair's internal elements, failing to meet building code requirements for horizontal and angular forces.
Innovation Solution
A bracket system is used to firmly connect the rail support post to the stair stringer, riser, or blocking, forming an 'L' shaped structure with flanges that distribute lateral forces into shear forces, enhancing the structural attachment by passing bolts through the bracket, stringer, and post, and using lag bolts for additional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a post is attached to the exterior of a stringer by bolting or nailing, then the attachment is simple to install, but the attachment strength is minimal and cannot withstand required lateral forces
Solution Approach 1:
A bracket member is introduced as an intermediary component between the post and the stair structure. The bracket attaches to the stringer, rise, and/or tread, providing a robust connection point that distributes lateral forces across multiple structural elements rather than relying on a single weak attachment point to the exterior of the stringer.
Solution Approach 2:
The attachment system transitions from a single-point exterior attachment to a multi-dimensional connection involving the bracket, stringer, rise, and tread. By engaging multiple dimensions of the stair structure (vertical rise, horizontal tread, and diagonal stringer), the system achieves superior load distribution and attachment strength.
2Ease of operation
If a post is fixed without attachment to the stair, then installation is simplest, but the firmness to support forces is insufficient and fails to meet building code requirements
Solution Approach 1:
The bracket serves as a mediator that provides structural connection between the post and the stair. Rather than leaving the post unattached or using simple exterior fastening, the bracket mediates the connection by anchoring into multiple structural elements (stringer, rise, tread), ensuring both ease of installation and code-compliant strength.
Solution Approach 2:
The attachment system merges multiple structural elements (stringer, rise, and tread) into a unified connection system. By combining these elements through the bracket, the system achieves reliable force support while maintaining practical installation simplicity.
3Device complexity
If lateral forces are applied directly to an exterior-mounted post, then the force transfer path is simple, but the forces cannot be effectively transferred to shear forces within the stair's internal elements
Solution Approach 1:
The force transfer path is extended from a simple exterior connection to a multi-dimensional load path. The bracket distributes lateral forces from the post into the stringer, rise, and tread, creating complex three-dimensional force vectors that effectively transfer loads to the stair's internal structural elements through shear and compression.
Solution Approach 2:
The bracket acts as a force-distributing intermediary that converts concentrated lateral forces applied to the post into distributed shear forces across multiple structural elements. This mediation transforms the force transfer mechanism from a simple direct load to a complex distributed load path that engages the stair's internal strength.
Data Source
AI summary
A method and apparatus is disclosed for mounting a rail support post to the perimeter of a stairway having stingers at the edge of the stairway and treads, risers and possibly blocking laterally across the stairway. The apparatus includes a bracket member that is attached to or against the interior of a stringer and includes at least one hole for accommodating a fastener that passes through the stringer and into or through a post member at the outside surface of the stringer. The bracket includes flanges that attach to a rise or a tread and/or a block to secure the assembly together.