Joist Hanger Connection Design

[mappryan]

Inexperienced with wood connection designs (ie Simpson Strong-Tie Connectors). Heres my question: 3 Span Timber Boardwalk. Have a 11' Timber span transitioning to a 33' Glulam span. 11' span joists are 4x12 Timber while 33' span are 5.5"x20-5/8" Glu-Lam. Was thinking of going with Simpson Joist Hangers for the Glu-Lams in order to make up the difference in superstructure depth. (see attached sketches). However I am wondering how these are typically analyzed or assumed to act. I turned all the beam reactions from the 33' span into a distributed load and computed the reaction that would be supported at the middle pile. Its quite a large reactions. My worry is that the large unbalanced reactions will cause some torsion in the pile cap. I realize that the pile cap is sort of braced against this torsion/rotation due to the joists framing into it. Do i need to provide some strap to help prevent this rotation. If i were to provide this strap, wouldn't that effectively be restraining the cap and required torsion. Joist looking for some advice and general ideas about how this connection behaves. Thanks, rm

 

[OHIOMatt]

I would consider cantelever framing with a Simpson HCA. You will want to make the width of the members the same.

 

[msquared48]

I don't like the detail. I would lower the top of the pile and the 8X12 bent to the point that the Glulam could bear on the 8X, then hang the 4X off the glulam.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[hokie66]

Agree with Mike, and would also query the materials you are using. Is this boardwalk over or near a body of water? The exposure condition would dictate the materials and corrosion protection required.