Basic truss chord splice question
Basic truss chord splice question
(OP)
A bit of office discussion around here and surprisingly the opinions are split down the middle, so curious what you all think.
If you were to analyze a Pratt truss in a program like RISA and determine the max tensile force (lets say 100k) in a lower chord midspan at a node, for a connection design is that 100k on each side of the node or the combined force at that node? What I'm getting at is lets says you have a splice plate on the lower chord with 2 bolts total (one each side of node), is the shear force on each bolt 100k or 50k? The 100k force is shown in the detail for the axial force at the end of the member on each side of the node.
If you were to analyze a Pratt truss in a program like RISA and determine the max tensile force (lets say 100k) in a lower chord midspan at a node, for a connection design is that 100k on each side of the node or the combined force at that node? What I'm getting at is lets says you have a splice plate on the lower chord with 2 bolts total (one each side of node), is the shear force on each bolt 100k or 50k? The 100k force is shown in the detail for the axial force at the end of the member on each side of the node.






RE: Basic truss chord splice question
RE: Basic truss chord splice question
RE: Basic truss chord splice question
RE: Basic truss chord splice question
RE: Basic truss chord splice question
Is it possible that the bolt shear question is not related to the issue you have brought up, but instead is about single vs. double shear of the bolts?
RE: Basic truss chord splice question
Lets kick the discussion up a notch (see attached Solidworks model picture), and see where the entire discussion is being had. We have prefabricated truss sections that are being joined end-to-end. First we have a lower chord splice, with the aformentioned two bolts in double shear. Then the verticals are angles that bolt together, three near the bottom that would be in tension and three near the top that merely keep the compression chord aligned. Analyzing this connection has been a headache, since the vertical angles in my opinion will act somewhat like a base plate in which the angles will bear on each other above the neutral axis. The lower three bolts as well as chord splice bolts will take up the tensile forces. Load path is through one splice bolt, up through the three lower angle bolts, and back down through the second splice bolt.
How would you approach this analysis? Neglecting one side of the joint, I'd have a compressive force from the upper chord, tensile force from lower chord, the full vertical angle with compression only springs throughout the length, and then have the three thru-bolts and single splice bolt all as pinned supports. Reactions from pinned supports would be used to determine bolt tension/shear. That was my thought. But following the load path, the splice bolt would have to first accommodate 100k shear, then the 3 bolts would resist the uplift/tension from a bearing analysis. So including that single splice bolt in the model would be underconservative/incorrect, no?
RE: Basic truss chord splice question
RE: Basic truss chord splice question
RE: Basic truss chord splice question