Expectations of the Professional Structural Engineer
Expectations of the Professional Structural Engineer
(OP)
I Design and Build Timber Frame Homes. I am an engineer but not certified. The Owner picks the structural engineer for analysis. I use beam tables and rules of thumb for the initial design before the approving engineer is involved. I have noticed wide variation in what the engineers "check" or analyze for their approval. Of course they cannot check every joint or beam as the price in a large timber frame would be prohibitive. I have asked several why they check what they do and I never get a really good answer, they seem somewhat intimidated that the lowly timber framer is asking such a question.
Is there a standard or guideline as to what level of analysis is required for approval? I have been unable to find one. I understand the code requires snow load, floor loads, seismic loads, wind loads etc, but these loads eventually end up in individual beams, posts and joints. Some check the "critical" beams posts and joints trusting me for the rest while others check much more. Any insight would be appreciated. Thanks in advance
Is there a standard or guideline as to what level of analysis is required for approval? I have been unable to find one. I understand the code requires snow load, floor loads, seismic loads, wind loads etc, but these loads eventually end up in individual beams, posts and joints. Some check the "critical" beams posts and joints trusting me for the rest while others check much more. Any insight would be appreciated. Thanks in advance






RE: Expectations of the Professional Structural Engineer
RE: Expectations of the Professional Structural Engineer
Also there are quick ways to check sizes relative to each other. Checking the worst case and using simple rules to compare the less critical members can be done with simplified rules and judgement.
Structural engineering is often more an art than a science.
RE: Expectations of the Professional Structural Engineer
Then pick a few critical joints. Check them - set a minimum type and size connection pattern and you are good to go.
That may be where experience comes in...
RE: Expectations of the Professional Structural Engineer
Personally I do not like engineers who are prepared to stamp anything which is submitted in front of them. I have been having many disputes lately with truss engineers who in my opinion have been doing this.
But with time, a compentant engineer who has designed many timber frame houses will know intuitively whether the sizes seem right by feel. Much like an excellent wine maker will know when the grapes are right to make a good wine.
RE: Expectations of the Professional Structural Engineer
If I were familiar with the type of structure, I would check for things I know get overlooked first. At a minimum: loads and specifications/general notes, member layout, load paths, design scheme, lateral system, member sizing for typical members, then all atypical members, connections, fasteners, anchorages, foundation. Compatibility of deflections on rigidly connected members, deflections, and other serviceability also have to be reviewed.
Most likely, I'd have to spend a significant amount of time figuring out how the design decisions were made, so I know how to assess the validity of the design. It is not "is this member the right size?" It is more like "how is the load going to move through this structure and get to the ground?"
RE: Expectations of the Professional Structural Engineer
I always believe that the best way to check a design is to ignore the calculations and check the drawings independently. Few structures are that complex that they cannot be understood easily by an unfamiliar but competent checking engineer.
That said, I agree that an engineer should not stamp drawings that they have not checked.
RE: Expectations of the Professional Structural Engineer
When I started, I was walked through the loading of a structure, given input and feedback on the layout, and calcs were checked as I went along. It was more process control than QA inspection.
RE: Expectations of the Professional Structural Engineer
Out of all the structures that I have checked I have always found mistakes. The mistakes are normally smaller the more experienced the engineer, but they are still there.