Eng-Tips’s functionality depends on members receiving e-mail. By joining you are opting in to practical stress analysis for design engineers flabel pdf e-mail. Example channel bolted to tubing, analyzing channel.
To consider the joint fixed I would want to see multiple bolts in a relatively large pattern. My recommendation for most cases: be conservative and assume the joint is pinned. Mechanics says that pinned joints allow rotation but not translation. Without seeing the connection or having more detail one can’t say for sure. For modeling purposes, I would also assume it is a pinned connection. This would undermine the purpose of the fixed connection.
It all depends on how you detail it and how you design the steel member for the end forces. As stated above by fellow engineers various connections allow rotation and or prevent it. I have a copy of an excellent connection illustration in PDF format that is published by the AISC. In this case, the simple answer is to be conservative. That may mean for example assuming pinned for the supported member but it may mean assuming fixed for the supporting member. You really need to look at both extremes to be certain your design is safe. For example, a pinned-pinned beam, point loaded in the middle, will have a maximum bending moment in the middle, zero moment at the end, and highest shear at the ends.
A fixed-fixed beam has a moment at both the end and the middle, and a high shear at the ends. Now if the beam is uniform along it’s length, then it can be easily seen that the pinned-pinned condition is conservative for all sections. This situation of Degree of Restraint is very well explained by Flabel in “Practical Stress Analysis for Design Engineers”, starting on page 39. So a little engineering judgement is required here. I have tried locating the file, on my own, at aisc. There are several excellent resources available for free downloads, but, I failed to locate the one which you refer to.
It is a bout 3 MB. You will need a cablee or DSL or faster connection. It is usually conservative approach that the connection is considered as pinned connection and most structural engineers do that. If you consider the connection between channel and tube, it is proper that the connection is pinned when the channel is bolted to the wall of tube that is transverse to longitudinal axis of channel, because the wall of tube is small stiffness. If with additional plates, the channel is bolted to the side wall of tube which is pallel to longitudinal axis of channel, this connection would be considered as fixed connection. Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.