structural drawings
structural drawings
(OP)
According to a recent publication by AISC, "When the engineer turns the structural drawings over to the fabricator the connections discussions start. These take a lot of time that could be greatly reduced if the engineer would indicate actual end reactions on the members." Has anyone been doing this? We usually leave connections up to fabricator,to develop full capacity of member at connection.






RE: structural drawings
RE: structural drawings
RE: structural drawings
RE: structural drawings
RE: structural drawings
Carl Bauer
www.bauerconsultbotswana.com
RE: structural drawings
Not so much with steel, but with other materials where the project is located 'out of the way', perhaps like Botswana, even for simple projects, I tend to 'overdetail' because the control or skill isn't there... saves a pile of questions afterwards...
RE: structural drawings
Some firms have taken upon themselves the task of connection design in all instances, probably out of concern for liability in the wake of the Hyatt Regency collapse, etc.
The firms I have been associated with have progressed from not showing anything to creating a full connection schedule. In cases of unique, odd, or skewed connections, we always detail and design it all. In the case of typical beam/column beam/beam connections we use a standard schedule through a spreadsheet and require our engineers to check each and every connection against the calculated capacity.
For standard connections, there isn't anything wrong with allowing the fabricator to design it, as long as you, the engineer of record, are satisfied with the process and result (checking their shops to spot check the more typical connections and fully verify the complex ones). After all....you are ultimately responsible for the connection...not the fabricator.
RE: structural drawings
Having worked for a Fabrictor in the past, I found that they prefer to do the connections in-house so that they can utilise their "standard cleats and endplates", for faster fabrication in the automated modern workshops.
This split works well as the Consultant make a saving on his fee by not having to carry out this part of the design, and the fabricator is happy as he can design and detail the connection to suit his workshop. A win-win solution.
For structural concrete detailing however the recent tendency in the UK is to leave the reinforcement detailing to the contractor .....once again the Consultant passing on a labour intensive element of the design work onto the Contractor. In this case the reinforcement detailing is rarely checked in thorough detail.
RE: structural drawings
For most straight forward connections, we can simply go to our AISC (ie AUSTRALIAN ISC) connections reference, check the number of bolts needed to provide the required capacity, and fully specify the connection (cleat dimensions, bolt diameter and spacing, coping details, weld quality etc) by means of a simple reference to the AISC publication.
The range of connections covered includes welded or bolted splices or end connections and five different types of flexible end connections, plus purlin cleats and base plates.
This practice avoids the need to consider each fabricator's 'special cleats and end plates' since all fabricators are set up for the standard sizes, whether automated or not.
Thus I would suggest that we have a real win/win situation. The fabricators are not faced with too many idiosyncratic connection details, and the engineers have full control over one of the most vital aspects of their designs.
As for leaving reinforcement detailing to a contractor ('unchecked in thorough detail'), my stomach churns at the very thought. The UK lawyers must be rubbing their hand in glee.
RE: structural drawings
RE: structural drawings
RE: structural drawings
RE: structural drawings
I always show the design forces for the connections on the drawings, call for the fasteners to be used, and show typical details of the connections.
I check all the connections when the shop drawings are submitted.
AEF
RE: structural drawings
Fabricators tend to each have their own favored setup when it comes to shear connections. Some like to use just bolts, others like to weld on one side and bolt on the other, etc. Its impossible to forecast which preference they will have during the design phase. Its no sin to let them design and fabricate connections in a way they are set up for, but of course make sure the connections work.
For welded moment connections, I will also indicate the maximum service level bending moment on the plan, provide a typical detail showing one way to do the connection, then review what the fabricator does during shop drawings.
This approach seems to work ok in this neck of the woods. It allows some flexibility but the Engineer still is doing his job. It also seems to save some time; beats detailing every single connection on the Construction Docs, if you ask me.
However, as mentioned in other posts, if you have a special situation or building, unusual loads, etc, it makes sense to do final details and designs up front. That way there is no confusion or argument about what is required or needed.
RE: structural drawings
We encountered a problem on many nodes where multiple bracings or bracings from multiple planes coincided at a node. The designer of the overall structure (the design was done in another country) had given only a maximum force for every member end through his range of load cases but without giving the individual load cases. When we came to design the joints, we were unable to obtain equilibrim of forces at nodes (out by up to 60% of the load) or to determine the critical load paths through the node.
If the structure designer leaves the joint design to someone else, the design information should be given in adequate engineering fashion.
RE: structural drawings
Now I work as Engineering Manager for fabricator. In many cases I decide to lower loads (short filler beams). Sometimes problem is in connection of deep beam into much smaller one. From engineering point of view everything is OK, but connection is difficult to make.
I agree, most fabricators have their own standards and it works very well. Provide all the details by EOR limits the fabricator choice and may be not economically sound.
Many fabricators use sophisticated detailing programs, able to make and check all AISC standard connections.
I agree, EOR should be a (leading) partner for fabricator in design of connections. Experianced Fabricators knows what they are doing.
RE: structural drawings
I design concrete details fully.