As connection engineers, our greatest challenge is to ensure a good interpretation of the structural engineers’ work and at the same time take into account the time and budget factors dictated by the steel fabricators.
Over time, we have identified a few simple elements that can make coordination easier during the construction phase of a steel structure.
1- Indicate the real loads on the structure drawings or grant access to the structural analysis model.
The general rules of conception such as:
• Reaction for a uniform charge, from which the ultimate moment of resistance of the beam section can be calculated (50% UDL)
• 50% of the shear capacity of the beam section.
Although these rules are useful for a large number of members, in many situations, they can pose quite a challenge for the connection engineer because they often require member reinforcement or very large welds. In both cases, it causes delays and additional costs for the steel fabricator. However, the structural analysis model includes all the actual loads so it’s up to us to make good use of it and avoid over-designed connection and extra costs.
2 – Allow the connection engineer to communicate directly with the structural engineer.
The communication path between the connection engineer and the structural engineer tends to be long and complicated, even more so when the connection engineer is a sub-contractor hired by the fabricator. Before a question can reach the structural engineer, it first has to go through the fabricator and the general contractor. The risk of misunderstanding increases with every intermediate and the same goes with the delays. In a fast-track project, a direct link between structural and connection engineers leads to a communication that is more efficient and quicker, thus keeping up with the schedule. This doesn’t mean however that the fabricator and the general contractor are out of the loop, since it’s essential to keep them informed of the decisions taken.
3 – Avoid connection design based solely on the weight of the members.
Standardizing member sizes throughout the project will simplify tremendously the work of connection engineers, but also procurement and fabrication. In fact, buying members of the same type leads to economy of scale on the materials, connections that are more uniform and less mistakes when manufacturing the pieces. Extra care when choosing the members could mean significant savings in construction phase.
4 – Sizing columns based on compression, but also on the connections they will support.
A common problem for connection engineers is having to deal with columns that are too small. Whether geometric considerations make it impossible to bolt through the web/flanges or the web/flanges is not meant to support lateral or axial stress. Columns that are too small are never a good starting point for the connection engineer and a simple project can turn into a complex one if the columns were not sized properly in the first place. The structural engineer should consider which type of connection will be used by the fabricator, if reinforcement will be needed, if eccentric connections will be required, and so on. Once again, this reflection will make a great difference in the good execution of the project.
We hope that this blog post will make our structural engineers readers more aware of the necessity to design structure with consideration for construction and not just loads supported by the members.
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This section aims to promote the best practices from the steel and engineering construction industry. We treat a variety of topics including the role of 3D technology and BIM (Building Information Modeling) in the process of designs connections, collaboration between structural engineers and engineers connections, and good practices to minimize costs fabrication and installation while following the standard norms
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