moyseh
Structural
- Sep 19, 2021
- 37
Hi All,
A common problem I have encountered when designing seismic restraints for services (ducting/piping etc) is the case where we have to brace to the roof structure, namely DHS or cold form steel purlins. This load can be relatively high in seismic areas and purlins typically span a large distance.
Following the load path you always tend to get out-of-plane bending of the purlin with these lateral loads. I haven't calculated their capacity but I expect it to be exceeded almost every time.
Sometime we have provided purlins on their flat to transfer the load to the main frame but often I see engineers not doing anything. Some even argue that the load gets transferred directly to the stiffer element, the roof sheathing. What is everyone's opinion on this? Am I expected to design a secondary steel system to take the lateral load in almost every case where the minor axis bending capacity is exceeded?
Interested to get your thoughts.
A common problem I have encountered when designing seismic restraints for services (ducting/piping etc) is the case where we have to brace to the roof structure, namely DHS or cold form steel purlins. This load can be relatively high in seismic areas and purlins typically span a large distance.
Following the load path you always tend to get out-of-plane bending of the purlin with these lateral loads. I haven't calculated their capacity but I expect it to be exceeded almost every time.
Sometime we have provided purlins on their flat to transfer the load to the main frame but often I see engineers not doing anything. Some even argue that the load gets transferred directly to the stiffer element, the roof sheathing. What is everyone's opinion on this? Am I expected to design a secondary steel system to take the lateral load in almost every case where the minor axis bending capacity is exceeded?
Interested to get your thoughts.