Long Span Steel Roofs in Seismic Zones-No isolators-Possible? 1

[IJR]

Pals

This is not AISC but I post it here for the sake of discussion

Long span roofs would rest on concrete columns. In high seismicity it seems logical to isolate the roof from the concrete supports.

But in my region, the term "isolation" unfortunately has come to mean "trendy" and therefore "expensive". So owners dont really like to here that, though I use them whenever I can.

What other methods that dont involve neoprenes and disks are there to ensure seismic safety? Can the roof be made very rigid for example? Can simple oversize bolting work?

Your opinion will be highly appreciated.

respects
IJR

 

[civilperson]

"Isolate" can mean different things. If truly floating on top of the structure, then some movement limiters need to be built into the design. When the movement limit is exceeded by the building oscillation then the full force of the unmoving roof will be transfered to the connection and the structure below. A better approach would be energy dissipators to counteract the seismic acceleration or design enough strength into the roof connections and structure to withstand the roof loads both vertical and horizontal..