ASCE 7-10 Seismic Loads - Cable Tray

[JeffVolcan]

I am performing calculations on a cable tray attached to a bridge structure. I get my ap=2.5 and Rp=6 from Table 13.6-1. In the formula Fp=(.4*ap*sps*Wp)/(Rp/Ip) * (1=2/h). I would like to set 2/h to zero since the cable tray is attached to a seismically designed structure (the bridge).

Is this an acceptable practice?

 

[MotorCity]

Nope, cant do it. That factor is meant to account for how high the cable tray is located on the structure relative to the ground. Has nothing to do with whether or not the base structure is designed for seismic. In general, the higher something is located, the longer the period. Incidentally, are you using AASHTO if this is a bridge structure?

 

[JeffVolcan]

OK, thank you for your response. Do you know which AASHTO section covers the seismic design of attachments to bridge structures?