Design in earthquake zones(acc.to CBC)?
Design in earthquake zones(acc.to CBC)?
(OP)
Hello,
I am a civil eng. in Germany and i am doing for the first time statical calculation according to the american norm and
in particular to California Building Code. That is way i have some questions about calculating steel buildings in earthquake
zones. Based on the code there should be generated two
general load combinations: basic load combination (BLC) and special seismic LC (1,2D+L+Em).
So when i am doing the design checks (ASD) for the BASIC LC i am using the allowable stresses
(nominal Value divided by the safety factor OMEGA) for the comparisson(all./req.). So far so good. Here's the question:
What shall i do by the seismic LC? Can i use the nominal strengths of the members (i mean without dividing by OMEGA,
for Example for Tension would be R=AFy)? If not i am bekomming enormous connections, because the earthquake load is
multiplied by the seismic overstrength factor Omega!!
If i have a comression members (single Angle Bracing), shall i design it for buckling with the special LC or it is enough
to design only the connections with it, and for buckling shall i take the basic LC.
I will be very gratefull if someone can help me with these Problems! A general answer would be ok too, for me
is the basic approach important (how it is proceeded by designing in earthquake zones).
Thanks for the help!
I am a civil eng. in Germany and i am doing for the first time statical calculation according to the american norm and
in particular to California Building Code. That is way i have some questions about calculating steel buildings in earthquake
zones. Based on the code there should be generated two
general load combinations: basic load combination (BLC) and special seismic LC (1,2D+L+Em).
So when i am doing the design checks (ASD) for the BASIC LC i am using the allowable stresses
(nominal Value divided by the safety factor OMEGA) for the comparisson(all./req.). So far so good. Here's the question:
What shall i do by the seismic LC? Can i use the nominal strengths of the members (i mean without dividing by OMEGA,
for Example for Tension would be R=AFy)? If not i am bekomming enormous connections, because the earthquake load is
multiplied by the seismic overstrength factor Omega!!
If i have a comression members (single Angle Bracing), shall i design it for buckling with the special LC or it is enough
to design only the connections with it, and for buckling shall i take the basic LC.
I will be very gratefull if someone can help me with these Problems! A general answer would be ok too, for me
is the basic approach important (how it is proceeded by designing in earthquake zones).
Thanks for the help!






RE: Design in earthquake zones(acc.to CBC)?
RE: Design in earthquake zones(acc.to CBC)?
RE: Design in earthquake zones(acc.to CBC)?
http://ww
RE: Design in earthquake zones(acc.to CBC)?
There is a set of Seismic Design Manual based on the IBC. If you need to comply with current California Building Code, be sure to get the 1997 UBC version.
RE: Design in earthquake zones(acc.to CBC)?
RE: Design in earthquake zones(acc.to CBC)?
If your using ASD and the special load combinations for seismic(omega=2.8) you can increase your allowable stress value by a 1.7 factor. The omega factor is used on connections designs and also in some of the diferent types of discontinuity listed on the Ubc Table 16-M and 16-L. The special Seismic combination is an Strengh design combination so you can use this 1.7 value to change from ASD(Allowable Stress Design) to Strengh design(Limit state design) You should only design the connection w/2.8 Factor, but sometimes for simple moment frames you could calc all the frame with the omega and you don´t have to check the connection and the drift.
I hope that this colud be helpfull for you.
LG