if you intend to use the third option for mass source definition, you have to separate self weight from your superimposed dead load. and define your mass source as superimposed dead load, part of live load. any mass defined in the model will also be included internally by ETABS aside from the building self weight.
05-12-2009, 03:45 PM (This post was last modified: 05-12-2009, 03:47 PM by piscesa.)
Yups... that's right any additional dead load besides the selfweight needs to be separated to prevent double calculating of selfweight in mass source. Additional dead load which known as superimposed load should be added when third option of mass source is used with load factor 1 and life load should be added with load factor according to the spesific code (Usually 0.3).
I usually use the second option (from loads). All the coeficients are those given in the seismic codes (1 for dead loads and permanent loads and 0.4/0.3 for live loads). The third option can also be used (in this case only the dead load is 0, the rest of the loads have the same coeficients).
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