Earthquake loads considering directional effects by adding 30% load of orthogonal direction?

[tngv752]

I know some codes from different country similar.
In Australian code AS1170.4 Section 5.4.2.1 say: "For structural components and footings that participate in resisting horizontal earthquake forces in both major axes of the structure, the effects of two directions determined separately shall be added by taking 100% of the horizontal earthquake forces for one direction and 30% in the perpendicular direction"

Does it mean that I have earth load in two directions x and y of Ex and Ey. And the RC column and shear (core) walls will be designed by (Ex+0.3Ey) and (Ey+0.3Ex) when considering the effect of earthquake in 2 directions ???

 

[KootK]

That's my undestanding of things.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Sarkheil]

in structure design procedures, (according to standards) we analyse and design the structure in two main direction; but it is really happened in real world?! of course not. it's so probable that earthquake occur in an oblique direction. so with calculating and designing structures in Ex+0.3Ey and Ey+0.3Ex, we keep in account the effect of obliquity. Notice that so many combinations of obliquity we can considered. but this two combinations (Ex+0.3Ey and Ey+0.3Ex) is in the direction of confidence and Pessimistic.