wind load in etabs

huangyhg

wind load in etabs
hi   
i use ubc 97 in desgin
my question in  option expsure and pressure cofficients in etabs programm
i do not know
when can we use each of that option
1-expossure from extents rigid diapham and
2-exposure from area object?

the rigid diaphragm assumption assumes the edge of the building cladding is at the edge of the diaphragm. the program will use the b and l of the diaphragm to compute the wind loads on the floor. it will apply the load at the geometric center of the diaphragm as a point load
the area object option applies the load to the areas you specify. the walls that clad the building must be modeled and the wind will be applied directly to these area objects. this requires more time because the exterior must be modeled.