Effective wind area ASCE-7-05 1

[sutki1]

Hello,

If I have a continuous member (say 5 span) would I use the centre to centre of supports(individual spans) to calculate the effective area for windload calculations or would I use the entire length of the continuous member (5 spans)
It is definitely conservative to use individual span but is it permissible to use the entire span.

Thanks

 

[civilperson]

The wind tributary area has no bearing as to the model of continuous or simple span. If the continuous member is a girt receiving the wall wind pressure, then the tributary area is the spacing of the girts times the length. That force in the the girt as a beam is then transmitted to the column/beam and thus to the footing. If the girt is continuous then numerous columns/beams will share the load, if it is simple span then just two columns/beams receive the load. The total load is the same on the columns, the savings is in the girt design since negative moment at the support is less than positive moment in the center of a simple span.

 

[MarcbSE]

ASCE's Guide to the Wind Load Provisions has a good discussion on this issue. You can not use the total length of a continuous member to determine the effective wind area. It is based on the span length not total length.

 

[twinnell]

Don't forget the width definition for effective area. Width does not need to be greater than 1/3 the span.

 

[DaveAtkins]

That should be width does not need to be LESS than 1/3 the span.

DaveAtkins