Vertical Transfer of Dead and Wind Uplift Loads

The following refers to dead and wind uplift loads that you input, usually as line loads, or dead loads that are generated. For vertical transfer of hold-down and compression forces the program creates from dead and wind uplift loads, refer to Vertical Transfer of Hold-down and Compression Forces.

Loads Distributed to Wall Segment Ends

For shear-resisting segments on segmented walls, or entire perforated or FTAO walls, that are subject to overturning, dead and wind uplift loads on the segment are transferred via simple span beam mechanics to the wall segment ends and become dead and wind uplift components of the hold-down or compression force at the segment end. Refer to Distribution of Dead And Wind Uplift Loads to End Chords. From there, the forces are transferred downwards as described in Vertical Transfer of Hold-down and Compression Forces.

Loads Passed Through to The Level Below

Transfer to the wall end chords does not occur and forces are instead passed through with the same profile (line or point) to the shear line below under the following circumstances:

• You have selected using in the Hold-down settings to restrict the concentration of dead and wind uplift load the wall ends to those loads within a specified distance from the wall segment end. Loads in the middle portion or the wall segment outside that distance are passed down directly.
• The dead load on the segment completely counteracts overturning and other sources of uplift, i.e. wind uplift and the vertical earthquake force E_v. All of the wind load and the portion of dead load not needed to counteract overturning is passed through as a line load. The rest of the dead load is distributed to the wall ends. Refer to Dead Load Completely Counteracts Overturning for more details.
• Dead or wind uplift loads on a shear wall segment that is too narrow to resist shear according to allowable aspect ratios. An exception to this is loads on too-narrow segments between openings in perforated walls; they are transferred to the wall ends as hold-down force components. Too-narrow segments at the ends of perforated walls are treated as if they were narrow segments in segmented walls and dead load and wind uplift load is transferred directly.
• Dead or wind uplift loads on non-shearwalls

Loads that are passed to the shear line below in this manner are then distributed further to levels below as if they were user-input or generated loads. The loads shown in Plan View and Elevation view are a combination of user-input or generated loads plus directly distributed loads. The loads shown in Load Generation view are generated loads on that level only.

Loads over Openings

Dead and wind uplift loads over openings in segmented walls are all assumed to be supported by a lintel over the opening or directly by the supports to that lintel. They are transferred to the wall supports via beam statics. The supports are assumed to also act as the adjacent shear wall segment end chords, so these forces are added to the dead and wind uplift components of hold-down or compression forces on the wall segment.

The dead loads include User-input loads, generated loads due to weight supported by the wall, and generated loads due to wall self-weight.For self-weight, this this is an accurate treatment of the area above the opening, of the weight of a supported door, and much of he weight of supported windows. There is a slight inaccuracy in that the weight of the area below the window and the extent to which the window bears on that area would be more accurately represented as a line load below the opening.

Dead and wind uplift loads over openings in perforated and FTAO walls are not distributed to the wall supports; rather to the ends of the entire wall. This is because these types of walls are analysed as a unit and only required to have hold-downs at the ends of the wall. .