At A Point

This command allows you to select the point for which drift values are desired. This requires that the current view be a plan view. If the current view is not a plan view, the View - Plan command will automatically be invoked. With the view in plan, use the target cursor to select the point at which the drifts are to be calculated and displayed. The point selected does not necessarily have to fall on a lateral member. The Drift output will be displayed showing the deflection, interstory drift, and drift-to-floor height ratio at that point for the selected load cases for every level, not just the level currently on the screen. The values at any number of points may be viewed in this manner.

A printed output can be obtained by selecting the Print command or the Print icon while in the Drift Output view screen.

At Control Points

This command allows you to predefine up to four points, called control points, for which drift values are desired. The points defined do not necessarily have to fall on lateral members. You first enter the coordinates of the Control Points. Control Point coordinates may be added, deleted, or changed at any time. The results can be displayed by selecting View Results. The Drift output will be displayed showing the deflection, inter-story drift, and drift-to-floor height ratio at the control points for the selected load cases for every level.

A printed output can be obtained by selecting the Print command or the Print icon while in the Drift Output view screen.

See Select Cases for more information on selecting load cases for output.

The output view screen is exited by selecting the lower control bar in the upper left hand corner of the screen.

If a level has no diaphragm or the selected point is outside a slab edge, the displacement of the point of interest at that story will be assumed to be zero. Drift is calculated by looking at the deflection of the next story below where the selected point is inside the slab edge.

For a rigid diaphragm, calculated drift related quantities (i.e., interstory drifts and drift/height ratios) are computed based on the rigid diaphragm displacements and distance between point of interest and diaphragm mass center (i.e., rotation of the diaphragm is taken into account for calculated drift values).

For a pseudo-flexible and flexible/none-rigid diaphragm, the drift related quantities are computed based on maximum nodal displacement within diaphragm boundary.

For a Semirigid diaphragm, the drift related quantities are computed based on average displacements of all nodes within diaphragm boundary.