Applying Non-Uniform loads to Shell Elements

 

In ETABS non-uniform loads can be assigned to shell elements via Assign > Shell Loads > Non-uniform. This option allows the user to assign non-uniform loads in any direction based on global coordinates.

As an example below, assume we want to assign a triangular load to a 24 ft. long and 12ft high wall and located in the X-Z plane.

The load will have magnitude of 1000lb/ft at the base and zero at top of the wall.

The values for A, and B are zero since the load will not change in the X or Y directions. The equations to solve are:

Cz + D = 1000 at z = 0 ft
Cz + D = 0       at z = 12 ft

Solving the system above: D = 1000 and C = -83.33

After running the analysis, we can check reactions using basic statics to make sure the load has been correctly applied.

Total load = 1000*24*12/2=144,000 lbs or 144 kips

Reaction at top of the wall =144*4/12=48 kips or 24 kips at each support
Reaction at bottom of the wall=144*8/12= 96 kips or 48kips at each support

Applied non-uniform loads can be displayed in plan via Display>Load Assign>shells, inside this form the user can chose to display values or contours. Note that restrictions for zero negative or positive values are not shown on these contours and are only applied during analysis.