## Example: One-Way System

In this example, the pressure load from the slab is transferred directly to the beams. Since the girders are not directly supporting the slab, the system is considered one-way. The area load is thus calculated as: [math]\begin{equation} w=qt_w=1.2 \times 3/2=1.8 kip / ft \end{equation}[math] A one-way system will divide up the area formed by the two members selected. In this example, since it is a rectangle, the profile of the area load is also rectangular as shown below. Note that the profile is not always rectangular, but rather it is always quadrilateral and represents an equal division of area between the two members. In some cases, point loads are added in order to force balance the system if the slab overhangs the member. ## Two-Way System

For the same structure as the previous example, if the slab were to instead be directly supported by members 2,8,5,9 then the system would be considered two-way. The slab occupies the same area as the previous question, however the load profile will change. For two-way systems, bisecting lines are drawn from the corners to create a pair of triangles and a pair of quadrilaterals as shown in the diagram below: Thus, the calculation for area load for members 8 and 9 is given by: [math]\begin{equation} w=qt_w=1.2 \times 3/2=1.8 kip / ft \end{equation}[math] And for members 2 and 5 (by simple trigonometry), [math]\begin{equation} w=qt_w=1.2 \times 1.5\tan(45^\circ)=1.8 kip / ft \end{equation}[math] Applying these area loads to the structure is shown below: Through these examples, we've examined the two type of area loads. To learn more about SkyCiv's implementation of this feature, check out our area load documentation here. William Kuang
Engineer and Software Developer
BEng Mechanical (Hons1)