8.7 Members - Contact Forces

When there are members with elastic foundations in the model (see Chapter 4.19), the contact forces and moments are displayed numerically in Table 4.7. To control the graphical display of results, select the Members check box in the Results navigator.

In the first two table rows, the numbers of the start and end node are displayed for each foundation member. The remaining rows provide information about the types of extreme values available for contact forces and moments.

To adjust the default settings for the output of extreme values, use the menu option

• Table → View → Result Filter

or the corresponding button in the table toolbar.

The table lists the contact internal forces of each member at the following locations:

• Start and end node
• Division points according to defined member division (see Chapter 4.16)
• Extreme values (Max/Min) of contact forces and moments

Contact forces that are effective in direction of the local member axes x, y, and z are shown in relation to a standard length. When asymmetrical cross-sections are used, you can select if contact forces refer to the principal axes u and v (see cross-section graphic) or to the standard input axes y and z. To set the results display, use the Results navigator.

To check the position of the local axes, select Model → Members in the Display navigator and activate the Member Axis Systems x y z (see Figure 8.23). The signs correspond to the usual provisions explained in Chapter 8.6 where the internal forces of members are described.

If you want to determine soil contact pressures on the basis of the table values, you additionally have to divide the results by the respective cross-section widths.

The contact moments about the longitudinal member axis x are also output in relation to a standard length. The moments m_x are influenced by the rotational spring constant C_φ.

The final table column provides information about the cross-sections used in members or, in case of result combinations, about the load cases and load combinations that were used to determine the maximum and minimum contact forces in the respective table row.

For load cases and load combinations, RFEM displays the check sums of loads and support reactions at the end of the table. Differences will occur between ∑ Forces and ∑ Loads if the model additionally has nodal and line supports, as well as surfaces with elastic foundations. Therefore, the ∑ Forces available in Tables 4.1, 4.3, and 4.21 must also be considered for the total summary.