The 3D Strut and Tie Force calculator that can be downloaded below considers the factors that mentioned in D. Equivalent Force System. The process of calculating the strut force with 3D STM was constructed based on the ideas obtained from the examples in Reference  ACI-ASCE Committee 445, SP-273. Two STM models across the pilecap are constructed and members are placed in any position that can be a strut.
The 3D Strut and Tie Force calculator that can be downloaded below is for the struts that are not considered in the previous models. When the pressure is considered, the calculations of the struts are the same as the calculations of the SP-1550s and SP-1530s. When the pressure is not considered, the STM has no effect on the strut force.
To see an example, please visit https://www.fema.gov/resources/download-solutions/download-a-solution-using-an-actual-fema-case-study . The equivalent force system and the resulting damage path can be viewed on screen. 827ec27edc