Minimum needed version to run this example:

STAAD Foundation Advanced 2025 (25.00.00)

Unit System Used: Kip-in or Kip-ft (Imperial)

Problem statement:

Load cases, load combinations, Post analysis checks, sizing criteria and design envelope are assigned to pile cap footing in previous steps. Next step is to analyze the footing to check base pressure and calculate the footing size that satisfy all checks and design requirements.

STAAD File: STAAD File for Example 3

SFA File: Example_3 Part-4

Solution: Step by step process

Step-1: Perform analysis and design.

Figure 1

Perform Analysis: Analysis of the pile cap is executed here. If the pile cap is analyzed as a rigid pile cap, pile reactions are calculated distributing the load transferred from the pedestal/column  as linearly using bolt theory. If the footing is analyzed as Finite element, the pile reaction and plate stresses are  calculated using Finite elements (modelling plates) with user provided pile spring values/ pinned support.

When ‘perform analysis’ step is executed, the program shows the pile reactions for the first load combination in the list. Users can check the pile reactions for any load combination. Refer  to snap below showing steps to check pile reactions.

 

Figure 2

The steps to check pile reactions, is same if footing is analyzed as rigid or Finite element. Another way of checking pile reactions is to select the pile cap on the project explorer. Refer to snap below,

 

Rigid pile cap footing.

As pile cap analyzed in rigid method, pile reactions are presented for all piles of the pile cap.

Figure 3

Finite element footing:

As pile cap analyzed using Finite Element , stress is presented at all plates. Outputs like Support reaction, node displacement, and shell stress etc. are available to user.

Figure 4

Perform post analysis check:

Upon clicking on this check, all Post analysis checks are performed. If the pile cap is colored red, then it is marked as failed for Post analysis checks. If it is marked Green, it is satisfying all Post analysis checks. When the user performs the Post analysis check, below screen is displayed,

Figure 5

To check the status of all Post analysis checks, users can click on the following tab to get Summary table of Post analysis checks.

 

Figure 6

Calculate plan size:

If any footing failed in Post analysis check, user must perform “Calculate configuration” step. The program uses the Sizing criteria defined to pile cap and calculates the pile cap arrangement which satisfy all post analysis checks. In case if the pile cap failed even for the maximum or defined configuration, it is marked as failed.

Figure 7

Perform design:

In this step, the program performs the cross-section design. This includes the flexural, one-way, Punching shear and load transfer checks. After executing the perform design step, the program shows the below screen showing the design of footing.

 

Figure 8

 

Concluding Remarks: Now, the footings are analyzed and designed. The Size of footing required to satisfy Post analysis checks and design checks are performed. Users can proceed to check the various design outputs and report further.