The following features have been implemented and/or enhanced since the CONNECT Edition V9.1 (Release 18.104.22.168) of STAAD Foundation Advanced.
Australian code AS3600-2018
The 2018 edition of the Australian code with Amendment 1 is now available for design of isolated footings, combined footings and pilecaps in the General mode of the program.
Isolated footings with the column located away from the center
This feature, which was disabled a few versions ago, has now been restored.
The offset distances along the global X and Z axes have to be specified as input. In the General as well as Toolkit modes of the program, this is done through the Footing Geometry page.
An offset is positive if it is along the positive direction of the respective axis. Similarly, a negative value should be specified if the column is located on the negative side of the corresponding global axis with respect to the center of the footing. The positive directions of the X and Z axis are as shown in the figure below.
For the purposes of calculating soil pressures, and the footing area in contact, the loads acting on the footing through the column/pedestal are transferred to the center of the footing. Hence, the vertical force transmitted by the column will induce a moment at the center of the footing equal to the force times the offset distance between the center of the column and center of the footing. Bending moments, oneway and two-shears are calculated based on the actual position of the column/pedestal.
As we know, the program supports two types of design:
1) The footing dimension is set by the user – also known as Set Dimension.2) The user instructs the program to calculate a suitable dimension – also known as Calculate Dimension.
The offset values of the column/pedestal are considered to be constant for both types of design. In other words, the column/pedestal is assumed to be at a fixed distance away from the center of the footing, as defined by the X and Z offsets, regardless of the footing size computed by the program.
For the purposes of calculating the overturning and restoring moments for stability checks, the rules described in the following figure are used.
Factor of safety against overturning = Restoring moment / Overturning moment
In the above figure, P is the vertical load, H the horizontal force and M the bending moment transmitted into the footing by the column or pedestal.
The program output is along the same lines as that for isolated footings without any eccentrically located column/pedestal.
Pedestal design enhancements
Pedestal design is now available in a few more modules of the program. The output too has been enhanced to include the P-M values for the provided reinforcement in a tabular form in the calculation report. In the General mode of the program, the P-M curve of the values in that table is also provided. The following table provides a summary of the pedestal design capabilities currently available in the General and Toolkit modes of the program.
Typical output for reinforcement calculation in a pedestal
Typical output for table of P-M values
Typical P-M curve plot
Horizontal vessels – reports of stability checks for sliding
For horizontal vessels, the results of stability checks for sliding are now reported in the calculation sheet. Results of checks against overturning have been available in the calculation sheet in past versions.
Pilecaps – reporting the pile reaction summary for service load cases
For the pilecap foundation in the general and toolkit modes, the maximum pile reactions for lateral, vertical and uplift for service load combinations are now reported in the calculation sheet. This feature is now available for several design codes.
Improvements in the creation and presentation of results in the calculation report
In past versions, a single calculation report was created that included the results of successful design of footings or pilecaps for every support that was included in the job. If the amount of data such as the number of load cases or number of supports was large, it often led to significant time taken in displaying the report and in printing it or saving it as a PDF because this report ran into dozens or even hundreds of megabytes of data.
In this version, the reporting system has been changed so that they are created and displayed only for one support at a time. Thus, a giant single document holding the results of all the foundations designed in a job has been replaced with multiple calculation sheets.
Once the analysis/design for the current job is completed, the program will shift the focus automatically to the View menu, and, the Calculation Sheet for the first support in the job will be displayed. One can change the support number from the drop-down list in the menu bar, and, the corresponding Calculation Sheet will get loaded.
For printing it or saving it as a PDF, the Print Calculation Sheet button has also been moved to the top of the sheet so that the extra step of scrolling to the bottom of the page can be avoided.
To view the summary table for all the supports in the job, click on the topic named “Show Summary Calculation Sheet”. The dropdown list provides access to the other supports in the job for which the report is available for the ones successfully designed.
Mat foundations - Report showing details for load cases for which static equilibrium is not met
For mat foundations, the analysis of the mat may not be successful due to reasons such as - a low vertical load combined with a high overturning moment may result in all the soil springs losing contact with the soil. Such cases are usually characterized by instability warnings in the output file for the STAAD.Pro FE model of the mat, large displacements, and a failure to meet static equilibrium for those load cases.
For those load cases, as shown in the next figure, a report titled “Static Equilibrium Mismatch Report” showing the total applied loads and total reactions is now provided in the calculation sheet. It also contains a row titled “Difference” in which non-zero values indicate the degrees of freedom for which the equilibrium is not satisfied.
Additionally, a warning will be shown in the output pane listing those load cases.
Multiplying factor for surcharge loads
In past versions, for the purpose of computing the soil pressures for service load cases, and for the stability checks (overturning and sliding), the surcharge load on footings was treated as a dead load. Thus, in the various load combinations, it was multiplied by the same load factor with which the dead load and selfweight of the footing was multiplied by.
Based on requests from various users, a greater amount of flexibility has been introduced in this version in how surcharge load should be treated. Thus, if the user wants SFA to use one load factor for concrete deadweight and soil weight, and another load factor for surcharge, on a load case by load case basis, he/she can now do that in the manner described here.
General Mode - Isolated, Combined footings and pilecaps for the ACI code : In the Apply Selfweight and Dead weight factor table, a separate column is now available for Surcharge in which users can specify the load factor that should be used for that load item in the individual load combinations.
Toolkit mode - Isolated and combined footings for the ACI code : See the following figure for an option available in the Cover & Soil page through which the user can instruct the program to treat surcharge as either a Dead Load or a Live Load.
For example, if one of service load combination that is being solved for finding the soil pressures happens to be
0.9*DL + 1.1*LL
then, if the user chooses to treat surcharge pressures as a
a) dead load, the multiplying factor used will be 0.9.b) live load, the multiplying factor used will be 1.1
4. The algorithm for sizing of combined footings has been improved. SFA will produce better economically sized footings by placing a higher priority on increasing lateral dimensions before increasing the thickness so that the added benefit of soil weight is obtained for stability checks for service load cases.
5. The mesh generation capabilities of the program for mat foundations has been enhanced. Models which, in the past, could not be meshed due to various reasons, some examples being:
should be meshed successfully now. Along with that, the procedures used for processing loads applied on the mat have been improved.
In this context, users should note that if a model that was meshed in an older version of SFA is opened in the current version, a message will appear suggesting that the mat be re-meshed. Without re-meshing, it will not be possible to re-analyze the mat or perform concrete design.
6. The better quality of meshes generated also means that in this version, there is less likelihood of errors such as poorly shaped elements, orphan nodes, plates and/or beams with missing properties causing the analysis of the mat to be terminated.
7. The solid-element mesh generation capabilities of the program for machine foundations has been enhanced. So, models for which meshing was unsuccessful in past versions are not likely to encounter messages to that effect in this version.
8. In mat foundation jobs, more checks have been added to identify inner regions or entities that have errors in their geometry that will interfere with a successful mesh generation, such as when their elevation (Y coordinate) doesn’t coincide with that of the mat’s outer region. Column supports that have been included in the mat but fall outside the boundary of the mat is another example.
9. An error that caused the member forces in grade beams to be identified as 0.0 has been corrected.
10. A tool is now available for viewing the output file created during the analysis of the STAAD.Pro FE model of the mat.
11. The 2014 edition of the ACI 318 code, which until now was available for only a few foundation types of the General mode, is now available for many more modules of the program. The list includes isolated, combined and pilecap foundations in the toolkit mode, octagonal footing in the General mode, etc.
12. Bill of materials also known as MTO table, which provides a report of the quantities of concrete, steel, soil excavation, and soil backfill, is now available in a few more modules of the program. Some of those are:
Combined footings – ACI code – General and Toolkit modesPilecaps – ACI code – General and Toolkit modesVertical vessel on Square footing – PIP code – PLANT modeOctagonal footing –PIP and ACI codes – General mode
Note that this feature is already available for isolated footings designed to the US code since version 22.214.171.124.
The following is a sample report for a pilecap design.
13. Improvements in the calculation reports for various modules to provide better clarity in the information provided. Some examples of this change are:
Reporting of selfweight of the footing for combined footingsTitles that better identify the global planes for which oneway shear design is performed
14. For isolated and combined footings in the General and Toolkit modes, an additional column showing the bearing capacity of soil for each load case is now included in the soil pressure table for service load conditions.
It also includes the word “Gross” or “Net” to indicate the type, depending on the choice the user makes under
Global Settings - Rigid Foundation Settings - Bearing Capacity Settings
as shown in the next figure.
What this means is that if the Global setting is chosen as “Net Bearing Capacity Input”, the actual soil pressures and the allowable soil pressure reported will both be of the type “Net”. Similarly, if the setting chosen is Gross, the actual and allowable values reported will be Gross.
For PLANT foundations too, the words “Gross” or “Net” are included in the soil pressure report.
15. A defect that caused the thickness of the pilecap of a 3-pile arrangement for various design codes to be significantly over-estimated or resulted in a failure to design has been corrected.
16. A defect that caused the program to fail reporting the punching shear calculations in mat foundations for certain codes like Eurocode or Canadian has been rectified.
17. More checks have been implemented to ensure that the basic data necessary for the design of isolated and combined footings, and pilecaps, such as column supports which transfer loads to the foundation, service and ultimate load cases/combinations, etc. are present before the footing is analyzed. This is to avoid design failures long after the design has commenced for large sized models.
18. More checks and warnings informing the user about errors in the input. Such as,
19. For Octagonal footings (General mode), and for Vertical vessels on octagonal footings (PLANT mode), if it was necessary to iteratively find a larger footing diameter than the minimum specified, the final size was mis-reported in the calculation sheet. Also, when the overturning moments on those footings is large, the program attempted to increase the thickness instead of plan dimensions. This led to extremely large thicknesses. These errors have been corrected.
20. The installation package has been modified to offer greater transparency and flexibility in choosing which components the user would like to install. Users can now
21. Pedestal length for column design
For determining the loads at the base of the pedestal, a choice is now available to the user through which the pedestal bottom can be set to either the top of footing or bottom of footing. The height of the pedestal will be calculated accordingly and will be used to calculate the axial load and bending moments at the bottom of the pedestal. The next figure illustrates this.
22. A defect that caused the oneway shear forces and consequently the thickness of combined footings to be overestimated when the columns are located close to each other has been corrected.
23. Explanatory notes have been added in some of the key input pages for some modules like Horizontal Vessels.
24. An error that caused the analysis to be pre-maturely aborted for machine foundation models has been corrected.
25. For horizontal vessel models, a defect that caused the program to fail to adhere to the pier load distribution percentages for lateral loads has been rectified.
26. For isolated footings, for uplift loads, the punching shear calculations are now done at the face of the column for various codes. The reduced value of the perimeter may lead to a larger footing thickness than in past versions.
27. For uplift loads from the column, the size of isolated footings is now chosen in such a manner that the weight of the footing and soil weight will counterbalance the uplift force.
28. If the water table is high enough that buoyancy needs to be considered during the analysis, the soil pressures reported for ultimate load cases include the effect of buoyancy. In past versions, the reported values did not include the buoyancy effect.
29. More foundation modules have now been enhanced to have a table of contents in the calculation sheet for easier navigation through the reports.
30. For isolated footings, development length of flexural bars is no longer used as a criteria to determine minimum dimensions. In the past, this condition used to dictate the sizing of footings with very small amounts of loads.