Isolated footings – new method to obtain optimum size
For isolated footings designed to the Indian code, a new method for finding the required footing size is now available in the Footing Geometry page. It is known as Equal Projection from column/pedestal edge. The Design Type should be set to Calculate Dimension to access this method, as shown in the figure below.
The program uses the following method to find the size of the footing if this option is chosen.
The minimum dimension of the footing along the global X direction is set to A+2*B, where
A = Dimension of the pedestal (or column if there is no pedestal) along global XB = Value specified in the above dialog box for minimum projection in X direction beyond the pedestal edge
The minimum dimension of the footing along the global Z direction is set to C+2*D, where
C = Dimension of the pedestal (or column if there is no pedestal) along global ZD = Value specified in the above dialog box for minimum projection in Z direction beyond the pedestal edge
These minimums form the starting values for the footing size. If the starting value is found to be inadequate, an iterative method is used to arrive at the final size. In each iteration that is performed for the service load cases, the footing size is increased in both plan directions (X and Z) by the value specified in the above dialog box for Plan Dimension Increment, until the size achieved satisfies all criteria such as base pressures, factors of safety in sliding and overturning, etc. should be within allowable limits.
This size is then used in the concrete design phase to determine the necessary thickness of the footing. If there are ultimate load cases with high moments and small vertical load (uplift load cases may produce such scenarios), it may require the footing plan dimensions to be increased further. The iterative approach described above is used for these situations too.
Thus, if the pedestal dimension is b x d, the final footing dimension will be (b+2p) x (d+2p) where p is the final value of the projection of the edge of the footing from the pedestal face. If (b+2p) or (d+2p) or the footing thickness required exceed the maximum dimensions permissible for those terms, the footing is deemed to have failed.
Exporting the Footing Data from STAAD Foundation Advanced to the IFC Format
It is now possible to export the data from STAAD Foundation Advanced to the IFC format which is supported by some programs created by other vendors.
It can be done using a 2-step approach:
2. Install a free Bentley application called Structural Synchronizer on your computer. Using this program, open the ISM file (created using Step 1) and then export it to an IFC file. That IFC file can then be opened in the application that is capable of displaying IFC files.
Import Data from STAAD.Pro Models that Use Z as the Vertical Axis
Users may be aware that there are two global axis system options in STAAD.Pro:
1. The default system —"Y Up" — where Y is the vertical axis, and X and Z are the horizontal axes.
2. The "Z Up" system where Z is the vertical axis and X and Y are the horizontal axes. It also often referred to using the phrase "SET Z UP" which is the command used in the STAAD.Pro input file to indicate that node coordinates and other data in the file are based on this system.
STAAD Foundation Advanced on the other hand has only one system, which is equivalent to STAAD.Pro's "Y Up" system.
In the past, importing data into STAAD Foundation Advanced from STAAD.Pro models that used the "Z Up" system wasn't always feasible because the column dimensions and forces and moments at the supports weren't properly transformed from STAAD.Pro's "Z Up" system into STAAD Foundation Advanced's.
With effect from this release, this transformation has been fully enabled.
This facility works best if the data exchange is between this version of STAAD Foundation Advanced and one of the versions from the CONNECT Edition of STAAD.Pro. Some of the data that is part of this exchange, such as section dimensions and properties of steel sections, is stored in files that are based on a format that is common between the two programs. The exchange may not be seamless between STAAD Foundation Advanced and the V8i versions of STAAD.Pro because of incompatible formats for their respective property databases.
Design of Pilecaps per the Eurocode
Pilecaps can now be designed to the Eurocode with the British National Annex.
The broad outline of the procedure used in the program is as follows.
The user first specifies the load carrying capacities of the individual piles under service conditions in the Pile Layout dialog boxes. Among the Pile Layout options, Predefined lets the user choose from a library of pile arrangements, with the spacing between the piles being determined by the program, while, Parametric lets the user specify his/her desired arrangement in terms of Rows and Columns or coordinates of pile locations in plan.
The program finds a suitable pile spacing that ensures that for each service load case included in the job, the vertical and lateral load transmitted to each pile doesn't exceed the pile's capacity. This is done for each pile arrangement, meaning, 3-pile, 4-pile, etc. All configurations that result in a safe arrangement are then presented to the user. The user must then select one of those arrangements. Reactions for all the service and ultimate load cases can be viewed for that arrangement.
Next, the program proceeds to perform the concrete design of the pile cap. The checks performed include oneway shear in both plan directions (X and Z), flexural check for both plan directions (X and Z), and, punching shear check. Design is performed using values specified for the various terms in the Design Parameters page and National Annex page.
Three examples illustrating the detailed procedure used to find the number of piles, and concrete design of the pilecap are available in the Examples/Euro Code (EC1992-1 2004) folder.
A calculation sheet is produced by the program for each support where a pile cap is designed. A snapshot of the calculation sheet is shown in the next figure.
Eurocode - Eccentricity Factor (beta) is now Calculated
For punching shear checks in EN 1992, equation 6.39 has a factor known as β. It is an enhancement factor for consideration of column eccentricity/ column moment and the procedure for its calculation is explained in Clause 6.4.3(3), etc.
In past version, Beta was conservatively assigned a value of 1.0. It is now calculated and reported in the punching shear output.
Job Setup Load Cases Selection Enhancements
The selection of more than one load case for inclusion into or removal from a job is now possible using the <Shift> + mouse click, as well as <Ctrl> + mouse click. On models with large numbers of load cases or combinations, this could be quite beneficial in terms of time saved and a more comfortable user experience.
More Information in the Calculation Sheet for Various Items of Output
Additional explanatory notes have been included in the calculation sheet to help users understand output terms that have been reported to be ambiguous. Some examples where such notes have been added are, sign conventions of applied loads, governing load case for pilecap design, references to code clauses where applicable, etc.
Changes in the License Configuration dialog
In the past (version 8.3 of STAAD Foundation Advanced), if you wanted to run STAAD Foundation Advanced using a STAAD.Pro license, the licensing dialog box required you to specify which type of STAAD.Pro license you had – the Standard version or the Advanced version.
In STAAD Foundation Advanced CONNECT Edition Update 4, these two options have been replaced with a single one, as shown in the figure below.
Tank Foundation Enhancements
Table of sliding and overturning ratios for each load combination is now available for tank foundations.
New examples have been added for tank foundations, pilecap design per the Eurocode, and, punching shear calculation for Mat foundations.
These can be accessed by clicking the Examples link on the Start page.
Rectification of Defects
A number of improvements have been made in the program in areas such as handling of input, removal of defects in calculations for some of the foundation modules, display of output, printing, drawing generation, stability related aspects that resulted in crashes or caused the program to freeze, extensive time taken for analysis of certain modules, etc.
1. Location for oneway shear check for pilecap design per Indian code
For pilecaps designed to the Indian code, oneway shear checks are now performed at a distance 0.5 x deff from the face of the pedestal where deff is the effective depth of the pile cap. This check is in accordance with Clause No. 22.214.171.124(a), Amendment 1 from the code committee. In the past, this check was performed at deff away from the column face. For other foundation types like isolated footings, combined footings and mat foundations, the check is still performed at deff away from the edge of the pedestal.
2. Table of Contents in calculation sheet for pilecap design reports
In the calculation sheet displayed for design of pilecap, a table of contents was lacking, due to which quickly accessing specific sections of the report was a tedious task. This facility is now available.
3. Better handling of isolated footings under uplift load cases
For isolated footings, if the load on the footing from the column causes an uplift, the program will attempt to increase the footing size until the uplift is negated by the selfweight of the footing and weight of soil on top. Only if it is unable to do so due to restrictions on the maximum lengths and widths permitted is the footing deemed to have failed.
4. Better depiction of corner pressures for service cases for combined footing in calc sheet.
5.More built-in checks and messages for avoiding errors
Features of the program that were prone to errors in user input have been equipped with more checks to detect them and inform the user. Examples are:
a. For quad pressure loads, a minimum of four nodes is required for the loaded region. b. If a meshed mat model is modified in ways such as addition of pile springs, addition / modification in the location of columns, the user is informed that he/she is required to re-mesh the mat and perform the analysis again. c. A check is now also included to detect and inform users about columns whose base lie outside the mat boundary.