RCD Tadpole (Ramboll Load Take-Down Tool)

A Load Take-Down is a procedure frequently performed by structural engineers to assess the amount of loading carried by the columns of a building into its foundations.  It is an important early-stage analysis necessary to inform the choice of column layout and foundation system, but it is also a notoriously tedious and time-consuming process that is regarded as something of a ‘rite of passage’ for young engineers to endure.

Typically, the take-down is performed in one of two ways.  Either the tributary areas (the region of loading that each column nominally supports) must be calculated manually for each column on each floor and then tallied up (commonly via a spreadsheet), or a full 3D finite element model of the entire building must be constructed and the forces extracted.  The latter requires resolution of a level of detail which is often inappropriate during the early phases of a project and the former is both slow and prone to errors.  Most importantly, both methods can require significant re-work in order to adapt the analysis to modifications of the geometry and this limits our ability to experiment and respond to design changes.
Illustration of tributary areas for a single column
RCD’s TADPOLE (TAke-Down Process On Loaded Elements) is an in-house software project that provides a new alternative method that automates and greatly speeds up the analysis.  The standalone tool can read in 2D floor plan drawings and assemble them, level by level, into a complete representation of the building.  Loading areas and column positions can be automatically interpreted by the tool if present, otherwise the software contains a full suite of drawing tools to allow the engineer to sketch out loads, columns, walls etc.  Once this data has been input the software automatically determines tributary areas and performs the take-down.  Changes to the input data can be made easily and the impacts assessed instantly.
Tadpole in operation

This eliminates the need for tedious manual calculation and, because the application is designed and streamlined for this specific purpose, there is no need for any extraneous data to be input.  Because the tool is graphical, odd results and input errors can be spotted and traced far more easily than in a spreadsheet.

To help further manage the data the results of the analysis can be output to an interactive online dashboard via Power BI, making it easy for the lead engineer and client to interrogate.  A full report can also be generated to document the process, results and assumptions.  To eliminate re-work, the tool can also assemble the input plans into a full 3D building model that can be exported to Autodesk Robot to form the basis of a more detailed analysis.
PowerBI dashboard presenting load take-down results
This has allowed us to do in hours what would previously have taken days, and in a way that would not have been possible without building the tool ourselves.  Commercial software is typically made to be as broad as possible in order to capture a wide user base.  This means that it is often poorly optimised for certain tasks.  By developing our own tools designed to meet our exact requirements and workflow we can plug these gaps and work more efficiently, enabling us to beat time pressures by responding faster, iterating more often and, ultimately, to produce better, more rigorously-checked designs.