CROSS Safety Report
Error in proprietary design program
This report is over 2 years old
Overview
It has been noted, says a reporter, that a current package for pad foundation design has no factor of safety against overturning, returning a ‘pass’ for unfactored loads and a utilisation ratio of 1.
Key Learning Outcomes
For civil and structural design engineers:
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It is good practice to check and validate all design outputs from proprietary design software
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If you are concerned with any of the output’s, consider raising this with the software technical support team and seeking clarification
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Raising awareness is the first step in the process of bringing about improvements to industry
Full Report
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It has been noted, says a reporter, that a current package for pad foundation design has no factor of safety against overturning, returning a ‘pass’ for unfactored loads and a utilisation ratio of 1. Furthermore, it has been noted that the same program returns a ‘pass’ without checking the bending capacity of the base in hogging.
As such a pad foundation can be designed of strange proportions with no top reinforcement, so that it would potentially snap under self-weight and overburden, but again gain a ‘pass’ in the software.
The suppliers are aware of, and concur with, both findings and have undertaken to correct them at some point but there may be, continues the reporter, many pad foundations in use which have been incorrectly designed using this program.
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Feedback
The (often complete) reliance on proprietary software and common lack of checking is a grave concern. We have identified similar problems with propped retaining walls designed by a well known software package. Why not name the software package to assist identification of areas of potential problems??
Expert Panel Comments
Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.
There is concern about reliance on computer output and there should always be a check to ensure that results are sensible. In simple cases such as a pad foundation this can be an approximate manual calculation. It would be expected that reputable software suppliers would issue alerts about known bugs to their customers so that users can assess the possible effect on their designs.