Independent Technical Review

A truly independent technical should not require access to the designers notes and decision making process, and thus should not require any submission of calculations. An independent review should only require access to the specification-of-intent. With a complete specification, it should be possible to send it to the other side of the world and get the object, described with in such document, fabricated without further information. If the documents are not directly suited for fabrication, then it should be possible to produce suitable production documents from the specification.

A technical review involves both a qualitative review and a quantitative review. The qualitative review checks for necessary characteristics. Characteristics can be either attributes or measurable quantities. An attribute is a characteristic which is either there or not there, it is one of many states, or otherwise a characteristic which has no measurable value. A measurable quantity for example has certain attributes: a name, units of measurement and a value. A qualitative review can be relatively quick and be carried out using checklists,; as such it is something that can basically be carried out by anyone or otherwise has the potential for computer automation.

A first stage qualitative review therefore is a check of completeness of the documentation, is all the information there to get a clear picture of the proposal, and necessary information not shown in such documents, is such information properly referenced to readily available publications, and manufacturers product documents. So for example in terms of structural design, no structural assessment can take place if the documentation is not a complete and proper specification of intent with respect to the structure. Drawings by plan drafters, building designers, builders and owner-builders and sales agents seldom contain adequate structural specification, such drawings are largely conceptual, often with little thought going into buildability. The result of not considering buildability, is the lack of support for some structural members. Prior to the qualitative stage of the technical review a drafting review should have been carried out: are the documents worth looking at in the first place.

The second stage of the qualitative review requires a suitably qualified person, and involves developing a familiarity of the object being described: in our case a structure. This is where missing elements are identified and the function and capability of the elements is questioned. For a structure, example questions may include:

  1. Do the roof purlin’s have support at both ends? {with a gable roof canopy, with two different spans placed end to end, rafters at the interface are commonly missing.}
  2. Considering a notional load in any of 12 directions (3 axes of translation, 3 axes of rotation, and 2 directions for each), is the structure free to move or does it offer resistance? How is that resistance provided?
  3. Is there cross-bracing in the walls and roof?
  4. If there is no cross-bracing are the connections of a type which are considered moment resisting?

After the qualitative review as determined completeness of specification and structure which is potentially adequate, then a quantitative analysis can be started. The quantitative analysis starts rough and ready and progressively gets more detailed. Unlike design the assessment does not need to find a solution, it only needs to determine whether or not the proposed object is fit-for-function. However the proposal is, if it has been designed, submitted with the intent of being fit-for-function. The reviewer therefore needs to refine their assessment, iteratively until such point as they are certain that there is no way any further iteration could possibly make the structure fit-fr-function.

For example a uniformly distributed load (UDL) on a an ideal single span beam can produce a maximum moment of M1=wL^2/8 or M2=wL^2/12, depending on whether the ends are considered simply supported or fixed. The load ‘w’ (kN/m) is largely determined from codes of practice, and following the load path from member to member. However, a useful starting point is simply to consider that w=1kN/m. If the structural section is less than M2 would require it to be, then there is a possible problem, if the structural section is larger than M1 requires it to be then possibly under estimating the load. From there can start looking in more detail at the magnitudes of the loads, can it be made less than 1kN/m, is it likely greater than this. slowly the loads get refined, and the structural form moves away from simple beams to more complex frameworks. A similar process of refinement is carried out for the connections, and support structure.

Now for complex structure may consider that the review process doesn’t provide adequate time for such iterative calculation process, and therefore a review should be done of the designers calculations. Not so! If the designers calculations are viewed, then the designer is leading the reviewer, it is no longer independent. The review process is not about finding design-solutions, the review process is assessing fitness-for-function only. The reviewer needs to convince themselves that further refinement of their assessment model could allow for the proposal being adequate, or conclude that there is no further refinement which could allow for the discrepancy. If the latter than they reject the proposal as having adequate evidence-of-suitability.

The Need for Automation and Other Design Aids

… to be continued