Review of O.M. Ledenboer, Q. Schouten, W. Van Itterbeeck, Shell structures, Report on the making of an orthogonal timber grid shell, Course CT3280 Shell Roofs, Delft University of Technology, Department of Civil Engineering and Geosciences, 2024, online: phoogenboom.nl/B&B_schaal_report_7.pdf by dr.ir. P.C.J. Hoogenboom, Delft, 12 January 2024 1. Complete report. Excellent report structure. Clear text but many bad sentences. Handed in on time (11 Jan 2024). 2. The summery is clear and reads well. However, it is just a description of things that happened, like a novel. Usually, in a technical report, we give meaning to the things that happened. We write a "story" that starts with a problem or opportunity, continues with a goal or research question, description of a lot of work and ends with the answer to the research question. The chapters of the report do tell a technical story. So, this summary is not a summary of this report. 3. Page 1. The research question is hidden in the last sentence: "... investigated ... how close the prediction was to the actual load." This is in the wrong order. It is better to merge Chapter 1 and Chapter 2. The right order in the introduction is: problem analysis; research question; approach 4. Page 3. Very beautiful drawing. But is page 3 the right place for this drawing? 5. Excellent that Rhino was used for drawing the design. 6. The technical drawing with dimensions are clear but too small. 7. Beautiful design. It needs strong edge beams. 8. Figure 4.4 and 4.5 are too small to read. 9. Page 9. The formula is presented and the result of the formula is presented. As if the results comes out of a black box computer program. This is uncheckable. This is not how engineers write hand calculations. The calculation needs to show every step. We used to do this with a pencil on paper and a calculator. Making little drawings to explain our thinking. Afterwards a colleague checked every number of every calculation. It is a proven procedure. ..... You do not need to redo all calculations on paper, especially because the present drawings and explanations are quite good. You can just extend the formulas with the numbers that were substituted and the result of the calculation. As long as there are no numbers "dropping out of the sky". 10. Page 11. "... scale ... by a factor 1.3 ...". What does this factor correct for? 11. The ropes and the distribution woods are not checked for strength. 12. There is much white on the pages. It would cost a lot of paper to print the report. Can you edit the white out? 13. 3 kN/m2 drops out of the sky. Is this selfweight plus snow load? The software computes selfweight too. Consequently, the loadcase selfweight needs to be omitted from the load combination. Was it? 14. Equation 4.6. The calculation is wrong in several ways. The correct calculation is: lath spacing = 10.49 m / 21 = 0.50 m. lath line load = 3 kN/m2 / 2 x 0.50 m = 0.75 kN/m. The 2 accounts for the fact that the load is carried by laths in 2 directions. 15. Good that you found out how to enter a grid in SCIA. 16. Page 12. Is the edge fixed or hinged? The text says both and that cannot be reality. 17. Page 13. The largest stress is not "halfway to the top". 18. Figure 4.19 is exactly the same as figure 4.17. Something must be wrong. 19. Page 13. The Von Mises stress is for steel not for wood. The first and third principal stresses are appropriate for wood. However, in this structure Von Mises probably gives almost the same result, except for the sign. 20. Page 14. Here the knockdown factor of 1/6 needs to be applied. 6.12 / 6 = 1.02. Buckling might be governing. 21. Page 15. Interesting that the vibration mode is shown. What is the vibration frequency? Did you tell the program of the mass of the structure? Did the calculation also include the mass of the snow? 22. Page 16. We do not apply a knockdown factor to the nonlinear analysis. After all, imperfections have already been included. 23. Page 16. What imperfection has been added? First buckling mode? Which amplitude? Did you use both a positive and a negative amplitude? Did these give the same collapse load? 24. Page 17. 2.516 kN drops out of the sky (again). My calculation: 37/90 x 3 kN/m2 = 1.23 kN/m2 25. Page 18. Why is this displayed? 26. Page 20. How was the laser-cut underlay made? It drops out of the sky. 27. The building process is explained well, however, the English sentences can be much improved. Write in the past tense because for your readers, the work has been done. 28. Good job in making the load distribution system; it is statically determined and all ropes are vertical. 29. Beautiful screen shots of the collapse. Solid explanation of what happened. 30. Where is the measured displacement? Did this go wrong? 31. The chapter on the real size model is nuanced, perhaps too doubtful. So, you think the 10 m shell would deflect too much. How much is too much? How do we fix this? Is a double wood layer enough? Are there more problems that need fixing? Is the collapse load okay? No? Does the double layer fix this too? If you want to build something, you need to push, otherwise it does not happen. If it really cannot be build, then say this clearly. That is a good conclusions too. 32. Good conclusion chapter. 33. Put the Discussion chapter before the Conclusion chapter. You want to end positively and clearly ... not with doubt. Received an improved version on 1 February 2024.