The following is a list of all questions submitted by participants of the blind prediction tests and the corresponding answers provided by the SERA AIMS team.
1. The contact in between the aggregates is defined as a dry connection. Is it a physical gap? And if so, how big is the void? Otherwise we were imagining a contact masonry-masonry. In such a case, we do not have information about the dry friction properties. Basically, our doubt is about the physical reality of that connection. Considering that is one of the key points that you pretend to study, it seems appropriate to define it to the fullest. We read that the building is being constructed right now, so maybe a picture also could help.
UPDATE JAN 2020: There is no physical gap between the units. The test specimen is an aggregate consisting of one two-storey unit and one single-storey unit. The two units will be built so that the connection is a dry connection (i.e., at a given height, first unit 2 and then unit 1 will be constructed). There will be no protruding stones, but the surface with natural roughness (not made smooth with mortar) will provide friction at the interface. Photos from the construction will be posted on the website.
2. (This is maybe something that we may find on our own, but I ask in any case) The material properties included in the document, are they already scaled? I guess that if we check the references we may find out…
The material properties are already scaled.
3. The testing sequence is said to be an initial tentative and may undergo changes. Ok, no prob, please just let us know if that happens. We understood that the sequence (for the actual experimental test) was linear, so 25%Y followed by 25%X followed by 25%Y+X, and then 50%Y and so on… Since you have only one specimen, there is no other way. However, for the numerical simulation, I do not know if you would rather have the analysis separated or in a sequential order. I mean, would you prefer to have each step studied in isolation or would you rather have the consecutive analyses? With a consecutive analysis we would drag the damage that might be caused in previous steps and it would be closer to what you will actually do in the shaking table; on the other hand, each analysis in isolation may give you preliminary information about the damage level expected in each case, which may be useful to finally decide the testing sequence… The excel file to fill seems to accept both cases… What is expected, then?
In case of changes in the testing sequence, or any other important change, the applicants will be notified and the change will instantly be published on the webpage and Zenodo. For the Blind Prediction Competition, in order to obtain results as similar as possible to the actual test, the analyses should be performed in the sequential order.
4. Because of the time constrains, I guess we will not have any dynamic identification test to calibrate our models (if there is, then cool). However, some of these guys said that it may be useful if you had any dynamic properties of the shaking table. I’ve never been there but some of them have worked with LNEC and they say that it is usual to perform a preliminary dynamic study of the shaking table with a mass equivalent to that of the building. Do you have that data?
At the present point we don’t have any specific properties of the shake table, apart from the essential ones – the acceleration limits according to the mass of the specimen. Before each run, a calibrating run will be performed. Also, the participants will be notified about the actual measured accelerations.
5. As it is usual, the influence that the slabs may have is another point of doubt. It is written that the connection beam-wall is going to be prepared in such a way that the behaviour is that of a simple supported beam. No more information whatsoever is given regarding the type of timber for beams/planks/lintels. A clearer insight into the function of the slabs would be of help: are they supposed to be flexible and just auxiliary to distribute some loads on the walls? Or are they thought as to have some kind of contribution to the box-like behaviour of the system?
Influence of slabs is certainly a significant source of uncertainty in this type of constructions. The building will have flexible slabs. As drawn in construction plans, each floors will comprise of 5 beams and one layer of wooden planks. Since the beams are placed on the walls and not fixed, the contribution to the box type behaviour will be limited. We will make sure to provide photos of all the construction details, including the slabs, planks, planks connections and beam supports.
6. We were wondering if displacements Rd1-Rd6 are meant to be absolute displacements or are relative to the shake table?
“Rd” stands for relative displacement, it is therefore the relative displacement with regard to the table.