 We have this idea for a case study which was presented already two months ago in the Zagreb meeting so most of you have seen this presentation, you have been at this workshop. The structure is here, we are dealing with another type of action which is snow loading and the structure considered is steel roof of a stadium. You might remember that there have been some collapses in central Europe a couple of years ago due to heavy snow. This is not only the heavy snow which was the reason for that but also the reduced resistance of the roofs. Well, we have to link the case study and I think it's a good idea to link the stadium case studies to some kind of framework but this is under development. I will present the results we presented also in Zagreb and also I will talk about some improvements, some conclusions and recommendations since I am a member of the working group 5 dealing with implementation into practice. Let's say you have to look at what kind of monitoring one has and this is already distinguished in the standards like permanent monitoring, periodic monitoring, spot monitoring. The issues which are dealt with in the standards are also described so I don't want to go into detail into that. Improvements which are necessary are acceptance and decision criteria because you might have some decisions which can be related to a prolongation of the lifetime or to the use of the structure for a certain event and these standards and improvement must be compatible to the other standards which are used in practical design. The idea came from as I said before from damages on roof in the Czech Republic and in Bavaria in the year 2006 due to heavy snowfalling and classical steel roofs have collapsed. The case study here is the roof of a stadium which has a cantilever system. It's a consequence class 3 structure. You know the Eurocodes are classifying the structures according to the consequences of failure of the three classes. The most dangerous class is the class number 3. The snow load is higher 33% compared to the code which was used at the design stage. We can have an online monitoring as it is used for the snow depth and there are sensors doing that described in the literature. One can define a limit state for bending, for exceeding the resistance of the structure and also monitor or use information about the variability of the influencing parameters like the yielding strength of the steel, the model uncertainty, the shape factor for the snow load and what is very important, the density which is a function of the snow depth. D is a snow depth. If you measure the snow depth, this is the easiest way of doing that and this is very well done in the practice. You will have a function of the reliability as a function of the snow depth. So if the snow depth is increasing, the reliability will decrease and you might also have the influence of the variability of important parameters like in this case of the shape factor me which is, there is a lot of work on the shape factor. But you have also what we were looking in the last two months, we found out that there are also direct measurements of the snow load so you don't need to measure the snow depth. We have early warning systems and patterns for such kind of, this is about half a meter by half a meter but they are also bigger one, two meters by two meters and you can put this, they are costing some money, 7,000 euros and you can put usually the owners put one or two of these warning systems for excessive roof loads on roofs. So the benefits which we will have, it can be for example a concert like Guns and Roses are here, it is not snowing but it is a big concert so you can have the benefit. If you use the stadium, you will have of course tickets, you will earn money but on the other hand you have the risk that something will happen so you have the consequences in case that something will happen so you have benefit versus consequences for the temporary use of structures so you have to use acceptability criteria for temporary use of structures which is not exactly the same as you will use for a 50 years period of design of a structure. So you will come out by some, if you define this criteria so you will see the influence of your information out in the ratio between benefit and cost of failure so you will see under what conditions your target reliability for this temporary use is covered. For example if you use a 3.8 here as acceptable value you will see under which condition of the ratio benefit versus cost this is covered. And again here you will see under which measured snow depth this acceptable criterion is fulfilled so you need some acceptable criterion also for your reliability level to see if this is fulfilled and if the structure can be used for the event. You can do it again as I said not through the snow depth but through the direct measurement of the snow load which has a reduced uncertainty. In addition you can use other type of information as we discussed in Zagreb survival of a high snow load satisfactory past performance of your structure so you can do updating of the limit state. You may have deformation also measurement again and updating of the limit state and you can also use weather forecast where you can use data of forecast of wet snow on the top of the existing snow depth. So just going into the possibilities for monitoring you may have weather stations you can use weather station data you can use snow depth measurements and you can also use direct snow load measurements. You may combine of them they have different cost so you can use the theoretical aspects. Discussing the past here so you have these three options you may combine you may use that you have however to be as a structure engineer to identify critical members where to put the sensors where to measure you have to identify through the target reliability the threshold values and you may also consider the robustness aspects which means system reliability aspects of your stadium roof. So this is the state of the situation we have of course we are open for discussion and we have to see the compatibility with the other case studies where we need this improvements especially in view of the implementation into guidelines as I mentioned before. So I would like to close here I don't want to repeat the more details which were presented and also have been published in the workshop in Zagreb. Thank you very much. Questions for clarification? You said the benefits are the set of the tickets. The cost? The cost. Yes you have the cost of monitoring you have the cost of the failure cost are the most considerable cost. This is a boy I have to go into details then you have costs which are economical costs and of course human life. Human life is through the societal willingness to pay criteria which we use. We are using numbers this is used in the new ISO document which number is the ISO document 2394 2394 and we can combine that. It's a document which is now very modern one which is also used for deriving targets in the future Euro codes. It's reflecting also the actual economy of the country. It depends on the LQI principle and this is the idea behind it. Thank you very much. So we can discuss more questions further on. I think the important yes I completely agree is to see the whole thing how can we integrate with it.