Consider this situation – you’re got a marking plan in front of you. You want to make sure that the ferrules in corner panels do not clash. How are you going to do that?
How would you solve the problem?
You’d have to find the corner panels, and then go to the appropriate drawing – both of them mind you – and you’d have to make sure that they are at different heights. That can get very tedious and it’s very time consuming, and more than likely, you’ll make some mistakes – because the panel elevations might not be adjacent to each other.
It’s not the easiest thing to see and compare in AutoCAD.
What is a better way to solve the problem?
But now you have a tool which allows you to easily compare the heights of the ferrules in two panels, straight from the marking plan.
There’s a lot of code and logic which goes with this. Perhaps I will outline it in another blog post.
For a very, very brief description of the overall route used, you can check out the code synopsis from my sister blog here. There I post the base class and interfaces used to derive the result – but have excluded all the implementation details.
Here is the video demonstration – and yet another example of the type of technologies and innovations you will have at your disposal if you work with us:
Cover refers to the distance between the outside of a concrete structure and the reinforcement. Perhaps see this from the diagram below:
You need to have a minimum cover:
There needs to be a minimal distance between the reinforcement bar and the outside of the panel.
Why do you need this?
Having a decent amount of cover reduces the rate of the corrosion of those reinforcement bars. If you have only 5 mm of cover – if the bar is literally just below the surface of the concrete, then that reinforcement is going to corrode away very quickly – especially if you are close to the sea. This means that the concrete will lose its strength very quickly, and a catastrophic failure might be on the cards. That’s why it is very important that the concrete does indeed have some minimal cover.
To Improve the Structural Integrity of the Concrete:
If you have the reinforcement bar too close to the concrete, then the structural integrity of the structure will be somewhat compromised.
If at all there is a fire, you don’t want the reinforcement bars igniting. If it does then the fire is sure to blaze out of control. That’s another reason why it’s very important that the bars some minimal distance away from the surface of the concrete. That will better enable the structure to remain in tact if at all there is a fire.
A Response to a Reader’s Question:
“(Q1) It appears that one of the lapped bar is bent while the other isn’t. Or is it just a drawing convention problem?”
(Q2) I don’t get why the lapped bars have to be positioned differently when placed on the top vs at the bottom in order to ensure that the concrete thickness will not reduce, as stated in the figure. My thought is that both positioning ways occupy the same volume.
The answer to this question is best understood by studying the below diagrams:
The Answers to the Questions
(A1) When I draw reinforcement, I do not add a lot of the essential details which are assumed to be standard workshop practice. We are required to maintain a minimum cover. The diagram you have posted above is an example of what actually occurs in practice (but is almost never drawn that way). The reason it is bent is to ensure that the minimum cover requirements are not compromised.
(A2) That is absolutely correct – the panel’s thickness will not be reduced, but the thickness of the cover will change, depending on how one places the “reo” (reinforcement) rods.
We’ve been noticing an increasing problem in that certain items are clashing with BubbleDeck Panel outlines. In order to eliminate these types of errors we’ve instituted a new check in our procedures. Everyone is now required to specifically check for this type of situation. This adds to our check list which is already quite long. I go into further explanations below in a video.
It’s a common problem apparently. There are far too many block references placed a little too close to those pesky shear lig points. It takes discipline, but when you have 5-10 people all working on the same drawing, with different practices, it’s something that’s really easy to miss, but really expensive to discover.
Ordering parts in precast panel projects is tricky. You need a BOM (Bill of Materials). You need to know what you need and how much. When there are thousands upon thousands of parts – that can be a very tricky endeavour.
Why should you bother counting inventory?
It all comes down to money. And how much of it you tie up in your inventory. And how quickly you’re gonna use it. Financial liquidity is like blood and oxygen. Without it, no organisation can survive. And you can maximise your liquidity (and profits too) if you manage your inventory well. You should be able to answer these questions:
How much inventory did you pay for?
How much inventory is in your shop?
How much did you use up in your projects?
How Tek1 solves inventory problems: Demo Video
We give you accurate numbers about what you’ve ordered. And what you need to order. This is how we come up with a Bill of Materials:
Cranes are used to lift the panels into place into their appropriate place. Because the mass involved is significant, it is very important that all the components of the lifting system are properly engineered and designed. If this is not the case then the panel could fall – and that can be lethal.
In those post we will be focusing on lifters.
This is how we denote a lifter:
This is how a lifter anchor looks like in real life.
Let us explain everything in detail – the purpose and what it does.
Precast panels are made in moulds. Items are placed in the mould and wet concrete is poured into it. The concrete is like water. You can’t have anything projecting out of the mould – everything must be contained within the mould itself. In other words, you need to provide a hook or latch onto the panel if you want to lift it. And the hook cannot project out of the panel because then it would be very hard to cast such a panel.
Imagine if someone fabricated the above panel – you will notice that the lifter is sticking out of the panel. This would be very hard to fabricate. Because it would require a hole to be exposed within the wet concrete for the lifter to protrude out from. Consequently, lifters are placed within the panel outline. And in order to facilitate the ability of a lifting system to latch onto the panel, a small depression and hook is provided within the panel. In reality, the panel will look something more like this:
You will notice that the actual concrete panel follows the white outline above, and that there is a depression in the panel. In addition – and this is not shown in the above diagram, there is a loop like feature on the end of the lifter which allows one to use it to haul the entire panel up into the sky etc. e.g. notice the hole at the top of the lifter shown below. It is this hole that is used to affix the lifter/panel to suspension systems.
The Tail bar and reo – it’s importance in the safety/stability of the lifting system
The second thing to note in the above diagram is the tail bar and reo. Why is this important? It’s important if you want to be able to safely lift the panel. If you forget to add the tail bar and reo, and simply add a lifter without those items – then when you attempt to lift the panel, the concrete will simply break off where the lifter is and the panel will fall to the ground – potentially killing people under the panel as it is being hauled up.
The tail bar and reo provide very important friction which ensures that the panel is safely secured to the lifter when it is in the concrete. Without it, the weight of the panel will simply cause it to separate from the lifter as it is being hauled up.
Generally Tek1’s practice is to draw the lifter only. It is assumed to be standard factory knowledge that the tail bar should be added when the panel is cast. We make assumptions that the guys on the factory know what they are doing.
The mesh is what gives the concrete some additional strength. It’s important.
In tomorrow’s post we will more closely investigate the lifter and certain matters pertaining to lifting.
Suppose someone makes a change in the layout but forgets to do so in the shop drawing (and vice versa). If you move a cast in plate, and if it’s actually produced and taken to site, then you have a big problem, and a big cost. How are you going to identify the differences which exist in the thousands of panels that you make? What if you had a tool which allowed you to easily identify differences between the two drawings?
This is what this Panel Comparison tool does. It gives you confidence that somebody hasn’t made a boo-boo. And moreover, if somebody has made one, then this tool identifies sloppy shop drawing practices.
It can work for all clients with only very minor modifications. Very well abstracted out in the code.
It is super fast. Comparing the thousands of elements in each drawing takes a bit of computing power – but with smart algorithms, you can cut down the time.
It works for all sorts of edge cases – what if the panel was made up of arcs, polylines and straight lines – this plugin can handle all sorts of things. It can also handle voids in the panel?
What if an item is on the edge of a panel line – it can handle that was well.
Every single panel that we draw will go through the above practices. It should give you a lot of confidence that we’ll get the drawings right. Yet another tool in the Tek1 arsenal that allows this firm to lead the industry in Precast Panel drafting.
This is a demo of my latest plug-in which demonstrates a proof of concept – i.e. a MVP (Minimum Viable Product). The programming was a little trickier than normal – because we are not using the .NET API, but the COM Interop API and the Revit API – something which I have not really explored prior to this post.
What does it do?
If you have drawn some panels in AutoCAD, this plugin allows you to quickly and accurately convert those panels into Native Revit walls. You can then give Architects and builders those Revit files – otherwise it will be very difficult for them to work with AutoCAD files.
This gives you a competitive advantage over your competition, because you can quickly and easily do it – and it makes the job of architects and builders easier – especially given the rapid push everyone’s making into BIM technologies.
(I’ve made the command so that it works even when you have AutoCAD open. This allows detailers to quickly switch to Revit and AutoCAD and to delete and restart if need be. Also requiring that AutoCAD be open ensure that detailers know exactly what file they are working with and what files they are converting. It eliminates a whole lot of errors.)
As you can see in the above picture, the top row of panel voids were doubled and in some cases tripled up. Obviously we don’t want this. Ordinarily, when such drawings are passed on to us we employ the overkill command. But for some reason it wasn’t working. And I couldn’t for the life of me figure it out.
That was until our lead Bubble Deck detailer suggested that the insertion points of the block references were not all on the same plane – some of them were in the Z plan – if that’s the case, then overkill would not recognise them as being the same block – and will allow them to continue to co-exist in the same drawing.
Check that all similar items have similar insertion points. If they’re different – that’s why overkill might not be working for you.