Open topic with navigation

Beam related parameters for physically non-linear calculations

We define the structure (the model of it). No load is required to be defined at this moment, but a new function is already added in the service Structure: Beam – PNL Member data, i.e. the member properties required for a non-linear calculation.

PNL Member data

Practical use of PNL member data

When these data are input, two questions must be answered:

(1)  "Do you want to have physically non-linear stiffness?"

And if so,:

(2)  "What type of reinforcement do you want: (i) no reinforcement, (ii) only practical (provided), (iii) only design (or required) areas, (iv) practical and if no such reinforcement is found, then use the design As, or (v) the design reinforcement and if it is missing, then use the practical (provided) reinforcement?"

Individual options use its own symbol in the graphical window, and thus we can immediately see what type of reinforcement is considered in the calculation.

We could say that there will be no reinforcement. It means that we can have no reinforcement and still we can perform the non-linear calculation. It is a reasonable choice for e.g. masonry or plain concrete.

However, normally we say that the Physically (and geometrically) non-linear calculation should be calculated for "Practical ONLY" reinforcement or for the option "1st Practical, 2nd Design As."

Let us select "1st Practical, 2nd Design As". We have no reinforcement calculated or defined, so the program opts for "No reinforcement". But, the initial setting is "1stPractical, 2nd Design As". Both these "values" can be seen in the property table. The program have not found any reinforcement and, therefore, selected the option "No reinforcement". But it also remembers the initial setting.

So far, we have defined a structure (the model of it). Let us create a load case: e.g. self-weight. Let us create a common combination consisting of it with the load factor set to e.g. 1.3. Then, let us define a non-linear combination, once again with the load factor set to 1.3. And start the calculation - the linear one.

This gives us a linear solution that is necessary just for the design of reinforcement. Let us perform the design of reinforcement for the calculated common combination. Open service Concrete Advanced and start function 1D member > Member design > Design. Select the beam(s) to be treated and press the Action button [Refresh]. The required reinforcement areas are calculated and (depending on the adjustment of View parameters) displayed. If required, in order to see the PNL member data symbol, we can open the View parameters setup dialogue and select option Member nonlinearities on the tab Structure.

Now we can start the calculation again. This time, we can run the non-linear calculation and therefore, we must not forget to adjust finer finite element mesh. The program found:

"The current status of ‘Reinforcement taken from’ of ‘Beam – PNL member data’ is different than default setup. Would you like to change it back to default setup?"

Let us say "Yes", the program finishes the calculation, regenerates the graphical window and we can see a new symbol for "PNL member data". The program has just performed the physically non-linear calculation for the design (required) reinforcement areas.

The results cannot be reviewed in the service Concrete Advanced, as they do not represent any check. It is true that we have calculated with concrete, but the results are general results of a general non-linear calculation and therefore they are in the service Results > PNL stress/strain and PNL stiffness. For example, ecc is the compressive strain in concrete, ert is the tensile strain in reinforcement.

Now, let us input the practical (provided) reinforcement. Let us open the service Concrete Advanced, open function New reinforcement and input the reinforcement bars. Now we can repeat the non-linear calculation. The program again checks the settings of PNL member data and again asks if we want to change it so that it corresponds to the initial setting (The initial setting was "1st Practical, 2nd Design As". Up to now, there was no practical reinforcement defined and therefore the calculations were performed with the required reinforcement areas. Now we have just input the real reinforcement, the program discovered it and asks if we insist on the initial adjustment, or whether the current results calculated for the required reinforcement are good enough). We answer "Yes", as we do want to perform the calculation with the defined practical reinforcement.

Procedure to define beam related PNL parameters

1. Open service Structure.

2. Start function Beam – PNL Member data.

3. Select the required options.

4. Confirm with [OK].

5. Select the beam(s) where the specified data should be assigned to.

Open topic with navigation