Bemutató

Structural design of a pier cap from DXF (EN)

Concrete

Detail 2D

EN (Eurocode)

Pier caps

Ez a cikk a következő nyelveken is elérhető

By following this step-by-step tutorial, you will learn how to design and code-check a pier cap by DXF references in IDEA StatiCa Detail.

1 New project

Let’s launch the IDEA StatiCa and select the application Detail. Create a new project by clicking New. Wizard window is opened and you can start with a selection of proper concrete grade and cover. Then continue with the General input section.

This will load a blank project where we start from scratch.

2 Geometry

Start with the addition of a wall element by the Import DXF button.

A dialog to locate and open the desired DXF file will pop-up. After the selection of pier_cap.dxf (available in source files), you will land in a dialog for selection. Select the part of the outline of the pier cap (if you used lines in DXF continue with Consecutive button) and click on Outline. Finish the selection by OK button.

Then import the upper part of the pier cap from the same DXF file.

The shapes of the wall elements have been generated by DXF, but the 2D DXF reference lacks the information about thickness, thus you need to adjust it manually now. Set the Thickness for both W1 and W2 members to 1,20 m.

Right now, our structure is statically overdetermined, you need to add boundary conditions. To create line support, click on the plus button and select the third type in Supports section.

Constraint the support in X, Z and Ry directions and change the edge number to 7. Also, switch off the Compression only functionality. The edge numbers can be seen in the Main window.

As a Point force-placed directly on the edge of a pier cap would crash the concrete locally in compression, we will use bearing plates to distribute the load more evenly. To add one, press Plus button once again, and in the Load transfer devices section, pick the first - Bearing plate.

Change the Width to 0,40 m and the Thickness to 0,040 m, then the Edge number to 3 and shift its X-Position to 0,45 m.

Then copy the Bearing plate and change its position to be measured From end.

3 Loads

One load case LC1 was automatically added by the software. You need two load cases to distinguish between permanent and variable loads and three combinations to cover one ULS and two SLS combinations (Characteristic and Quasi-permanent) for all checks.

Let's modify the automatically added load case LC1 for permanent effects. In the Load impulses tab, click on the Plus button and apply a Point load. It will be automatically placed on one of the bearing plates.

As the last step, change its value to -2500 kN.

Copy that force to the other bearing plate BP2.

Switch back to Load cases & Combinations tab to create LC2 load case by plus Load case button. Change the load case type to the variable.

Repeat the steps for the addition of point load.

Adjust the value of force.

Copy the force to the bearing plate BP1.

Let's go back to Load cases & Combinations for the last time. Create the first nonlinear combination by plus Combination button. The combination C1 is set by default to ULS type. Set the partial factors after the definition of all combinations at once.

Now you can repeat the steps to introduce the second combination of C2. This time, it will be SLS type and Characteristic.

The last defined combination will be as expected - Quasi-permanent. Select one in the combo box right next to the SLS type selection.

Now, change the partial factors for all combinations. To do that, click on the pen icon in any combination you defined and change the partial factors you see in the following picture.

The last step in the definition of loads will be the unticking of checkboxes for load cases. The calculations will be performed just for the ticked items, and by excluding load cases, you will speed up the calculation. You will require the checks for three combinations.

4 Reinforcement

The next step is to reinforce the model. Combine the definition from scratch in IDEA StatiCa with the batch import of the reinforcement from the DXF file. In this tutorial, we assume that the user knows how to reinforce a pier cap and prepared some reinforcement in DXF in advance from drawings thus, we leave the tools for reinforcement design for another tutorial, and you can switch to Input/Edit.

In input mode, start with the definition of the DXF reference. Click on Import DXF.

A dialog to locate and open the desired DXF file will pop-up. After the selection of pier_cap.dxf (available in the source files), you will land in a dialog for selection. Select all the polylines (rebars shape) you need in order shown on the following picture and click on Select after each polyline (the order is not important in general, we just want to keep track in this tutorial when we talk about the specific name of an item). Finish the selection by OK button.

The 2D DXF file transfers the global width of a polyline as the diameter for each rebar, but it does not contain information about the number of bars in the perpendicular direction, and we need to adjust them manually.

Change the number of bars in a layer for the group of bars GB1, GB2, GB3, and GB4 to 10.

To finish the reinforcement in this example, combine the reference from DXF with reinforcement defined in IDEA StatiCa Detail. In this case, add some horizontal and longitudinal reinforcement into the pier cap and a few layers of reinforcement representing the stirrups in the pier. Click on the plus button and select the first reinforcement item Group of bars.

Change the definition to On outline or opening edge. Then adjust the number of layers, their distances, the diameter, the number of bars in a layer, anchorage type for both ends and edges according to the following picture:

Use the copy function to create GB6, which will represent the stirrups, and switch the edge to 7. Set all parameters according to the picture below:

The last reinforcement items will introduce the longitudinal reinforcement of the pier cap. To do that, add a new group of bars. Change the properties as follows:

Use the copy button for the last time. Change the edge to 8.

Switch in the navigator to Check. This is how your final reinforcement should look like:

5 Calculation and Check

Start the analysis by clicking Calculation in the ribbon. The analysis model is automatically generated, the calculations are performed and you can see the summary of checks displayed together with the values of check results.

To go through the detailed checks of each component, start with the Strength tab. This will show concrete checks such as utilization in stress, principal stresses, strains, and a map of reduction factor k_c, which can be switched on the ribbon.

For detailed results of reinforcement, you need to click on the row Reinforcement. This will change the ribbon icons and unroll the table for results. You can display the results for strains and stresses in each bar and their utilization.

All results can be displayed in the same way. Let´s show the difference in the ribbon for SLS checks of crack-width and deflection. Besides the icons to switch between the results, there are settings in the ribbon to set the limit value of cracks or to display the results of deflections from short/long-term models.