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# Design Standard

## 1. Introduction

In Slide3, design standards such as Eurocode 7 can be used to add partial factors to the different components of the analysis. Note that theses partial factors are applied prior to the analysis to give design values that are used in calculation. For more information on Eurocode7, refer to Design Standards for details.

Open the tutorial file in File > Recent > Tutorials > Design Standards and open the file Design Standard - starting file.

The starting file model is an unreinforced simple earth dam on impermeable base.

## 2. Model

The model is based on Example 5.12 in Smith (2006). It is a simple earth dam on an impermeable base for which the downstream side is to be analyzed. First the problem will be analyzed in the traditional way and a factor of safety will be obtained. Then the Eurocode design analysis will be performed.

Some features of this model to note:

• The dam is assumed to sit upon a high strength material that is not included in the model.

• The Groundwater Method = Water Surfaces

We will first check the water table is assigned to the materials in the model.

Select: Groundwater > Assign Water to Materials

Make sure to select the Water Table in drop down menu and select Apply To All Materials.

Select OK.

We will then check the surface option of the model.

Select: Surfaces > Slip surface options .

When you select the Slip surface tab you will see the model has a slope limit shown below. This limits the analysis to consider just the downstream slope:

## 3. Compute

Save the file with different name and Compute.

To see the results, go to Results tab , and you will see the result as shown below.

## 4. Eurocode 7 – Design Approach 1 – Combination 1

For this tutorial, we will demonstrate how to apply the Eurocode7 factors for Design Approach 1 only. As a disclaimer, this is by no means a comprehensive guide for determining which design standards to use for a specific problem.

Design Approach 1 specifies two different combinations of partial factors. The first factors the action forces, and the second factors the resisting forces through the material properties. We will test both combinations in this tutorial. Now we will apply Eurocode 7 - Design Approach 1 – Combination 1 to the model first.

Select: Analysis > Project Settings .

Select Design Standard and under the Design Standard dropdown, select: Eurocode 7 – Design Approach 1, Combination 1. Click the View Partial Factors button to check which factors are being applied.

Here you can see that the factor for the Permanent actions (unfavourable) is 1.35. This essentially means that the driving force in the analysis will be multiplied by 1.35. The factors for the material properties are 1, so that they will be unchanged in the analysis. For more information regarding the design standards factors, please see the Design Standards documentation.

Click OK to close the Partial Factors dialog and click OK to close the Project Setting dialog.

## 5. Compute Combination 1

Save the file as Combination 1, and Compute.

To see the results, go to Results tab , and you will see the result as shown below.

So, you can see that for Design Approach 1, Combination 1, the over-design factor = 1.235. Now let’s compare Combination 2.

## 6. Eurocode 7 – Design Approach 1 – Combination 2

Select: Analysis > Project Settings .

Select Design Standard and under the Design Standard dropdown, select: Eurocode 7 – Design Approach 1, Combination 2. You can check the factors applied by selecting ‘View Partial Factors’ button.

Click OK to close the Partial Factors dialog and then click OK to close the Project Settings dialog.

## 7. Compute Combination 2

Save the file as Combination 2, and Compute.

To see the results, go to Results tab , and you will see the result as shown below.

You can see the over-design factor is 0.979 with Design approach 1 – combination 2. This is less than 1.

For more details on this example, there is Slide2 Tutorial 21 – Slope Design with Eurocode 7 which shows the 2D model of the slope with more details on model. You will notice the Factor of Safety is slightly different from 2D to 3D model due to extrusion, but the applied partial factors from Design Standard to the model is similar for both of the programs.

## 8. References

Bond, A. J. and Harris, A. J., 2008. Decoding Eurocode 7, Taylor & Francis.

British Standards Institution, 2004. Eurocode 7: Geotechnical design – Part 1: General rules, BS EN 1997-1, London, UK.

Smith, 2006. Smith’s Elements of Soil Mechanics, 8th Edition, Blackwell Publishing.