Instalación manual

by data item. Click on “OK” to close the titles form.

Define Erection Loads

3. Next we will define erection of beam loads using “Generate” to include two extra components; one for the temp 1kN/m and the other for the support loads (upwards).

Use the menu item Data|Define Loading... to open the Define Pre-tensioned Beam Loads form. Click on the Loading Description drop down and select “Erection of beam” from the list of design load cases then click on the

“Generate” button. Click on “Yes” on the confirmation form that appears. The Generate Beam Loads form will now open.

The program automatically calculates the dead load for the beam and adds it as the first component of the generated load, called “Beam dead load”.

This load needs to be applied equally to the two temporary support locations. The UDL intensity is 12.67853kN/m which applies a total load of 266.24913kN to the beam. Since the program can’t apply a point load to a beam, this needs

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to be applied using two, 100mm long UDLs. The equivalent applied UDL intensity over a 100mm length is 1331.24565kN/m.

Click on the “Add Load Component” button and enter the UDL Intensity Start and End as “1331.24565kN/m”. Set Start Dimension to “0.95m” and the End Dimension to “1.05m”. Change the ULS and SLS Load Factors to “-1.265” and “-1” respectively to make this an upward load and set the Component Ref. to “Left Temp Support”.

Click on the “Add Load Component” button and repeat the process

(remembering to make ULS and SLS Load Factors negative), this time setting the Start Dimension to “19.95m”, the End Dimension to “20.05m” and the Component Ref. to “Right Temp Support”.

Finally we need to define the temporary construction load. Click on the “Add Load Component” button again and enter the UDL Intensity Start and End as “1kN/m”. Leave all the other fields at their default values and set the

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In the Increments section, set Beam span equally divided by to “50” then click “OK” to close the Generate Beam Loads form. The Define Pre-tensioned Beam Loads form will now show the total load applied by the four load components.

Define Construction Stage 1 Loads

4. The next step is to define the loads for construction stage 1. Click on the Loading Description drop down on the Define Pre-tensioned Beam Loads form and select “Construction Stage 1A” from the list of design load cases then click on the “Generate” button. The Generate Beam Loads form will now open. The program automatically calculates the UDL intensity for the construction loads. Click “OK” to close the form.

Remove Temporary Loads and Supports

5. Next we will define a load case to remove the effects of the temporary loads and supports.

Click on the Loading Description drop down on the Define Pre-tensioned Beam Loads form and select “SDL non-structural concrete etc” from the list of design load cases then click on the “Generate” button. The Generate Beam Loads form will now open.

Set the UDL Intensity Start and End as “1331.24565kN/m”. Set Start

Dimension to “0.95m” and the End Dimension to “1.05m”. Change the ULS and SLS Load Factors to “1.265” and “1” respectively and set the Component Ref. to “Rm Left Temp Sup”.

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Click on the “Add Load Component” button and repeat the process, this time setting the Start Dimension to “19.95m”, the End Dimension to “20.05m” and the Component Ref. to “Rm Right Temp Sup”.

Finally we need to remove the temporary construction load. Click on the “Add Load Component” button again and enter the UDL Intensity Start and End as “1kN/m”. Change the ULS and SLS Load Factors to “-1.265” and “-1”

respectively and set the Component Ref. to “Rm Temp Const”.

In the Increments section, set Beam span equally divided by to “50” then click “OK” to close the Generate Beam Loads form. The Define Pre-tensioned Beam Loads form will now show the total load applied by the three load components.

Define Surfacing and Live Loads

6. The next step is to define the SDL surfacing loads.

Click on the Loading Description drop down on the Define Pre-tensioned Beam Loads form and select “Superimposed dead load” from the list of design load cases then click on the “Generate” button. The Generate Beam Loads form will now open.

Set the UDL Intensity Start and End as “2.5kN/m” then click “OK”. 7. Next we will import some results from a separate live load analysis.

Click on the “Interface” button, select Direct ASCCI File Import and click “OK”. Select the supplied file “BS Live Loads.sld” and click “Open”. This will import loads into the Live load BM and Live load SF + associated BM design load cases.

Click “OK” to close the Define Pre-tensioned Beam Loads form. The program will display the following confirmation dialog:

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When you export enveloped live load results from the analysis module, it exports the absolute values of shear, i.e. all negative shears are converted to positive values. The dead load shears created using the Generate option in this example are actual shears. This means the program can’t add the dead and live load shears together. By answering yes on this form, you force the program to convert the dead load shears into absolute values so they can be combined with the live loads.

Click on “Yes” to close the dialog.

Enter Temperature Profile and Shrinkage and Creep Parameters

8. We now need to create a temperature profile and enter values in the shrinkage and shear parameters.

Click on the Calculate|Analyse... menu option to open the Pre-tensioned Beam Analysis form. Click on the Set parameters for drop down and select “Differential temp. Appx C” from the list of options.

The program will open the BS 5400 Part 2 Appendix C Temperature Profile form and display the default positive and reverse temperature profiles.

Click on “OK” to use this temperature profile.

Next, click on the Set parameters for drop down and select “Shrinkage and creep” from the list of options. This will open the Data for Shrinkage & Creep form.

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Set the Shrinkage strain to “-0.00025”, the Shrinkage before in situ cast to “20%”, the Differential shrinkage strain to “-0.0001” and the Creep reduction

factor to “0.43”.

Click “OK” to save the parameters. Tendon Optimisation

9. The next step is to design the required tendon layout.

To do this, click on the “Tendon Optimisation” button on the Pre-tensioned Beam Analysis form. This will open the Tendon Optimisation form. Tick both the Applied Load tick boxes and the Straight and Debond tick boxes. For this example we will set the Locations / Limit field to “4”. Use the default values for all the other fields on the form.

Click on the “Design Optimised Layout” button. The program will now consider a series of tendon arrangements to come up with the optimised layout for the beam.

At the end of the optimisation, the program produces an error message and provides a summary on the right hand side of the form.

Click “OK” to close the error message then click on the “OK” button to close the optimisation form. Click “OK” to close the Pre-tensioned Beam Analysis form.

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10. In order to resolve this error we need to change the material properties used on the beam.

Click on the Data|Define Material Properties... to open the Define Material Properties form. Click on the 2nd row in the Name column to increase the grade of concrete for the precast beam to grade 60. Click “OK” on the Define Property Details form to save the change.

Click in the 5th row in the Type column and select “Concrete – BS 5400” from the list. Enter a value of “45N/mm2_{“ in the Characteristic Strength fcu field for} the strength at transfer.

Close both forms (using both “OK” buttons to ensure that the changes are saved) then click on the Data|Define Beam... menu to open the Pre-tensioned Beam Definition form. Click on the Define drop down and select “Section” from the list to open the Pre-tensioned Beam Section Definition form. Change the Transfer Property for the PC beam to grade 45 concrete. You will see the Final Property is already set to grade 60 concrete.

Click on the “OK” button twice to close both forms then click on the Calculate|Analyse... menu to re-analyse the beam.

11. Click on the “Tendon Optimisation” button then click on the “Design Optimised Layout” button to re-run the tendon optimisation with the new material

properties. This time the tendon optimisation will complete without an error message. A small summary is produced at the bottom of the report at the end of the tendon optimisation process. Click “OK” to close the Tendon

Optimisation form. Design for Shear

12. The next step is to check the beam for shear.

Click on the Analyse for drop down and select “Shear force + BM 1 load comb. 1”. You will see that the beam just fails at the left hand end.

In order to prevent this failure we need to change the shear resistance of the beam. To do this, click “OK” to close the analysis form then click on the Data|Define beam... menu item. Click on the Define drop down and select “Section” from the list of options. In the Shear resistance section of the form,

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change Width to “300mm”. This is roughly the width of the beam where the shear stress is at its maximum.

Click on the “OK” button twice to close both forms then click on the

Calculate|Analyse... menu to re-analyse the beam. You will see that the beam now passes when the “Shear force + BM 1 load comb. 1” load case is applied.

Shear Link and Transverse Reinforcement Requirements

Now that the beam design passes for the shear force case, the next step is to design the shear links in the beam. We are going to design the shear links at 5 locations. These are:

 0m

 5.25m

 10.5m

 15.75m

 21m

Click on the “Results” button to view the shear calculations. Scroll down to the bottom of the results to see summary of link requirements.

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Use the arrows by the Design section for results printout field to select point 1 at 0m then click on the “Results” button. Scroll to the bottom of the results and look at the table for link arrangement.

From the table we can see that there are several possible arrangements that could be used. The best arrangement would be 2 legs of 12mm links at 100mm spacing.

13. We can repeat this for the other locations to get the following results: Location Diameter Legs Spacing

0m 12mm 2 100mm

5.25m 6mm 4 150mm

10.50m 6mm 2 150mm

15.75m 6mm 4 150mm

21m 12mm 2 100mm

14. Finally we will use the results to define the transverse reinforcement requirement to resist longitudinal shear at shear plane 2-2.

Click on the Analyse for field and select “Longitudinal shear 1 load comb 1” from the drop down list. Set the design section location to the left hand end (point 1) and click on the “Results” button. Scroll down to the bottom of the results so you can see the reinforcement requirement across shear plane 2-2:

Repeat this for the other locations then close the results viewer and click “OK” to close the Pre-tensioned Beam Analysis form.

15. When the analysis form is open the results graphs can be displayed in a 3D isometric window by clicking on the icon on the graphics window:

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Also, it is worth noting that when the print preview window is opened by clicking on the icon at the top of the graphic window, a pdf of the graphic window can be generated by clicking on the icon at the top of the print preview window.

16. Click on the File|Save As... menu item. Set the file name to “My BS Example