Over head water tank analysis using STAAD.Pro

In this tutorial, over head water tank analysis will be done using STAAD.Pro V8i. The detailed procedure is given below.

Open STAAD.Pro V8i and create a new Space structure with Meter and KiloNewton as Length Units and Force Units.

Select the Beam page under Geometry tab; the Snap Node/Beam window is displayed.

Close the Snap Node/Beam window.

In the Nodes window, create the nodes with the data given below. Figure-1 shows the nodes created.

Figure-1 The Nodes created

Now, we will create the members in the upward direction so that the plates could be created with the same orientation. If the plates are created in different orientation, you cannot assign a single load case to plates with different orientations.

Create the members with the data given below. Figure-2 shows the members created.

Figure-2 The Members created

Now, we will create a segment of the tank using the Circular Repeat tool.

Select all the members and then choose the Circular Repeat tool from the Geometry menu; the 3D Circular dialog box is displayed.

Enter the values as shown in Figure-3.

Figure-3 The 3D Circular dialog box

Choose the OK button; the model will be repeated at 20 degrees with rotational axis as Y-axis.

Select all the members and then select the Create Infill Plates option from the Geometry menu; the plates will be automatically created in the areas enclosed by the members.

Select the outer periphery beams as shown in Figure-4 and delete them.

Figure-4 Periphery beams to be deleted

Now, we will apply loads to the plates.

Select the Loads & Definition page from the General tab; the Load & Definition window is displayed.

Select the Load Cases Details node in the Load & Definition window and choose the Add button; the Add New: Load Cases dialog box is displayed with the Primary node selected by default.

Select the Fluids option from the Loading Type drop-down list and enter Fluid Loads in the Title text box.

Choose the Add button; the primary load case will be created under the Load Case Details node of the Load & Definition window. Close the Add New: Load Cases dialog box.

Select the newly created Fluid Loads load case and choose the Add button from the Load & Definition window; the Add New: Load Items dialog box is displayed.

Select the Plate Loads node in the Add New: Load Items dialog box; the Pressure on Full Plate page is displayed by default.

Enter -76 as load intensity in the W1 text box and select GY as the load direction. Choose the Add button; the load is added under the Fluid Loads load case.

Select the Hydrostatic page from the Plate Loads node in the Add New: Load Items dialog box; the Hydrostatic page is displayed.

The options are unavailable as no plates are selected.

Choose the Select Plate(s) button from the Add New: Load Items dialog box; the Selected Items dialog box is displayed.

Choose the Plates cursor and select the plate as shown in Figure-5; the plate number is displayed in the Selected Items(s) dialog box.

Figure-5 The selected plate onto which load is applied

Choose the Done button from the Selected Items(s) dialog box; the Selected Items(s) dialog box is closed and the options are available in the Hydrostatic page.

Enter -53.9 in the W1 edit box and -0.009 in the W2 edit box.

Select the Y and Local Z radio buttons in the Interpolate along Global Axis and Direction of pressure areas, respectively.

Choose the Add button; the load is added under the Fluid Loads load case.

Similarly, add the hydrostatic load of the magnitude ranging from -53.9 to -66.4 kN/m2 on the plate just below the vertical plate, as shown in Figure-6.

Figure-6 The selected plate onto which load is applied

Now we will assign the uniform pressure created in previous steps onto the bottom plate of tank.

Select the uniform pressure load and assign it to the plate as shown in Figure-7.

Figure-7 The load applied onto the bottom most plate

Create a new load case for dead loads and add self weight and a uniform load for railing. The railing will be placed onto the beam situated at the edge of the cantilever plate, as shown in Figure-8.

Figure-8 The self weight and railing load applied

Now we will provide sectional properties to the model.

Select the Properties page from the General tab; the Properties – Whole Structure window is displayed.

Choose the Thickness button from the Properties – Whole Structure window; the Plate Element/Surface Property dialog box is displayed.

Enter 0.15 as thickness in the Node 1 edit box and make sure that the Concrete option is selected from the Material drop-down list. Choose the Add button; the Plate Element/Surface Property dialog box is closed.

Select the Assign to View radio button from the Properties – Whole Structure window and then choose the Assign button; the property is assigned to each plate created.

Choose the Define button from the Properties – Whole Structure window; the Property dialog box is displayed.

Select the Rectangle node; the Rectangle page is displayed. Enter 0.45 and 0.30 in the YD and ZD edit boxes respectively.

Choose the Add button; the Property dialog box is closed and the property is added to the Properties – Whole Structure window.

Assign the newly created property to the members in the model.

Similarly, assign a cross sectional property of 0.15m x 0.15m to the member carrying railing load.

Figure-9 Properties added and assigned to the model

Select the Support page from the General tab; the Supports – Whole Structure window is displayed.

Choose the Create button; the Create Support dialog box is displayed with the Fixed tab chosen by default.

Choose the Add button; the fixed support is added to the Supports – Whole Structure window.

Assign the fixed support created to the lowermost nodes, as shown in Figure-10.

Figure-10 Fixed supports added to the model

Select the plates and members using the Geometry Cursor and choose the Circular Repeat option from the Geometry menu; the 3D Circular dialog box is displayed.

Enter the values as shown in Figure-11.

Figure-11 The 3D Circular dialog box

Choose the OK button; the model will be repeated at 360 degrees with rotational axis as Y-axis

Figure-12 shows the water tank created.

Figure-12 Model of water tank created

Figure-13 and Figure-14 shows the 3D rendered views of the water tank.

Figure-13 3D rendered view of the water tank model

Figure-14 3D rendered view of the water tank model

Now, we will analyze the model created.

Select the Perform Analysis option from the Analysis fly-out in the Commands menu; the Perform Analysis dialog box is displayed.

Close the Perform Analysis dialog box and select the Run Analysis option from the Analyze menu; the STAAD Analysis and Design window is displayed showing the progress of solution.

Once the analysis is complete; select the Go to Post Processing Mode radio button and choose the Done button; the Results Setup dialog box is displayed.

Choose the Apply and the OK button; the post-processing mode is displayed along with various results.

Choose the Plate tab; the Diagrams dialog box is displayed.

In the Diagrams dialog box, select the MY (local) option from the Stress type drop-down list and choose the OK button; the stress contours is visible in the model along with the legend.

Figure-15 shows the MY (local) stress contours in the model.

Figure-15 MY (local) stress contours of the model

Similarly, you can view various other stress contours for the plate elements.