Staad Excelents

(1)

STAADPRO ELEVATED INTZ TANK MODELING AND DESIGNING

T.RANGARAJAN, STRUCTURAL ENGINEER STAADPRO Page 1

ELEVATED INTZ TANK

MODELING , LOADINGS , ANALYSIS AND DESIGN OF ELEVATED INTZ TANK

Modeling:

1. Space-file name : RC NTZ TANK 2. Unit-Met, Kn

3. Add beam 4. Finish

5. View from +Z –X_Y Plane .Snap Node/Beam 6. Use Circular Repeat tool.

(2)

(3)

Insert node- vertical side into 2 and to Slope by 3. Use circular repeat tool to model the tank.

(4)

Select all beams and choose Create Infill Plate to Infill plate tool and fill with PLATE ELEMENTS. (Plate member)

Structure Diagrams… and click to Fill Plates

Ctrl+Z ….Undo ….. Circular Repeat

(5)

Circular Repeat

Create Infill Plate Label tool…. Structure Diagrams… Fill Plates

Select Beam Cursor and select beams and click fill plates to view the plates. General menu- property- 200 mm for plate and provide Fixed Support to the bottom 2 nodes as shown.

(6)

Load case 1 : Water Pressure-General - Add.. Plate Loads | Hydrostatic - Select Plate(s).

(7)

W1 = -20Kn/m2 and W2 = 0 Kn/m2.

Select Hydrostatic and enter ,W1 = -40 Kn/m2 and W2 = -20 Kn/m2

(8)

Select Plate Cursor and select the plates . Use Circular Repeat as shown.

(9)

Local Z

---

Ctrl+Z

…….

Circular Repeat

…

Command- Analysis/Print .. Print Option .No Print

Choose Analyze | Run Analysis…

Choose Post-processing - Plate | Contour …choose Max Absolute

(10)

Use Cut Section … Select to View ... View Highlighted Only

View From +Z … Plate Cursor

(11)

Cut Section … Select to View | View Highlighted Only

Cut Section … Show All Surface Element and Plate Element Modeling …. View From +Z

Cut Section …Select to View | View Highlighted Only

(12)

Define Mesh Region ……. Div. = 1

(13)

Support …………. Fixed Support

General | Property ……. Thickness… Plate/Surface Thickness …0.3 m, Material = Concrete … Add … Close

Assign To View …. Assign

(14)

Add.. Plate Loads | Pressure on Full Plate …Add … Close …Assign To View

Analyze | Run Analysis… Run Analysis

Post-processing case2 : PLATE LOAD Plate | Contour

(15)

Modeling :

1 … (X=2, Y=20, Z=0) (X=0, Y=0, Z=0) …. (Circular Repeat) Modeling …. Geometry | Beam

(16)

Snap Node/Beam

Snap Node/Beam …. (X=2, Y=20) … (X=0, Y=0)

Property … Define… Rectangle : YD = 1.0 m, ZD = 0.5 m, Material = Concrete

(17)

Circular Repeat

3D Rendering

(18)

(19)

(20)

Support …. Edit List

Load case 3 : Design Load …… Repeat Load … L2 : PLATE LOAD … 1.4

Commands | Loading | Load List… L3 : DESIGN LOAD Design | Concrete … Define Parameters…

FC : Compressive strength of concrete = 25 N/m2 • FYMAIN : Yield strength of steel = 415 N/m2 • MAXMAIN : Max. main reinforcement bar = 25 • TRACK = (2)

(21)

View From +Z

Commands… DESIGN COLUMN

(22)

(23)

(24)

By: Jignesh V Chokshi

L&T Sargent & Lundy Limited, Vadodara

Procedure to Calculate Tributary Area and Vertical Spring Constants for foundation modeled with soil as elastic supports in FE based programs

Introduction

In Foundations, many times to estimate true behavior of mat; elastic property of soil is taken into consideration in FEM models. The base slab is divided into finite number of 2D plate elements representing the mat and the support condition is elastic based on the modulus of subgrade reaction of soil. Some popular FE programs do not include the facility of surface support and hence to model soil as elastic support, calculation of vertical spring stiffness at each node of the mesh becomes necessary.

The spring value shall be in Force/Unit displacement. The unit of Modulus of subgrade reaction is force/unit area/unit deflection. Hence, when vertical spring constant is to be calculated for each joint, the tributary area of mat at each node shall be calculated and then multiplied with the modulus of subgrade reaction. This procedure is simple for regularly divided meshes. However for most practical problems, it is a cumbersome process to calculate the tributary area at each node and then calculate the spring constants. Also, after the analysis is completed, the output of such programs provides only vertical spring force in force unit. For determination of actual base pressure, it becomes necessary to divide the spring force by the tributary area at each node.

Procedure

To simplify the calculation of tributary area and vertical spring constant, a simple, accurate and quicker method is suggested.

STEP 1 – Prepare the model with or without superstructure and the base modeled as 2D plate elements. STEP 2 – Copy the model and extract the mesh at base by deleting all members/elements above base level. STEP 3 – Provide PIN support at each node of the base and create two loading cases.

STEP 4 – In Load case 1, apply surface load equal to the magnitude of modulus of subgrade reaction on the base mat and in Load case 2, apply surface load equal to Unity on the mat.

STEP 5 – Run the model for static analysis and print the support reactions.

It is evident that, the vertical support reaction due to uniform surface load will be tributary area multiplied by the surface load. This is nothing but the spring constant when the surface loading is equal to modulus of subgrade reaction and tributary area when surface loading is unity. Thus, we achieved the spring constant and tributary area at each node. In the original model export these values as spring supports by providing appropriate command. Retain the tributary area for future use.

Alternatively, to calculate tributary areas from load case 1 only,

STEP 5 – Extract the output of support reaction for load case 1 and import it in the Excel. Divide each reaction by modulus of subgrade reaction. This gives the tributary area at each node.

STEP 6 – After the analysis of entire original model is completed; the support reaction will be spring force at each node of base mesh. To obtain base pressure magnitude, divide each spring force by corresponding tributary area obtained in the STEP – 5.

(25)

Getting Started

December 18, 2013 in STAAD Pro |

STAAD.Pro V8i screen is shown below. The screen has five major elements as

shown below.

1. Menu bar. 2. Tool bar. 3. Page control. 4. Main Window. 5. Data Window.

(26)

In STAAD.Pro V8i:

Geometry is the “Elements of your Structure”. The Elements are given below:



_Nodes



Members (beams and columns)



_{Plates (Slab, Walls and Raft Foundations)}



Surfaces (Slab, Walls and Raft Foundations)

Nodes:

Stiffed Joint with 6 reactions. It is located at each end of the Beam and each corner

of the Plate Nodes considered the essence of the geometry of any structure in

STAAD.Pro. Each node holds the following information:



_{Node Number.}



Node Coordinates in XYZ space.

Beam:

Any member in the structure, that can be beam, column, bracing member or truss

member. Beams are actually defined based on the Nodes at their ends. Each beam

holds the following information:



_{Beam Number.}



The Node numbers at its ends.

Plates:

A thin shell with 4 node shaped element. It can be slab or wall element. Each plate

will holds the following information:



Plate Number.



Node Number at each corner of it.

Surface:

A thin shell in green color with mutli-nodded shape starting from 3 nodes and

more. It can be anything of slabs, walls and raft foundations. It holds the following

information:

(27)



Surface Number.



Node Numbers at each corner of it.

Hardware Requirements:

The following requirements are suggested minimums. Systems with increased

capacity provide enhanced performance.



PC with Intel-Pentium or equivalent.



_{Graphics card and monitor with 1024×768 resolution, 256 color display (16}

bit high color recommended).



128 MB RAM or higher.



_{Windows NT 4.0 or higher operating system. Running it on Windows 95 &}

Windows 98 systems is not recommended as performance may be

degraded. The program works best on Windows 2000 and XP operating

systems.



Sufficient free space on the hard disk to hold the program and data files.

The disk space requirement will vary depending on the modules you are

installing. A typical minimum is 500MB free space.



A multi-media ready system with sound card and speakers is needed to run

the tutorial movies and slide shows.

(28)

Starting STAAD.Pro V8i

December 18, 2013 in STAAD Pro

Creating a Project:

Once you stared the STAAD.Pro application follow the instructions: 1. In the Project Tasks box, click New Project.

2. A New Project dialog box appears is shown below:

3. Before starting a project, you must be aware of the type of structure. The structure type can be defined as Space, Plane, Floor, or Truss.

 Space: A SPACE structure, which is a three-dimensional framed structure with loads applied in

any plane, is the most general. The loading causes the structure to deform in all 3 global axes.  Plane: The type of geometry, loading and deformation are restricted to the global X-Y plane

only.

 Floor: The geometry of structure is kept at the X-Z plane.

 Truss: The structure transmits loading by pure axial action. Truss members are considered to be

(29)

4. Set the length units and loading units and click Next button.

Note: The units can be altered later if needed, at any point of the model creation.

5. Now Where do you want to go? dialog box appears. You have specify the method for building



Add Beam:

Sets the program in the Snap Node/Beam dialog and snap grid to construct

your model by creating new joints and beams using the construction grid,

drawing tools and spreadsheets.



Add Plate:

Sets the program up with the Snap Node/Plate dialog to construct your

model by creating new joints and 3-noded and 4-noded plate elements

using the construction grid, drawing tools and spreadsheets.



Add Solid:

Sets the program up with the Snap Node/Plate dialog to construct your

model by creating new joints and 8-noded solid/brick elements using the

construction grid, drawing tools and spreadsheets.

(30)



Open Structure Wizard:

Opens the library of readymade structure templates which can be

extracted and modified parametric model standard, parametric structural

templates for trusses, surfaces, bay frames and much more.



Open STAAD.Editor:

Allows you to build your model using STAAD syntax commands

(non-graphical interface) through the STAAD editor.



Edit Job Information:

Automatically opens the Job Information dialog box which provide

information about the job (i.e. client’s name, job title, engineers involved,

etc.) before building your model.

(31)

Methods Of Model Generation

STAAD.Pro V8i consists of three parts:



_{Pre Processor: Generates the model with all the data needed for the}

analysis.



Analysis Engine: Calculates displacements, member forces, reactions,

stresses, etc.



Post Processing: Displays the results of the analysis and design.

Creating Nodes:

When you select the Nodes command in geometry menu, it shows a dialog box

where you can enter the joint coordinates.

After creating the joint i.e. entering the coordinates, you can able to see the joint in

the modeling area.

JOINT COORDINATES

i1, x1, y1, z1, (i2, x2, y2, z2, i3)

REPEAT n, xi,yi1, zi1, (xi1, yi2, . . . . xin, yin, zin)

(32)

Enhanced Grid Tool:The options in Snap/Grid Node tools in the geometry menu

have been improved to

1. Allow multiple grids to be created.

2. Import a DXF file and use it as be created.

(33)

Beams, plates and 8 nodes solid element can be created using the suitable

Snap/Grid tool. When this function is propelled, the following dialog is opened

which includes a Default Grid. This grid will be of type ‘linear’, there are also

options to create Radial, and Irregular grids.

As new grids are added or modified, the information is stored in the STAAD.Pro

data folder with a GRD allowance that permits other STAAD.Pro file to re-use

these defined grids. To alter the starting of this grid, click on the Edit button to

show the existing grid properties.

The current plane of the grid is set by selecting the required option. This can

rotated about one of the global planes by selecting the axis of rotation and setting

the angle.

The origin of the grid is marked on the graphics, with a small circle. The location

of the origin, specified in global coordinates, can either be defined explicitly in the

given X.Y and Z coordinates, or it can be set to the coordinates of an existing node

by clicking on the icon and then on the node itself in the graphical window. Note

that at this point the origin coordinate is updated.

(34)

The construction lines are used to specify how many gridlines are created either

side of the origin, the spacing between the gridlines and if there should be a skew

in degrees along either axis.

Click on the OK button to accept these settings.

Additional grids can be defined by clicking in the Create button. Three different

types of standard grid can be created:



Linear



_Radial



Irregular

The type of the grid required can be selected from the drop down list available at

the top of the property sheet.

Each new grid should be identified with a unique name for future reference. The

functionality for each type of grid is given below:

Linear:



Two dimensional system of regularity spaced linear construction lines

creating a plane of snap points.



Plane is defined as being coincident with the global XY, XZ or YZ planes or at

an angle skewed with respect to the global planes.



Location of the origin can be defined with respect to global X, Y and Z

coordinates systems.

Radial:



Two dimensional system of regularly spaced radial and circumferential

construction lines creating a plane of snap points.



Plane is defined as being coincident with the global XY, XZ and YZ planes or

at angle skewed with respect to the global planes.



Location of the origin can be defined with respect to global X, Y and Z

coordinates systems.

(35)

The settings for a Radial grid are defined in the following window:

The Plane, Angle of Plane and Grid origin option are as for the linear.

Irregular:



Two dimensional system of regularity or irregularly spaced linear

construction lines creating a plane of snap points.



Plane is defined as being coincident with the global XY, XZ or YZ planes or at

an angle skewed respect to the global planes or at an arbitrary plane.

(36)

(37)

Translational Repeat

December 22, 2013 in

STAAD Pro

|

Translational Option allows to copy the entire structure or a portion of the

structure in a linear direction. We may generate one or more several copies of the

selected components. Select the structural elements to repeat. Select

Geometry→ Translational Repeat option from the geometry menu or Click

Translational Repeat Icon

. The Translational Repeat dialog box appears as

shown below:

Global Direction:

Choose any one of the three possible global direction along which the selected

structural elements should be copies.

No of Steps:

Specify the numbers of steps to repeated you need.

Default Step Spacing:

Type the default spacing between steps in the edit box in current length units. For

each step, the default value of the spacing will be what we provide in the Default

step spacing box. We can change the spacing of individual steps if we choose to do

(38)

Step Spacing Table:

This table consists of two columns: Step and Spacing. We can change the spacing

of any type in the table.

Renumber Bay:

This is the way of instructing the program to use a user-specified starting number

for the members generated in each step of the translational repeat activity.

Geometry Only:

The Translational Repeat allows the copying of the elements without having their

loads properties, steel design parameters, etc. being copied with it. By default

(when the Geometry Only option is not checked) all loads, properties, design

parameters, members releases, etc. on the selected elements will automatically be

copied along with the elements. By checking the option labelled Geometry Only,

the translational repeating will be per formed using only geometry data.

Link Steps and Open Base:

If you want to automatically connect the steps or copies by new members, along

the specified global directions, check the Link Steps check box. In other words, the

Link Steps option is applicable when the newly created units are physically

removed from the existing units and when one wishes to connect those using

members. To avoid joining the base of the copied structures, check the Open Base

box. Here you can see the Frame model copied using the Translational Repeat

option:

(39)

Circular Repeat

Circular Repeat allows to copy of the entire structure on an portion of if in a circular direction. Select the structural elements to repeat and select the Circular Repeat option from the geometry menu. The 3D Circular dialog box appears as shown in the figure.

Axis of Rotation:

Click the radio button to choose the axis of rotation for repeating the selected components. Through:

The new highlight node button selects the Node on Plane. Click on this icon to be able to select the node from the main model. Once the cursor changes the shape, simply select a node from the model. The Node and Point boxes will automatically fill up with the correct information.

Otherwise, type an existing Node number or location Point coordinates to define the axis of rotation.

Use this as Reference Point for Beta angle generation. In previous versions of STAAD.Pro, one limitations of the Circular Repeat feature was that the member orientation was not taken into consideration during the circular generation. This limitation has been addressed now.

If the Use this as Reference Point for Beta angle generation switch is turned on, the point through which the axis for circular repeat operation passes will be used as the member reference point for all the generated members. This point along with the local X axis of the generated member will

(40)

define the local X-Y plane of the member and hence the member orientation gets automatically set.

Total Angle:

Provide the total sweep angle of rotation between the original structure and the last copied structure.

No of Steps:

Provide the number of steps we want over the specified Total Angle. Link Steps and open Base:

If you want to automatically connect the steps by new members, check the Link Steps check box. To avoid joining the base of the copied structure, check the Open Base box.

The Circular Repeat. Rotate and Mirror dialog boxes have been enhanced to remain open so that the selection beams, nodes, etc. can be accomplished even while the box is open. Also, selection of critical points such as the node, point or plane where the axis of rotation crosses can now be selected graphically while the box remains open. This eliminates the inconvenience in the past where if this location was known before selecting one of the geometry options, the box had to be closed down to determine the location first.

1. Select the objects to be copied.

2. Click Geometry→ Circulation Repeat.

3. In 3D Circular dialog box, select the Axis of Rotation and Point or Coordinate of Axis. 4. Type the Total angle and No of Steps.

(41)

5. Click OK.

Insert Node

This facility allows the user to insert node on an existing member. The member is split into the

corresponding number of segments with automatic generation of node and member numbers, member properties and loads.

If you choose this option, the Insert Node cursor appears. By using that cursor, you can select the member to split. The Insert Node dialog appears, as shown below:

Beam Length:

(42)

New Insertion Point:

Provide the Distance from the start node of the member in current length units. Alternatively, provide Proportion of the total length of the member to position the new node. Click Add New Point to add the node.

Add New Point:

After providing the Distance or the Proportion, click on the Add New Point to add the node. Add Mid Point:

To split the member into two segments, click on this button. Add n Points:

To divide the beam in a number of equal segments, provide the number of intermediate points in the n = edit box and click on Add n Points. Note that this value should be an integer.

Insertion Points:

The locations of the newly created points are listed in this list box, shown as the distance from the start node of the member, To accept the new nodes that appear in the Insertion Point list box, click the OK button.

Remove:

To remove a node from the list of inserted nodes, highlight the desired node and click on this button.

Enhancement of Insert Node Operation:

Users can now select multiple members and split the members at a given fractional position or a specified distances from the starting node positions. The new feature will enable the users to perform the operation in one sight command which will reduce the modelling time.

New point by distance:

Specify the distance in current length units at which the beam is to split. The value for the distance is entered in the Distance edit box and is measured from the start node of the beam. New point by proportion:

(43)

This option allows the users to specify the distance in terms of a ratio. For example, to split a beam at the midpoint, enter 0.5 as the proportion .To split the beam at quarter points, use a proportion value of 0.25.

Add mid point:

The beam are split at their midpoints. Add ‘n’ points:

To split a beam by inserting ‘n’ number of points, use this option. The beams are split up into n+1 segments.

Add Beam

This option in geometry menu allows you to add members by connecting existing nodes. Choosing this option brings up the following sub-menu.

Add Beam from Point to Point:

In prior versions to STAAD.Pro, the Add Beam option was a facility for adding a beam between two existing nodes. This has now been extended to be able to create beams from nodes that have not been previously defined. The nodes can now be dynamically generated at the time of creating the beam similar to the way beams are created using the Snap/Grid Beam command.

To create a beam dynamically without the start and end nodes defined, go to Geometry|Add Beam|Add Beam from Point to Point from the main menu. The Add Beams cursor appears. Click on any point on the existing beam where the starting node of the new beam will lie. if an existing node is not present at that point, a dialog box will prompt for a new node to be created.

(44)

Click on Yes to create a new node. The Insert Nodes dialog box will prompt for the exact location where the nodes is to be created. once the desired node or nodes have been input that box, click on the OK button to generate the new nodes on the selected beam. If the new node input is not within a close proximity of the point clicked on the screen, no “draggable”line will be shown. Click on the new node to start the creation of the beam. Then, drag the mouse to another existing node location or repeat the same steps again to dynamically create another new node.

Run Structure Wizard

The Run Structure Wizard option offers a library of ore-defined structure prototypes, such as Pratt truss, North light Truss, cylindrical Frame, etc. We may parametrically generate a structural model and then transfer and superimpose it on the current structure.When we select the Run Structure Wizard option from the Geometry menu, the Structure Wizard window appears as shown below.

(45)

The Protype Models and Saved User Models options on the top of the left side of the screen. If the Prototype Models option is selected, the Model Type will list the types of prototype structure available as shown below. If the Saved User Models option is selected, the Model Type will display the list previously done and saved models by the user.

Adding and Deleting items to the library:

Items can be deleted or added with certain settings from and to the list. The modified item list can be saved in different files and called when requires. In brief , the item list is customizable.

To insert any customized item under any Model type, select that Model Type and click the mouse at the bottom of the same pane. Right-click the mouse and from the context menu, select Add Plug-in and you can load the corresponding “.dll” file. We can also delete a particular structural item by selecting that particular item and by clicking the Delete Model Plug-in from the context menu. A structural item under any Model Type may be renamed by using Rename Model Generator from the context menu.

The customized list of the Prototype can be saved in different files. By default,

STAAD.Pro/Structure Wizard uses the default .STP file. We can save any changes in this file. Also changes can be saved in any file other than default .STP. To save the changes, select Save As…. from the File menu in the Structure Wizard window. Provide the path and name of the .STP file and press OK.

(46)

To open any .STP file to use the customized Structure Libraries, select the File|Open menu option from Structure Wizard main menu. Specify the path and name of the .STP file and press OK.

Use the View, Zoom, Pan and Rotate icons to change the orientation of the model.

Generation of Structure from Models

In this section, the process of generating a structural model and combining it with the existing

STAAD.Pro structure will be explained using a Howe Roof Truss. Follow these steps to create the other truss types also.

Selection of Unit:

The unit of the length should be specified before the generation of a model. From the File menu, click Select Unit and the Select Unit dialog box will appear as shown below. We can select any unit of length from Imperial or SI/Metric system of units.

Model Type: Truss

Select the Howe Roof structure type under model type Trusses. Drag the item into the right side window and release the button. The Select Parameters dialog box will appears to specify the Truss parameter as shown below:

After defining the parameters click Apply and the prototype truss will appears with the X, Y and Z axes on the screen.

(47)

Right click in the right side window containing the generated model. The context-menu will display the options Change Property, Scale and Delete. We can edit the value of the parameters by clicking the Change Property, which will pop-up the select Parameters dialog box. Enter the length, height and width of the truss and the number of bays along those directions. To modify the spacing of individual bays, click the browse button and in the dialog box that appears, type new spacing and click OK. Click the Apply button to parametrically generated the truss model. Click Close to finish.We can re-scale the model in X, Y and Z directions separately using Scale from the context menu. You can also delete the particular model by clicking Delete from the context menu.

Merging the Generated Model to STAAD.Pro

Select the Merge Model with STAAD.Pro sub menu from the File menu to combine the generated model. to the current STAAD.Pro structure

(48)

The structure Wizard window will now close. In the STAAD.Pro window, the Paste Prototype Model dialog box will appears., in which we can type the shift of the origin of the Structure Wizard model from the origin of the STAAD.Pro axis system or we can type coordinate of the node of the STAAD.Pro structure with which we can want to connect the Structure Wizard model or click on the Reference Pt button to connect the node of the existing structure in STAAD.Pro with the Structure Wizard model by clicking on the joints where they will be connected. Click OK to finish.

In the Frame Models Continuous Beam, Bay Frame, Grid Frame and Floor Grid have similar parameters in the Select Parameter dialog box. Type values for Length, Height & Width and number of bays for each. To modify the spacing of the bays, click the browse button and in the dialog box that appears, type new spacing and click OK. Click the Apply button to the

parametrically generated model.

The Cylindrical Frame, Reverse Cylindrical Frame and Circular Beam have similar Parameter in the Select Parameter dialog box. Type values for Length, Radius, Angle and number of bays along length and periphery. To modify the spacing of bars, click the browse button and in dialog box that appears, type new spacing and click OK, Click the Apply button to parametrically generate the model.

(49)

Support Specification

This allows the user to define the support conditions of the structure by providing fixed, pinned, roller, inclined, spring supports, etc. Supports can defined and assigned from the General| Support page also. This menu option is used to specify the supports on the structures. The Support Specification menu offers several sub-menu options, as follow.

Click Commands→ Support Specifications.

Pinned:

This allows user to create the pinned support tag and assigned it to the selected nodes. A pinned support is restrained in all three translational degree of freedom and free in the 3 rotational degrees of freedom

(50)

Fixed:

This allows the user to create a fixed support tag and assign that to the selected nodes. A fixed support is restrained in all 6 degree of freedom.

Fixed But / Spring:

This allows the user to create various types of roller, hinge and spring support with specified restrained degrees of freedom and to assign them to selected nodes.

Enforced:

The Enforced support is the same the fixed support except that the restrained degrees of freedom are defined in terms of being stiff springs. Enforced supports are identical to the ‘FIXED’ type of supports in most respects. The real advantage of using the ENFORCED type lies in the fact that is enables STAAD to accept loads such as support displacements loads in case of plates and solids. Support displacement loads are not permitted for plates and solids if the FIXED support type is used. So, for structures without these characteristics, the FIXED type of support offers the same level of functionality as the ENFORCED support type.

(51)

Enforced But:

Enforced But support type is the same as the “Enforced” support except that we have the choice on the degrees of freedom we wish to restrain. For example, we can select Enforced But and restrain just the FX, FY and FZ degree of freedom and let the remaining 3 free to deformation. Inclined:

This allows the user to create supports that restraints in an axis system that is inclined with respect to the global axis system. There are two aspects defining the inclined supports:

 The reference point which inclined axis system.

 The restraints, releases and springs.

Foundation:

To define a spring support for an isolated footing, click the Footing radio button. Provide the dimension of the footing in current units settings and choose the Direction of the spring action. Provide the soil Sub-grade value in the edit box. Click the Add button to add the foundation support tag to the structure or click Assign to assign this support to selected nodes.

(52)

Elastic Mat: In this method, the area is calculated using a Delaunay triangle principle. Hence the candidates for this options are nodes which define the mat. To achieve best results, one needs to ensure that the contour formed by the nodes form a convex hull.

Plate Mat: If the foundation slab is modeled using plate elements, the spring supports can be generated using an influence area calculated using the principles used in determining the tributary area of nodes from the finite element modelling standpoint. Hence the candidates for this option are the plates which define the mat. When the mat is modeled using plates. this produces superior results than the ELASTIC MAT type.

(53)

Support Page

When the General | Support Page is opened, a Supported Nodes tables and a Supports dialog box appears in the data area. We may specify supports in two ways. We must first create Support Specification and then select the nodes to which this support is to be attached to. Alternatively, we may first select the nodes and then specify a support to be assigned to the selected nodes. In second case, a new Support Specification is created along with a support reference number. Also note that the Assign button become active if we have already selected the nodes to which the support is to be applied.

Supported Nodes Table list all nodes for which supports have been defined. The type of support is also displayed. The Supports dialog box allows us to define supports and assign them to nodes. All supports that have been defined for the model are listed in the Supports dialog box.

Create:

The Create button is for creating the supports to be applied on the structure. When you click this button Create Support dialog box appears.

(54)

Edit:

For certain types of supports, the parameters of the support can be modified after the support is created. The Edit button is available for that purpose. To do this, first select that support type from the list. Click on Edit and dialog box corresponding to that support will be re-displayed, allowing for changes to be made.

Delete:

Use this button to delete a previously assigned support.

Assignment Method:

The options under the Assignment Method offer different choices for assigning supports to the structure.

Assign To Selected Nodes:

To assign a support to selected nodes, first select the support from the supports dialog box. The support selected is highlighted. Then select the nodes to which this support is to be assigned. When all the desired nodes are selected, click the Assign To Selected Nodes radio button, then click the Assign button.

Assign To View:

To assign a support to all free nodes in a view, first select the support from the Supports dialog box. The selected supported is highlighted. Select the Assign To View radio button, then click the Assign button. All free nodes in the structure are assigned this support after getting the confirmation.

Use Cursor To Assign:

To assign a support to nodes using the cursor, first select the support from the Supports dialog box. The selected support is highlighted. Select the Use Cursor To Assign radio button, then click the Assign button. The button will appear depressed and label will change to Assigning. Make sure that the Nodes Cursor is selected so that we can select the nodes. Using the cursor, click on the nodes to which this support is to be assigned. Click on the Assign button again to finish.

Assign To Edit List:

To assign a support using a typed list of node numbers, first select the support from the Supports dialog box. The selected support is highlighted. Select the Assign To Edit List radio button, then type the list of node numbers and click the Assign button.

(55)

Member Property

This allows the user to provide the cross sectional properties of members with or without the material specification. The same options can be gained access from the General | Property page. The Member Property menu option is used to create the property tag and then assign the specified property tag to select members through the Property Page. Alternatively, we may first select members and then define the member property to be assigned to these members.

The Member Property menu offers several sub-menu options as shown below:

Prismatic:

This allows the user to assign Circular, Rectangular, Tee, Trapezoidal, General, etc. Cross sections to the frame members.

When we select the Prismatic option, the Property dialog box appears as shown below. Also note that the Properties dialog box also opens simultaneously letting us utilize some of the other operations available from that dialog box.

(56)

Material: Check this box and select the material from the drop down list if the new member property tag should include the materials constants.

Circle: To define a circular section, click on the Circle tab as shown in the previous figure. Enter the section diameter YD and select teh material.

Rectangle: To define the rectangle section, Click on the Rectangle tab. Enter the height YD and width ZD of the section and select the material.

Tee: To define a tee section, click on the tee tab. Enter the height YD, width ZD stem height YB and stem width ZB and select the material.

Trapezoidal: To define a trapezoidal section, click on the Trapezoidal tab. Enter the height YD, top width ZD, bottom width ZB and select the material.

(57)

Tapered Tube: This allows the user to specify a I-section having a varying depth over the length of the member by using 7 parameters as shown below:

Member Offset

The beams and columns of structure are characterized by lines in the computer model. In the actual structure, a beam spans distance which in the clear span between the faces of columns. But in the computer model, the line for the beam spans among the centerlines of the column. The half depth portion of either column is significantly stiffer than the beam itself from the stand point of bending. To take benefit of this extra stiffness, we may affirm that the start and end faces of the beam are offset from the node by a distance identical to the half-column-depths.

Member offsets can be specified in other situations too. Examples are

 When a bracing member does not meet the node which is defined in its incidence list.

 A girder and top slab in the bridge where the centerline of the girder is several inches below the centerline of the slab.

This facility becomes very useful when the user wants to have the structural parameters of a member viz. shear force, bending moment by considering the clear distance of the member between the supports. This facility can accessed from the General | Specification also. When you select the offset menu option in the command menu, the Member Specification dialog box appears as shown below.

(58)

Location:

Location defines the offset end of the member. Start is the starting point of the member and End is the Ending point of the member. Start and End depends on the Member Incidence of the member. Selecting one of these options defines the member offset to be at the start point or at the end point of the member.

Direction:

Choose the Local for assigning the offsets in the local axis system. Otherwise, choose the global axis system.

Offsets:

Type the offset distance from the joint in the three global directions. Click the Add button to add this specification to the structure or click Assign to assign the specification to selected member as well as add this specification to the structure.

(59)

Loading – 1

In STAAD.Pro V8i, loads in a structure can be detailed as Dead load, Live load, Wind load, Snow load, Seismic load, temperature load and fixed-end member load. STAAD.Pro V8i can also calculate the self-weight of the structure and make it as uniformly distributed loads (UDL) in analysis. Self-self-weight of the members can be applied in any desired direction.

Click Commands→ Loading→ Primary Loading.

Now the Create New Definitions / Load Cases / Load Items dialog box appears. Now you have to define the loads, then click Add button.

Dead Load or Self-weight:

Self-weight of all active members of the structure are calculated and applied as a uniformly distributed load. Please note that the property of the member must be defined before this command used.

(60)

 Direction- Specify the direction in the self-weight load is to be applied by clicking on the X, Y or Z

buttons.

 Factor- Specify the factor with which the calculated self-weight are to be multiplied. A negative

value indicates that the load is applies along the negative direction of the selected axis. Nodal Load:

Nodal loads is the combination of forces and moments, it may be applied to any free node of a structure. These loads act in the global coordinate system of the structure. Two options are available under Nodal Load: Node and Support Displacement. Positive value forces acts in the positive coordinate directions of the axis.

Member Load:

(61)

Concentrated Load:

To specify a concentrated force or moment, click the Concentrated Force or Concentrated Moment tab. The data items are explained below.

(62)

Linear Varying Load:

(63)

Loading – 2

Area Load: This allows the user to apply load over area, which will be distributed on surrounding beams based on the one way distribution. This load is a one-way distributed pressure load on members that circumstances a panel. Enter the value of area load in current units. This load always acts along the positive local y direction on the two longest member on each panel.

Note: Area load should not specified on members declared as Member Cable, Member Truss or Member Tension.

Floor Load: User can apply the load over the panel, which will be distributed on surrounding beams based on a two-way distribution. This load is two-way distributed pressure load on members that circumscribe a panel. The data items are explained below:

Load – Floor load value in the current units. This load will act parallel to the global vertical axis. Direction – The floor may be considered as acting perpendicular to plane of the panel on which it is defined. This is normal load static condition.

(64)

Range – Define X Range/ Y Range/ Z Range. Specify the location of the floor using the Define X Range option. The load will be calculated for all members lying between this range.

One Way Distribution – Check the box for one way distribution to get a one way type distribution of the pressure. In such cases, the program find out the shorter side of the panel. It then divides the load in between the long direction beams. No load is generated by this option if the panel is square in shape.

Plate Load: The Plate Load tab allows the user to apply elements loads. The Plate Load tab offers several sub-menu options as shown below.

(65)

Pressure On Full Plate:

Load – W1 is the variable using which the pressure value is defined, in pressure units.

Direction – The load may be applied along the local Z – axis, or along one of the global X, Y or Z – axis (GX, GY, GZ)

(66)

Use this option to define a concentrated load that acts on specific point within the boundary of the element. If a load acts at a node point of an element, it is advisable to apply it using the Nodal Load option described in earlier pages.

Load – The magnitude of load is specified in the box alongside Force. X and Y define the location of the load, in terms of the distance from the origin of local X and Y axes of the element.

Direction – The load may be applied along the local Z-axis, or along one of the global X, Y or Z – axis (GX, GY, GZ).

Partial Plate Pressure:

To Specify a uniform pressure on the entire element or a non user specified portion of the element, use this facility. The data items are explained below:

Load – The element pressure (force per unit area) or Concentrated load (force unit). For

concentrated load the values of X2 and Y2 must be omitted, while X1 and Y1 must be specified. X1, Y1, X2, Y2 – For element pressure (force per unit area), these values represent the

coordinates of the rectangular bpundary on which the pressure is applied. If X1, Y1, X2 and Y2 are all zero; the pressure is applied over the entire element. If X1 and Y1 are specified but X2 and Y2 are omitted, then W1 is treated as concentrated load.

Direction – GX, GY, GZ represent the global X, Y and Z direction along which the pressure may be applied Local Z indicates that the pressure is applied normal to the element in the local Z direction.

Trapezoidal: To specify a trapezoidal varying pressure load on a plate, select the Trapezoidal tab. The load is applied over the entire element in the local Z direction, varying along the positive local X or Y direction. The data items are explained below.

(67)

Direction of Pressure – GX, GY and GZ represent the global X, Y and Z direction along which the pressure may be applied. Local Z indicates that the pressure is applied normal to the element in the local Z direction. Enter the pressure intensity F1 at the lowest local coordinate location (start) and the intensity F2 at the highest local coordinate location (end), Start and End are defined basd on the positive direction of the local X-axis or local Y-axis.

Variation along element – Define the direction in which the pressure varies as either the local X ot Y direction or Choose the joint option, which is discussed next.

Joint – Check the joint option to apply different value of pressure at different nodes of the plate element. When checked, the dialog box will change as shown below. Apply different values of pressure in the edit boxes for the different nodes.

Hydrostatic: To model loads due to hydrostatic pressure on one or more adjacent elements, select the Hydrostatic tab. The hydorstatic load is converted to Trapezoidal loads on the elements. The load is applied over the entire area of the element. The data items are explained below:

(68)

Force – Enter the value of the load at the minimum and maximum global axis in current units. For example, to model a retaining wall with soil pressure, W1 is the force at the bottom of the wall and W2 is the force at the top of the wall.

Interpolate along Global Axis – Specify the global axis (X, Y or Z) along which the load vary from W1 to W2. For example, the load would vary along the Y – axis on a vertical retaining wall.

Select Plate(s) – Unlike the load definition options, we must select plate(s) for this option to became active. Click on this button to select plate(s). Click on the Select Plates button. A dialog box will appear. Select all the plates of a wall on which we wish to apply hydrostatic load. Click on Done. The hydrostatic dialog box will re-appear.

Direction of pressure – Specify the direction of design pressure as Local Z axis or global axes (GX, GY or GZ) and click on Add. This will assign a linearly varying hydrostatic load on all the selected elements.

Element Joint Load: To specify a varying pressure at each joint on a plate, select the Element Joint Load option. The data items are explained below.

Joint Load Data – Choose Three Noded Facet / Four Noded Facet depending on whether the plate element is 3 noded 4 noded.

Direction – The load may be applied along the local Z – axis or along one of the global X, Y or Z – axis (GX, GY, GZ)

Add – After defining a load, click the Add button to add this under current load case in the Loads dialog box.

(69)

Wind Load Generation

The wind load generation is a utility, which takes place as an input wind pressure and height ranges over which these pressures act and generates nodal point and member loads.

This facility is available for two types of structures: 1. Panel type or closed structures.

2. Open structures.

Closest structures are ones like where non-structural entities like glass facade, aluminium sheets, timber panels or non-load bearing walls act as an obstruction to the wind. If these entities are n and ot included in the structural mode, the load generated because of wind blowing against them needs to be computed. Therefore, the steps involved in load generation for such structure are

1. Identify the panels – regions circumscribed by members so that a polygonal closed area is formed. The area may also be formed between the ground level along one edge and members along other.

2. Calculate the panel area and multiple it by wind pressure. 3. Convert the resulting force into nodal point loads.

Plates and solids are not considered in the calculation of the panel area. Openings within the panels may be modelled with the help of exposure factors. An exposure factors is associated with each joint of the panel can be reduced or increased.

Open structures are those like transmission towers, in which the region between members is “Open” allowing the wind to blow through it. The procedure for load generation for open structures is

1. Calculate the exposed area of the individual members of the model.

2. Multiply that exposed area by the wind pressure to arrive at the force and apply the force on the individual members as a uniformly distributed load. It is assumed that all members of the structures within the specified Rangers are subjected to the pressure and hence, they will all receive the load. The concept of members on the Windward side shielding the members in the inside regions of their structures does not exist for open structures.

At a large structure may consist of hundreds of panel and members, the user with the help of this facility can avoid a considerable amount of work in calculating the loads.

The wind load menu option allows the user to define the parameters for automatic generation of wind loads on the structure.

(70)

STAAD.Pro V8i is now capable of generating the wind pressure profile for a structure in accordance with the ASCE-7-95 as well as the ASCE-7-02 codes. The pressure profile is the table of values of wind intensity versus height above ground.

The calculated pressure may then be applied on the structure to compute loads on the member using the in-built program’s wind load generation algorithm for the closed as well as open-lattice type structures.

When the wind load B&B of my menu option is selected, the new wind type dialog box appears, as shown below.

Enter the ‘Type No.’ which denotes the number by which the wind load type will be identified. Multiple wind types can be created in the same model. Click on the Add button within this dialogue box and then click on close.

(71)

Select the TYPE 1 name in the tree control and click on the Add button. The dialogue box shown below will prompt for the pressure profile for this wind definition.

As we said earlier, the pressure profile is the table of wind intensity versus height above ground. If we know that, that information can be typed into the box above.

To calculate the wind intensity, use the following formula from IS 875-Part 3. Vz = Vb k1 k2 k3 and pz = 0.6 Vz2

where, Vz = Design wind speed at any height

Vb = Base wind speed.

k1 = probability factor.

k = terrain, height and structure size factor. k3 and = topography factor.

(72)

pz = design wind pressure.

Exposure:

The exposure tab is used to modify the influence area of wind load associated with particular joints in the structure. By default, the exposure factor is 1.0, thus the wind force is applied on the full influence area associated the joints. Click on Add to add this load under the current load case in the load dialogue box.

Assigning Wind Load

This tab allows the user to apply previously created wind load type on the structures through the means of a load case.If the model already contains previously defined wind load cases, a

(73)

Select type:

Choose a previously defined wind load type from the drop down list. Direction:

Specify the global direction in which the wind load is to be generated by clicking the X, Z, -X or –Z radio button. When wind is generated in X direction, the wind load is applied on the near side and when –X is chosen the load is applied on the far side. Generation in Z or –Z also works the same way.

Factor:

Specify the factor to multiply the calculated wind loads. Open structure:

By default, the load generation is based on the assumption that the region between members is covered by panels. To generate loads on open structures like highway signs or transmission towers, switch on this box. The members are selected and X is used and the factor is positive, then the exposed surface facing in the –X direction will be loaded in the positive X direction. If X and a negative factor, then the exposed surface facing in the X direction will be loaded in the negative x direction. If –X is entered and a positive factor, then the exposed surfaces facing in the +X direction will be loaded the positive X direction.

(74)

Analysis

STAAD.Pro V8i offers STAAD engine for general purposes structural analysis and design. The modelling mode of STAAD environment is used to prepare structural input data. After the analysis is performed, used the menu option File→ View→ Output File→ STAAD Output to view the output files.

The STAAD Analysis engine perform analysis and design simultaneously. However, to carry out the design, the design parameters too must be specified along with the geometry, properties, etc. Before you perform the analysis. Also, note that you can change the design code to be followed for design and the code check before performing the analysis/design.

Perform analysis:

To do the analysis must be need to add the command from Commands→ Analysis→ Perform analysis…

(75)

This allowed the user to specify the instructions for the type of analysis to be performed using STAAD engine. In addition, this command may be used to print various analysis-related data such as load information, statics check information, mode shapes etc.

The analysis menu offers several sub menu options. When you select one of the analysis

commands, you may specify the analysis-related data to be printed in the STAAD output (.ANL) file by selecting the print option radio buttons, explained below:

Load data: print all the load data.

Statics check: provides summation of the applied load and support reaction as well as summation of moment of load and reactions taken around the origin.

Statics load: print everything that statics check does and summation of all internal and external forces at each joint.

Mode shapes: print mode shapes values at the joints or are calculated mode shapes. Both: this option is equivalent to the load data plus statics check option.

All: this option is equivalent to load data plus statics data. Run Analysis:

The Analysis is performed under the commands under the analyse menu in the Modelling Mode. Select the Run Analysis option to perform Analysis/Design.

(76)

This dialog box displays the status of the analysis process. If an error occurs during the analysis, the above dialog box displays the error message.

View Output File: it will invoke the STAAD viewer with the analysis results presented in a textual format.

Go to Post Processing Mode: it will take you to the STAAD.Pro Post processor where you can graphically.

Stay in Modelling Mode: it will keep you in Modelling environment.

During the analysis, an output file is generated. This file may contain selected input data items, results and error messages. To include a report of the input data items in the output file, use the menu options under Commands | Pre Analysis Print. The generated output file may be viewed using the menu option File | View | Output File | STAAD Output.

Any errors that occur during the analysis process may be viewed using the menu option File→ View→ Output File.

(77)

Concrete Design

STAAD has the capabilities of performing concrete design on limit state method of IS 456 (2000).

Beam Design:

Beams are designed for flexure, shear and torsion. If required the effect the axial force may be considered. For all these forces, all active beam loadings are pre-scanned to identify the critical load cases at different section of the beams.

Column Design:

Columns are designed for axial forces and biaxial moments at the ends. All active load cases are tested to calculate reinforcement. The loading which yield maximum reinforcement is called the critical load. Column design is done for square, rectangular and circular sections. By default, square and rectangular column and designed with reinforcement distributed on each side equally for the sections under uni-axial moment.

Design Parameters:

The program contains several parameters which are needed to perform design as per IS 456 (2000). Default parameter values have been selected that they are frequently used numbers for conventional design parameters. These values may be changes to suit the particular design performed.

Performing Concrete Design:

1. Click Commands→ Design→ Concrete Design.

2. Now the user can specify the design parameters for the structure. 3. Concrete Design dialog box appears.

(78)

4. Click the Select Parameters button. Now you can select the desired parameters for the concrete design.

(79)

Important Parameters To Be defined Are Given Below: Parameter Name Default Value Description

FC 25000 KN/mm2 Concrete yield strength.

FYMAIN 415000 KN/mm2 Yield stress for main reinforcing steel. FYSEC 415000 KN/mm2 Yield stress for secondary reinforcing steel.

MAXMAIN 60 mm Maximum main reinforcement bar size.

MAXSEC 12 mm Maximum secondary reinforcement bar size.

MINMAIN 10mm Minimum main reinforcement bar size.

MINSEC 8 mm Minimum secondary reinforcement bar size.

(80)

7. Click Add button to add the parameters, then assign the commands to the respective members.

8. Assign the DESIGN BEAM to the members parallel to X and Z direction.

 Click Select→ Beam Parallel To X.  Click Select→ Beam Parallel To Z.

9. Assign the DESIGN COLUMN to the members parallel to Y direction.

 Click Select→ Beam Parallel To Y.

10. Then Run Analysis, the result provide the suitable concrete design for the structure. NOTE: After the analysis,double – click the member of the structure, it show the concrete design, if the concrete design of the element is missing, then it is said to unsafe.

(81)

Time History Analysis

Time history analysis is an advanced method of dynamic analysis. It has an ability to incorporate harmonic forcing functions that can be described by sinusoidal curves with a specified arrival time, frequency, amplitude and duration.

Define Time History Dialog:

Used to define the Forcing Function of a time varying load.

Click Commands→ Loading→ Definitions→ Time History→ Forcing Functions is selected or The Add… button is clicked in the Load & Definition dialog found on the General | Load & Definition page.

(82)

Integration Time Step:

Solution time step used in the step-by-step integration of the uncoupled equations. Type:

This refers to the number of the type of functions. Loading type:

Select the Acceleration, Force or Moment option to define the type of functions being input. Save:

Select this option to create an external file containing the history of displacements of every node of the structure at every time step.

Function Options:

(83)

Used to specify a time history forcing function, where the loading type is that selected above. Specify the values Time and corresponding Force or Acceleration. The time history function is plotted on the bottom of the dialog as data pairs are entered.

Harmonic:

Curve Shape:

Specify if the harmonic function is a SINE or COSINE curve. Frequency or RPM:

Choose Frequency and enter circular frequency in cycles per second or RPM and enter revolutions per minute.

Amplitude:

Max. Amplitude forcing function in current units. Phase:

Phase angle in degrees. Cycles:

(84)

No.of cycles of loading. Step of Sub Div:

Choose the step option to time step of loading SubDiv to sub divide a 1/4 cycle into this many integer time steps.

Spectrum:

Select this Function Option to provide spectrum parameters for your time history loading. Time History Parameters Dialog:

Time Step:

Specify a solution time step to be used in the step-by-step integration of the uncoupled equations. Damping:

The following options are available for specifying damping:

Damping-this is to be used for specifying a single model damping ratio which will be applied to all mode. The default value is 0.05.

CDAMP – if a damping ratio has already been specified under CONSTANTS based on the type of material in the structure, the value may be used directly in time history analysis. Check this option for that purpose.

MDAMP – we wish to utilise individual damping ratios for individual modes, that is achieved through the means of the MDAMP option. The first step to doing this is the specification of those individual damping ratios, as explained under section 5.26 .3 of the STAAD technical reference manual and is done graphically from the command-define damping menu. If this first step has been completed, the instruction to utilise MDAMP done by selecting this option shown above.