COMMANDS AND FUNCTIONS

SNAPBoxBeam^tm is a family member of SNAPBridge: Bridge Analysis and Design Suite, which is used for Steel Box Girder Bridge Analysis and Design.

This chapter desbribes the commands and their functions of SNAPBoxBeam.

SNAPBoxBeam commands are classified into 9 categories.

The commands listed under these menu items can be accessed from the menu bar located at the top of the SNAPBoxBeam window.

SNAPBoxBeam offers a shortcut menu, which contains some of the frequently-used commands. The shortcut menu can be initiated when you click the right button of your mouse. The shortcut menu includes the following commands:

This command will close the opened project workspace and create a new workspace. Before the operation, the program open a confirmation dialog box to ask you if you are sure to do so.

If you click Yes, then a File Open common dialog box will appear. The File Open dialog box contains the standard Windows file open functions. In the file type listbox, you specify what type of file you want to create. If you select .snp file, the program will close the existing project workspace and create a new workspace with the name you specify.

If there is a file with new data in the workspace when activating the New command, a warning message box will appear to ask if any current changes in the file are to be saved. Selecting OK will save the existing data. The user must supply a file name to save the data under.

Selecting Cancel will not not proceed to create a new workspace.

If there is existing data in the work space when activating the Open command, a message box will appear asking if the current change to the existing file in the work space is to be saved. Selecting OK will save the data and require the user to supply a file name in which to save the data.

This command will save the existing problem using the current name. No warnings will be issued from this command. This command is useful for saving intermediate steps during a work session.

If the data is not saved using the Save As command first, the file will not have a specified name and the Save command will do the same task as Save As.

This command will allow the user to rename a problem file and save it under a new name. The previous file will be retained. Program changes will not be updated under the old file name. The Windows File Save common dialog box is used for the Save As command…

This command connects with the Windows printer setup. It will activate the Printer Setup dialog box.

This command will allow users to preview the screen images to be printed.

This command will print the screen image. The image can be the structural mode, deflection, camber, moment, shear, stress diagram or typical bridge section, girder elevation and framing plan.

This command exits SNAPBoxBeam and returns to SNAPManager.

This command is used to invoke the Select mode. When the command is pressed, user can move the mouse cursor to the position of element or node and click the left button of the mouse to select the element or node. When a element is selected, Divide Element and Assign Girder Section can be performed for the selected element.

Clicking this command will make all the elements and nodes of the structural model be selected.

This command is used to invoke the Window Select mode. When the command is pressed, user can press the left buttom of your mouse, move the mouse to change the rubber-band window. When the button is released, all elements and nodes located inside the window will be selected.

Clicking this command will make all the elements and nodes set to be in un-selected model.

This command is used to divide a selected element to small elements. This command will open a dialog box which asks the user to input how many segments the selected element will be divided.

This command is used to turn on or turn off the Grid in the drawing mode.

This command is used to turn on or turn off the Node ID in the drawing mode.

This command is used to turn on or turn off the Element ID in the drawing mode.

This command is used to turn on or turn off the Element Section ID in the drawing mode.

This command is used to move the drawing on the screen.

This feature is included for drawing convenience, allowing objects to be moved on the screen and this procedure is very useful when a portion of an image has been enlarged by zooming.

Panning can be used to manipulate an image around the screen instead of constantly zooming back and forth to work on different regions of an image.

Click on the Pan button. Move the mouse pointer on the screen.

Press on the left mouse button and without releasing the button, move the pointer in the direction to pan. Panning is achieved when the left mouse button is released.

This command allows the enlargement of a portion of a drawing on the screen.

Click on the Zoom Window button. Click on the corner of the zoom area using the left mouse button and drag the mouse, thus forming a rectangular zoom boundary containing the drawing or portion of the drawing to be enlarged. Do not release the left mouse button, until satisfied with the zoom boundary.

This command is used to reset the drawing extend and origin to the imediate previous values.

This command is used to reset the drawing extend and origin to their original default values.

This command is used to define the general information for the bridge. It will open a General Information Definition dialog box, which asks user to input/change the following data:

• Project Name
• Project Number
• Comments
• Type of Road
• ADTT
• ADTT (Single Lane ADTT for LRFD)
• Number of Design Lanes

If you create a new SNAPBoxBeam file, the General Information Definition dialog box will automatically open to ask these information.

To input span length, type the number and press Add button. Use Modify buttom to revise the span length which you selected from the span length listbox. Use Remove button to remove a span you selected.

After you click on OK button of the dialog box, a structural model will appear on the client area of the screen. Then you can divide the elements into more short elements to increase the calculation precision (see EDIT-DIVIDE ELEMENT command).

This command is used to set values for concrete and steel material properties.

Clicking on the command will open a Material Property definition dialog box.

The steel properties requires the definition of the following fields:

E (Modulus of Elasticity)

fy (Yield Stress)

w (Unit Weight of Steel)

The concrete properties requires the definition of the following fields:

wc (Unit Weight of concrete)

This command is used to define the girder section dimensions. The Girder Sections Definition dialog box will be opened after users click Girder Sections command.

To add a new Girder Section, input the dimension fields and press Add button.

To modify or remove a Section, select the section from the list box and change the numbers in the related text boxes, click Modify or Remove button.

To define Box Girder Section, set focus to Section Name field and type a name. The text boxes associated with box girder section will be enabled, Then click Add button.

Remember, there are two top flanges for a box girder. The top flange dimension defined here is for one top flange. The web inclination ratio is defined to be the ratio of horizontal dimension to a unit vertical dimension (1.0).

This command is used to define the dimension of roadway /typical bridge section.

Please remember that the haunch thickness defined here includes the depth of top flange. Therefore, the distance between top of web and bottom of deck slab is equal to the haunch thickness. The distance between top of top flange and bottom of deck is equal to the haunch thickness minus the thickness of top flange.

This command is used to define the composite ratio and rebar information in the negtive moment region near the intermediate supports. The rebar area is defined to be the area of steel in one linear foot of deck slab width.

This command is used to define the loads.

After clicking Loads command, the Load Definition dialog box will apear. To add a load case, select an item from the Load Case combo box. There are six predefined load groups:

• Self Load
• 3N Superimposed Distributed Dead Load
• 3N Superimposed Concentrated Dead Load
• 1N Superimposed Distributed Dead Load
• 1N Superimposed Concentrated Dead Load
• Highway Live Load
• Sidewalk Live Load

Distributed loads can start and end at any point on a beam. The load intensity can be varied by entering different Left End and Right End intensity values. Positive distributed loads are downwards and negative distributed loads are upwards.

Concentrated loads can be entered with positive or negative values to define the direction in which the load is applied. Positive means downwards and negative upwards.

Existing loads can be modified by selecting the load name from the list box, revising the data and clicking on the Modify button. Note, the Modify button must be pressed to record the revised data. To remove a load, highlight the load in the load list box and click on the Remove button.

Click on the OK button to accept the selections and close the Loads dialog box. Pressing Cancel will close the Loads dialog box and erase any data which has been entered.

Please remember that the loads or load intensity defined for superimposed dead load is for one box girder instead of the girder system.

This command is used to define cross frame, transverse and longitudinal bottom flange stiffener and shear connector information.

To define the lateral bracing information, input the starting and end coordinates, the number of spacings and an unique Name, and press Add button. To modify, select a name first and revise the numbers and press Modify button. To delete a lateral bracing group, select it from the list box and press Remove button.

Please remember that for Channel shear connectors, one channel at each top flange is placed at each location. For Shear Studs, the number of studs per line here means how many studs at each top flange are provided in transverse direction at each location. For Other Types of Connector, the Zr and Su values are for one line of connectors in transverse direction.

This command is used to assign a section ID for selected element. Assign Section dialog box will appear after clicking this command.

This command is used to solve the problem.

When you click the command, a dialog box will be displayed, which shows you the progress of the program execution. When the run finishs, the OK button is enabled, you can click it to exit.

This command is used to display the output file. When you click on this command, SNAPTxtEditor is activated to open the output file (.obb). You can browse, print the file in SNAPTxtEditor. When you finish looking at the file, select Close command in File Menu of SNAPTxtEditor to return.

This command is used to display the undeformed structural model on the screen. Whatever is displyed on the screen right now, it will switch to undeformed model after you click this command.

This command is used to display the deflection diagram of the girder on the screen. A dialog box will be opened after you click this command, which asks you to specify which of the following 3 load cases to be displayed:

• Steel Dead Load only
• Deck Dead Load only
• Steel and Deck Dead Load

This command is used to display the camber diagram of the girder on the screen. A dialog box will be opened after you click this command, which asks you to specify which of the following 3 load cases to be displayed:

• Steel Dead Load only
• Deck Dead Load only
• Steel and Deck Dead Load

This command is used to display the moment or shear diagram of the girder on the screen. A dialog box will be opened after you click this command, which asks you to specify which of the

following 4 diagrams to be displayed:

• Unfactored Moment Diagram
• Unfactored Shear Diagram
• Factored Moment Diagram (LFD and LRFD)
• FactorShear Diagram (LFD and LRFD)

When you select Factored Moment to show, the screen will display the Factored Moment Diagram. When you select Factored Shear, the Factored Shear Diagram will be shown.

This command is used to display the typical roadway section of the bridge on the screen.

This command is used to display the framing plan of the bridge on the screen.

This command is used to display the girder elevation on the screen.

This command is used to set the code information etc. The Settings dialog box is opened when you click on this command. The dialog box asks you to select the following options:

Unit System Option: There are two unit system radio buttons: Metric System and US Customary. By press the button to set the Unit System you want to use for this project. SNAPBoxBeam Version 2 only support US Customary Unit System.

Design Method Option: SNAPBoxBeam Version 2 supports AASHTO Allowable Stress Design (ASD), Load Factor Design (LFD), and Load and Resistance Factor Design (LRFD). You have to select which method to be used for this girder design. The default is LFD.

Live Load Analysis Precision Option: Because live load analysis takes most of the CPU time for SNAPBoxBeam analysis, SNAPBoxBeam offers the option for live load analysis precision. You select any of Low, Medium and High precision for the run. The default is Medium-Precision, which is normally good enough.

Construction Option: This option allows you to specify the girder to be designed as Composite or Non-Composite girder. Based on current engineering practice, Composite is strongly recommended. Therefore, SNAPBoxBeam Version 2 only supports Composite Structure option. If you select Non-Composite Structure, the girder will still be analyzed and designed as Composite. SNAPBoxBeam Version 3.0 and later supports non-composite option.

Standard Windows command to arrange the opened windows in cascade mode.

Standard Windows command to arrange the opened windows in tile mode.

This command activates Tips of Today dialog box.

This command activates the HTML help.

This command activates the program information dialog box which gives the SNAPBoxBeam version number, user information and the user's serial number.