Floor System Tutorial

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1 AASHTOWare BrD/BrR 6.8 Floor System Tutorial FS3 - Floorbeam Stringer Floor System Example

2 Topics Covered Superstructure composed of floorbeams and stringers System Superstructure Definition Rolled beam stringers Plate girder floorbeams, linearly varying web Using wizards to create member alternatives for stringer and floorbeam members This example demonstrates entering a Floorbeam-Stringer superstructure in BrR using the System superstructure definition approach. It is assumed that the user of this example is an advanced user who is familiar with the basics of BrR. As such, the details of creating bridge materials, beam shapes, etc., are not presented in great detail in this example. If you have already completed example problem F-Floorbeam Stringer Line Example, you can open the bridge you created in that example and jump to Page FS4-5 to start this example. If you have not completed F- Floorbeam Stringer Line Example, continue with this page. Last Modified: 8/30/2016 1

3 From the Bridge Explorer, select File/New/New Bridge to create a new bridge. Enter the following description data: Last Modified: 8/30/2016 2

4 Create the following materials for the bridge. (The structural steel can be copied from the library.) Last Modified: 8/30/2016 3

5 Copy the following steel beam shapes from the library to the bridge. These shapes will be used for the stringers in this superstructure. Last Modified: 8/30/2016 4

6 Add the following appurtenances to the bridge. Last Modified: 8/30/2016 5

create a new superstructure definition. The dialog shown below will appear.

7 Double click on SUPERSTRUCTURE DEFINITIONS (or click on SUPERSTRUCTURE DEFINITIONS and select File/New from the menu or right mouse click on SUPERSTRUCTURE DEFINITIONS and select New from the popup menu) to create a new superstructure definition. The dialog shown below will appear. Selecting Floor System Superstructure will display three types of floor system superstructure definitions. Last Modified: 8/30/2016 6

8 Select Floorbeam Stringer and click OK. The Floorbeam Stringer Floor System Superstructure Definition window will open. Enter the appropriate data as shown below. Last Modified: 8/30/2016 7

9 The following describes some of the terminology on this window. As shown by the sketch, this structure has 6 stringers. Each floorbeam in a Floorbeam-Stringer superstructure is considered to be a support line so this superstructure has 5 support lines since it has 5 floorbeams. Floorbeam Stringer Stringer Units are the portions of the structure where the stringers are to be analyzed as structurally continuous units. In this structure, the stringers are simple span between the floorbeams and there are 4 stringer units. Each stringer unit contains 6 stringer members. Stringer Unit 1 Stringer Unit 2 S1 S1 Stringer Unit 3 Stringer Unit 4 S1 S1 Floorbeam1 Floorbeam2 Floorbeam3 Floorbeam4 Floorbeam5 S1 S1 S1 S1 45'-0" 45'-0" 45'-0" 45'-0" Framing Plan (Stringers are shown in red, they are single span between floorbeams.) 4 Stringer Units in this superstructure definition Last Modified: 8/30/2016 8

10 The partially expanded Bridge Workspace tree is shown below: Last Modified: 8/30/2016 9

If you have created a new bridge for this superstructure definition, now create a Bridge Alternative, a Superstructure, a Superstructure Alternative and assign the superstructure definition we just

11 If you have created a new bridge for this superstructure definition, now create a Bridge Alternative, a Superstructure, a Superstructure Alternative and assign the superstructure definition we just created to the Superstructure Alternative. Enter the data shown in the following windows. If you are adding this superstructure definition to the bridge you created in Example F, simply assign this superstructure definition to the Superstructure Alternative you created in Example F. Last Modified: 8/30/

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13 Now go back to defining the superstructure definition. Double click on Load Case Description to define the dead load cases. Click the Add Default Load Case Descriptions button to add four default load cases. The completed Load Case Description window is shown below: Last Modified: 8/30/

14 Enter the appropriate data on the Framing Plan Details window as shown below: Last Modified: 8/30/

15 Next enter the data describing the typical section as shown below. Last Modified: 8/30/

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17 This superstructure does not contain any transverse or bearing stiffeners so we will not create any stiffener definitions. Last Modified: 8/30/

The floorbeam member locations for the structure are shown below: These floorbeam member locations were created when the superstructure definition was created based on the number of support lines and

18 The floorbeam member locations for the structure are shown below: These floorbeam member locations were created when the superstructure definition was created based on the number of support lines and the span lengths between floorbeams entered on the Superstructure Definition window. You cannot revise the location of the floorbeam members on this window because their locations are set by the span lengths entered on the Superstructure Definition window. Enter the distance from the left edge of the deck to the left edge of the floorbeam for each floorbeam. This data positions the floorbeam relative to the structure typical section and the lane positions. Last Modified: 8/30/

19 Double click on STRINGER GROUP DEFINITION GEOMETRY to define the geometry for a stringer group definition. A stringer group definition contains data regarding a portion of the structure where the stringers are structurally continuous. The stringers in this structure all have the same span data. They are single span between 2 floorbeams. You can create one stringer group definition to contain this geometry data and then later apply this stringer group definition to all 4 stringer units in your structure. The Stringer Group Definition Geometry window opens as shown below. Last Modified: 8/30/

20 The default value for the Number of floorbeams that support this stringer group definition is 2. The Possible Floorbeam Spacing list shows all of the possible combinations of adjacent floorbeam spacings between 2 floorbeams. BrR uses the information shown in the Floorbeam Member Locations window to produce this list. This structure has a constant floorbeam spacing of 45 feet so this list only has one entry, 45. Select Yes for the field All floorbeams are perpendicular to the structure definition reference line. The Skew Angle column in the Floorbeam Spacing grid will now be disabled. If some of the floorbeams in the superstructure definition were not perpendicular to the superstructure definition reference line, you would select NO and then pick the appropriate skew angle in the Floorbeam Spacing grid. It is necessary to know which floorbeams in the stringer group definition are skewed because skewed floorbeams will cause the stringer span lengths in the stringer group definition to vary. The stringers in this stringer group definition have the following support types. Stringer Stringer Support Type: FB A Simple FB B Simple Enter data in the Floorbeam Spacing grid to describe the span lengths of the stringer members that will be in the stringer units to which this stringer group definition is assigned in the Floor System Geometry window later. In this example, the default values in the grid are correct and we do not need to enter any data in the grid. Last Modified: 8/30/

21 Click Apply to save the Stringer Span Length data to memory before we enter the diaphragms on the Diaphragms tab. You can click F1 while this window is open to view examples illustrating how to define stringer group definitions. Select the Diaphragms tab to enter diaphragm spacing for the stringer group definition. Each diaphragm bay contains only 1 diaphragm along the length of the stringer group definition. Enter the following data for Diaphragm Bay 1 and use the Copy Bay To button to copy the data to the other diaphragm bays. Last Modified: 8/30/

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Assigning Stringer Group Definitions to Stringer Units: Open the Floor System Geometry window and assign stringer group definitions to stringer units in the floor system superstructure definition.

23 Assigning Stringer Group Definitions to Stringer Units: Open the Floor System Geometry window and assign stringer group definitions to stringer units in the floor system superstructure definition. Enter the following information. Checking the Include in Analysis checkbox for a stringer unit will mark all stringer members in the unit to be included in when a batch analysis is run for the superstructure definition. Last Modified: 8/30/

24 When we first open this Floor System Geometry window, we know the total number of stringer members in this structure is 24 since there are 4 stringer units and each unit contains 6 stringers. We don t know where the stringer members are located along the length of the structure nor do we know how long each stringer is. The stringer members in the structure are all located at the beginning of the structure and do not have any length to them until a stringer group definition is assigned to the stringer units. The stringer group definition defines the stringer span lengths. Assigning stringer group definitions to the stringer units also locates the stringer members along the length of the structure. Click F1 while this window is open to view examples illustrating how to assign stringer group definitions to stringer units. End of previous unit is intersection of last floorbeam in the stringer group definition and superstructure def. reference line S1 S1 Stringer group definition workpoint is intersection of first floorbeam in the stringer group definition and the superstructure def. reference line. S1 S1 Floorbeam1 Floorbeam2 Floorbeam3 Floorbeam4 Floorbeam5 S1 S1 S1 S1 45'-0" Stringer Unit 1 (Uses Stringer Group Def 1) 45'-0" Stringer Unit 2 (Uses Stringer Group Def 1) Framing Plan 45'-0" Stringer Unit 3 (Uses Stringer Group Def 1) 45'-0" Stringer Unit 4 (Uses Stringer Group Def 1) Superstructure Definition Reference Line If we now view the Structure Framing Plan Schematic, we see dashed lines representing the stringer member and floorbeam member locations. The members appear as dashed lines because we have not yet assigned member definitions to the members. The diaphragms we entered in the stringer group definition are also displayed in the Framing Plan Schematic. Last Modified: 8/30/

Select Steel for the Material Type and Plate for the Girder Type. The Floorbeam Definition window will open.

25 Describing a Floorbeam Member Definition: This superstructure contains 1 floorbeam definition that is applied to all floorbeam members. Expand the MEMBER DEFINITIONS tree item and double click on FLOORBEAM DEFINITIONS. Select Steel for the Material Type and Plate for the Girder Type. The Floorbeam Definition window will open. Enter the appropriate data as shown below. Select Schedule based Floorbeam property input method. This definition is used to describe FB1 in the structure. Last Modified: 8/30/

26 Describe the floorbeam profile with the following data. Last Modified: 8/30/

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28 Describe the deck profile with the following information. Floorbeam deck effective flange width is calculated according to AASHTO Article , the effective flange width shall not exceed one-fourth of the span length of the floorbeam, 35'/4 = 105, the distance center to center of floorbeams, 45', and twelve times the least thickness of the slab, 12x8.5 = 102. One-fourth of the span length of the floorbeam, 102 controls. Last Modified: 8/30/

29 Enter the top flange lateral support information as shown below. The description of the floorbeam definition is complete. Last Modified: 8/30/

Describing a Stringer Member Definition: This superstructure contains 2 different stringer definitions that will be assigned to the interior and exterior stringer members in the superstructure

30 Describing a Stringer Member Definition: This superstructure contains 2 different stringer definitions that will be assigned to the interior and exterior stringer members in the superstructure definition. We will first create the exterior stringer definition. Expand the MEMBER DEFINITIONS tree item and double click on STRINGER DEFINITIONS. Select Steel for the Material Type and Rolled for the Girder Type. Last Modified: 8/30/

31 The Stringer Definition window will open. Enter the appropriate data as shown below. Select Schedule based Stringer property input method. You can select the Associate with stringer group definition button so that the stringer span lengths will be populated for you based on the stringers span lengths you specified in the Stringer Group Definition Geometry window. Last Modified: 8/30/

32 Enter the following stringer profile data. Last Modified: 8/30/

33 Next open the Deck Profile window and enter the data describing the structural properties of the deck. Stringer deck effective flange width is calculated according to AASHTO Article , the effective flange width shall not exceed one-fourth of the span length of the stringer, 45 /4 = = 135, the distance center to center of stringers, 7 /2+2.25' = 69, and twelve times the least thickness of the slab, 12x8.5 = 102. The distance center to center of stringers, 69 controls. Last Modified: 8/30/

34 Enter the following the haunch profile data. Last Modified: 8/30/

35 Enter the following lateral support data for the top flange. The description of the exterior stringer definition is complete. Last Modified: 8/30/

36 We now need to define the interior stringer definition. The interior stringer definition is very similar to the exterior stringer definition we just created so we will make a copy of the exterior stringer definition and change the following data. Make a copy of the stringer definition Type S1 and change the name of the copy to Type on its Stringer Definition window. Change the rolled shape assigned to the stringer profile to a W24x117. Last Modified: 8/30/

37 Change the Std Effective Flange Width on the Deck Profile window to 84 inches. The description of the Type stringer definition is complete. Last Modified: 8/30/

Defining a Stringer Member Alternative: There are two methods that you can pick from to create stringer member alternatives for the stringer members in your structure: 1.

38 Defining a Stringer Member Alternative: There are two methods that you can pick from to create stringer member alternatives for the stringer members in your structure: 1. You can manually create a stringer member alternative in the BWS tree and assign a stringer definition to this alternative. 2. The Stringer Unit Layout Wizard can also be used to quickly create stringer member alternatives for all of the stringer members in your structure. You can access this wizard by selecting the Wizard toolbar button while the STRINGER UNIT LAYOUT is selected in the BWS tree. This example uses the Stringer Unit Layout Wizard in Option 2 to create stringer member alternatives for the stringer members in this structure. Right click on STRINGER UNIT LAYOUT in the BWS tree and choose the Wizard toolbar button. Last Modified: 8/30/

39 The first screen in the wizard appears. The Stringer Unit Layout Wizard uses templates to store the data we enter in this wizard. Stringer group definition templates let you assign stringer definitions and live load distribution factors to stringer members in all of the stringer units to which a stringer group definition has been applied. This wizard contains a lot of data and templates are provided so you can save this data if you are interrupted while using the wizard. If for some reason you have to close BrR while entering this data, you can re-open the template to continue entering data at a later time. Our example has only 1 stringer group definition and it has been assigned to all of the stringer units in the Floor System Geometry window. The data we will enter in this will pertain to this stringer group definition and will thus create stringer member alternatives for all of the stringer members in the superstructure definition. The first screen of the wizard is shown below. Last Modified: 8/30/

The second screen in the wizard lets you assign stringer definitions to and enter names for the stringer member alternatives that will be created by the wizard.

40 The second screen in the wizard lets you assign stringer definitions to and enter names for the stringer member alternatives that will be created by the wizard. Use the Generate Stringer Member Alternative Names button to have the wizard generate the names for you using the specified prefix. Assign the stringer definitions to the alternatives as show below. Since we are assigning the same definition to both the existing and current alternative for each stringer member, the wizard will create only 1 alternative that is assigned as existing and current for each stringer member. Last Modified: 8/30/

41 The third screen of the wizard lets you assign live load distribution factors to stringer member alternatives. Use the Compute from Typical Section button to compute the Std live load distribution factors for the alternatives that will be created for Stringer 1. You will see a warning message that the distribution factors computed using simple beam distribution are zero for this member. This is due to the fact that this exterior stringer is not located under a travelway since it is under the sidewalk. Change the Shear at Supports value from 0.0 to and click Apply to save these distribution factors. Select Stringer 2 and repeat these actions to define the live load distribution factors. Repeat for the remaining stringer members. Last Modified: 8/30/

42 The last screen of the wizard is shown below. Select Finish to close the wizard and create the stringer member alternatives. Last Modified: 8/30/

43 The Bridge Workspace tree with the expanded Stringer Unit 1 Layout branch is shown below: Last Modified: 8/30/

44 Open the Stringer Unit 2 Layout window and check Stringer 1 and Stringer 2 for Include in Analysis. Last Modified: 8/30/

Defining a Floorbeam Member: There are two methods that you can pick from to create floorbeam member alternatives for the floorbeam members in your structure: 1.

45 Defining a Floorbeam Member: There are two methods that you can pick from to create floorbeam member alternatives for the floorbeam members in your structure: 1. You can manually create a floorbeam member alternative in the BWS tree and assign a floorbeam definition to this alternative. 2. The Floorbeam Member Alternative Wizard can be used to quickly create floorbeam member alternatives for all of the floorbeam members in your structure. You can access this wizard by selecting the Wizard toolbar button while the FLOORBEAM MEMBERS label is selected in the BWS tree. This example uses the wizard approach in Option 2 to create floorbeam member alternatives for the floorbeam members in this structure. Right click on FLOORBEAM MEMBERS in the BWS tree and choose the Wizard toolbar button. Last Modified: 8/30/

46 Use the Generate Floorbeam Member Alternative Names to create the member alternative names. Assign the FB1 definition to all of the member alternatives. Check the Include in Analysis box for Floorbeam 2. Last Modified: 8/30/

47 The Bridge Workspace tree with the expanded FLOORBEAM MEMBERS branch is shown below: The description of the bridge is complete. Last Modified: 8/30/

All members are drawn as solid lines since we have now assigned member definitions to

48 The following is the structure typical section schematic view. The structure framing plan schematic view is shown below. All members are drawn as solid lines since we have now assigned member definitions to all members. The members that were checked off to be included in a batch analysis are shown with bold lines. Last Modified: 8/30/

49 Select the superstructure definition Floor System FS in the BWS tree and perform a rating for the H0 vehicle. The floorbeam and stringer member alternatives that were marked for include in analysis will be rated as shown in the Analysis Progress window. View the results by selecting a member alternative and clicking the View Analysis Report button on the toolbar. The window shown below is the Rating Results Summary of the Unit 2 Stringer 2 member alternative. Last Modified: 8/30/

50 Floorbeam 2 supports the stringers in both Stringer Unit 1 and Stringer Unit 2. Part of the analysis of Floorbeam 2 involves the dead load transferred from the stringers to the floorbeam. If the stringer dead load reactions to be used in a floorbeam analysis do not exist or are not up to date or do not have a user defined override value, BrR will trigger a dead load analysis of the stringer prior to initiating the floorbeam analysis. Then a Virtual stringer analysis is run. This analysis is run to obtain the live load reactions from the stringers the floorbeam supports. For this virtual analysis, the stringer cross section is assumed as prismatic and only the stringer span lengths and live load are actually obtained from user input. Once the live load reaction from the stringers is obtained, an analysis of Floorbeam 2 is run. The following shows the View Latest Analysis Output window after a rating of the superstructure definition is performed. An analysis of each of the stringers that the floorbeam supports has been performed to obtain the stringer dead load reactions on the floorbeam even though we only marked the Unit 2 Stringer 1 and Unit 2 Stringer 2 members to be included in the analysis. If we were to analyze the superstructure definition again without closing the Bridge Workspace in between analyses or making any changes to the data for these stringer members, analyses of the stringers in Stringer Units 1 and 2 for their dead load reactions would not be performed again since that data is currently available in memory and up-todate. Last Modified: 8/30/

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52 Each Stringer Unit Layout has a Computed Stringer Reactions window that displays the computed stringer dead load reactions for all of the stringer members in that unit. This window displays any previously computed reactions and any newly computed reactions. Last Modified: 8/30/

53 The appearance of this window is dependent on the Analysis Preferences (menu View Preferences) you have set for your PC. If you have selected to Automatically save the new computed stringer reactions the window will appear as shown above. If you have not selected to automatically save these reactions, the window will appear with the reactions in the New Computed Reaction column and you should click the Select All button and then OK or Apply to copy these reactions to the appropriate floorbeams. Last Modified: 8/30/

54 Each floorbeam member has a similar window that displays the stringer dead reactions acting on the floorbeam. You are given the opportunity to override these computed dead load reactions on this window. Last Modified: 8/30/

AASHTOWare BrD/BrR 6.8 Floor System Tutorial FS1 - Girder Floorbeam Stringer Example

AASHTOWare BrD/BrR 6.8 Floor System Tutorial FS1 - Girder Floorbeam Stringer Example AAHTOWare BrD/BrR 6.8 Floor ystem Tutorial F1 - Girder Floorbeam tringer Example CL 2'-0" 15'-0" 15'-0" 2'-0" 9" 21WF62 (typ) 5 spaces @ 6 = 30-0 Concrete curb & railing = 0.3k/ft each side Fy = 36ksi