Precast I Girder [PIG]
- mert.goktas (Unlicensed)
- Melis Ceylan
- Umut Nuhat Sevinc
- Cagin Yakar
Girder Parameters
Girder Layout: The girder layout is utilized to determine the position of the girder in both the longitudinal and transverse directions. The user is not required to input the vertical elevation of the precast girders; instead, the precast girders are vertically positioned automatically based on the alignment, deck thickness, and haunch thickness of the girder.
Tendon Layout Type[Straight/Harped]: Tendon layout type can be selected as 'harped' or 'straight.' Then, the tendons in the defined sections will be used to automatically generate a 3D representation of the tendons.
If 'straight' tendon is selected, one section is required.
If 'harped' tendon is selected, two sections—one at the start and one in the middle—and the harped region length are required to create a 3D representation of the tendons. The tendons in the two sections will be automatically connected based on tendon coordinates; the user must ensure that the number of tendons in both sections is the same. The correctness of entered inputs can be quickly verified in the 3D view.
Follow the instructions below to model tendons for the girder. Also note that the modeled tendons and rebars (under Properties - Sections) will not be included in the FEA but can be used in design and code checks according to definitions made by the user.
To define tendons in the section editor, follow these steps:
If you require multiple tendon layouts for various girders or need harped tendon definitions, you can efficiently duplicate the sections as necessary. To do this, start by navigating to the "Sections" in the tree view, locate the prestressed I Girder section, and then click on the three-dot menu to duplicate it as needed.
Click on 'Section Editor' in the three-dot menu to view the section in the section editor. Next, click on 'Tendons' using the + Shapes icon to add a tendon layout.
Typically, parametric tendons are used to quickly define tendons with respect to the bottom or top reference line of the section. However, users can click on the 'Enter Parameters' button to activate the UI for drawing tendons.
Refer to the screenshots below to understand the meaning of the parameters. Typically, the bottom reference edge will be selected for straight tendons to enter the distance with respect to the bottom reference line of the section, and the top reference edge will be used for harped tendons defined at the top.
Refer to the parameter explanations below for any parameters that are not defined in the screenshot.
Prestressing Type: The prestressing type is utilized solely for certain code check procedures and does not impact any other calculations.
Strand per Tendon and Strand: The parameters "Strand per Tendon" and "Strand" will be employed to calculate the tendon's cross-sectional area.
Force in Tendon: Input "0" to utilize a force equivalent to 0.75 times Fu (ultimate tensile strength) multiplied by the tendon's cross-sectional area. For any other desired value, users should enter it accordingly.
Debonding Length: Usually, the debonding length is not entered when defining the tendon layout. Instead, it is entered after the tendon layout is exploded for a single tendon. Use the edit menu to “Explode” the tendon layout after the definition is completed. Then Edit debonding length value for each tendon. Debonding lengths will be displayed graphically, as shown in the screenshot below, to represent different lengths. This allows users to verify their entered data.
Girder Start-End Section: Enter the start and end section of the girder with tendons. When the harped tendon layout is active, tendons that are at the top should be defined in this section.
Girder Mid Section: Enter the mid-section of the girder with tendons when the harped tendon layout is active.
Hor. Dist. of Harped Tendon Region: This parameter is used to determine the horizontal distance between the start and end of the harped tendon region. A symmetrical assumption is made for both the start and end regions of the girder, so the entered value will also be applied to the both parts.
Haunch Thickness: The vertical distance between the top of the girder and the bottom of the deck. This parameter will also be utilized in load calculations.
The modeled tendons under Properties > Sections and the longitudinal reinforcements modeled on the Precast I Girder > Reinforcement tab should be visible in the 3D model after completing the steps mentioned above. Note that the longitudinal reinforcements defined under Properties > Sections will not be generated for the 3D model.
FEA Settings
Rigid Section: Rigid beams are employed to link the nodes of girders with bearing locations/supports as seen in the screenshot below. Please refer to the following documentation to understand how to define rigid sections.
Moment Release Start[Fixed/Free]: If the user needs to connect two different, discontinuous girders using a single bearing location, the 'Moment Release Start' can be set to 'Fixed'—based on the location of the girder to be connected—which will enable moment transfer between the two connected girders. Otherwise, when girder segments are defined with two bearings individually and separately, the moment release can be defined using the 'Free' option.
Moment Release End[Fixed/Free]: If the user needs to connect two different, discontinuous girders using a single bearing location, the 'Moment Release Start' can be set to 'Fixed'—based on the location of the girder to be connected—which will enable moment transfer between the two connected girders. Otherwise, when girder segments are defined with two bearings individually and separately, the moment release can be defined using the 'Free' option.
Mesh Size (Longitudinal): The maximum distance between nodes in the longitudinal direction is specified using the longitudinal mesh size. In most cases, a smaller mesh size compared to the entered value might be generated due to bracing locations, deck pouring, or deconstruction definitions
# of Result Extraction St.: The result extraction station settings are solely for viewing FEA composite results in either the spreadsheet or FEA view, and do not impact standard finite element analysis results like member end forces, node displacement, and node reactions. For girder code checks, exact code check stations will be utilized for FEA composite results.
Visual Settings
Girder Opacity: The opacity of the girder can be specified using this parameter. A value from 0 to 1 can be used, where a higher value results in a more opaque element. An opacity value of 1 may prevent viewing tendons through the section.
Tendon Opacity: The opacity of the tendons can be specified using this parameter. Similar to girder opacity, a value from 0 to 1 can be used, where a higher value results in a more opaque appearance.
Reinforcement Opacity: The opacity of the reinforcements can be specified using this parameter. Similar to girder opacity, a value from 0 to 1 can be used, where a higher value results in a more opaque appearance.
Circular Smoothness: This parameter can be used to adjust the visual representation of both tendons and rebars modeled for a precast I girder. A higher value for circular smoothness will result in a smoother shape for the rebar or tendon when displayed in 3D.
Reinforcement
Show [Yes/No]: Users can specify whether the longitudinal reinforcements modeled using the Precast I Girder object (under the Reinforcement tab) should be displayed in the model. To ensure that the reinforcements are displayed, users must set the Show parameter to YES and turn on the Detailing option in the top sidebar.
Longitudinal Reinforcement Data:
To further define the longitudinal reinforcements of the related Precast I Girder, the parameters listed below can be used.
Reinforcement Profile: A profile for longitudinal reinforcements can be assigned using this parameter. The profile can either be imported or assigned from previously defined ones under the section Properties.
Reinforcement Material: A material can either be imported or assigned from previously defined materials to the longitudinal reinforcements using this parameter.
# of Bars: The number of bars can be specified using this parameter.
Inner Rebar Spacing: The spacing for the bars located in the inner parts can be specified using this parameter.
Outer Rebar Spacing: The spacing for the bars located in the outer parts can be specified using this parameter.
Reference Edge [Top/Bottom]: The reference edge can be specified using the options Top and Bottom.
Distance to Reference Edge: The location of reinforcements with respect to the reference edge can be specified using this parameter.
Offset from Start: An offset value can be specified for the reinforcements beginning from the start of the precast girder.
Offset from End: An offset value can be specified for the reinforcements beginning from the end of the precast girder.
Horizontal Offset from Center: The horizontal offset of the rebar group (defined in a row) can be specified using this parameter. A positive value indicates an offset to the right when looking upstream along the PGL.
Shear Reinforcement Data:
To further define the shear reinforcements associated with a specific Precast I Girder, this section can be used.
The shear reinforcements modeled in this section will not be displayed in the 3D model and will only be used for code checks and design purposes.
Start Distance (From Start of Girder): This parameter can be used to specify the distance where the initial shear reinforcement will be placed.
End Distance (From Start of Girder): This parameter can be used to specify the endpoint of the shear reinforcement.
Reinforcement Profile: A profile for shear reinforcements can be assigned using this parameter. The profile can either be imported or assigned from previously defined ones under the section Properties.
Reinforcement Material: A material can either be imported or assigned from previously defined materials to the shear reinforcements using this parameter.
Spacing: The spacing values of the shear reinforcements can be defined using this parameter.
Number of Legs: The number of legs for the shear reinforcements can be specified using this parameter.