Overview of the Concrete Composite Girder Bridge Application in midas Civil
MIDAS has recently developed and implemented the modeling wizard for Prestressed concrete composite girder bridges for any girder type including I girder, T girder, Box girder, Void box girders, etc. This one-window modeling wizard creates a finite element analysis model based on the bridge layout, properties, boundary/substructure information, loading, and construction sequence information input. The wizard can handle both pre-tensioned precast girder composite bridges and post-tensioned spliced girder composite bridges. The instructor provides step-by-step guidance in wizard modeling using examples.
Wizard Modeling Process
Wizard Capability - Curve Geometry
Q: Can you model a bridge that goes from straight to curve mid-length? Can the wizard handle varying super-elevation of bridge superstructure?
A: Yes & Yes. Please refer to the online help manual: http://manual.midasuser.com/EN_Common/Civil/851/index.htm (or press F1 key in the midas Civil window.) > Content menu > Start menu > Structure tab > Wizard tab > Prestressed Composite Bridge Wizard > Layout > Multi-Curve option. You can also download a couple examples at: https://drive.google.com/file/d/0B-wfdCwh0wJfYjBySV9PTXRPLU0/view?usp=sharing
Wizard Capability - How to consider Expansion Joints and Locations
Q: Can you reflect the expansion joints between bridges using the wizard?
A: Yes. Please refer to the online help manual: http://manual.midasuser.com/EN_Common/Civil/851/index.htm (or press F1 key in the midas Civil window.) > Content menu > Start menu > Structure tab > Wizard tab > Prestressed Composite Bridge Wizard > Layout > "a" and "b" on the middle right side of the wizard.
Wizard Capability - General
Q: Please clarify what data does the Wizard File store.
A: MIDAS Wizard file saves the number and options that are entered in the wizard. (If you do not have the program installed at the moment, please refer to the online help manual at: http://manual.midasuser.com/EN_Common/Civil/851/index.htm > Content menu > Start menu > Structure tab > Wizard tab > Prestressed Composite Girder Bridge Wizard. The data that are not saved as a part of the wizard are the data that are a part of the Finite Element Analysis model such as the section property and material property. Also, if you wish to enter further data than what the wizard asks for the input, you can always enter the additional information after using the wizard. However, this data cannot be preserved if you wish to re-generate the model using the wizard. For example, the wizard does not ask for temperature loading input. If you want to define and apply temperature loading, user needs to execute the wizard first to create the model. Then, using the "define temperature loading" function outside the wizard, users can define the temperature load. If the user wishes to modify the wizard data and re-generate the model, this data needs to be re-entered after executing the wizard.
Q: How do you define the abutment soil springs using spring stiffness?
A: You have multiple options. 1. You can define it rigid type or input very high value stiffness to make the link or spring support rigid. 2. If you know the spring stiffness already, you can manually input them. 3. If you need the program to calculate the stiffness, you can use "Rigid type" spring. Then, you can run the analysis and review the analysis result for the spring stiffness value the program calculates automatically.
Q: Can we create the overall bridge with large geometry configuration using wizard, then modify elements as necessary?
A: Yes, of course. The wizard will create the finite element analysis model according to the bridge information input in the wizard. After the FEA model is created by the wizard, you have full access to EVERY functions of the program. You can enter additional data or modify the existing data of any type (node/element, property, load, boundary, etc.).
Q: After we use wizard to create the model, is there any easy way to modify the tendon profiles?
A: You have three options. 1. Since you can save your wizard data, you can always newly execute the wizard by bringing the wizard data saved previously. Then, you can modify the wizard data again. 2. If you do not wish to go back to the wizard, you can fix the tendon points at the Load main menu > Prestress > Tendon Profile. 3. If you do not wish to go back to the wizard, you can also use the Tendon Template to newly input tendon using template wizard at the Structure main menu > PSC Bridge > Tendon Template function. Refer to the online help manual for more details: http://manual.midasuser.com/EN_Common/Civil/851/index.htm (or press F1 key in the midas Civil window.)
Q: Can the wizard handle continuity post-tensioning of spliced girders?
A: Yes. Of course. Please refer to the online help manual: http://manual.midasuser.com/EN_Common/Civil/851/index.htm (or press F1 key in the midas Civil window.) > Content menu > Start menu > Structure tab > Wizard tab > Prestressed Concrete Composite Bridge wizard > Tendon tab > Guide tab. Also, during the training, this topic is covered specifically. Please refer to the training recording.
Q: Is it able to distinguish between one end and both end jacking?
A: Yes. By default, the wizard will apply jacking at both ends. After the wizard model is created, you can freely modify such detail at: Load main menu > Prestress Load Type > Prestress Loads tab > Tendon Prestress function > "Begin" and "End" option of Jacking.
Live Load Analysis
Q: In the girder design, the liveload effects are based on AASHTO liveload distribution factors or is it based on true moments/shears from the analysis?
A: By default, as a Finite Element Analysis program, midas Civil live load analysis takes the influence analysis approach as basis. However, by defining traffic lane directly above each girder and assign the distribution factor as the "scale factor" input in midas Civil, you can see the live load effect based on the distribution factor approach. The distribution factor needs to be computed outside the program.
Review Other Courses from This Series
Canadian Highway Bridge Design Code (CSA-S6-14) for Computational Analysis and Design
Introduction to Bridge Load Rating
Session 3: Essential Soil-Structure Interaction for Bridge
Session 2: All-In-One Super & Sub Structure Design
Session 1: Accurate 3D Substructure Design
Steel Composite Tub Girder Bridge Design and Load Rating in midas Civil
Suspension Bridge Design in midas Civil Step by Step Training
[Steel Composite Bridge] Part 1 - Wizard Modeling & Post-Wizard Modifications for Complex Bridges
[Prestressed Concrete Girder Composite Bridge] - Design Check/Load Rating/Excel Report