Construction Analysis of Precast Bridge

March 4, 2021
BLOG CASE STUDY

In March 2020,  we hosted a webinar, “Case Study : Construction Stage Analysis of Precast Bridge" by Saathwik Vudayagiri, Structural Engineer, BECA.

 

In this webinar, we will introduce the advantages of midasCivil using essential functions especially for precast bridge analysis.

 


Key Points

 

The useful features of midasCivil in precast bridge analysis :

 

1. Construction Staging and Composite Sections

2. Creep and Shrinkage Calculator

3. Prestressing Load Application and Calculation of losses

4. Moving Load Analysis

 


 

The precast girders bridge in the webinar

 

The project example below is  from Monash Freeway. A 3 span Continuous bridge with Precast Super-T Girders. Note that the bridge is only continuous for Wearing Course, Crash barriers and Live Loads.

 

The precast girders bridge in the webinar

Group function allows us to proceed construction stage definition.

 

  • Step 1. Generation of all temporary and permanent members, boundary conditions and loading.

  • Step 2. Definition of  Structure Groups, Boundary Groups and Load groups.

  • Step 3. Allocation of elements, boundary conditions and load cases to each group.

  • Step 4. Activation of deactivation of each group on each stage.

 

modeling


 

Construction Sequence in the example bridge 

 

1. Installation of precast Super-T girders supported on temporary supports.

2. Pouring the deck on the girder.

3. Continuous slab and transverse diaphragm over permanent supports. 

 


 

Advantages of Construction Stage Analysis

 

- Model view window simulate  each construction stage model.

 

- Results show the change of behavior from when deck is simply supported under dead loads to continuous deck  under permanent dead loads and Live loads.


- Composite Section function allows a single model to be analyzed considering  both non-composite and composite girder.


- Stresses calculation is provided along the stages considering time dependent tendon losses.

 

- Prestressing forces is able to be activated on different stages.

 

 

 

 


 

Consideration of long term effect

 

- Time dependent material properties are linked to Material Properties of Longitudinal elements.
- Auto calculation of Hypothetical thickness for longitudinal elements based on sectional properties.

 

 

Consideration of long term effect

5


 

Definition of Tendon Profile

 

- Tendon profile in the analysis model allows us to consider eccentricities of the tendon in the cross section of the girder. 

 

- If the strand layout is symmetrical in the cross section, each layer of strands can be applied as a single of Typical tendon by applying the number of the symmetrical tendons.

 

Definition of Tendon Profile


Watch the Full Case Study Here

 

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About the author
Saathwik Vudayagiri | Structural Engineer | BTech MSc

Saathwik is a Structural Engineer within Beca Bridges & Civil Structures in Melbourne. He has over 5 years of experience in the design of transportation infrastructure and other ancillary structures in Australia, UAE and Qatar. He is familiar with international standards including AS 5100, Eurocodes, AASHTO Bridge Design Specifications and Indian standards. 

 

Project Experience

- Monash Freeway Stage 2 Upgrade, (Melbourne, VIC)
- SRU Initial Rectification Works
- West Gate Tunnel Project, (Melbourne, VIC) 
- Moggs Creek Bridge Replacement, (Melbourne, VIC)
- M1 Motorway Extension, (NSW, AU

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