Midas Civil - MIDAS Useruk.midasuser.com/web/upload/sample/Construction_Stage_Analysis... · Contents Why Construction Stage Analysis? Conventional Analysis vs Construction Stage

Construction Stage AnalysisMidas Civil

Presenter:

Robert Salca – technical support engineer, Midas UK

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Contents

Why Construction Stage Analysis?

Conventional Analysis vs Construction Stage Analysis

Construction Stage Analysis in Midas Civil

Procedure for Construction Stage Analysis

Time Dependent Material Properties

Construction Stage Definition

Construction Stage Results

Live Demonstration

Q&A

Sutong Bridge


Each temporary structure arrangement ca lead to critical internal forces or displacements in specific members;

Each temporary structure at a particular stage of construction affects the subsequent stages;

It is common to install and dismantle temporary supports and cables during construction;

The structural behaviours such as deflections and stressre-distribution continue to change during and after the construction due to varying time dependent properties such as concrete creep, shrinkage, modulus of elasticity (aging) and tendon relaxation;

The safest and most economical construction process must be chosen, especially for complex construction operations.

Contents








Live Demonstration

Q&A

Stonecutters Bridge


General analysis is performed under the assumption that all loads are simultaneously applied to a completed structure;

This assumption is not valid in a real construction sequence because most bridges are constructed by segments and the dead load acts sequentially.

Conventional Analysis vs Construction Stage Analysis Conventional Analysis

Construction Stage Analysis Stage 1

Stage 2

Stage 3


Conventional analysis

Construction Stage Analysis

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Live Demonstration

Q&A

Basarab Viaduct Bridge


Time dependent material properties

Creep effects of concrete members having different maturities;

Shrinkage effects of concrete members having different maturities;

Time dependent compressive strength gain for concrete members;

Prestressing tendon relaxation.

Expression of Construction Stages

Creation (activation) and deletion (deactivation) of members with certain maturities;

Loading (activation) and unloading (deactivation) of loads relative to time;

Change of boundary conditions relative to time.

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Live Demonstration

Q&A

Lange Wapper Bridge


Create a structural model. Assign elements, loads and boundary conditions to be activated or deactivated to each construction stage together as a group;

Define the time dependent material properties such as creep and shrinkage. The time dependent material properties may be user defined or defined by the standards such as ACI and CEB-FIP;

Link the defined time dependent material properties to the general material properties through which the change of the concrete member material properties with time are automatically calculated and reflected;

Create the construction stages and time steps considering the true sequence of construction;

Define the construction stages using the predefined Element groups, Boundary groups and Load groups;

Specify the desired analysis conditions and carry out the analysis;

Combine the results of the construction stage analysis and that of the completed structure analysis as necessary.

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Live Demonstration

Q&A

El Marquez Bridge


Creep Increase in water/cement ratio increases creep;

Creep decreases with increases in the age and strength of concrete when the concrete is subjected to stress;

Creep deformations increase with increase in ambient temperature and decrease in humidity;

It also depends on many other factors related to the quality of the concrete and conditions of exposure such as the type, amount, and maximum size of aggregate; type of cement; amount of cement paste; size and shape of the concrete mass; amount of steel reinforcement; and curing conditions.

Shrinkage The rate of shrinkage decreases rapidly with time;

Finer aggregates and finer gels result in increased shrinkage;

The moisture content of the concrete and the relative humidity of the ambient medium have a big influence on carbonation shrinkage;

Harder aggregates with higher modulus of elasticity decrease shrinkage.


Creep & Shrinkage Strength Gain

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Live Demonstration

Q&A

La Jabalina Bridge


Group activation/deactivation concept;

Four types of groups: Structure groups;

Load groups;

Boundary groups;

Tendon groups.

Elements can be activated at any age, with properties accounting for the passage of time;

Partial or total force redistribution can be considered at deactivation of elements;

Loads can be activated/deactivated at any time during a construction stage;

Supports can be activated/deactivated at any time, either at the deformed or at the originalposition of the nodes.


Composite Section for Construction Stage

Pre-composite stage

Composite stage

Construction Stage Analysis Control Data

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Live Demonstration

Q&A

Lazarevsky Bridge


Load Case Results Description

1. CS: Dead Load

Reaction

Results due to all loadings excluding Erection Load and the effects of Creep, Shrinkage and Tendon PrestressDeformation

Force

2. CS: Erection Load

ReactionResults due to dead loads, which are separated from CS: Dead Load, defined in Construction Stage Analysis Control

Data dialogDeformation

Force

3. CS : Tendon Primary

Reaction

Deformation Deformation resulting from tendon prestress

Force Member forces resulting from tendon prestress

4. CS: Tendon Secondary

Reaction Reactions caused by Tendon Prestress in an indeterminate structure

Force Member forces caused by Tendon Prestress in an indeterminate structure

5. CS: Creep Primary

Reaction

Deformation Deformation due to imaginary forces required to cause creep stain

Force Imaginary forces required to cause creep stain

6. CS: Creep SecondaryReaction Reactions caused by creep in an indeterminate structure

Force Member forces caused by creep in an indeterminate structure

7. CS: Shrinkage Primary

Reaction

Deformation Deformation due to imaginary forces required to cause shrinkage stain

Force Imaginary forces required to cause shrinkage stain

8. CS: Shrinkage Secondary

Reaction Reactions caused by shrinkage in an indeterminate structure

Force Member forces caused by shrinkage in an indeterminate structure

CS: Summation

Reaction 1+2+4+6+8

Deformation 1+2+3+5+7

Force 1+2+3+4+6+8


Summation

Shrinkage

Creep

Prestress

Dead Load

Construction Stage Results for Tendon Prestress Loss

Construction Stage Results for Composite Sections

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Live Demonstration

Q&A

Ironton-Russell Bridge

Construction Stage Model

Stage 1 Activate substructure;

Activate Self Weight load;

Activate substructure supports.


Stage 2 Activate girders;

Activate Prestress load;

Activate Wet Concrete load;

Activate temporary supports and links.


Stage 3 Long-term stage;

Activate slab part of composite section and transverse grillage elements;

Activate Superimposed Dead load;

Deactivated Wet Concrete load;

Deactivate simply supported condition;

Activate final supports for girders.

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Live Demonstration

Q&A

Bang Hwa Bridge

Q&A

Thank you!

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Documents

Midas Civil - MIDAS Useruk.midasuser.com/web/upload/sample/Construction_Stage_Analysis... · Contents Why Construction Stage Analysis? Conventional Analysis vs Construction Stage