Director, Tony Gee, UAE

Peter Revees-Toy

MIDAS Elite Engineer

MIDASELITE ENGINEER TALK

Case Studies of Steel Bridge Design using FEM Analysis

Contents

1. Introduction of Case Studies

1) Bahrain Bridge

2) Doha Metro Station Roof

3) Doha Metro Temporary Bridge

2. Other Project Applications

3. Useful Functionality

1. Introduction of Case Studies

1. Bahrain Bridge – 2012

Temporary works and erection stress analysis

Construction stages, lift off supports, support displacement and structural interaction

2. Doha Metro Roof – 2015

Permanent Works

Complex steel frame, connection modelling

3. Doha Metro Greenline – 2015

Temporary Bridge for Tunnel Boring Machine

Plate and frame analysis

1. General Description (32pt)1) Bahrain Bridge

Client: US Navy

Contractor: Contrack

TG Role:

Erection stress analysis

Installation master plan

Temporary Works design

Installation Supervision

Bow String Arch Bridge, 122m Span, 6000T

1. General Description (32pt)1) Bahrain Bridge_What we needed to model

Construction stages

Cable Stressing and load transfer

Bridge beam interaction

1. General Description (32pt)1) Bahrain Bridge_How we modelled

Bridge modelled in midas Civil

Full 3D line element model with all construction stages, modelled as a gr

illage

Tension only elements for hangers, stressed in sequence, with rigid links

for connection

Compression only supports to simulate false work during casting

Forced displacement of supports to simulate jacking and transfer load

Modelling of lifting girder with the bridge

1. General Description (32pt)1) Bahrain Bridge_Challenges of Modelling

Anomalies occur due to point connections

Arch to deck connection shows peak but within the foot connection

A common effect in most FE packages

Anomalies due to grillage

Transverse bending induced in the longitudinal deck members

Deck is actually a single member so the effect can’t occur

1. General Description (32pt)1) Bahrain Bridge_Construction Stage Analysis

• Enables accurate build up of forces

• Provides the build up of defection for the pre-camber

• Enables stresses in members to be checked at each step of the erection

process

• The CS analysis identified flexibility in the structure that the original

designer had not considered

1. General Description (32pt)1) Bahrain Bridge_Construction Stage Analysis

1. General Description (32pt)1) Bahrain Bridge_Iterative Pre-camber derivation

• Reason – arch stiffness changes with pre-camber

• Final shape modelled initially

• Deformed shape then recorded and reverse modelled

• This process was repeated five or six times to converge on the correct

pre-camber

1. General Description (32pt)1) Bahrain Bridge_Transfer to SPMT

• Tension is applied to the cables (approx 20kN)

• This nominal tensioning takes up the slack and the cables become

effective.

• The deck is still fully supported by the falsework at this time.

• The bridge is then jacked up by the SPMT at the bearing locations.

• The deck load is progressively transferred and the bridge sags to its final

profile.

1. General Description (32pt)1) Bahrain Bridge_Load transfer by reaction

1. General Description (32pt)1) Bahrain Bridge_Lifting beam interaction

1. General Description (32pt)1) Bahrain Bridge_During installation

1. General Description (32pt)1) Bahrain Bridge_Working through the night

1. General Description (32pt)1) Bahrain Bridge_Bridge Deck Connection

1. General Description (32pt)1) Bahrain Bridge_Video

Demo – 09’51’’~11’56’’

1. General Description (32pt)2) Doha Metro Station Roof

• Major Station

• Building application but behaviour of a bridge

• Use of solid elements imported into line model for complex connections.

• Connection dxf exported from midas Civil, manipulated in CAD and

imported into midas FEA.

• Connection modelled in full in midas FEA, meshed and then inserted in

to midas Civil via MCT(Text fomate)

1. General Description (32pt)2) Doha Metro Station Roof_Doha Metro Line

1. General Description (32pt)2) Doha Metro Station Roof_Msheireb Station

• Major Station

• Building application but behaviour of a bridge

• Use of solid elements imported into line model for complex connections.

• Connection dxf exported from midas Civil, manipulated in CAD and

imported into midas FEA

• Connection modelled in full in midas FEA, meshed and then inserted in

to midas Civil via MCT(Text fomate)

1. General Description (32pt)2) Doha Metro Station Roof_Msheireb Station

1. General Description (32pt)2) Doha Metro Station Roof_Education City

1. General Description (32pt)2) Doha Metro Station Roof_What we needed to model

• Steel frame with complex geometry

• Correct connection relationships

• Temporary support condition during construction

• Complex full moment connections within the steel frame for stress

check

• Verification of constructability

1. General Description (32pt)2) Doha Metro Station Roof_How we modelled

• Full 3d frame model in midas Civil

• Use of construction stages to control articulation of supports

• Complex full moment connections modelled in midas FEA

• Connections imported back into Midas Civil frame model for direct

stress assessment

1. General Description (32pt)2) Doha Metro Station Roof_Step 1

• Divide the incoming elements to at connection

• Export the elements immediately connected to the node including

shape and thickness

1. General Description (32pt)2) Doha Metro Station Roof_Step 2

• Import into AutoCAD or similar (can be done in FEA directly)

• Rationalise the geometry

• Define additional connection elements, such as fin plates and splice

plates etc.

1. General Description (32pt)2) Doha Metro Station Roof_Step 3

• Import the AutoCAD DXF into midas FEA

• Create surfaces at member ends and extrude

• Working from the primary elements first subtract and fuse using the

Boolean commands.

1. General Description (32pt)2) Doha Metro Station Roof_Step 4

• Use the auto mesh function setting a mesh size similar to the plate

thickness.

• Depending on geometry set mesh controls a local discontinuities to help

mesher

1. General Description (32pt)2) Doha Metro Station Roof_Step 5

• Set material number to the same as midas Civil

• Re number the nodes and elements

• Export to MCT and then import in to midas Civil

• Maintain the same coordinate system through out.

• Connect the face of the solid to frame with rigid link.

• Large coordinates presented an glitch

1. General Description (32pt)

• Follow the same convention each time

• Don’t rush or cut corners

• Make us of local coordinate systems to ensure planar surfaces

• Label objects clearly including tools

• Use overlapping tools

• Subtract or fuse progressively

• Avoid narrow discontinuities

2) Doha Metro Station Roof_Solid modelling top tips

1. General Description (32pt)

TBM Bridge

• Spanning the excavation for the Blue Line

• 36m single span

• Shallow depth

• Minimises site operations

• Supports TBM and MSV in different configurations

• Line Model and Plate model

• Plate model enabled detailed consideration of deflections at different

fabrication stages

3) Doha Metro Temporary Bridge

1. General Description (32pt)

• Complex box steel box girder bridge

• Used in two different configurations

Ground bearing

Simply supported

• Models to allow for variations in loading and detailed connection

requirements

• Accurate plate model required for stiffness and local effects

3) Doha Metro Temporary Bridge_What we needed to model

1. General Description (32pt)3) Doha Metro Temporary Bridge_Cross-section

1. General Description (32pt)3) Doha Metro Temporary Bridge_How we modelled

• Grillage models for bending design

• Plate model for deflection analysis

• Plate model for stiffener design and plate buckling

1. General Description (32pt)3) Doha Metro Temporary Bridge_How we modelled

• Compression only links at connections

• Moving load analysis for MSV

1. General Description (32pt)3) Doha Metro Temporary Bridge_Stress plot example

• Stress concentrations at links

1. General Description (32pt)3) Doha Metro Temporary Bridge_During Installation

1. General Description (32pt)3) Doha Metro Temporary Bridge_During Installation

1. General Description (32pt)3) Doha Metro Temporary Bridge_Bridge in use

1. General Description (32pt)3) Doha Metro Temporary Bridge_Bridge with MSV

1. General Description (32pt)2. Other Project Applications

1. Assessment of radial forces in solid element modelling

• Use of embedded tendons

2. Assessment of equilibrium stresses between blisters in box girders

• Use of Embedded Tendons

3. Track Structure interaction

1. General Description (32pt)2. Other Project Applications

Radial Tendon Forces

1. General Description (32pt)2. Other Project Applications

Radial Tendon Forces

1. General Description (32pt)2. Other Project Applications

Embedded Tendons

1. General Description (32pt)2. Other Project Applications

Shear key failure

1. General Description (32pt)2. Other Project Applications

Track Structure Interaction

Incredibly Fast and Easy

1. General Description (32pt)3. Useful Functionality

• MCT Command Shell

• Structural Wizards

• Rendering and dxf output capability

• Use of Construction Stage to simulate changes in stiffness

THANK YOU

Contact: midasoft@midasit.com