Midas International Symposium

Peter Reeves-Toy

Director, UAE

7th December 2015

Tony Gee Case Study

Seminar Contents

• Project Overview

– Doha Metro

• Structural Frame

– Construction Stages

– Load Manipulation

• Connection Modelling

– Solid Elements

Doha Metro

• Major Station

• Use of Construction stages to manage loads and

deflections

• Use of solid elements imported into line model

for complex connections

• Connection dxf exported from Civil, manipulated

in CAD and imported into FEA.

• Connection modelled in full in FEA, meshed and

then inserted in to Civil via MCT

Doha Metro

Msheireb

Msheireb Station

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

Structural Frame

• 3D Line Model

• Plate Elements use for the supporting walls

• Beam end releases modelled as per connection

design assumptions

• Offsets between connection centrelines

modelled with links for accurate load transfer

• Construction stages modelled to manipulate the

load distribution.

Structural Frame

1

2

7

654

38

Stage 1

• Activate the supporting walls (existing)

Stage 2

• Activate Module 6 Steelwork

• Apply selfweight

Stage 3

• Activate Module 6 tension rods

• Apply pretension to load

cantilevers

Stage 4

• Activate the Module 7 Steelwork

• Selfweight already active

Stage 5

• Activate Module 7 tension rods

• Apply pretension to load

cantilevers

Stage 6

• Activate Module 1 steelwork

• With props or self-

supporting

Stage 7

• Activate Module 2 Steelwork

• With or without props

Stage 8

• Activate Module 3 steelwork

• With or without props

• Apply all SIDL loads (cladding etc)

Stage 9

• Activate Module 4 steelwork

• With props

Stage 10

• Activate Module 8 steelwork

Stage 11

• Deactivate the tensile rods

• Apply post-construction variable loads

Connection Modelling

• Connection solid modelling

• Extraction of geometry from frame model

• Manipulation in AutoCAD

• Solid modelling in Midas FEA

• Meshing of connection in Midas FEA

• Importing solid model back in to frame model

Step 1

• Divide the incoming elements to at connection

• Export the elements immediately connected to

the node including shape and thickness

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.

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.

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

Step 5

• Set material number to the same as Midas Civil

• Renumber the nodes and elements

• Export to MCT and then import in to Civil

• Maintain the same coordinate system through

out.

• Connect the face of the solid to frame with rigid

link.

• Large coordinates presented an glitch

Example Stress Plot

Solid modelling top tips

• 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

QUESTIONS!?