Finite Element Analysis

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Finite Element Analysis
Glulam Arch Bridge

• Daniel Maslin and Derek Langman

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Why The Glulam arch Bridge?

• Innovative design
• Use of timber as main support material
• Challenging to model in Strand 7
• Allows for own creativity

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Investigation Aims

• Design and model the bridge
• Perform convergence study to find the point of
  maximum deflection
• Model 2 trucks passing as the maximum load and
  hence find maximum deflections and forces acting
  on the bridge

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Investigation Aims

• Model snow covering on bridge
• Model wind loading on side of bridge
• Model the displacement of a car hitting one of
  the arches
• Model a stationary load on the bridge
• Investigate all displacements and forces for each
  different load case

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The Bridge!
Arches
MaterialTimber (12 m.c.) Stress Grade
F34 Height 800mm Width 100mm Element 1D Beam

• Lengthwise beams

MaterialTimber (12 m.c.) Stress Grade
F34 Height 500mm Width 100mm Element 1D Beam
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The Bridge!
Cross Beams
Material Timber (12 m.c.) Stress Grade
F34 Height 200mm Width 100mm Element 1D Beams

• Slab

Material Concrete Compressive Strength fc 32
MPa Thickness 100mm Element plate/shell
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The Bridge!
Cables
Material Steel Diameter 25mm Element 1D beam

• Supports

Material Timber (12 m.c.) Pine, radiata Height
100mm Width 80mm Element 1D Beams
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Design Assumption
PIN CONNECTION

• No pin connection at the top of the arches
• No pin connection at ends of bridge (make Fixed)
• All material properties and cross sections
• Design of bracing under road surface

BRACING
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Convergence Study

• With load cases of 1Kpa applied to each
  subdivision, the displacement converged at 6.8 mm

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Load Cases
Truck Stationary on Bridge

• Stationary Truck

Load 43 kPa per tyre Max Displacement in Y
7.88mm Max Allowable deflection 12.5mm
Deflection of supporting Beams
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Load Cases

• Stationary Truck

Max Axial Stress in Beams 4.18 MPa Stress in XZ
plane of plate 0.0175 MPa Stress in YY plane of
plate 0.309MPa
Axial Stress in Beams
Truck Stationary on Bridge
Plate stress in YY Plane
Stress in XZ Plane
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Load Cases

• Wind Load

Load UDL 5N/m Max Displacement in Y
0.04mm Max Displacement in X 0.02mm Max
Displacement in Z 4.07mm
Deflection in Y
Deflection of supporting Beams
Deflection in X
Deflection in Z
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Load Cases

• Wind Load

Axial Force in the beams
Max Axial forces in the beams 5.6 kPa
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Load Cases
Deflection

• Car Crash

Load in X 50kN Z 10kN Max Deflection in X
0.358mm Max Deflection in Z 7.7mm
Deflection
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Load Cases
Axial Forces

• Car Crash

Max Axial force in the beams 4.49 MPa
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Load Cases

• Snow Load

Loads On beams 1N/m On plate 0.1kPa
Max Y Deflection in the beams 1.27mm
Max Y Deflection in the plate 0.607mm
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Load Cases
Plate stress YY

• Snow Load

Plate Stress in YY 90.7 kPa Max Axial stress
1.44 MPa
Axial stress
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Load Cases

• Maximum Case Two 42t trucks

Max Y Deflection in the beams 48.8mm
Max Y Deflection in the plate 48.8mm
Maximum Deflection Failure
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Truck Animation
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Issues with Design and Analysis

• Difficult to Model Arch due to not being a semi
  circle
• Offsetting cross beams from Long beams and
  subsequent offset off plate
• Difficulty seeing plate connections due to offset

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THANKYOU!