uq structural engineeringusing origami design techniques to invent and improve thin-walled...

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UQ Structural Engineering

2016/12/1 12016/12/1 11 CCAA Academics Forum, Sydney, 29/11/2016

UQ Structural Engineering:▫ 13 academics staff▫ 5 research staff▫ 4 laboratory staff▫ ~25 PhD students



Title Research Interests

Prof. Jose ToreroFire safety of complex environments; Sanitation, waste management and contaminated land remediation

Prof. Sritawat Kitipornchai

Structural stability; nonlinear analysis; thin-walled/cold-formed structures; transmission towers; smart materials.

Prof. Chien Ming WangStructural stability, vibration, optimization, plated structures, Mega-Floats, underground structures and nanostructures.

E.Prof Peter Dux Concrete technology and structures.

A.Prof Faris Albermani Structural engineering; Stability and nonlinear analysis; Biomechanics.

Dr Liza O'MooreCreep and shrinkage of concrete structures, durability, high performance concretes.

Dr Johnny Ho Low-carbon-footprint and high-performance concrete using fillers;Stress-strain model of confined concrete with silica fume;Rheology of cement powder paste.

Dr Vinh DaoConcrete technology and structures: Performance of concrete at earlyages; Fire performance of concrete structures.

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Title Research Interests

Dr Dilum FernandoComposite structures, bridge structures, advanced numerical modelling, sustainable design and management of infrastructure assets

Dr Joe GattasUsing origami design techniques to invent and improve thin-walled structures and devices.

Dr Matthew Mason Wind engineering, stochastic modelling of structural vulnerability

Dr Angus Law Fire engineering, structural fire safety engineering

Dr Cristian Maluk Fire engineering, structural fire safety engineering

Dr Juan Hidalgo MedinaFire safety of timber construction; Fire dynamics and fire safety strategies in modern infrastructure.



Structural Engineering: Facilities

15m by 14m Strong floor, 1 MN anchors 750mm-750mm grid

5m tall Strong Walls, 750 kN anchors 750mm-750mm grid

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10MN MTS-Compression 1MN MTS-Universal 250kN Instron-Universal 100kN MTS-Universal




Testing machines 10 MN MTS – Compression3 MN Tecnotest – Compression 1 MN MTS – Universal300 kN Tecnotest – Compression250 kN Instron – Universal100 kN MTS – Universal 100 kN Tecnotest – Bending

Actuators 1 MN (1); 500 kN (2); 250 kN (2); 100 kN (2).

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Dedicated concrete research facilities

Storage, Mixing, Curing Space Aggregate hoppers; 130/70 L mixers; Mortar mixers;Curing, Creep and Shrinkage rooms;

A suit of test apparatus RheometersVicat needle apparatusFlow tableV-funnel; J-ring; L-box; U-box;Compacting factor test; Concrete penetrometer; Vibration table;

Prestressed concrete Prestressing bed; Steam curing unit;

Material characterisation Microscopy; X-ray diffraction;…

Testing of early-age concrete Unique setups for direct-tensile and uniaxial-restrained tests




Dedicated fire research facilities

A suit of test apparatus

▫ iCone Calorimeter▫ Fire Propagation Apparatus▫ Fourier Transform Infrared Spectroscopy▫ Mass Loss Calorimeter▫ Large Scale Heat Release Analyser ▫ Transient Plane Source ▫ Muffle Furnace ▫ Thermo-gravimetric Analysis and Differential

Scanning Calorimetry ▫ Modular Radiant Burner Array▫ Environmental Chamber

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Material characterisation: microscopy; X-ray diffraction;…

Digital fabrication workshop Modelling: ABAQUS, ANSYS, LUSAS,…



Concrete-related research projects:

Fillers’ application in concrete using wet packing theory – use of non-cementitious fillers toimprove strength, workability and durability of concrete simultaneously (Dr Ho)

Rheology of cement powder paste –shear thickening of cement powder paste and themethod of minimisation (Dr Ho)

Role of nano-fibres in high-performance concrete development (Dr Ho) Application to concrete-steel or FRP-steel tubular columns to improve strength and

ductility (Drs Ho and Fernando) Performance/strengthening of RC concrete bridges (Drs Fernando, O’Moore, Ho, Dao). Performance of concrete at early ages (Drs Dao, O’Moore & Prof Dux) Effective crack control in concrete structures (Drs Dao, O’Moore & Prof Dux) Performance of concrete at elevated temperatures (Drs Dao, Maluk & Prof Torero)

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Concrete Research at UQ

Presentation at CCAA Academics Forum, Sydney, 2016

Vinh Dao

[email protected]

Tel: 07-3365 4162 / 0422 293 998

Vinh Dao

[email protected]

Tel: 07-3365 4162 / 0422 293 998

#12

Effective crack control in concrete structures

Effects of cracking:

↓ Safety ↓ Durability ↓ Aesthetic

↓ Serviceability ↑ Cost: repair/litigation

Early-age cracking remains a serious problem due to incomplete understanding:

Among major deterioration mechanisms;

Among the most common causes of litigation;

Risk of such cracking increases during the last decades:

Modern materials & faster construction (↑ C3S; early

strength; mass construction)

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#13

Cracking: Mechanisms, Assessment & Control

Early-age deformation components: ps; as; ds; th.If such deformation is restrained,…

If tensile capacity of concrete is reached, cracking is the result.

Tensile strains/stresses develop.

tloadingthdsaspsct RKE

#14


�� = �� = �� + �� + �� + �� → ��

�� = ��∆� = �� − ��,� ?Aim:��

��< 1. [FactorofSafety]

Proper assessment of:

▫ Cracking risk;

▫ Residual stresses and their effects;

requires holistic understanding of all parameters; which is currently lacking due partly to a lack of suitable combination of tests for such holistic assessment.

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#15

What should T be?

tccthct TRKERKE

T=Tz: is zero;

T>Tz: is compressive;

T<Tz: is tensile;

TTRKE zcct

#16

Zero-stress temperature Tz

T>Tz: compressive stress; T<Tz: tensile stress;

e.g. for T=20oC: ▫ t[Tz=40oC]= 20RKEcc;▫ t[Tz=30oC]= 10RKEcc;▫ Tensile stress is halved if Tz is lowered

from 40oC to 30oC. Implications:

▫ Knowledge of Tz is important.▫ Crack control using only Tc inadequate?▫ Effects of Tz(t) on residual stresses?

Tz1

Tz2

TTRKE zcct

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#17


�� = �� = �� + �� + �� + �� → ��

#18

Uniaxial restrained test�� = �� = �� + �� + �� + �� → ��

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#19

Direct tensile test

Max. tensile stress; Strain at max. tensile stress; Young’s modulus; Strain at zero stress/crack opening; Fracture mechanics properties; Stress-crack opening curve; Creep/relaxation characteristics;

�� = �� = �� + �� + �� + �� → ��

#20


�� = �� = �� + �� + �� + �� → ��

Aim:��

��< 1. [FactorofSafety]

Holistic understanding/knowledge of involved parameters Better assessment ofcracking risk and residual stresses/their effects;

Where to from here?

▫ Academic partners?

▫ Industry partners: possible funding?

OR WITH THE CRACKS!

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Vinh [email protected]

Tel: 07-3365 4162 / 0422 293 998


Tel: 07-3365 4162 / 0422 293 998

#22

Performance of concrete at elevated temperatures

Fire can lead to severe structural damage, loss of contents, and possible loss of life.

To assure adequate fire performance, proper knowledge of fundamental properties of concrete at elevated temperatures is critical.

Performance-based design.

Reliable numerical modelling. Realistic constitutive models that:

Reflect true behaviour of concrete; Based on reliable test results.

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#23

Temperature increase in an element is due to imposed heat flux. In conventional tests, typically gas temperature is actively

controlled. Heat flux imposed on a test specimen is a complex function of:

Inconsistent and poorly repeatable thermal boundary condition in conventional tests:▫ Significant variation in test results;▫ Effects of temperature gradients and associated processes

(thermal stresses, moisture transport, and pore pressures)?

Background – Thermal boundary conditions?

��" = ��

" + ��" + ��

"

��" = �. ��

" − �. �. �� + ℎ �� − ��

#24

A research program is thus underway at The University of Queensland to re-examine the thermal and mechanical performance of concrete at elevated temperatures by establishing well-defined and consistently-controlled heat flux boundary conditions.

Background – Thermal boundary conditions?

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#25

Background – Deformation capturing at elevated temperatures?

Deformation capturing methods

Contact-Pointwise Compressometer; LVDT; Strain gauges;

Noncontact-Pointwise Laser sensors

Noncontact-Full-field DIC

The new test setup also greatly facilitates reliable non-contact full-field capturing of deformation by DIC.

#26

Integrated approach

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#27

Performance of concrete at elevated temperatures

More reliable data on realistic performance of concrete in fire, through:▫ well-defined and consistently-controlled thermal boundary

conditions;▫ reliable noncontact/full-field capturing of deformation by DIC;

Improved knowledge of fundamental properties of concrete at elevated temperatures

More reliable numerical modelling, enabling effective performance-based fire design and analysis of concrete structures.

Where to from here?▫ Industry/Academic partners: possible funding?




Tel: 07-3365 4162 / 0422 293 998


Tel: 07-3365 4162 / 0422 293 998

uq structural engineeringusing origami design techniques to invent and improve thin-walled...

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