Brian Uy | The University of New South Wales (original) (raw)

Papers by Brian Uy

Journal of Constructional Steel Research, 2015

A numerical study of hollow and concrete-filled square tubular steel columns subjected to near-fi... more A numerical study of hollow and concrete-filled square tubular steel columns subjected to near-field detonations has been undertaken and validated through the experimental results. The experiments used concrete-filled and hollow square tubular columns (100 × 5 mm SHS Grade C350) made out of cold-formed structural steel hollow sections (SHS) that were simply supported at both ends. High explosives TNT charges were placed above the top surface of the column at two different scaled standoff distances of 0.12 m/kg 1/3 and 0.15 m/kg 1/3 . Failure patterns and permanent mid-span deformations were recorded and compared with the numerical analysis results. Arbitrary Lagrangian-Eulerian (ALE) formulations coupled with fluid-structure interaction (FSI) algorithms that are available in the advanced finite element code LS-DYNA were used in the numerical study. A detailed description of the numerical technique adopted in the study is presented. The models were validated with the experimental results and were used to obtain the failure pattern, permanent plastic deformation, pressure and impulse time histories, stress distribution, and energy absorption of the different configurations of the columns. The performance of hollow and concrete-filled SHS tubes for blast load mitigation was assessed and discussed.

Materials Science Forum, 2014

Engineers are increasingly encouraged to consider sustainability in the design and construction o... more Engineers are increasingly encouraged to consider sustainability in the design and construction of new civil engineering infrastructure. Sustainability can be achieved through the use of high strength materials thereby reducing quantity of materials required in construction where possible. Knowledge of residual stresses in fabricated columns is important in identifying whether the fabricated columns can be classified as heavily welded (HW) or lightly welded (LW). The determination of residual stresses can be used to determine the local buckling of stub columns. Residual stress magnitudes are also essential in the numerical modelling of buckling behaviour of columns. This paper outlines the challenges in measurement of residual stresses using neutron diffraction in fabricated high strength steel square tubes. The residual stress line scans and maps were measured using the Kowari Strain Scanner located at the Australian Nuclear and Science Organisation (ANSTO) in Australia.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

ABSTRACT For the damage evaluation of a structure after exposure to fire, residual mechanical pro... more ABSTRACT For the damage evaluation of a structure after exposure to fire, residual mechanical properties of the structural materials used need to be evaluated. Many factors can affect the post-fire behaviour of steel. In this paper, existing test data are collected from an extensive survey of the open literature, and a statistical analysis is carried out to analyse the influence of heat exposure on the residual modulus of elasticity, yield strength and ultimate strength of hot-rolled structural steel. A simplified stress-strain model is developed for structural steel after cooling down.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

ABSTRACT This paper presents a finite element model to perform heat transfer analysis of concrete... more ABSTRACT This paper presents a finite element model to perform heat transfer analysis of concrete-filled stainless steel tubular (CFSST) columns exposed to fire. The selection of suitable values for the convective heat transfer coefficient and emissivity coefficient is discussed. Verification of this model is achieved by comparing the results obtained from the model with test results presented in the literature. Based on the finite element modelling, the temperature development in CFSST columns is compared with that of conventional concrete-filled carbon steel columns.

Incorporating Sustainable Practice in Mechanics and Structures of Materials, 2010

Australian Journal of Structural Engineering

Abstract: Procedures given in the Australian bridge design standard AS 5100 (Standards Australia,... more Abstract: Procedures given in the Australian bridge design standard AS 5100 (Standards Australia, 2004) for the design of concrete-filled steel tubular (CFST) columns, beams and beam-columns are presented and described briefly in this paper. A wide range of ...

Proceedings of the 10th Pacific Structural Steel Conference (PSSC 2013), 2013

Test results of six concrete-filled double-skin steel tubular (CFDST) stub columns are presented ... more Test results of six concrete-filled double-skin steel tubular (CFDST) stub columns are presented in this paper. Circular hollow section (CHS) and square hollow section (SHS) were used to fabricate the inner and outer skins of the composite columns. The main parameters explored in this test programme were the section type (CHS inner and CHS outer, SHS inner and SHS outer, CHS inner and SHS outer) and whether or not exposure to fire. It was found that the strength of the CFDST columns decreased significantly after exposure to fire. However, the residual strength of these innovative columns was still comparable to that of conventional concrete-filled steel tubular columns. Of all the three types of sections with a same hollow section ratio, the one with CHS inner and SHS outer shown the highest residual strength.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

Journal of Constructional Steel Research, 2014

ABSTRACT This paper describes the blast loading trials on steel tubular members with and without ... more ABSTRACT This paper describes the blast loading trials on steel tubular members with and without concrete infill. The standoff distances considered in this trial were selected to demonstrate the response of these steel sections to contact and very close-range detonations of high explosive (HE). The main objective of the trials was to investigate the effects of contact and near-field explosions on steel square tubular members and to demonstrate the effect of standoff variations on the mode of response and failure of steel square sections. The experimental data collected during these trials can be used for verification of theoretical and numerical models of response of steel tubular columns subjected to contact and close-range blasts. Due to difficulties with collecting quantitative data (displacements, blast pressures, etc.) in the close proximity of a detonating HE charge, analysis of the steel tubes in this paper is confined mostly to qualitative assessment based on visual observations of the structural damage and limited numerical simulations of the blast–structure interaction using LS-DYNA aimed at clarifying some important phenomena that were not available to be obtained directly from the explosive tests. A new simplified approach to predicting the dynamic response of square tubular steel members subjected to the near-field airblast loading is proposed. The comparison of the analytically predicted dynamic response parameters of the concrete-filled steel tubular members with the experimental data shows very good agreement with the predicted failure mechanism and level of damage of the structural element.

Journal of Structural Engineering, 2014

Steel yielding hysteretic devices provide a reliable way to increase the energy dissipation capac... more Steel yielding hysteretic devices provide a reliable way to increase the energy dissipation capacity of structures under seismic loading. Steel cylindrical pins with hourglass shape bending parts (called web hourglass shape pins-WHPs) have been recently used as the energy dissipation system of posttensioned connections for self-centering steel moment-resisting frames. This work evaluates the cyclic behavior of WHPs made of high-strength steel and two grades of stainless steel, i.e., austenitic grade 304 and duplex. Design rules for WHPs are established using principles of mechanics. Twenty-six tests using different cyclic loading protocols and different WHP geometries were conducted. The tests showed that the WHPs have stable hysteretic behavior and high fracture capacity. WHPs made of duplex stainless steel have the most favorable and predictable performance for seismic applications. Two micromechanics-based fracture models, i.e., the void growth model and the stress-modified critical strain model, were calibrated and their parameters are provided for high-strength steel and the two types of stainless steel. The ability of the cyclic void growth model to predict fracture in WHPs under cyclic loading is also evaluated. individual papers. This paper is part of the Journal of Structural Engineering, © ASCE, ISSN 0733-9445/04014087 /$25.00. © ASCE 04014087-1 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-2 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-3 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-7 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-9 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-11 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

Journal of Structural Engineering, 2014

Steel-concrete composite beams are currently designed against shear by neglecting the contributio... more Steel-concrete composite beams are currently designed against shear by neglecting the contributions of the concrete slab and composite action, while the moment-shear interaction is not addressed in current structural codes of practice. This paper presents an experimental and numerical study on the shear strength and moment-shear interaction in simply-supported steel-concrete composite beams. Fourteen composite beams and one steel beam were tested under combined bending and shear. The effects of partial shear connection and shear reinforcement in the slab were also studied. A nonlinear finite element model was developed and found capable of accurately predicting the behavior of the composite beams. Extensive parametric studies were then conducted using the validated numerical model. The results allowed for the derivation of a moment-shear interaction law for composite beams and highlighted the high degree of conservatism in current structural specifications. It is shown that both the concrete slab and the composite action contribute significantly to the shear strength of a composite section and that the main factors that influence the shear capacity of a composite beam are the slab thickness and the degree of shear connection. Based on the experimental and numerical results, a design model is proposed for a more efficient design of compact composite beams in regions where the acting shear is high.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

Advanced Steel Construction

The purpose of this paper is to recalibrate the capacity reduction factors, estimate the reliabil... more The purpose of this paper is to recalibrate the capacity reduction factors, estimate the reliability of current equations, and investigate the effect of these factors in AS 5100.6, the Australian Bridge Standard for concrete-filled steel tubular columns. This work has important ramifications for other international codes of practice as the Australian code has the identical or similar underlying design philosophy with Eurocode 4, AISC and the code of practice in Hong Kong. The method developed by Johnson and Huang is extensively applied to the Australian code format to recalibrate the capacity factors in AS 5100 for a target reliability of β = 3.04 based on an extensive database of 1,583 test results covering a wide range of input parameter values. In addition, an inverse analysis procedure based on Johnson and Huang's method is proposed to estimate the reliability of design equations with known capacity factors. The analysis results show that the interaction between the concrete and steel needs to be considered for the current capacity factors in AS 5100. The results also show that the current capacity factors provide greater reliability than the target reliability suggested in AS 5104:2005/ISO 2394:1998, but after considering the additional uncertainties created due to the application of multiple capacity factors, the reliability was almost the same as the recommended value. In conclusion, the current capacity factor values in AS 5100 are adequate with regards to safety and can be maintained, but better optimised values would be preferable to improve the cost-safety balance.

Steel and Composite Structures

This paper presents the experimental studies to consider the effects of elevated temperatures on ... more This paper presents the experimental studies to consider the effects of elevated temperatures on the behaviour of headed stud shear connectors on composite steelconcrete beams for both solid and profiled steel sheeting slabs. Sixteen push tests were undertaken to study the behaviour of headed stud shear connectors when subjected to elevated temperatures. Due to elevated temperatures, the material properties change according to temperature. The push tests were loaded progressively up to the ultimate load to illustrate the capability of a structure to withstand load during fire. The experiment studies allowed the investigation of the shear resistance of headed stud shear connectors as a function of temperatures.

Journal of Constructional Steel Research, 2015

A numerical study of hollow and concrete-filled square tubular steel columns subjected to near-fi... more A numerical study of hollow and concrete-filled square tubular steel columns subjected to near-field detonations has been undertaken and validated through the experimental results. The experiments used concrete-filled and hollow square tubular columns (100 × 5 mm SHS Grade C350) made out of cold-formed structural steel hollow sections (SHS) that were simply supported at both ends. High explosives TNT charges were placed above the top surface of the column at two different scaled standoff distances of 0.12 m/kg 1/3 and 0.15 m/kg 1/3 . Failure patterns and permanent mid-span deformations were recorded and compared with the numerical analysis results. Arbitrary Lagrangian-Eulerian (ALE) formulations coupled with fluid-structure interaction (FSI) algorithms that are available in the advanced finite element code LS-DYNA were used in the numerical study. A detailed description of the numerical technique adopted in the study is presented. The models were validated with the experimental results and were used to obtain the failure pattern, permanent plastic deformation, pressure and impulse time histories, stress distribution, and energy absorption of the different configurations of the columns. The performance of hollow and concrete-filled SHS tubes for blast load mitigation was assessed and discussed.

Materials Science Forum, 2014

Engineers are increasingly encouraged to consider sustainability in the design and construction o... more Engineers are increasingly encouraged to consider sustainability in the design and construction of new civil engineering infrastructure. Sustainability can be achieved through the use of high strength materials thereby reducing quantity of materials required in construction where possible. Knowledge of residual stresses in fabricated columns is important in identifying whether the fabricated columns can be classified as heavily welded (HW) or lightly welded (LW). The determination of residual stresses can be used to determine the local buckling of stub columns. Residual stress magnitudes are also essential in the numerical modelling of buckling behaviour of columns. This paper outlines the challenges in measurement of residual stresses using neutron diffraction in fabricated high strength steel square tubes. The residual stress line scans and maps were measured using the Kowari Strain Scanner located at the Australian Nuclear and Science Organisation (ANSTO) in Australia.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

ABSTRACT For the damage evaluation of a structure after exposure to fire, residual mechanical pro... more ABSTRACT For the damage evaluation of a structure after exposure to fire, residual mechanical properties of the structural materials used need to be evaluated. Many factors can affect the post-fire behaviour of steel. In this paper, existing test data are collected from an extensive survey of the open literature, and a statistical analysis is carried out to analyse the influence of heat exposure on the residual modulus of elasticity, yield strength and ultimate strength of hot-rolled structural steel. A simplified stress-strain model is developed for structural steel after cooling down.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

ABSTRACT This paper presents a finite element model to perform heat transfer analysis of concrete... more ABSTRACT This paper presents a finite element model to perform heat transfer analysis of concrete-filled stainless steel tubular (CFSST) columns exposed to fire. The selection of suitable values for the convective heat transfer coefficient and emissivity coefficient is discussed. Verification of this model is achieved by comparing the results obtained from the model with test results presented in the literature. Based on the finite element modelling, the temperature development in CFSST columns is compared with that of conventional concrete-filled carbon steel columns.

Incorporating Sustainable Practice in Mechanics and Structures of Materials, 2010

Australian Journal of Structural Engineering

Abstract: Procedures given in the Australian bridge design standard AS 5100 (Standards Australia,... more Abstract: Procedures given in the Australian bridge design standard AS 5100 (Standards Australia, 2004) for the design of concrete-filled steel tubular (CFST) columns, beams and beam-columns are presented and described briefly in this paper. A wide range of ...

Proceedings of the 10th Pacific Structural Steel Conference (PSSC 2013), 2013

Test results of six concrete-filled double-skin steel tubular (CFDST) stub columns are presented ... more Test results of six concrete-filled double-skin steel tubular (CFDST) stub columns are presented in this paper. Circular hollow section (CHS) and square hollow section (SHS) were used to fabricate the inner and outer skins of the composite columns. The main parameters explored in this test programme were the section type (CHS inner and CHS outer, SHS inner and SHS outer, CHS inner and SHS outer) and whether or not exposure to fire. It was found that the strength of the CFDST columns decreased significantly after exposure to fire. However, the residual strength of these innovative columns was still comparable to that of conventional concrete-filled steel tubular columns. Of all the three types of sections with a same hollow section ratio, the one with CHS inner and SHS outer shown the highest residual strength.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

Journal of Constructional Steel Research, 2014

ABSTRACT This paper describes the blast loading trials on steel tubular members with and without ... more ABSTRACT This paper describes the blast loading trials on steel tubular members with and without concrete infill. The standoff distances considered in this trial were selected to demonstrate the response of these steel sections to contact and very close-range detonations of high explosive (HE). The main objective of the trials was to investigate the effects of contact and near-field explosions on steel square tubular members and to demonstrate the effect of standoff variations on the mode of response and failure of steel square sections. The experimental data collected during these trials can be used for verification of theoretical and numerical models of response of steel tubular columns subjected to contact and close-range blasts. Due to difficulties with collecting quantitative data (displacements, blast pressures, etc.) in the close proximity of a detonating HE charge, analysis of the steel tubes in this paper is confined mostly to qualitative assessment based on visual observations of the structural damage and limited numerical simulations of the blast–structure interaction using LS-DYNA aimed at clarifying some important phenomena that were not available to be obtained directly from the explosive tests. A new simplified approach to predicting the dynamic response of square tubular steel members subjected to the near-field airblast loading is proposed. The comparison of the analytically predicted dynamic response parameters of the concrete-filled steel tubular members with the experimental data shows very good agreement with the predicted failure mechanism and level of damage of the structural element.

Journal of Structural Engineering, 2014

Steel yielding hysteretic devices provide a reliable way to increase the energy dissipation capac... more Steel yielding hysteretic devices provide a reliable way to increase the energy dissipation capacity of structures under seismic loading. Steel cylindrical pins with hourglass shape bending parts (called web hourglass shape pins-WHPs) have been recently used as the energy dissipation system of posttensioned connections for self-centering steel moment-resisting frames. This work evaluates the cyclic behavior of WHPs made of high-strength steel and two grades of stainless steel, i.e., austenitic grade 304 and duplex. Design rules for WHPs are established using principles of mechanics. Twenty-six tests using different cyclic loading protocols and different WHP geometries were conducted. The tests showed that the WHPs have stable hysteretic behavior and high fracture capacity. WHPs made of duplex stainless steel have the most favorable and predictable performance for seismic applications. Two micromechanics-based fracture models, i.e., the void growth model and the stress-modified critical strain model, were calibrated and their parameters are provided for high-strength steel and the two types of stainless steel. The ability of the cyclic void growth model to predict fracture in WHPs under cyclic loading is also evaluated. individual papers. This paper is part of the Journal of Structural Engineering, © ASCE, ISSN 0733-9445/04014087 /$25.00. © ASCE 04014087-1 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-2 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-3 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-7 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-9 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014087-11 J. Struct. Eng. J. Struct. Eng. Downloaded from ascelibrary.org by Heriot-Watt University on 05/28/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

Journal of Structural Engineering, 2014

Steel-concrete composite beams are currently designed against shear by neglecting the contributio... more Steel-concrete composite beams are currently designed against shear by neglecting the contributions of the concrete slab and composite action, while the moment-shear interaction is not addressed in current structural codes of practice. This paper presents an experimental and numerical study on the shear strength and moment-shear interaction in simply-supported steel-concrete composite beams. Fourteen composite beams and one steel beam were tested under combined bending and shear. The effects of partial shear connection and shear reinforcement in the slab were also studied. A nonlinear finite element model was developed and found capable of accurately predicting the behavior of the composite beams. Extensive parametric studies were then conducted using the validated numerical model. The results allowed for the derivation of a moment-shear interaction law for composite beams and highlighted the high degree of conservatism in current structural specifications. It is shown that both the concrete slab and the composite action contribute significantly to the shear strength of a composite section and that the main factors that influence the shear capacity of a composite beam are the slab thickness and the degree of shear connection. Based on the experimental and numerical results, a design model is proposed for a more efficient design of compact composite beams in regions where the acting shear is high.

Proceedings of the 10th International Conference on Advances in Steel Concrete Composite and Hybrid Structures, 2012

Advanced Steel Construction

The purpose of this paper is to recalibrate the capacity reduction factors, estimate the reliabil... more The purpose of this paper is to recalibrate the capacity reduction factors, estimate the reliability of current equations, and investigate the effect of these factors in AS 5100.6, the Australian Bridge Standard for concrete-filled steel tubular columns. This work has important ramifications for other international codes of practice as the Australian code has the identical or similar underlying design philosophy with Eurocode 4, AISC and the code of practice in Hong Kong. The method developed by Johnson and Huang is extensively applied to the Australian code format to recalibrate the capacity factors in AS 5100 for a target reliability of β = 3.04 based on an extensive database of 1,583 test results covering a wide range of input parameter values. In addition, an inverse analysis procedure based on Johnson and Huang's method is proposed to estimate the reliability of design equations with known capacity factors. The analysis results show that the interaction between the concrete and steel needs to be considered for the current capacity factors in AS 5100. The results also show that the current capacity factors provide greater reliability than the target reliability suggested in AS 5104:2005/ISO 2394:1998, but after considering the additional uncertainties created due to the application of multiple capacity factors, the reliability was almost the same as the recommended value. In conclusion, the current capacity factor values in AS 5100 are adequate with regards to safety and can be maintained, but better optimised values would be preferable to improve the cost-safety balance.

Steel and Composite Structures

This paper presents the experimental studies to consider the effects of elevated temperatures on ... more This paper presents the experimental studies to consider the effects of elevated temperatures on the behaviour of headed stud shear connectors on composite steelconcrete beams for both solid and profiled steel sheeting slabs. Sixteen push tests were undertaken to study the behaviour of headed stud shear connectors when subjected to elevated temperatures. Due to elevated temperatures, the material properties change according to temperature. The push tests were loaded progressively up to the ultimate load to illustrate the capability of a structure to withstand load during fire. The experiment studies allowed the investigation of the shear resistance of headed stud shear connectors as a function of temperatures.