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Nimal J Perera

QUT Queensland University of Technology, Science and Engineering, Faculty Member

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Civil and Structural engineer with professional practice experience in •Australia, United Kingdom, Indonesia, Malaysia, Thailand, Sri Lanka, Nigeria, Trinidad W.I., UAE, Morocco, Saudi Arabia, Kuwait, Brazil and Kazakhstan. Adjunct Professor of Structural Engineering at the Queensland University of Technology, Australia. Co-investigator and supervisor of post graduate research programmes with over 80 refereed journal and conference papers.

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Kansas State University

Armando Marques-Guedes

UNL - New University of Lisbon

Francisco Vaz da Silva

ISCTE - University Institute of Lisbon (ISCTE-IUL)

University of Aberdeen

University of Pennsylvania

American University of Sharjah

Davide Ermacora

Università degli Studi di Torino

J Richard Middleton

Roberts Wesleyan University

University Of Nusa Cendana

Troy Bruggemann

Queensland University of Technology

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Papers by Nimal J Perera

Modelling the in-plane/out-of-plane interaction of brick and stone masonry structures using Applied Element Method

Journal of Building Engineering

Effects of loading rate on impact response of axially loaded reinforced concrete members and performance enhancement by AFRP

Insights and Innovations in Structural Engineering, Mechanics and Computation, 2016

Impact response and capacity enhancement of reinforced concrete columns

Frontal columns in buildings are vulnerable to vehicular impacts as conventional design methods d... more Frontal columns in buildings are vulnerable to vehicular impacts as conventional design methods do not cover the accidental effects of impacts. This paper studies the response of reinforced concrete columns in multi-storey buildings under vehicular loads and investigates means of enhancing their impact capacities. The research is carried out using dynamic computer simulation techniques which have been validated with results from experimental testing. Strain rate effects and hour glass controls are incorporated into the analysis. Effects of design parameters such as concrete strength, reinforcement ratio and axial load level are investigated. The effectiveness of glass fiber reinforced polymers in enhancing impact capacities is examined by comparing results before and after retrofitting. Results indicate that this type of retrofitting enhances the impact performance of the reinforced concrete columns.

Enhancing the lateral performance of modular buildings through innovative inter-modular connections

Structures, 2021

Steel modular constructions involve the manufacture of fully equipped three-dimensional prefabric... more Steel modular constructions involve the manufacture of fully equipped three-dimensional prefabricated modules in factory-controlled settings which are then transported to construction sites and assembled to form a complete structure. Adjacent modules are attached to each other only at their corners at inter-modular connections. Typical inter-modular connections are incapable of providing resistance against lateral dynamics loads. Current research shows that under lateral dynamic loads, steel modular buildings with rigid unyielding connectors are vulnerable to failure of the columns which result in either partial or complete collapse of the structure. Modular systems would therefore require additional in-situ lateral load resisting systems, such as shear cores, which would devalue the benefits of purely modular construction as they would need to be built in-situ. To address this shortcoming, this research proposes a novel steel inter-modular connection, with two variations, to achieve safe, reliable and ductile dynamic performance of a modular building under seismic actions. An extensive experimental program was undertaken to study the feasibility of the strength hierarchy and expected ductile failure patterns of the newly proposed inter-modular connections under monotonic and cyclic lateral loads. The experimental study revealed that the proposed inter-modular connections display superior dynamic behaviour with respect to response parameters such as moment-carrying capacity, energy dissipation and ductility. Ductile failure patterns within the connection region and away from the columns, which are critical members, were observed. This information will contribute to the design of safe and efficient inter-modular connections and enable enhanced lateral performance of steel modular buildings under dynamic loads. A comprehensive numerical model of the connection was also developed and validated for use in future parametric studies.

Comparative analysis of blast response of cable truss and cable net façades

Engineering Failure Analysis, 2019

This paper presents the development and application of comprehensive numerical modelling techniqu... more This paper presents the development and application of comprehensive numerical modelling techniques to simulate the blast response of cable supported façades (CSFs) and compares the responses of cable truss and cable net façades which are two popular types. The results of the comparative analysis are used to evaluate the influence of the façade type on the key response parameters and hence their effective performance under blast loads. Modelling approaches, material models and constraint types used are presented along with the validation of the procedure. Results from numerical models created in LS DYNA are compared with existing numerical and experimental results from literature to validate the modelling techniques. Behaviour of cable net and cable truss façades under a credible blast event are then compared by analysing the effects of cable and panel configurations. The findings of the comparative analysis, show that cable truss façades (in general) have reduced deflections and higher energy absorption capacities, but with larger cable forces. This information can be used in the design of either façade type to obtain the desired blast response. The numerical modelling techniques developed in this paper deliver important information on the blast response and failure assessment of cable supported façades and the comparative analysis will provide guidance in future research and investigation to enable safer designs.

Influence of interlayer properties on the blast performance of laminated glass panels

Construction and Building Materials, 2015

Influence of interlayer properties on the blast performance of laminated glass panels. Constructi... more

Vibration characteristics of plate elements subjected in-plane loads (axial loads)

Proceedings of 2011 …, 2011

Axial deformations resulting from in-plane loads (axial forces) of plate elements impact signific... more

Performance of reinforced concrete columns under bi-axial lateral force/displacement and axial load

Engineering Structures, 2015

Accurate and realistic assessment of the performance of columns in general and those in critical ... more Accurate and realistic assessment of the performance of columns in general and those in critical locations that may cause progressive failure of the entire structure, in particular, is significantly important. This performance is affected by the load history, pattern and intensity. Current design code does not consider the effect of load pattern on the load and displacement capacity of columns. In the study reported here, monotonic material models, cyclic rule, and plastic hinge models have been utilized in a fiber-based analytical procedure, validated against experimental data. Comparison of the analytical predictions and experimental data, through moment-curvature and force-deflection analyses, confirmed the accuracy and validity of the analytical algorithm and models. The analytical model was then used in a parametric study considering the effects of axial load variation and lateral force/displacement paths on the flexural strength and energy dissipation capacity of reinforced concrete columns.

Using heritage building registers to characterise unreinforced masonry buildings of Brisbane, Australia

Australian Journal of Structural Engineering

Infrastructure Sustainability

Urban Management, Engineering, and Design

Axial deformations resulting from in-plane loads (axial forces) of plate elements impact signific... more Axial deformations resulting from in-plane loads (axial forces) of plate elements impact significantly on their vibration characteristics. Although, numerous methods have been developed to quantify axial forces and hence deformations of individual plate elements with different boundary conditions based on their natural frequencies, these methods are unable to apply to the plate elements in a structural system. This is because the natural frequency is a global parameter for the entire structure. Thus, this paper proposes a comprehensive vibration based procedure to quantify axial deformations of plate elements in a structural framing system. Unique capabilities of the proposed method present through illustrative examples.

Energy Dissipation and Behaviour of Building Façade Systems under Seismic Loads

Proceedings of the Eighth International Conference on Computational Structures Technology

Hareer, Rahila, Perera, Nimal, Thambiratnam, David, Hareer, Rahila, Perera, Nirmal, &amp; Tha... more

Quantifying in-plane deformation of plate elements using vibration characteristics

Journal of Sound and Vibration, 2011

This is the author's version of a work that was accepted for publication in Journal of Sound and ... more This is the author's version of a work that was accepted for publication in Journal of Sound and Vibration. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published

Discussion of “Study of viscoelastic and friction damper configurations in the seismic mitigation of medium-rise structures”

Journal of Mechanics of Materials and Structures, 2006

The discusser is very interested in the paper presented by Julius Marko, David Thambiratnam and N... more The discusser is very interested in the paper presented by Julius Marko, David Thambiratnam and Nimal Perera. This paper includes various interesting aspects, for example, comparison of the effectiveness of various damper systems (viscoelastic, friction and hybrid), optimal damper configuration and location, and the influence of different types of earthquake ground motions on the response reduction by dampers. The authors draw several references for readers. In the discusser's opinion, more versatile investigations on optimal damper configuration and location have been made in the scientific community of earthquake engineering, and computing algorithms based on certain theoretical backgrounds have been proposed [

Numerical simulation of axially loaded concrete columns under transverse impact and vulnerability assessment

International Journal of Impact Engineering, 2010

With a view to assessing the vulnerability of columns to low elevation vehicular impacts, a non-l... more With a view to assessing the vulnerability of columns to low elevation vehicular impacts, a non-linear explicit numerical model has been developed and validated using existing experimental results. The numerical model accounts for the effects of strain rate and confinement of the reinforced concrete, which are fundamental to the successful prediction of the impact response. The sensitivity of the material model parameters used for the validation is also scrutinised and numerical tests are performed to examine their suitability to simulate the shear failure conditions. Conflicting views on the strain gradient effects are discussed and the validation process is extended to investigate the ability of the equations developed under concentric loading conditions to simulate flexural failure events. Experimental data on impact force time histories, mid span and residual deflections and support reactions have been verified against corresponding numerical results. A universal technique which can be applied to determine the vulnerability of the impacted columns against collisions with new generation vehicles under the most common impact modes is proposed. Additionally, the observed failure characteristics of the impacted columns are explained using extended outcomes. Based on the overall results, an analytical method is suggested to quantify the vulnerability of the columns.

Blast response and safety evaluation of a composite column for use as key element in structural systems

Engineering Structures, 2014

This paper presents the blast response, damage mechanism and evaluation of residual load capacity... more This paper presents the blast response, damage mechanism and evaluation of residual load capacity of a concrete-steel composite (CSC) column using dynamic computer simulation techniques. This study is an integral part of a comprehensive research program which investigated the vulnerability of structural framing systems to catastrophic and progressive collapse under blast loading and is intended to provide design information on blast mitigation and safety evaluation of load bearing vulnerable columns that are key elements in a building. The performance of the CSC column is compared with that of a reinforced concrete (RC) column with the same dimensions and steel ratio. Results demonstrate the superior performance of the CSC column, compared to the RC column in terms of residual load carrying capacity, and its potential for use as a key element in structural systems. The procedure and results presented herein can be used in the design and safety evaluation of key elements of multi-storey buildings for mitigating the impact of blast loads.

Monotonic behaviour of composite column to beam connections

Engineering Structures, 2001

An experimental investigation into the behaviour of composite column-to-beam connections using te... more An experimental investigation into the behaviour of composite column-to-beam connections using ten large-scale connections has been conducted, four under monotonic loading and six under cyclic loading. This paper presents the details and results of the four preliminary monotonic tests. Details and results of the cyclic tests are reported in a companion paper. All connections consisted of a circular concrete-filled steel tubular column, a compact universal beam section and a shop fabricated connection stub. It is a direct connection of the beam to the tube wall (using flange connection plates, and web cleat plates) and four straight reinforcing bars welded to the top and bottom flanges and embedded into the concrete core. It was found that the connection strength increased as the capacity of the embedded bars increased, to a stage where no connection failure occurred, and the beam formed a plastic hinge outside the zone of influence of the bars. The bars were very effective in transferring both compressive and tensile loads directly into the column, and connection behaviour in terms of strength and stiffness was adequate to classify it as a rigid connection.

Blast response and failure analysis of pile foundations subjected to surface explosion

Engineering Failure Analysis, 2014

Blast response and failure analysis of pile foundations subjected to surface explosion.

Damage assessment of 3D reinforced concrete frame under external explosion loading

Multi-storey buildings are highly vulnerable to terrorist bombing attacks in various parts of the... more

Finite Element Analysis of a Rollover Protective Structure for a Komatsu 630E Dump Truck

Barker, Nicholas, Clark, Brian, Perera, Nimal, & Thambiratnam, David (2004) Finite Element Analys... more

Coupling coefficient and lateral vibration of slender suspension footbridges

Computers & Structures, 2008

... According to the assumptions, the walking dynamic load will consist of three parts: vertical ... more

Modelling the in-plane/out-of-plane interaction of brick and stone masonry structures using Applied Element Method

Journal of Building Engineering

Effects of loading rate on impact response of axially loaded reinforced concrete members and performance enhancement by AFRP

Insights and Innovations in Structural Engineering, Mechanics and Computation, 2016

Impact response and capacity enhancement of reinforced concrete columns

Frontal columns in buildings are vulnerable to vehicular impacts as conventional design methods d... more Frontal columns in buildings are vulnerable to vehicular impacts as conventional design methods do not cover the accidental effects of impacts. This paper studies the response of reinforced concrete columns in multi-storey buildings under vehicular loads and investigates means of enhancing their impact capacities. The research is carried out using dynamic computer simulation techniques which have been validated with results from experimental testing. Strain rate effects and hour glass controls are incorporated into the analysis. Effects of design parameters such as concrete strength, reinforcement ratio and axial load level are investigated. The effectiveness of glass fiber reinforced polymers in enhancing impact capacities is examined by comparing results before and after retrofitting. Results indicate that this type of retrofitting enhances the impact performance of the reinforced concrete columns.

Enhancing the lateral performance of modular buildings through innovative inter-modular connections

Structures, 2021

Steel modular constructions involve the manufacture of fully equipped three-dimensional prefabric... more Steel modular constructions involve the manufacture of fully equipped three-dimensional prefabricated modules in factory-controlled settings which are then transported to construction sites and assembled to form a complete structure. Adjacent modules are attached to each other only at their corners at inter-modular connections. Typical inter-modular connections are incapable of providing resistance against lateral dynamics loads. Current research shows that under lateral dynamic loads, steel modular buildings with rigid unyielding connectors are vulnerable to failure of the columns which result in either partial or complete collapse of the structure. Modular systems would therefore require additional in-situ lateral load resisting systems, such as shear cores, which would devalue the benefits of purely modular construction as they would need to be built in-situ. To address this shortcoming, this research proposes a novel steel inter-modular connection, with two variations, to achieve safe, reliable and ductile dynamic performance of a modular building under seismic actions. An extensive experimental program was undertaken to study the feasibility of the strength hierarchy and expected ductile failure patterns of the newly proposed inter-modular connections under monotonic and cyclic lateral loads. The experimental study revealed that the proposed inter-modular connections display superior dynamic behaviour with respect to response parameters such as moment-carrying capacity, energy dissipation and ductility. Ductile failure patterns within the connection region and away from the columns, which are critical members, were observed. This information will contribute to the design of safe and efficient inter-modular connections and enable enhanced lateral performance of steel modular buildings under dynamic loads. A comprehensive numerical model of the connection was also developed and validated for use in future parametric studies.

Comparative analysis of blast response of cable truss and cable net façades

Engineering Failure Analysis, 2019

This paper presents the development and application of comprehensive numerical modelling techniqu... more This paper presents the development and application of comprehensive numerical modelling techniques to simulate the blast response of cable supported façades (CSFs) and compares the responses of cable truss and cable net façades which are two popular types. The results of the comparative analysis are used to evaluate the influence of the façade type on the key response parameters and hence their effective performance under blast loads. Modelling approaches, material models and constraint types used are presented along with the validation of the procedure. Results from numerical models created in LS DYNA are compared with existing numerical and experimental results from literature to validate the modelling techniques. Behaviour of cable net and cable truss façades under a credible blast event are then compared by analysing the effects of cable and panel configurations. The findings of the comparative analysis, show that cable truss façades (in general) have reduced deflections and higher energy absorption capacities, but with larger cable forces. This information can be used in the design of either façade type to obtain the desired blast response. The numerical modelling techniques developed in this paper deliver important information on the blast response and failure assessment of cable supported façades and the comparative analysis will provide guidance in future research and investigation to enable safer designs.

Influence of interlayer properties on the blast performance of laminated glass panels

Construction and Building Materials, 2015

Influence of interlayer properties on the blast performance of laminated glass panels. Constructi... more

Vibration characteristics of plate elements subjected in-plane loads (axial loads)

Proceedings of 2011 …, 2011

Axial deformations resulting from in-plane loads (axial forces) of plate elements impact signific... more

Performance of reinforced concrete columns under bi-axial lateral force/displacement and axial load

Engineering Structures, 2015

Accurate and realistic assessment of the performance of columns in general and those in critical ... more Accurate and realistic assessment of the performance of columns in general and those in critical locations that may cause progressive failure of the entire structure, in particular, is significantly important. This performance is affected by the load history, pattern and intensity. Current design code does not consider the effect of load pattern on the load and displacement capacity of columns. In the study reported here, monotonic material models, cyclic rule, and plastic hinge models have been utilized in a fiber-based analytical procedure, validated against experimental data. Comparison of the analytical predictions and experimental data, through moment-curvature and force-deflection analyses, confirmed the accuracy and validity of the analytical algorithm and models. The analytical model was then used in a parametric study considering the effects of axial load variation and lateral force/displacement paths on the flexural strength and energy dissipation capacity of reinforced concrete columns.

Using heritage building registers to characterise unreinforced masonry buildings of Brisbane, Australia

Australian Journal of Structural Engineering

Infrastructure Sustainability

Urban Management, Engineering, and Design

Axial deformations resulting from in-plane loads (axial forces) of plate elements impact signific... more Axial deformations resulting from in-plane loads (axial forces) of plate elements impact significantly on their vibration characteristics. Although, numerous methods have been developed to quantify axial forces and hence deformations of individual plate elements with different boundary conditions based on their natural frequencies, these methods are unable to apply to the plate elements in a structural system. This is because the natural frequency is a global parameter for the entire structure. Thus, this paper proposes a comprehensive vibration based procedure to quantify axial deformations of plate elements in a structural framing system. Unique capabilities of the proposed method present through illustrative examples.

Energy Dissipation and Behaviour of Building Façade Systems under Seismic Loads

Proceedings of the Eighth International Conference on Computational Structures Technology

Hareer, Rahila, Perera, Nimal, Thambiratnam, David, Hareer, Rahila, Perera, Nirmal, &amp; Tha... more

Quantifying in-plane deformation of plate elements using vibration characteristics

Journal of Sound and Vibration, 2011

This is the author's version of a work that was accepted for publication in Journal of Sound and ... more This is the author's version of a work that was accepted for publication in Journal of Sound and Vibration. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published

Discussion of “Study of viscoelastic and friction damper configurations in the seismic mitigation of medium-rise structures”

Journal of Mechanics of Materials and Structures, 2006

The discusser is very interested in the paper presented by Julius Marko, David Thambiratnam and N... more The discusser is very interested in the paper presented by Julius Marko, David Thambiratnam and Nimal Perera. This paper includes various interesting aspects, for example, comparison of the effectiveness of various damper systems (viscoelastic, friction and hybrid), optimal damper configuration and location, and the influence of different types of earthquake ground motions on the response reduction by dampers. The authors draw several references for readers. In the discusser's opinion, more versatile investigations on optimal damper configuration and location have been made in the scientific community of earthquake engineering, and computing algorithms based on certain theoretical backgrounds have been proposed [

Numerical simulation of axially loaded concrete columns under transverse impact and vulnerability assessment

International Journal of Impact Engineering, 2010

With a view to assessing the vulnerability of columns to low elevation vehicular impacts, a non-l... more With a view to assessing the vulnerability of columns to low elevation vehicular impacts, a non-linear explicit numerical model has been developed and validated using existing experimental results. The numerical model accounts for the effects of strain rate and confinement of the reinforced concrete, which are fundamental to the successful prediction of the impact response. The sensitivity of the material model parameters used for the validation is also scrutinised and numerical tests are performed to examine their suitability to simulate the shear failure conditions. Conflicting views on the strain gradient effects are discussed and the validation process is extended to investigate the ability of the equations developed under concentric loading conditions to simulate flexural failure events. Experimental data on impact force time histories, mid span and residual deflections and support reactions have been verified against corresponding numerical results. A universal technique which can be applied to determine the vulnerability of the impacted columns against collisions with new generation vehicles under the most common impact modes is proposed. Additionally, the observed failure characteristics of the impacted columns are explained using extended outcomes. Based on the overall results, an analytical method is suggested to quantify the vulnerability of the columns.

Blast response and safety evaluation of a composite column for use as key element in structural systems

Engineering Structures, 2014

This paper presents the blast response, damage mechanism and evaluation of residual load capacity... more This paper presents the blast response, damage mechanism and evaluation of residual load capacity of a concrete-steel composite (CSC) column using dynamic computer simulation techniques. This study is an integral part of a comprehensive research program which investigated the vulnerability of structural framing systems to catastrophic and progressive collapse under blast loading and is intended to provide design information on blast mitigation and safety evaluation of load bearing vulnerable columns that are key elements in a building. The performance of the CSC column is compared with that of a reinforced concrete (RC) column with the same dimensions and steel ratio. Results demonstrate the superior performance of the CSC column, compared to the RC column in terms of residual load carrying capacity, and its potential for use as a key element in structural systems. The procedure and results presented herein can be used in the design and safety evaluation of key elements of multi-storey buildings for mitigating the impact of blast loads.

Monotonic behaviour of composite column to beam connections

Engineering Structures, 2001

An experimental investigation into the behaviour of composite column-to-beam connections using te... more An experimental investigation into the behaviour of composite column-to-beam connections using ten large-scale connections has been conducted, four under monotonic loading and six under cyclic loading. This paper presents the details and results of the four preliminary monotonic tests. Details and results of the cyclic tests are reported in a companion paper. All connections consisted of a circular concrete-filled steel tubular column, a compact universal beam section and a shop fabricated connection stub. It is a direct connection of the beam to the tube wall (using flange connection plates, and web cleat plates) and four straight reinforcing bars welded to the top and bottom flanges and embedded into the concrete core. It was found that the connection strength increased as the capacity of the embedded bars increased, to a stage where no connection failure occurred, and the beam formed a plastic hinge outside the zone of influence of the bars. The bars were very effective in transferring both compressive and tensile loads directly into the column, and connection behaviour in terms of strength and stiffness was adequate to classify it as a rigid connection.

Blast response and failure analysis of pile foundations subjected to surface explosion

Engineering Failure Analysis, 2014

Blast response and failure analysis of pile foundations subjected to surface explosion.

Damage assessment of 3D reinforced concrete frame under external explosion loading

Multi-storey buildings are highly vulnerable to terrorist bombing attacks in various parts of the... more

Finite Element Analysis of a Rollover Protective Structure for a Komatsu 630E Dump Truck

Barker, Nicholas, Clark, Brian, Perera, Nimal, & Thambiratnam, David (2004) Finite Element Analys... more

Coupling coefficient and lateral vibration of slender suspension footbridges

Computers & Structures, 2008

... According to the assumptions, the walking dynamic load will consist of three parts: vertical ... more