Peter Dux - Academia.edu (original) (raw)

Papers by Peter Dux

This paper presents a personal view of changes in tertiary education and the possible long term i... more This paper presents a personal view of changes in tertiary education and the possible long term influence on the quality of professional engineering. The bodies that make up Austroads are large employers of both new graduates and experienced engineers and, like other engineering groups, have a vested interest in ensuring that the standard of engineering in Australia is enhanced by each succeeding generation of engineers. This paper discuses the quantum of learning undertaken by undergraduates, the decline in postgraduate studies, the effect on personal scholarship of the practicing professional and the likelihood or otherwise of the emergence of new experts to replace older expert engineers as they move towards retirement. The paper uses research programs to highlight the positive influence that funding of research, and in particular the funding of research scholars by organisations from the ranks of Austroads have had on engineering in general and on knowledge of close relevance to...

Masonry International, 2014

Several researchers have shown experimentally that grouted blockwork masonry walls under axial co... more Several researchers have shown experimentally that grouted blockwork masonry walls under axial compression fail by separation of the face shell from the grout core, that is, by a splitting failure. This paper reports elastic finite element analyses conducted using the program LUSAS to identify the critical stress distribution leading to failure. The analyses show that splitting occurs as a result of the lateral horizontal tensile stresses that arise due to the different stiffnesses of the concrete block, grout and mortar comprising the blockwork. It is also shown that imperfections such as internal voids and cracks, and mortar intrusions into the grout increase these stresses. In addition, unrestrained vertical and horizontal reinforcement are shown to have no significant effect on the horizontal stresses that cause the splitting failure, although vertical reinforcement does increase the compressive load at which this failure occurs.

The purpose of this paper is to present designers with accurate elastic buckling solutions for be... more The purpose of this paper is to present designers with accurate elastic buckling solutions for beams subjected to common loading and restraint conditions, so that a more economical design may be achieved. Simply supported beams and cantilevers under moment gradient loading, point loading and uniformly distributed loading are considered. Solutions are also presented for single span beams with a variety of end restraint conditions. The influence of the level of application of transverse loading is also examined. Elastic beams and cantilevers with internal bracing are examined. The influence of brace type and location is investigated along with that of the level of application of load above and below the shear centre. Moment gradient loading, point loading and uniformly distributed loading are considered. Data on optimum internal brace location is provided. A general method for determining the elastic buckling loads of laterally continuous structures is presented. These range from beams with multiple supports and braces to grid structures. An analysis procedure and worked examples are presented.

... Effectiveness of permeability-reducing admixtures in marine concrete. Dao, Vinh, Dux, Peter, ... more ... Effectiveness of permeability-reducing admixtures in marine concrete. Dao, Vinh, Dux, Peter, and Morris, Peter (2007) Effectiveness of permeability-reducing admixtures in marine concrete. ISBN 2 ... Engineering @ 100%. SEO Codes ...

Lecture Notes in Civil Engineering

Together with drying shrinkage and autogenous deformations, thermal strain is one of the driving ... more Together with drying shrinkage and autogenous deformations, thermal strain is one of the driving force of cracking of cement-based materials at early ages. However, current understanding of these early-age deformations remains unsystematic and further studies are needed. In this paper, evolution of thermal strain and coefficient of thermal expansion (CTE) are reviewed. Based on a newly built test setup at The University of Queensland, the development of the CTE of concrete at early ages was measured and investigated. It is found that CTE shows a clear rising trend after setting, meaning that CTE cannot be seen as constant even though this has often been done for modelling and design purpose. Based on newly-measured CTE, the separation process of self-desiccation shrinkage and thermal strain was studied. It is noted that the separation process is rather complicated due to the effects of delayed thermal strain. Through literature review, it is demonstrated that the delayed thermal strain is closely linked to relative humidity change inside concrete. Since the development of self-desiccation shrinkage is also affected by such relative humidity change, there appears a coupling effect between self-desiccation shrinkage and delayed thermal strain, which should be further studied in the future.

The flat plate system is currently widely used in construction. It permits architectural flexibil... more The flat plate system is currently widely used in construction. It permits architectural flexibility, more clear space, less building height, easier formwork, and shorter construction time. However, there remains the problem of brittle punching failure due to the transfer of shearing forces and unbalanced moments at the flat plate-column connection. It is the purpose of this paper to investigate the effects of various interdependent factors that govern the punching shear resistance and behaviour of the flat plate-column connection, as well as their inclusion in current Codes.

A research program was initiated to investigate the adequacy of the design requirements and perfo... more A research program was initiated to investigate the adequacy of the design requirements and performance of a sinusoidal and a ribbed profile helical culvert for a range of low overburden fills. This paper examines the response of a 3000mm diameter sinusoidal profile and a ribbed profile culvert with 900mm of fill. Each culvert was instrumented with pressure transducers, displacement transducers and strain gauges. The test program has measured significant bending effects in association with hoop loads on the culvert. This paper examines the distribution of the hoop and bending effects about the circumference of the culvert. There is significant difference in response between the two culverts. There were also major differences between the measure behaviour of the two culverts from the assumed ring compression design methodology in the current Australian Standards.

A method for estimating the inelastic buckling moment of a simply supported I-Beam under a moment... more A method for estimating the inelastic buckling moment of a simply supported I-Beam under a moment gradient is proposed. The concept of the stiffness modification factor j, is introduced. The moment capacity is obtained from the elastic buckling moment and from the stiffness modification factor, the latter being related to the reduced lateral bending stiffness at the maximum moment or critical end of the partially yielded beam. Comparison of results with accurate computer curves shows that the proposed method gives good estimates of inelastic buckling moments. /Author/TRRL/

A method for estimation the inelastic buckling moment of a simply supported I-beam under a moment... more A method for estimation the inelastic buckling moment of a simply supported I-beam under a moment gradient is proposed. The concept of the stiffness modification factor is introduced. The moment capacity is obtained from the elastic buckling moment and from the stiffness modification factor, the later being found to be related to the reduced lateral bending stiffness at the maximum moment or critical end of the partially yielded beam.

Cracking in concrete arises from numerous causes. Sometimes cracking is significant but in many i... more Cracking in concrete arises from numerous causes. Sometimes cracking is significant but in many instances it is not. Classification is often made into subjective categories such as structural and non-structural cracks. The cause giving rise to the stress involved in each instance of cracking can often be readily identified. However, it is more difficult to identify the underlying reason for significant cracks. For example, cracks in the category ‘drying shrinkage cracks’ in slabs might be put down to excessive drying shrinkage of the concrete. The reality is that while the prime mover may be drying shrinkage, activities as compaction and curing are important, and a slab with relatively low shrinkage concrete may still develop significant shrinkage cracks.

This paper presents a personal view of changes in tertiary education and the possible long term i... more This paper presents a personal view of changes in tertiary education and the possible long term influence on the quality of professional engineering. The bodies that make up Austroads are large employers of both new graduates and experienced engineers and, like other engineering groups, have a vested interest in ensuring that the standard of engineering in Australia is enhanced by each succeeding generation of engineers. This paper discuses the quantum of learning undertaken by undergraduates, the decline in postgraduate studies, the effect on personal scholarship of the practicing professional and the likelihood or otherwise of the emergence of new experts to replace older expert engineers as they move towards retirement. The paper uses research programs to highlight the positive influence that funding of research, and in particular the funding of research scholars by organisations from the ranks of Austroads have had on engineering in general and on knowledge of close relevance to...

Masonry International, 2014

Several researchers have shown experimentally that grouted blockwork masonry walls under axial co... more Several researchers have shown experimentally that grouted blockwork masonry walls under axial compression fail by separation of the face shell from the grout core, that is, by a splitting failure. This paper reports elastic finite element analyses conducted using the program LUSAS to identify the critical stress distribution leading to failure. The analyses show that splitting occurs as a result of the lateral horizontal tensile stresses that arise due to the different stiffnesses of the concrete block, grout and mortar comprising the blockwork. It is also shown that imperfections such as internal voids and cracks, and mortar intrusions into the grout increase these stresses. In addition, unrestrained vertical and horizontal reinforcement are shown to have no significant effect on the horizontal stresses that cause the splitting failure, although vertical reinforcement does increase the compressive load at which this failure occurs.

The purpose of this paper is to present designers with accurate elastic buckling solutions for be... more The purpose of this paper is to present designers with accurate elastic buckling solutions for beams subjected to common loading and restraint conditions, so that a more economical design may be achieved. Simply supported beams and cantilevers under moment gradient loading, point loading and uniformly distributed loading are considered. Solutions are also presented for single span beams with a variety of end restraint conditions. The influence of the level of application of transverse loading is also examined. Elastic beams and cantilevers with internal bracing are examined. The influence of brace type and location is investigated along with that of the level of application of load above and below the shear centre. Moment gradient loading, point loading and uniformly distributed loading are considered. Data on optimum internal brace location is provided. A general method for determining the elastic buckling loads of laterally continuous structures is presented. These range from beams with multiple supports and braces to grid structures. An analysis procedure and worked examples are presented.

... Effectiveness of permeability-reducing admixtures in marine concrete. Dao, Vinh, Dux, Peter, ... more ... Effectiveness of permeability-reducing admixtures in marine concrete. Dao, Vinh, Dux, Peter, and Morris, Peter (2007) Effectiveness of permeability-reducing admixtures in marine concrete. ISBN 2 ... Engineering @ 100%. SEO Codes ...

Lecture Notes in Civil Engineering

Together with drying shrinkage and autogenous deformations, thermal strain is one of the driving ... more Together with drying shrinkage and autogenous deformations, thermal strain is one of the driving force of cracking of cement-based materials at early ages. However, current understanding of these early-age deformations remains unsystematic and further studies are needed. In this paper, evolution of thermal strain and coefficient of thermal expansion (CTE) are reviewed. Based on a newly built test setup at The University of Queensland, the development of the CTE of concrete at early ages was measured and investigated. It is found that CTE shows a clear rising trend after setting, meaning that CTE cannot be seen as constant even though this has often been done for modelling and design purpose. Based on newly-measured CTE, the separation process of self-desiccation shrinkage and thermal strain was studied. It is noted that the separation process is rather complicated due to the effects of delayed thermal strain. Through literature review, it is demonstrated that the delayed thermal strain is closely linked to relative humidity change inside concrete. Since the development of self-desiccation shrinkage is also affected by such relative humidity change, there appears a coupling effect between self-desiccation shrinkage and delayed thermal strain, which should be further studied in the future.

The flat plate system is currently widely used in construction. It permits architectural flexibil... more The flat plate system is currently widely used in construction. It permits architectural flexibility, more clear space, less building height, easier formwork, and shorter construction time. However, there remains the problem of brittle punching failure due to the transfer of shearing forces and unbalanced moments at the flat plate-column connection. It is the purpose of this paper to investigate the effects of various interdependent factors that govern the punching shear resistance and behaviour of the flat plate-column connection, as well as their inclusion in current Codes.

A research program was initiated to investigate the adequacy of the design requirements and perfo... more A research program was initiated to investigate the adequacy of the design requirements and performance of a sinusoidal and a ribbed profile helical culvert for a range of low overburden fills. This paper examines the response of a 3000mm diameter sinusoidal profile and a ribbed profile culvert with 900mm of fill. Each culvert was instrumented with pressure transducers, displacement transducers and strain gauges. The test program has measured significant bending effects in association with hoop loads on the culvert. This paper examines the distribution of the hoop and bending effects about the circumference of the culvert. There is significant difference in response between the two culverts. There were also major differences between the measure behaviour of the two culverts from the assumed ring compression design methodology in the current Australian Standards.

A method for estimating the inelastic buckling moment of a simply supported I-Beam under a moment... more A method for estimating the inelastic buckling moment of a simply supported I-Beam under a moment gradient is proposed. The concept of the stiffness modification factor j, is introduced. The moment capacity is obtained from the elastic buckling moment and from the stiffness modification factor, the latter being related to the reduced lateral bending stiffness at the maximum moment or critical end of the partially yielded beam. Comparison of results with accurate computer curves shows that the proposed method gives good estimates of inelastic buckling moments. /Author/TRRL/

A method for estimation the inelastic buckling moment of a simply supported I-beam under a moment... more A method for estimation the inelastic buckling moment of a simply supported I-beam under a moment gradient is proposed. The concept of the stiffness modification factor is introduced. The moment capacity is obtained from the elastic buckling moment and from the stiffness modification factor, the later being found to be related to the reduced lateral bending stiffness at the maximum moment or critical end of the partially yielded beam.

Cracking in concrete arises from numerous causes. Sometimes cracking is significant but in many i... more Cracking in concrete arises from numerous causes. Sometimes cracking is significant but in many instances it is not. Classification is often made into subjective categories such as structural and non-structural cracks. The cause giving rise to the stress involved in each instance of cracking can often be readily identified. However, it is more difficult to identify the underlying reason for significant cracks. For example, cracks in the category ‘drying shrinkage cracks’ in slabs might be put down to excessive drying shrinkage of the concrete. The reality is that while the prime mover may be drying shrinkage, activities as compaction and curing are important, and a slab with relatively low shrinkage concrete may still develop significant shrinkage cracks.