A short-span pre-stressed concrete bridge was the subject of several in-situ experimental investi... more A short-span pre-stressed concrete bridge was the subject of several in-situ experimental investigations and analyses including experimental modal analyses and continuous live strain monitoring campaigns. Data from the latter was used to examine whether the cost of carrying the monitoring exercise can be justified by a tangible reduction in the risk of structural failure as assessed with the benefit of the data. To that end, the bridge risk was quantified initially using structural reliability methods and loads mandated by a design code but without any information from monitoring, and then the risk assessment was repeated with the measured strain data incorporated into the process. The comparison of the two risk values enabled quantifying the value of information derived from structural health monitoring, which was found to bring an overall net benefit.
The Changi Mezzanine Bridge is a 140m span flat arch footbridge constructed from welded tubular s... more The Changi Mezzanine Bridge is a 140m span flat arch footbridge constructed from welded tubular steel sections inside a tunnel that connects two passenger terminals at Changi Airport, Singapore. A series of vibration measurements were made on the bridge during construction, showing that non-structural cladding added mass and reduced the natural frequencies while also increasing the modal damping, from as little as 0.2% originally to around 0.4% for critical vibration modes. From these preliminary studies leading up to the opening of the bridge in early 2002, it was clear that the first symmetric lateral vibration mode (LS1) at approximately 0.9Hz and the first symmetric torsional vibration mode (TS1) at approximately 1.64Hz could be excited easily by pedestrian movement. The modal parameters for mode LS1 suggested that the bridge could suffer from synchronous lateral excitation for a walking pace of 1.8Hz while for TS1 the potential problem was the coincidence of the mode frequency ...
Precast-cast insitu concrete bridge construction is widely practiced for small to medium span str... more Precast-cast insitu concrete bridge construction is widely practiced for small to medium span structures. These bridges consist of precast pre-stressed concrete beams of various cross-sections with a cast in-situ reinforced concrete slab. The connection between the beams and the slab is via shear links often included during the manufacturing process of the beams. This form of construction is attractive as it provides for standardisation, reduced formwork and construction time. The assessment of the integrity of shear connectors in existing bridges is a major challenge. A procedure for assessment of shear connectors based on vibration testing and finite element model updating is proposed. The technique is applied successfully to a scaled model bridge model and an existing bridge structure.
Journal of the South African Institution of Civil Engineers
The objective of the paper is to provide an understanding of the South African concrete industry&... more The objective of the paper is to provide an understanding of the South African concrete industry's environmental burden in terms of natural resource consumption and carbon dioxide equivalent emissions (CO2-e). The review covers current practices in the concrete construction field in South Africa (SA) and their implications for the environment. Elaboration in terms of detail and quantification is given for the environmental burden generated during the manufacture of raw materials for concrete and their transportation to site. Four-year average (2005-2008) data is provided for resources consumed and wastes emitted during the quarrying and manufacture of raw materials for concrete. Carbon dioxide-equivalent emissions data per unit of material produced was obtained from the InEnergy Report produced for the Cement and Concrete Institute (C&CI) of South Africa. The study determined that, on average, 39.7 Mt of raw materials are consumed per year and 4.92 x 109 kg CO2-e emissions are e...
... H. Beushausen (&) Á C. Masuku Á P. Moyo Department of Civil Engineering, University of Ca... more ... H. Beushausen (&) Á C. Masuku Á P. Moyo Department of Civil Engineering, University of Cape Town, Rondebosch, Western Cape ... Beushausen and Alexander [5, 17, 18] found that tensile relaxation in bonded concrete overlays subjected to restrained drying shrinkage relieved ...
ABSTRACT: This paper presents the results of an experimental study conducted to characterize the ... more ABSTRACT: This paper presents the results of an experimental study conducted to characterize the structural behaviour of beams corroded whilst subjected to a constant sustained load. Corrosion on tensile steel bars was induced by an accelerated corrosion ...
Proceedings of the GeoHunan International Conference II: Emerging Technologies for Design, Constr... more Proceedings of the GeoHunan International Conference II: Emerging Technologies for Design, Construction, Rehabilitation, and Inspection of Transportation Infrastructure, held in Hunan, China, June 9-11, 2011. This Geotechnical Special Publication contains 25 papers addressing contemporary geotechnical subjects. These papers focus on current issues in materials, design, construction, maintenance, and testing of civil infrastructure, as well as sustainability issues through innovative use of materials.
ABSTRACT: A probabilistic model for chloride diffusion under South Africa (SA) marine conditions ... more ABSTRACT: A probabilistic model for chloride diffusion under South Africa (SA) marine conditions has been developed. The model is a further improvement of a service life prediction model developed earlier on by Mackechnie (1996), as it takes into account the ...
Repair and strengthening using Fiber Reinforced Polymers (FRP) have been one of worldwide methods... more Repair and strengthening using Fiber Reinforced Polymers (FRP) have been one of worldwide methods used to improve the load carrying capacity and durability of reinforced concrete structural elements such as beams, in decline mainly due to corrosion of steel reinforcement resulting from the deterioration of the concrete cover. The main objective of this study was to investigate the behavior of reinforced concrete beam patch repaired and strengthened with FRP composites. The 3D finite element analysis was conducted using Abaqus software, while the repair consisted of varying the length of the patch, where four patch lengths were considered. Isotropic concrete damaged plasticity model was applied to describe the behavior of both concrete and repair material. Linear elastic-perfectly plastic and linear elastic isotropic model were used for steel and FRP; respectively, while cohesive bond model was used for the interface between concrete and FRP. Numerical results show good agreement with experimental findings in terms of load-deflection curves, crack pattern and modes of failure. The study also revealed that for proper structural crack distribution, it is better to use force control while for failure mechanism, displacement control is the best choice. Finally, once again it was proved that both patch repair and FRP strengthening increased the load carrying capacity and affected crack distribution.
Monitoring programs on four very different highway bridges originating from a range of require-me... more Monitoring programs on four very different highway bridges originating from a range of require-ments related to calibration of numerical models, assessment of load capacity and long term track-ing of performance are summarized in order to draw out lessons relevant to the future development of structural health monitoring ‘systems’. These lessons concern validation of structural models, appropriate methods for instrumentation, communication, data management and system identifica-tion. The paper presents experience obtained by collaboration in a form intended to educate, by ex-ample, bridge operators about potential and limitations of SHM systems
A short-span pre-stressed concrete bridge was the subject of several in-situ experimental investi... more A short-span pre-stressed concrete bridge was the subject of several in-situ experimental investigations and analyses including experimental modal analyses and continuous live strain monitoring campaigns. Data from the latter was used to examine whether the cost of carrying the monitoring exercise can be justified by a tangible reduction in the risk of structural failure as assessed with the benefit of the data. To that end, the bridge risk was quantified initially using structural reliability methods and loads mandated by a design code but without any information from monitoring, and then the risk assessment was repeated with the measured strain data incorporated into the process. The comparison of the two risk values enabled quantifying the value of information derived from structural health monitoring, which was found to bring an overall net benefit.
The Changi Mezzanine Bridge is a 140m span flat arch footbridge constructed from welded tubular s... more The Changi Mezzanine Bridge is a 140m span flat arch footbridge constructed from welded tubular steel sections inside a tunnel that connects two passenger terminals at Changi Airport, Singapore. A series of vibration measurements were made on the bridge during construction, showing that non-structural cladding added mass and reduced the natural frequencies while also increasing the modal damping, from as little as 0.2% originally to around 0.4% for critical vibration modes. From these preliminary studies leading up to the opening of the bridge in early 2002, it was clear that the first symmetric lateral vibration mode (LS1) at approximately 0.9Hz and the first symmetric torsional vibration mode (TS1) at approximately 1.64Hz could be excited easily by pedestrian movement. The modal parameters for mode LS1 suggested that the bridge could suffer from synchronous lateral excitation for a walking pace of 1.8Hz while for TS1 the potential problem was the coincidence of the mode frequency ...
Precast-cast insitu concrete bridge construction is widely practiced for small to medium span str... more Precast-cast insitu concrete bridge construction is widely practiced for small to medium span structures. These bridges consist of precast pre-stressed concrete beams of various cross-sections with a cast in-situ reinforced concrete slab. The connection between the beams and the slab is via shear links often included during the manufacturing process of the beams. This form of construction is attractive as it provides for standardisation, reduced formwork and construction time. The assessment of the integrity of shear connectors in existing bridges is a major challenge. A procedure for assessment of shear connectors based on vibration testing and finite element model updating is proposed. The technique is applied successfully to a scaled model bridge model and an existing bridge structure.
Journal of the South African Institution of Civil Engineers
The objective of the paper is to provide an understanding of the South African concrete industry&... more The objective of the paper is to provide an understanding of the South African concrete industry's environmental burden in terms of natural resource consumption and carbon dioxide equivalent emissions (CO2-e). The review covers current practices in the concrete construction field in South Africa (SA) and their implications for the environment. Elaboration in terms of detail and quantification is given for the environmental burden generated during the manufacture of raw materials for concrete and their transportation to site. Four-year average (2005-2008) data is provided for resources consumed and wastes emitted during the quarrying and manufacture of raw materials for concrete. Carbon dioxide-equivalent emissions data per unit of material produced was obtained from the InEnergy Report produced for the Cement and Concrete Institute (C&CI) of South Africa. The study determined that, on average, 39.7 Mt of raw materials are consumed per year and 4.92 x 109 kg CO2-e emissions are e...
... H. Beushausen (&) Á C. Masuku Á P. Moyo Department of Civil Engineering, University of Ca... more ... H. Beushausen (&) Á C. Masuku Á P. Moyo Department of Civil Engineering, University of Cape Town, Rondebosch, Western Cape ... Beushausen and Alexander [5, 17, 18] found that tensile relaxation in bonded concrete overlays subjected to restrained drying shrinkage relieved ...
ABSTRACT: This paper presents the results of an experimental study conducted to characterize the ... more ABSTRACT: This paper presents the results of an experimental study conducted to characterize the structural behaviour of beams corroded whilst subjected to a constant sustained load. Corrosion on tensile steel bars was induced by an accelerated corrosion ...
Proceedings of the GeoHunan International Conference II: Emerging Technologies for Design, Constr... more Proceedings of the GeoHunan International Conference II: Emerging Technologies for Design, Construction, Rehabilitation, and Inspection of Transportation Infrastructure, held in Hunan, China, June 9-11, 2011. This Geotechnical Special Publication contains 25 papers addressing contemporary geotechnical subjects. These papers focus on current issues in materials, design, construction, maintenance, and testing of civil infrastructure, as well as sustainability issues through innovative use of materials.
ABSTRACT: A probabilistic model for chloride diffusion under South Africa (SA) marine conditions ... more ABSTRACT: A probabilistic model for chloride diffusion under South Africa (SA) marine conditions has been developed. The model is a further improvement of a service life prediction model developed earlier on by Mackechnie (1996), as it takes into account the ...
Repair and strengthening using Fiber Reinforced Polymers (FRP) have been one of worldwide methods... more Repair and strengthening using Fiber Reinforced Polymers (FRP) have been one of worldwide methods used to improve the load carrying capacity and durability of reinforced concrete structural elements such as beams, in decline mainly due to corrosion of steel reinforcement resulting from the deterioration of the concrete cover. The main objective of this study was to investigate the behavior of reinforced concrete beam patch repaired and strengthened with FRP composites. The 3D finite element analysis was conducted using Abaqus software, while the repair consisted of varying the length of the patch, where four patch lengths were considered. Isotropic concrete damaged plasticity model was applied to describe the behavior of both concrete and repair material. Linear elastic-perfectly plastic and linear elastic isotropic model were used for steel and FRP; respectively, while cohesive bond model was used for the interface between concrete and FRP. Numerical results show good agreement with experimental findings in terms of load-deflection curves, crack pattern and modes of failure. The study also revealed that for proper structural crack distribution, it is better to use force control while for failure mechanism, displacement control is the best choice. Finally, once again it was proved that both patch repair and FRP strengthening increased the load carrying capacity and affected crack distribution.
Monitoring programs on four very different highway bridges originating from a range of require-me... more Monitoring programs on four very different highway bridges originating from a range of require-ments related to calibration of numerical models, assessment of load capacity and long term track-ing of performance are summarized in order to draw out lessons relevant to the future development of structural health monitoring ‘systems’. These lessons concern validation of structural models, appropriate methods for instrumentation, communication, data management and system identifica-tion. The paper presents experience obtained by collaboration in a form intended to educate, by ex-ample, bridge operators about potential and limitations of SHM systems
Despite the recent considerable advances in structural health monitoring (SHM) of civil infrastru... more Despite the recent considerable advances in structural health monitoring (SHM) of civil infrastructure, converting large amount of data from SHM systems into usable information and knowledge remains a great challenge. This paper addresses the problem through analysis of time histories of static strain data recorded by an SHM system installed in a major bridge structure and operating continuously for a long time. The reported study formulates a vector seasonal autoregressive integrated moving average (ARIMA) model for the recorded strain signals. The coefficients of the ARIMA model are allowed to vary with time and are identified using an adaptive Kalman filter. The proposed method has been used for analysis of the signals recorded during construction and service life of the bridge. By observing various changes in the ARIMA model coefficients, unusual events as well as structural change or damage sustained by the structure can be revealed.
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Papers by Pilate Moyo