ORCID Profile
0000-0003-1930-5704
Current Organisations
Queensland University of Technology
,
WHO Alliance for Health Policy and Systems Research
,
National Institute for Health Research
,
Bartlemas Surgery, East Oxford Health Centre
,
University of Oxford
,
NHS England
,
Royal College of General Practitioners
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Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 12-2021
Publisher: BMJ
Date: 02-02-2002
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 06-2023
Publisher: Elsevier BV
Date: 11-2019
Publisher: MDPI AG
Date: 06-07-2021
DOI: 10.3390/BUILDINGS11070294
Abstract: Prefabrication has been shown to be an effective way of construction in the modern-day context. Although much progress has been made in developing reinforced concrete (RC), timber and steel prefabricated elements/structures, prefabrication of masonry walling systems has received limited attention in the past. Conventional masonry construction is labour-intensive and time-consuming therefore, prefabrication can be an effective solution to accelerate the masonry construction to make it more cost-effective. Therefore, in this paper, an attempt has been made to evaluate the effectiveness of prefabricated masonry systems (PMS) in terms of their structural characteristics and sustainability perspectives in an Australian context. Subsequently, the available studies related to PMS and the prospects of developing prefabricated masonry walling systems were appraised and reported. In order to assess the applicability of PMS, a case study was carried out by designing four types of prospective prefabricated masonry walling systems for a typical housing unit in Australia. It was shown that the reinforced (RM), post-tensioned (PT) and thin layered mortared (TLM) masonry systems are better suited for prefabrication. Later, in order to assess the sustainability of the considered masonry walling systems, life cycle energy analyses were carried using the Environmental Performance in Construction (EPIC) database. It was found that there can be nearly 30% and 15% savings, respectively, in terms of energy saving and CO2 emissions in prefabricated construction than the conventional masonry construction. Finally, the prospects of developing PMS and the need for future research studies on these systems are highlighted.
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 07-2021
Publisher: ISEC Press
Date: 11-2020
DOI: 10.14455/ISEC.2020.7(2).STR-48
Abstract: This paper reviews the approach of eleven national codes on the analysis and design of masonry-infilled frames. It is shown that, in general, codes can be ided into two groups. The first group isolates the masonry and frame members by providing gaps to minimize the interaction between them. This method ensures that the complexities involved in analyzing the structure is avoided. However, the width of the gaps recommended is different for each of the codes. The second group takes advantage of the presence of high stiffness and strength masonry infill. In this technique, an equivalent-strut modeling strategy is mostly recommended. It is shown that the strut model suggested in each of the codes is different. An attempt to obtain a generic model for masonry-infilled frame failed largely due to the existence of many behavior-influencing parameters. Finally, it is suggested to have a paradigm shift in the modeling strategy where the masonry-infilled frames are classified into different categories and a model is suggested for each of them.
Publisher: ISEC Press
Date: 11-2020
DOI: 10.14455/ISEC.2020.7(2).STR-47
Abstract: Most masonry arch railway bridges in the world are servicing the communities well beyond their intended design lives. However, these bridges would have undergone numerous deteriorations over the period of several decades of service life. The asset owners of these bridges are confronted with the decision over whether to continue servicing or decommissioning these bridges. Such decisions are critical from safety and economic points of views, and it can be addressed only by conducting a proper investigation of such structures. This paper presents the capacity assessment of typical in-service masonry arch bridges based on properties of masonry obtained through core testing. The bridges were modeled and analyzed for the ultimate capacity through limit state analysis method. Important parameters such as influence of backfill properties, strength of masonry, and span-to-rise ratio are discussed. The results indicate that the investigated bridges can sustain the current operating loads with a reasonable margin of safety index.
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2019
Publisher: Elsevier BV
Date: 04-2016
Publisher: MDPI AG
Date: 28-04-2022
Abstract: Bonded brickwork used for loadbearing walls is widely found in heritage structures worldwide. The evaluation of bonded masonry structures and their strengthening strategies against dynamic actions require appropriate understanding under cyclic loading. Subsequently, a simplified 3D microscale numerical model is developed in this paper to analyse bonded brickwork under cyclic compression. A plasticity-based damage constitutive model to represent damage in masonry bricks under cyclic compression loading was employed, and zero-thickness interfaces were considered with non-linear damage properties to simulate the mechanical behaviour of masonry. A threshold strain level was used to enact the element deletion technique for initiating brittle crack opening in the masonry units. The developed model was validated against the experimental results published by the authors in the past. The models were able to accurately predict the experimental results with an error limit of 10% maximum. Mainly, two types of strengthening materials, possessing (1) high energy absorption characteristics (auxetic fabric) and (2) high strength properties (carbon fibre reinforced polymer composites/CFRP) were employed for damage mitigation under cyclic compression. Results show that the CFRP-strengthened masonry failure was mainly attributed to de-bonding of the CFRP and crushing under compression. However, the auxetic strengthening is shown to significantly minimise the de-bonding phenomenon. Enhanced energy dissipation characteristics with relatively higher ductility (up to ~50%) and reduced damages on the bonded brickwork were observed as compared to the CFRP-strengthened brickwork under cyclic compression loading. Additionally, the auxetic fabric application also increased the compressive resistance of brickwork by 38–60% under monotonic loading, which is comparably higher than with the CFRP strengthening technique.
Publisher: Elsevier BV
Date: 10-2020
Publisher: BMJ
Date: 17-01-2023
Publisher: SAGE Publications
Date: 29-06-2016
Abstract: A generalised model based on damage mechanics for predicting the response of masonry subjected to compression is presented. The model accounts for the behaviour of the constituents of the masonry, viz., the units, the mortar and the unit–mortar interfaces in this paper, the unit–mortar interfaces and the mortar layers have been treated as a homogenised continuum. The principles of damage mechanics coupled with limiting damage surfaces have been used to simulate the behaviour of the masonry constituents. The novelty is the use of a non-linear, progressively stiffening stress–strain curve to simulate the viscoelastic behaviour of the homogenised mortar–interface (for conventional masonry) or dry surface–interface (for dry-stack masonry) layers until a threshold strain is reached. Beyond the threshold strain, their behaviour is assumed to have changed to progressive softening common for concrete like materials. The damage model for compression and tension due to progressive stiffening and softening criteria respectively have been formulated for the masonry constituents. The parameters which characterise the tensile and compressive behaviours, the volumetric change and the damage behaviour of the masonry constituents have been calibrated using some available experimental data in the literature. The model is shown to predict the average compressive strength and stress–strain behaviour of the masonry prisms appropriately. The model is capable of capturing the behaviour including appropriate stiffness degradation and post peak softening that are comparable to the experimental predictions reported in the literature for various types of masonry.
Publisher: BMJ
Date: 06-12-2022
DOI: 10.1136/BJSPORTS-2022-106092
Abstract: Primary cam morphology is highly prevalent in many athlete populations, causing debilitating hip osteoarthritis in some. Existing research is mired in confusion partly because stakeholders have not agreed on key primary cam morphology elements or a prioritised research agenda. We aimed to inform a more rigorous, inclusive and evidence-based approach to research on primary cam morphology and its natural history by working towards agreement on a set of research priorities for conditions affecting the young person’s hip. An international expert panel—the Young Athlete’s Hip Research (YAHiR) Collaborative—rated research priority statements through an online two-round Delphi exercise and met online to explore areas of tension and dissent. Panellists ranked the prioritised research statements according to the Essential National Health Research (ENHR) ranking strategy. Reporting of results followed REPRISE (REporting guideline for PRIority SEtting of health). A erse Delphi panel (n=65, Delphi rounds 1 and 2 three ENHR strategy surveys: n=49 n=44 n=42) from 18 countries representing six stakeholder groups, prioritised and ranked 18 of 38 research priority statements. The prioritised statements outlined seven research domains: (1) best practice physiotherapy, (2) rehabilitation progression and return to sport, (3) exercise intervention and load management, (4) primary cam morphology prognosis and aetiology, (5) femoroacetabular impingement syndrome prognosis and aetiology, (6) diagnostic criteria, and (7) screening. The panel recommended areas of tension and dissent for the research community to focus on immediately. While informing more rigorous, inclusive and evidence-based research, this consensus is a roadmap for researchers, policy-makers and funders to implement research dedicated to reducing the cost and burden of hip disease related to primary cam morphology.
Publisher: SAGE Publications
Date: 03-03-2022
DOI: 10.1177/20414196211073502
Abstract: This paper summarises the development of a state-of-art impact testing machine for simulating impacts such as vehicular crashes or debris impacts onto structures. The machine has a 200 kg pneumatically powered projectile which can travel horizontally within the barrel of the machine with a maximum velocity of 50 m/s to impact the target structure. The maximum kinetic energy that can be generated by the projectile is 125 kJ by using different combinations of mass and velocity. The diameter of the projectile is 214 mm, and its impacting face can be changed to different shapes, such as flat circle, flat square or an elliptical nose to suit different impact scenarios. An innovative braking mechanism incorporating a crush tube is attached within the barrel to ensure safety when the projectile fails to be restrained by the impact. The crush tube can absorb the maximum imparted by the moving projectile. An advanced data acquisition system is installed to collect quantitative and qualitative test data during a period of 50 ms to 1 s. Two high-speed digital image correlation (DIC) cameras are attached and synchronised with the operation of the impact testing machine to record the images at the rate of 50,000 frames per second. Outputs in terms of strains, deformations, accelerations of the target structure with a record of damage history can be analysed using this 3D DIC technique. The paper also briefly presents the first application of this machine for impact testing masonry wall structures.
Publisher: Elsevier BV
Date: 07-2022
Publisher: Informa UK Limited
Date: 19-08-2021
Publisher: Elsevier BV
Date: 07-2020
Publisher: Trans Tech Publications, Ltd.
Date: 07-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.846.151
Abstract: Building structures use brittle materials extensively. Under impact or blast loads these structures perform poorly due to tensile strains caused by Poisson’s effect normal to the direction of such loadings. Auxetic materials exhibit negative Poisson’s ratio – a property which can be exploited to eliminate those tensile strains. In this study, Auxetic layers embedded masonry is modelled using a representative volume element (RVE) with periodic boundary conditions and an explicit finite element (EFE) modelling method for a boundary value problem of a masonry wall with an Auxetic foam rendered face is subject to out-of-plane load. The RVE is limited to in-plane loads only and hence subjected to in-plane shear and compression and the EFE was used to assess the performance under out-of-plane loading. The results show significant post-yield strain hardening under axial compression and in-plane shear and high increase in capacity for walls under out of plane flexure.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Public Library of Science (PLoS)
Date: 08-07-2016
Publisher: BMJ
Date: 06-12-2022
DOI: 10.1136/BJSPORTS-2022-106085
Abstract: Primary cam morphology is a mostly benign bony prominence that develops at the femoral head-neck junction of the hip, but it is highly prevalent in many athlete populations. In the small proportion of athletes for whom it is not benign, the resulting hip osteoarthritis can be debilitating. Clinicians, athletes, patients and researchers do not yet agree on important primary cam morphology elements. We aimed to ascertain and improve the level of agreement on primary cam morphology definitions, terminology, taxonomy and imaging outcome measures. To collect and aggregate informed opinions, an expert panel—the Young Athlete’s Hip Research Collaborative—rated primary cam morphology definition, terminology, taxonomy and imaging outcome statements through an online Delphi exercise followed by an online meeting to explore areas of tension and dissent. Reporting followed Conducting and REporting DElphi Studies. A erse and inclusive Delphi panel (n=65 for rounds 1 and 2, representing 18 countries 6 stakeholder groups 40% women) agreed on 35 of 47 statements in 4 domains, while surfacing areas of tension and dissent. This Delphi panel agreed on four key issues essential to moving research and clinical care forward around primary cam morphology. They agreed on: (1) definition, confirming its conceptual attributes (tissue type, size, location, shape and ownership) (2) terminology—use ‘morphology’ and not terms with a negative connotation like ‘lesion’, ‘abnormality’ or ‘deformity’ (3) taxonomy, distinguishing between primary and secondary cam morphology, and (4) imaging outcomes, a continuous bone/cartilage alpha angle on radial femoral head-neck MRI for primary cam morphology aetiology research. This consensus provides athletes, patients, clinicians and researchers with a strong foundation to guide more precise communication, better clinical decision-making and higher value research about primary cam morphology and its natural history.
Publisher: Springer Science and Business Media LLC
Date: 19-01-2023
DOI: 10.1617/S11527-023-02102-2
Abstract: Masonry construction is popular around the world, but the use of mortared masonry presents numerous challenges. In recent decades, masonry construction systems incorporating interlocking masonry units have been proposed to eliminate mortar. The interlocking between masonry units can be achieved using specially shaped units. This paper presents a comprehensive experimental study to determine the behaviour as well as basic material properties of one such semi-interlocking mortarless masonry. The experiments included testings of ungrouted masonry units, prisms, and wallets. In addition, masonry prisms and wallets with grouted cores were also investigated to study the effect of grouting. A detailed description of the construction procedure is explained. The failure mechanisms, maximum strengths, force–displacement relationships, and modulus of elasticity of the s les are obtained and contrasted with the relevant results from the literature. Finally, recommendations are made that may assist material model development required for micro- and macro-modelling of mortarless masonry. The new information generated in this research will enable better understanding of the behaviour and properties of semi-interlocking mortarless masonry and will be useful for validating numerical models in future research.
Publisher: Elsevier BV
Date: 2024
Publisher: Elsevier BV
Date: 12-2023
Publisher: SAGE Publications
Date: 18-03-2022
DOI: 10.1177/20414196211062620
Abstract: Auxetic materials, possessing negative Poisson’s ratios (NPRs), have the ability to shrink (or expand) in the lateral direction under an axial compressive (or tensile) force respectively. Due to this unique feature, an auxetic material is found to sustain high energy absorption capacity, fracture toughness and shear resistance and thus regarded as one of the future materials in the field of impact protection. However, civil engineering applications of auxetic structures or materials are minimal due to miscellaneous restrictions on NPR effects. Accumulative developments in auxetics have facilitated their applications in cementitious materials in recent years. This paper presents an overview of recent advances in the development of auxetic cementitious composites and analyses and summarises their mechanical properties under different loading conditions. Prior to extensive finite element simulations, more attention has been given to the limited experimental results. Particular attention is paid to the expansionary feasibility of the parent material to introduce auxetic behaviour, with precise identification of the limitations, innovative composition methods and facilitation of auxetic features. Finally, the paper outlines the limitations of the current research and envisages few future research opportunities in auxetic cementitious composites.
Publisher: JMIR Publications Inc.
Date: 07-2020
Abstract: reating an ontology for COVID-19 surveillance should help ensure transparency and consistency. Ontologies formalize conceptualizations at either the domain or application level. Application ontologies cross domains and are specified through testable use cases. Our use case was an extension of the role of the Oxford Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) to monitor the current pandemic and become an in-pandemic research platform. his study aimed to develop an application ontology for COVID-19 that can be deployed across the various use-case domains of the RCGP RSC research and surveillance activities. e described our domain-specific use case. The actor was the RCGP RSC sentinel network, the system was the course of the COVID-19 pandemic, and the outcomes were the spread and effect of mitigation measures. We used our established 3-step method to develop the ontology, separating ontological concept development from code mapping and data extract validation. We developed a coding system–independent COVID-19 case identification algorithm. As there were no gold-standard pandemic surveillance ontologies, we conducted a rapid Delphi consensus exercise through the International Medical Informatics Association Primary Health Care Informatics working group and extended networks. ur use-case domains included primary care, public health, virology, clinical research, and clinical informatics. Our ontology supported (1) case identification, microbiological s ling, and health outcomes at an in idual practice and at the national level (2) feedback through a dashboard (3) a national observatory (4) regular updates for Public Health England and (5) transformation of a sentinel network into a trial platform. We have identified a total of 19,115 people with a definite COVID-19 status, 5226 probable cases, and 74,293 people with possible COVID-19, within the RCGP RSC network (N=5,370,225). he underpinning structure of our ontological approach has coped with multiple clinical coding challenges. At a time when there is uncertainty about international comparisons, clarity about the basis on which case definitions and outcomes are made from routine data is essential.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 04-2018
Publisher: JMIR Publications Inc.
Date: 17-11-2020
DOI: 10.2196/21434
Abstract: Creating an ontology for COVID-19 surveillance should help ensure transparency and consistency. Ontologies formalize conceptualizations at either the domain or application level. Application ontologies cross domains and are specified through testable use cases. Our use case was an extension of the role of the Oxford Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) to monitor the current pandemic and become an in-pandemic research platform. This study aimed to develop an application ontology for COVID-19 that can be deployed across the various use-case domains of the RCGP RSC research and surveillance activities. We described our domain-specific use case. The actor was the RCGP RSC sentinel network, the system was the course of the COVID-19 pandemic, and the outcomes were the spread and effect of mitigation measures. We used our established 3-step method to develop the ontology, separating ontological concept development from code mapping and data extract validation. We developed a coding system–independent COVID-19 case identification algorithm. As there were no gold-standard pandemic surveillance ontologies, we conducted a rapid Delphi consensus exercise through the International Medical Informatics Association Primary Health Care Informatics working group and extended networks. Our use-case domains included primary care, public health, virology, clinical research, and clinical informatics. Our ontology supported (1) case identification, microbiological s ling, and health outcomes at an in idual practice and at the national level (2) feedback through a dashboard (3) a national observatory (4) regular updates for Public Health England and (5) transformation of a sentinel network into a trial platform. We have identified a total of 19,115 people with a definite COVID-19 status, 5226 probable cases, and 74,293 people with possible COVID-19, within the RCGP RSC network (N=5,370,225). The underpinning structure of our ontological approach has coped with multiple clinical coding challenges. At a time when there is uncertainty about international comparisons, clarity about the basis on which case definitions and outcomes are made from routine data is essential.
Publisher: Elsevier BV
Date: 11-2023
Publisher: CRC Press
Date: 06-07-2020
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 08-2021
Publisher: Elsevier BV
Date: 04-2021
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 08-2017
Publisher: Journal of Mechanics of Continua and Mathematical Sciences
Date: 23-04-2019
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 05-2023
Publisher: CRC Press
Date: 03-11-2016
DOI: 10.1201/B21889-133
Location: United Kingdom of Great Britain and Northern Ireland
Location: Switzerland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Tatheer Zahra.