Toomebridge, United Kingdom
Toomebridge, United Kingdom

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Mokhtar M.R.,Multimedia University | Owens K.,Queen's University of Belfast | Kwasny J.,Queen's University of Belfast | Taylor S.E.,Queen's University of Belfast | And 13 more authors.
IEEE Sensors Journal | Year: 2012

This paper presents an innovative sensor system, created specifically for new civil engineering structural monitoring applications, allowing specially packaged fiber grating-based sensors to be used in harsh, in-the-field measurement conditions for accurate strain measurement with full temperature compensation. The sensor consists of two fiber Bragg gratings that are protected within a polypropylene package, with one of the fiber gratings isolated from the influence of strain and thus responding only to temperature variations, while the other is sensitive to both strain and temperature. To achieve this, the temperature-monitoring fiber grating is slightly bent and enclosed in a metal envelope to isolate it effectively from the strain. Through an appropriate calibration process, both the strain and temperature coefficients of each individual grating component when incorporated in the sensor system can be thus obtained. By using these calibrated coefficients in the operation of the sensor, both strain and temperature can be accurately determined. The specific application for which these sensors have been designed is seen when installed on an innovative small-scale flexi-arch bridge where they are used for real-time strain measurements during the critical installation stage (lifting) and loading. These sensors have demonstrated enhanced resilience when embedded in or surface-mounted on such concrete structures, providing accurate and consistent strain measurements not only during installation but subsequently during use. This offers an inexpensive and highly effective monitoring system tailored for the new, rapid method of the installation of small-scale bridges for a variety of civil engineering applications. © 2012 IEEE.

Mokhtar M.R.,City University London | Mokhtar M.R.,Multimedia University | Sun T.,City University London | Grattan K.T.V.,City University London | And 14 more authors.
Journal of Physics: Conference Series | Year: 2011

This paper presents a novel sensor design and packaging, specifically developed to allow fibre grating-based sensors to be used in harsh, in-the-field measurement conditions for accurate strain measurement, with full temperature compensation. After these sensors are carefully packaged and calibrated in the laboratory, they are installed onto the paragrid of a set of flat-packed concrete units, created specifically for forming a small-scale, lightweight and inexpensive flexi-arch bridge. During the arch-bridge lifting process, the sensors are used for real-time strain measurements to ensure the quality of the construction. During the work done, the sensors have demonstrated enhanced resilience when embedded in concrete structures, providing accurate and consistent strain measurements during the whole installation process and beyond into monitoring the integrity and use of the structure.

Long A.,Queen's University of Belfast | McPolin D.,Queen's University of Belfast | Gupta A.,Macrete Ireland Ltd. | Courtenay D.,Macrete Ireland Ltd.
Structural Engineer | Year: 2014

Experts share their views on the 'FlexiArch' system, which has been developed to address the challenges of cost constraints and quality control limitations associated with the production of stone voussoirs. The FlexiArch is constructed and transported to site in fl at pack form using polymeric reinforcement to carry the self-weight of the arch unit during lifting. The FlexiArch units can be cast in convenient widths to suit the design requirements, site restrictions and available lifting capacity. Concrete hinges form in the screed and the integrity of the unit is provided by tension in the polymeric reinforcement and the shear resistance of the screed. The arch shaped units are then lifted and placed on precast footings at the bridge site, with all the self-weight and transferred from tension in the polymeric reinforcement to compression in the voussoirs.

Long A.,Queen's University of Belfast | Kirkpatrick J.,Macrete Ireland Ltd | Gupta A.,Macrete Ireland Ltd | Nanukuttan S.,Queen's University of Belfast | Polin D.M.,Queen's University of Belfast
Proceedings of the Institution of Civil Engineers: Bridge Engineering | Year: 2013

Masonry arches are strong, durable, aesthetically pleasing and largely maintenance free, yet since 1900 there has been a dramatic decline in their use. However, designers, contractors and clients now have access to a new method of constructing arches incorporating precast concrete voussoirs interconnected via polymeric reinforcement and a concrete screed. No centring is necessary, as the FlexiArch, when it is lifted, transforms under the forces of gravity into the desired arch shape. After discussing general aspects of innovation, the basic concept of the arch bridge system is presented along with technological advances since it was patented. Experiences gained from building over 40 FlexiArch bridges in the UK and Ireland and from model and full-scale tests carried out to validate the system during installation and in service are described. Thus under load the system behaves like a traditional masonry arch and existing analysis methods can be used for design and assessment.

Long A.E.,Queen's University of Belfast | Mcpolin D.,Queen's University of Belfast | Nanukuttan S.,Queen's University of Belfast | Gupta A.,Macrete Ireland Ltd | Robb D.,Macrete Ireland Ltd
Multi-Span Large Bridges - Proceedings of the International Conference on Multi-Span Large Bridges, 2015 | Year: 2015

The potential benefits of combining the elegance of the stress ribbon concept with the robustness and speed of construction of the FlexiArch is discussed. In combination, multi-span pedestrian/cycle bridges which are innovative, highly durable and have optimal full life cycle costs can be produced with lengths of over 100 m. As the stress ribbon system is well known, the main emphasis of this paper will be on the FlexiArch. Since 1900 few arch bridges have been built, but with the development of the innovative FlexiArch this trend can be reversed as they can be installed rapidly, are cost competitive, have all the attributes of masonry arches and are very sustainable. Thus the FlexiArch represents a very attractive alternative to heavily reinforced cast in situ arches currently used in combination with stress ribbon deck systems. © 2015, Taylor & Francis Group, London.

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