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Lynnwood, South Africa

Shaw Q.H.W.,ARQ Pty Ltd
International Journal on Hydropower and Dams | Year: 2010

The impact of new materials model for high strength RCC on the design of large dams is discussed through the example of Changuinola 1 dam in Panama, focusing on aspects of particular importance for arch dams. An approach combining field measurement with structural modeling to predict and demonstrate actual materials behavior is discussed. The finite element (FE) analysis confirmed that the anticipated residual tensile stresses between induced joints spaced at 20 m are minimal, peaking at only 50 microstrain for a temperature drop of the order of 20°C. The study finds that applying a uniform temperature drop of 6°C, arch action concentrated more towards the upstream side and the top of the structure, is observed. The design approach of Changuinola 1 dam requires installation of cooling pipes in the RCC above the upper gallery if shrinkage and creep are evident in the RCC. Source

Shaw Q.H.W.,University of Pretoria | Shaw Q.H.W.,ARQ Pty Ltd
International Journal on Hydropower and Dams | Year: 2010

An outline of a doctoral program of research and analysis on the basis of which a new model for the early behavior of RCC has been postulated and motivated is discussed. Replicating the measured behavior of the prototype, the model demonstrates the early shrinkage/creep behavior of RCC to be quite different to that of CVC. The network of long-base-strain-gauge-temperature- meters (LBSGTM) installed across the induced joints at Woiwedans and Kneilpoort dams provided very useful indications in relation to the temperature/strain performance of RCC. Significant attention should be given to the composition and structure of RCC mixes and the findings of this study are not considered to be applicable in the case of lower quality aggregates, with a tendency for drying shrinkage. Adoption of significantly lower shrinkage and creep values for RCC during the hydration cycle will imply that the effective temperature drop for the design of induced joints and evaluation of cracking parallel to the dam axis will be reduced. Source

Miller R.G.,ARQ Pty Ltd | Nel R.,ARQ Pty Ltd | Kruger E.J.,South African National Roads Agency SOC Ltd SANRAL
Beton- und Stahlbetonbau | Year: 2015

Der vorliegende Beitrag befasst sich mit der Instandsetzung, Verstärkung und Verbreiterung der "Nels River Bridge" in der Provinz Mpumalanga in Südafrika. Es werden die Komplexität der einzelnen Bemessungsschritte dargestellt und Lösungen und Konstruktionstechniken erörtert, die angewendet wurden, um das Projekt erfolgreich zum Abschluss zu bringen. Repair and Widening of the Nels River Bridge on Road R37 in South Africa This paper deals with the repair, strengthening, improvement and widening of the Nels River Bridge situated in the Mpumalanga province of South Africa. The paper outlines the design complexities and discusses the solutions and the construction techniques followed that resulted in a successful project. Copyright © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Nel R.,ARQ Pty Ltd | Kramer S.S.,ARQ Pty Ltd | Miller R.G.,ARQ Pty Ltd
Concrete Repair, Rehabilitation and Retrofitting III - Proceedings of the 3rd International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2012 | Year: 2012

This paper describes the unique retrofitting methodology adopted on three major bridge interchanges as part of the Gauteng Freeways Improvement Project (GFIP). William Nicol Drive, Rigel Avenue and Garstfontein Road Bridges were all widened over high traffic volume freeways to accommodate new single point interchanges. © 2012 Taylor & Francis Group. Source

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