Existing reinforced concrete (RC) structure can be strengthened upon the addition of externally bonded high-strength light-weight fibre-reinforced polymer (FRP) composites. An abundance of research over the last two decades has established the effectiveness of the externally bonded FRP via extensive experimental testing. Perhaps the most commonly occurring failure mode though is premature debonding of the FRP and debonding generally occurs at strains well below the strain capacity of the FRP. Debonding failures are undesirable as they are typically brittle and represent an under-utilisation of the FRP material. A straightforward means to prevent or at least delay debonding is by the addition of mechanical anchors, however, research to date on anchors is extremely limited. Of the various anchor concepts examined to date by researchers, this dissertation will focus on anchors made from FRP which are herein referred to as FRP anchors. The details and results of a program of research on the performance of FRP anchors in FRP-strengthened structures are presented in this dissertation. An extensive review of exiting literature helps establish knowledge gaps which serve to justify the need and the scope of the research reported herein. A novel bow-tie FRP anchor concept is then proposed and tested in smaller-scale single-shear FRP-to-concrete joint assemblages as well as larger-scale simply-supported FRP-strengthened RC slabs. The anchors are shown to increase the strength and slip capacity of the joints by up to 41 % and almost 600 %, respectively, in comparison with unanchored control joints. The anchors are then shown to increase the load and deflection capacity of slabs by 30 % and 110 %, respectively, above an unanchored control slab. In addition to strength, it is the ability of FRP anchors to introduce deformability into FRP-strengthened RC slabs which is particularly beneficial in order to produce safer structures. An analytical model is then developed which is based on a novel quad-linear moment-curvature response which can capture the complete load-deflection response of the FRP-strengthened slabs anchored with FRP anchors. The analytical modeling approach enables closed-form equations to be derived which can then be used by design engineers to relatively easily construct load-deflections responses and accurately predict member responses. Following the concluding comments for the project as a whole, future research topics of relevance are identified. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

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Thesis (M.Eng.(Transportation Engineering)--University of Pretoria, 2001. / Summaries in Afrikaans and English. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains ix, 86 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 83-84).

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Maintaining structural stability is an integral component of building fire safety. Stability must be ensured to provide adequate time for safe egress of the buildings occupants, fire fighting operations and property protection. Structural fire engineering endeavours to design structures to withstand the effects of fire in order to achieve this objective. The behaviour of reinforced concrete in fire is not as well understood as other construction materials, such as steel. This is in part due to the complexity of concrete material behaviour and also due to concrete’s reputation of superior fire performance. Concrete technology is, however, continually evolving; structures are increasingly slender, more highly stressed and have higher compressive strengths. A more robust understanding of concrete’s behaviour in fire will enable predictions of the implications of changing concrete technology and also help to properly quantify the fire safety risk associated with concrete structures. A fundamental key to understanding structural fire performance is the relationship between the thermal environment induced by the fire and the structure. Significant thermal variation has been found experimentally to exist within fire compartments. Despite this the design of structures for fire almost universally assumes the compartment thermal environment to be homogeneous. In this thesis the implications of compartment fire non-uniformity for concrete structural behaviour is investigated to assess the validity of the uniform compartment temperature assumption. The investigation is conducted using numerical tools; a detailed review of the necessary background knowledge, material modelling of reinforced concrete, finite element modelling of reinforced concrete structures and compartment fire thermal variation is included. The behaviour of a two-way spanning reinforced concrete slab is used as a structural benchmark. The membrane behaviour exhibited by two-way spanning RC slabs at high temperatures has been previously studied under uniform thermal conditions. They therefore are an ideal benchmark for identifying the influence of non-uniform thermal environments for behaviour. The relationship between gas phase temperature variation and concrete thermal expansion behaviour, which is fundamental to understanding concrete high temperature structural behaviour, is first investigated. These preliminary studies provide the necessary fundamental understanding to identify the influence of gas phase temperature variation upon the membrane behaviour of reinforced concrete slabs. The individual influences of spatial and temporal variation upon slab membrane behaviour are investigated and the behaviour under non-uniform thermal variation contrasted with uniform thermal exposure behaviour. The influence of spatial variation of temperature is found to be strongly dependent upon the structural slenderness ratio. The tensile membrane action of slender slabs is particularly susceptible to the distorted slab deflection profiles induced by spatial variation of gas temperature. Conversely the compressive membrane behaviour of stocky slabs is found to be insensitive to the deformation effects induced by spatial variation of temperature. The influence upon slender slabs is demonstrated under a range of temporal variations indicating that the thermal response of concrete is sufficiently fast to be sensitive to realistically varying distributions of temperature. Contrasting behaviour induced by uniform and non-uniform thermal exposures indicates that uniform temperature assumptions provide both conservative and unconservative predictions of behaviour. The accuracy of the uniform temperature assumptions was also found to be dependent upon the type of fire, for example, fast hot and short cool fires. Additionally, the sensitivity of structural performance to deformations caused by spatial variation of temperature demonstrated in this thesis challenges the purely strength based focus of traditional structural fire engineering. Spalling is an important feature of concrete’s high temperature behaviour which is not currently explicitly addressed in design. The incorporation of spalling into structural analysis is not, however, straightforward. The influence of spalling upon behaviour has therefore been dealt with separately. A spalling design framework is developed to incorporate the effects of spalling into a structural analysis. Application of the framework to case studies demonstrates the potential for spalling to critically undermine the structural performance of concrete in fire. It also demonstrates how the framework can be used to quantify the effects of spalling and therefore account for these in the structural fire design addressing spalling risk in a rational manner.

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Thesis (Ph.D.)--Royal Institute of Technology (Stockholm, Sweden), 2005. / "ISRN KTH/BKN/B-80-SE." "Dept. of Civil and Architectural Engineering, Division of Structural Design and Bridges, Royal Institute of Technology, Stockholm. " Includes bibliographical references. Available from the Royal Institute of Technology (Sweden) Library as a .pdf document http://www.lib.kth.se/main/eng/

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.