Experimental and analytical assessment of ductility in lightly reinforced concrete members

This is the post-print version of the final paper published in Engineering Structures. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2010 Elsevier B.V.This paper is concerned with the ultimate behaviour of lightly reinforced concrete members under extreme loading conditions. Although the consideration given to the assessment of ductility is of general relevance to various applications, it is of particular importance to conditions resembling those occurring during severe building fires. The main purpose of the investigation is to examine the failure of idealised members representing isolated strips within composite floor slabs which become lightly reinforced in a simulated fire situation due to the early loss of the steel deck. An experimental study, focusing on the failure state associated with rupture of the reinforcement in idealised concrete members, is presented. The tests enable direct assessment of the influence of a number of important parameters such as the reinforcement type, properties and ratio on the ultimate response. The results of several tests also facilitate a detailed examination of the distribution of bond stresses along the length. After describing the experimental arrangements and discussing the main test results, the paper introduces a simplified analytical model that can be used to represent the member response up to failure. The model is validated and calibrated through comparisons against the test results as well as more detailed nonlinear finite element simulations. The results and observations from this investigation offer an insight into the key factors that govern the ultimate behaviour. More importantly, the analytical model permits the development of simple expressions which capture the influence of salient parameters such as bond characteristics and reinforcement properties, for predicting the ductility of this type of member. With due consideration of the findings from other complementary experimental and analytical studies on full slab elements under ambient and elevated temperatures, this work represents a proposed basis for developing quantified failure criteria.Engineering and Physical Sciences Research Council (EPSRC

Experimental Evaluation of the Mechanical Properties of Steel Reinforcement at Elevated Temperature

This paper describes an experimental investigation into the influence of elevated temperatures on the mechanical properties of steel reinforcement. The study includes tests carried out at ambient temperature as well as under steady-state and transient elevated temperature conditions. A complementary test series, in which the residual post-cooling properties of reinforcing bars were examined, is also described. The experimental study focussed on assessing the performance of reinforcement of 6 and 8 mm diameter, although 10 mm bars were also considered in some cases. The specimens included both plain and deformed bars. After providing an outline of the experimental set-up and loading procedures, a detailed account of the test results is presented and discussed. Apart from the evaluation of stress–strain response and degradation of stiffness and strength properties, particular emphasis is given to assessing the influence of temperature on enhancing the ductility of reinforcement. The findings of this study have direct implications on procedures used for predicting the ultimate behaviour of structural floor elements and assemblages during, and following, exposure to elevated temperatures

Progressive collapse of multi-storey buildings due to sudden column loss — Part I: Simplified assessment framework

Accepted versio

Progressive collapse of multi-storey buildings due to sudden column loss—Part II: Application

Accepted versio

Earthquake resistance of composite beam-columns

SIGLEAvailable from British Library Document Supply Centre-DSC:DX194614 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Numerical simulation of glass-reinforced plastic cylinders under axial compression

The results of a numerical simulation study for the buckling behaviour of laminated composite cylinders are presented in this paper. The laminates are made from glass-reinforced plastic (GFRP) of type 'DF 1400' consisting of woven glass fibre roving within a polyester resin matrix. Two-ply cylinders with various laminate orientations, subjected to axial compression, are considered. The numerical simulations are compared to the results of a previous experimental investigation which is briefly described. The finite element model, used to carry out the numerical simulations, is presented and associated limitations are discussed. Linear eigenvalue analysis as well as geometrically non-linear simulations are undertaken using a general purpose finite element program. Detailed measurements of thickness variations and geometric imperfections, carried out within the experimental study, are directly introduced in the analysis. Several thickness representations are considered and their influence on the results is assessed. The correlation between numerical and experimental results is also discussed in terms of buckling strength, axial stiffness, buckling modes and surface strains. In addition to demonstrating the influence of various modelling idealisations on the results, this numerical study highlights the effect of the specific material and laminate construction detail on the buckling behaviour of composite cylinders