Ee Loon Tan

Behaviour and design of composite beams subjected to sagging bending and axial compression

Abstract This paper presents an experimental and numerical study on the ultimate strength of steel–concrete composite beams subjected to the combined effects of sagging (or positive) bending and axial compression. Six full-scale composite beams were tested experimentally under sagging bending and increasing levels of axial compression. A nonlinear finite element model was also developed and found to be capable of accurately predicting the nonlinear response and the combined strength of the tested composite beams. The numerical model was then used to carry out a series of parametric analyses on a range of composite sections commonly used in practice. It was found that the sagging moment resistance of a composite beam is not reduced under low-to-moderate axial compression, while it significantly deteriorates under high axial compression. Sectional rigid plastic analyses confirmed the experimental results. The moment–axial force interaction does not change significantly between full and partial shear connection. Based on the experimental and numerical results, a sagging moment–axial compression interaction law is proposed which will allow for a more efficient design of composite beams.

Characterisation of recycled aggregate concrete through x-ray mapping

Every year, urban development generates large volumes of solid waste due to the construction and demolition. Most of the waste from construction becomes landfilled; however, as the population grows continuously, land demand soon becomes a shortage. Therefore landfill is no longer a suitable option to deal with construction waste. Over the last decades, many researches have been carried out on the usage of recycled coarse aggregate. These researchers are primarily focused on the possibility of using recycled concrete aggregate (RCA) as a replacement for natural aggregate [1, 2]. RCA is produced by the crushing of original concrete, it is usually either fully or partially used in the recycled aggregate concrete (RAC) [3]. The use of recycled aggregate in concrete opens a whole new range of possibilities in the reuse of the waste materials.

Behaviour and design of composite beams subjected to negative bending and axial compression

article i nfo This paper investigates the behaviour of steel-concrete composite beams subjected to the combined effects of negative bending and axial compression. For this study, six full-scale tests were conducted on composite beams subjected to negative moment while compression was applied simultaneously. The level of the applied axial compression varied from low to high. Following the tests, a nonlinear finite element model was developed and calibrated against the experimental results. The model was found to be capable of predicting the nonlinear response and the ultimate failure modes of the tested beams. The developed finite element model was further used to carry out a series of parametric analyses on a range of composite sections commonly used in practice. It was found that, when a compressive load acts in the composite section, the negative moment capacity of a compositebeamissignificantlyreducedand local bucklinginthe steel beamismorepronounced, compromising the ductility of the section. Rigid plastic analysis based on sectional equilibrium can reasonably predict the com- bined strength of a composite section and, thus, can be used conservatively in the design practice. Detailing with longitudinal stiffeners in the web of the steel beam in the regions of negative bending eliminate web buckling and increase the rotational capacity of the composite section. Based on the experimentaloutcomes and the finite element analyses a simplified design model is proposed for use in engineering practice.