Prediction of the structural behaviour of oil palm shell lightweight concrete beams

The use of structural lightweight concrete (LWC) has the potential to substantially reduce construction costs as its lower density allows for longer spans, reduced self-weight and a reduction in foundation size. Despite its usefulness, LWC with natural aggregates sees limited use in design due to a lack of design guidelines. This lack of guidance arises primarily due to the highly empirical nature of the design standards in predicting behaviour at all load levels i.e. empirical equations are used at the serviceability limit to predict for flexural rigidities and crack widths as well as at the ultimate limit to predict hinge rotation and moment redistribution. It is thus costly and time-consuming to conduct large scale member testing for a particular type of LWC in order to establish design guidelines. To address this, a generic, mechanics based, segmental moment-rotation (M/θ) approach has been proposed to simulate the flexural behaviour of reinforced concrete at all load levels, in which the only empiricisms required are the definition of fundamental material properties. In this paper, it is shown that the M/θ approach and the subsequent existing closed-form solutions derived based on the approach can predict the full range of flexural behaviours of oil palm shell (OPS) LWC beams such as load-deflection and crack width at all load levels. The successful application of the M/θ approach suggested that the approach can be used as a basis for developing design guidelines for LWC. This was further enforced by the good agreement between the predicted response using the M/θ approach and the published test results for other types of LWC material.