Comparative study on analytical modelling of short- and long-term behaviour in timber-concrete composite systems

Recent studies have shown that design of timber-concrete composite (TCC) floors may be governed by serviceability or ultimate limit states and therefore, the design requirements need to be satisfied under both short- and long-term actions. However, the long-term behaviour in medium to long span beams under heavy environmental conditions mainly governs the design. Conducting experimental tests to investigate the behaviour of TCC floors are expensive to run and are time consuming whereas analytical studies offer an efficient alternative for predicting the short- and long-term responses with reasonable accuracy. Time-dependant behaviour of TCC floors is not only affected by the long-term load but also driven by the variation of the environmental conditions such as temperature and relative humidity. The factors that affect the long-term behaviour of TCC floors are quite complex and non-linear. Some simplified as well as more comprehensive approaches have been developed to-date and reported in literature. This paper presents a comparison of several finite element models about the behaviour of TCC systems. It starts with analytical models of timber beams under ultimate and serviceability loads. Furthermore, the finite element models developed to date for predicting the short- and long-term responses of TCC beams are discussed. This paper also outlines a novel method for analysis of TCC beams and highlights the potential of the proposed formulation to capture both the short-and long-term behaviour with sufficient accuracy.