Over the last two decades many constitutive models with different degrees of accuracy have been developed for analysis of sawn timber and engineered wood products. However, most of the existing models for analysis of timber members are not particularly practical to implement, owing to the large number of material properties (and associated testing) required for calibration of the constitutive law. In order to overcome this limitation, this paper presents details of 1D, 2D and 3D non-linear fi nite element (FE) models that take advantage of a quasi-brittle material model, requiring a minimum number of material properties to capture the load-defl ection response and failure load of timber beams under 4-point bending. In order to validate the model, four tapered timber piles with circular cross-section (two plains and two retrofi tted with steel jacket) were tested and analysed with the proposed 3D FE modelling technique; and a good correlation between experimentally observed and numerically captured ultimate load was observed. Consequently, it was concluded that the developed FE models used in conjunction with the quasi-brittle constitutive law were able to adequately capture the failure load and load-defl ection response of the fl exural timber elements.
This paper reports the results of experimental push-out tests on three different types of timber–concrete composite (TCC) connections, including normal screw, SFS and bird-mouth. The load-slip diagrams obtained from lab tests are employed to calculate the slip modulus of the connections for serviceability, ultimate and near collapse cases based on Eurocode 5 recommendations. Additionally, four full-scale TCC beams with normal screw, SFS and bird-mouth are constructed and tested under four-point bending within the serviceability load range to verify the slip modulus of connections which derived from the push-out tests. Further, based on the experimental results and using nonlinear regression, an analytical model each one of the connections is derived which can be easily incorporated into nonlinear FE analyses of TCC beams.
Australasian Conference on the Mechanics of Structures and Materials
Research Status
Complete
Notes
December 11-14, 2012, Sydney, Australia
Summary
Timber-concrete composite (TCC) beams are made up two materials, i.e. wood and concrete, which exhibit different behaviours under long-term loading. The time-dependent behaviour of TCC beam 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. In particular, the maximum deflection under service loads may govern the design requirement for medium to long span TCC beams subjected to heavy environmental conditions. For such structures, application of simplified methods adopted by different codes may lead to significant errors. Hence investigating the long-term behaviour of TCC beams subject to variable environmental condition is of great importance for designers and researchers. In this paper the research undertaken on long-term behaviour of TCC floors is critically reviewed and the recent findings are highlighted. The most important references in the literature were selected to provide more depth into the time-dependent performance of TCC structure.
This paper presents the structural response of timber-concrete composite (TCC) beams predicted by finite element models (i.e. continuum-based and 1D frame) and manual calculations. Details of constitutive laws adopted for modelling timber and concrete are provided and application of the Hashin damage model in conjunction with continuum-based FE for capturing failure of timber under bi-axial stress state is discussed. A simplified strategy for modelling the TCC connection is proposed in which the connection is modelled by a nonlinear spring and the full load-slip behaviour of each TCC connection is expressed with a formula that can be directly implemented in the general purpose FE codes and used for nonlinear analysis of TCC beams. The developed FE models are verified by examples taken from the literature. Furthermore, the load-displacement response and ultimate loading capacity of the TCC beams are determined according to Eurocode 5 method and compared with FE model predictions.
