Development of Creep Deformations during Service Life: A Comparison of CLT and TCC Floor Constructions

Abstract

Cross-laminated timber (CLT) slabs in residential buildings need additional weight, e.g., in the form of screeds or gravel layers, to fulfill the criterion for the highest impact-sound class. The additional mass is, however, not exploited for the load bearing behavior, but adds additional weight and leads to an increased height of the floor construction. In this study, such a CLT floor construction with a construction height of 380 mm is compared with a composite slab consisting of a CLT plate with a concrete layer on top with a floor construction height of 330 mm. The timber concrete composite (TCC) slab has a different creep behavior than the CLT slab. Thus, the development of the time-dependent deflections over the service life are of interest. A straightforward hybrid approach is developed, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behavior. The introduced approach allows to investigate load redistribution between the layers of the composite structure and the evolution of the deflection of the slab during the service life. The investigated slab types show a similar deflection after 50 years, while the development of the deflections over time are different. The CLT slab has a smaller overall stiffness at the beginning but a smaller decrease in stiffness over time than the investigated TCC slab.

Long-Term Behavior of Timber–Concrete Composite Structures: A Literature Review on Experimental and Numerical Investigations

“…Thus, in numerical simulations, those parameters of creep behaviors beyond the range of elasticity and viscoelasticity need to be determined in the future. In addition, besides the effects of different tree species and size effects, the creep parameters reflected in new engineered wood products, such as CLT, NLT, and SLT [18,[140][141][142][143] also require further exploration.…”

Analytical Procedure for Timber−Concrete Composite (TCC) System with Mechanical Connectors

“…Several researchers [5,36] have stated that the cracking of concrete should be accounted for in the design of TCC, as it negatively impacts load-carrying capacity and bending stiffness. Besides, deflection of the TCC system increases over time in the longterm due to the creep, mechano-sorptive creep, and shrinkage of all the components, which can affect the stresses and therefore capacity of the components significantly [5,9,37,38]. To facilitate the practical application of the TCC system, this rheological behaviour also needs to be considered in the simplest way possible.…”

Modelling of creep behaviour of timber dowelled beams

“…A straightforward hybrid approach is developed by Binder et al, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behaviour. 25 This paper is focused on the study of the visco-elastic behaviour of timber structures under creep loading. The numerical model is employed to capture the macroscopic creep compliance.…”

“…A straightforward hybrid approach is developed by Binder et al, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behaviour. 25…”