Calibration and Validation of a Linear-Elastic Numerical Model for Timber Step Joints Based on the Results of Experimental Investigations.

Matthias Braun,Jan Pełczyński,Anna Al Sabouni-Zawadzka,Benjamin Kromoser

doi:10.3390/ma15051639

Abstract

The paper is dedicated to the numerical analysis of a single-step joint, enabling the prediction of stiffness and failure modes of both single- and double-step joints. An experimental analysis of the geometrically simplest version, the single-step joint, serves as a reference for the calibration of the subsequent finite element model. The inhomogeneous and anisotropic properties of solid timber make detailed modelling computationally intensive and strongly dependent on the respective specimen. Therefore, the authors present a strategy for simplified but still appropriate modelling for the prediction of local failure at certain load levels. The used mathematical approach is based on the linear elasticity theory and orthotropic material properties. The finite element calculations are performed in the environment of the software Abaqus FEA. The calibrated numerical model shows a good conformity until first failures occur. It allows for a satisfactory quantification of the stiffness of the connection and estimation of the force when local failure begins and is, therefore, recommended for future, non-destructive research of timber connections of various shapes.

Highlights

We are currently confronted with a steadily increasing CO2 concentration in the atmosphere, resulting in global warming [1]
The comparison of different construction materials shows that timber exhibits advantageous properties with regard to these environmental aspects, as it stores part of the CO2 absorbed during the growth phase of the trees [3]
If timber is to be used in larger quantities as a construction material, a higher degree of utilisation is, essential

Summary

Introduction

We are currently confronted with a steadily increasing CO2 concentration in the atmosphere, resulting in global warming [1]. The authors of this paper pursued two main goals while driving research forward in this area: (1) Experimental investigation of the load-bearing behaviour of new timber step joint designs with a set focus on maximising the performance (maximum load, stiffness and producibility) [6] (BOKU, Institute of Structural Engineering) and (2) Development of a modelling strategy for timber–timber joints under compression for the best possible prediction of the load-bearing behaviour (Warsaw University of Technology, Faculty of Civil Engineering). The main focus of the presented paper was the investigation of the performance and applicability of a simplified FE model based on linear-elastic material behaviour and an orthotropic constitutive model, allowing for a comparatively low computation effort.

Experimental Investigations

Test Setup and Test Specimens

Numerical Calculations

Findings

Application of the Calibrated Numerical Model on a Double-Step Joint