Lateral load carrying capacity of timber walls filled hemp concrete: experimental and numerical investigation
The use of bio-based materials in structures improve the insolation level and sound absorption. In response to this need, the use of bio-aggregate such as hemp shives is increasing in Europe and especially in France. Hemp concrete is now used in construction as a sustainable and carbon neutral infill wall material around timber-framed construction. This study concerns on the effect of wall dimensions on the in-plane racking strength of timber frame walls filled with hemp concrete. Two wooden geometrical configurations were used, the first was diagonal bracing walls , and the second was vertical stud walls. These two types of timber walls are most widely used in construction subjected to lateral loads. In this study, a numerical and an experimental investigation of large-scale timber walls both with and without hemp concrete were carried out to investigate the contribution of this filling material against the lateral loads. Digital Image Correlation (DIC) technique was used in order to track local displacements and shear strains fields of hemp concrete in the wall. The hemp walls then compared to empty frames.
This study focuses also on the numerical investigation of the lateral-load carrying capacity of hemp concrete as infill material in timber frame walls, investigating and highlighting the parameter that significantly affect the lateral resistance of hemp walls. For this purpose, the vertical studs timber frame walls with dimensions (2.5m height and 1.2m length) were used as the bench mark to validate the previous experimental work. Also a numerical study of three timber walls filled with hemp concrete has been studied to verify the effect of wall length of the lateral load carrying capacity of hemp concrete. Three vertical stud timber walls with a standard height 2.5m and different lengths (1.2 m, 1.6 m and 2.4 m) were investigated using Abaqus software. Based on the numerical and experimental tests, this study confirms, firstly, that hemp concrete has a small participation against lateral loads with wall dimensions 2.5 m height and 1.2 length. In fact it cannot be generalized that hemp concrete has always a significant strength in timber wall. The filling material could not work mechanically against lateral load without a complete form of compression diagonal zone which make the material loaded under shear forces. This zone is related to the dimensions of the wall and is present when the ratio between the height and the length of the wall (L/h) ≥1. Within this limit, the material mechanically works, otherwise, the results are totally different.