Lateral load-carrying capacity of hemp concrete as a natural infill material in timber frame walls

This study focuses on the racking behaviour of hemp concrete as infill material in timber frame walls, investigating and highlighting the parameters that significantly affect the lateral resistance of hemp walls. For this purpose, two different designs of timber frame walls are used as wall units, the first consisting of vertical studs and the second using diagonal bracing elements under compression. These two designs of timber frames are those most widely used as external walls in construction. In this research, an experimental investigation of large-scale timber frame walls with dimensions (2.5 m height and 1.25 m length), both with and without hemp concrete, was carried out to assess the contribution of hemp concrete as infill material against lateral loads. The hemp walls were then compared to empty timber frames to determine the real contribution of hemp concrete to lateral strength. Digital Image Correlation (DIC) was used in order to determine and track local displacement and shear-strain fields of hemp concrete as infill material in the timber wall. Based on the results obtained from the experimental tests, it is obvious that hemp concrete makes a slight contribution against lateral loads in a vertical stud timber wall of length 1.25 m. However, hemp concrete did not improve the lateral strength in walls with diagonal bracing elements. This study confirms, firstly, that the length of timber wall plays a significant role in the lateral strength of the hemp concrete. In other words, decreasing the length of the wall will significantly decrease the contribution of hemp concrete to lateral resistance. Secondly, the use of diagonal elements increases the overall rigidity of the timber wall, which negatively affects the contribution of hemp concrete and prevents hemp concrete from increasing the lateral strength of the wall.