Källsner and Girhammar [1] have presented a new plastic design method for wood-framed shear walls at ultimate limit state. This method allows the designer to calculate the load-carrying capacity of shear walls partially anchored, where the leading stud is not fully anchored against uplift.
The parameters varied are the size of the washer and the orientation of the pith. The bottom rail was subjected to loading perpendicular to grain through two-sided sheathing. In this report the different set of series are presented. Five sets were conducted depending on the size of the washer and in each set the pith was placed upwards and downwards.
Källsner and Girhammar [1] have presented a new plastic design method for wood-framed shear walls at ultimate limit state. This method allows the designer to calculate the load-carrying capacity of partially anchored shear walls, where the leading stud is not anchored against uplift.
In this report hold downs have been experimentally studied with respect to the strength and stiffness of the connection. Four different types of hold downs have been tested. The specimen was subjected to tension load applied to the stud. Four tests series are presented. Each series was divided into different sets according to the type of fastener used with the hold down device.
The results show that the failure load is higher when hold downs with anchor bolts are used, up to ten times higher than the anchorage that uses only screws or nails. The failure mode vary with the type of hold down and the type of fasteners used. The tests showed three primary failure modes: failure of the stud when a bolt is used as the fastener between hold down device and stud, failure due to pull-out of the screws or nails from the rail and failure due to failure or pull-out of screws or nails from stud. Also, failure of the stud itself occurred in some tests caused by some defect of the timber.
A research study on a new plastic design method for timber frame shear walls partially anchored is under development in Sweden [1]. In this research an important focus has been put on the problem of the possible splitting of the bottom rail. In partially anchored timber frame shear walls there are not hold downs taking the vertical loads so the corresponding forces can be replaced by vertical loads from upper storeys, the roof or connection between shear wall and transversal wall. In this case the bottom row of rail transmits the vertical forces in the sheathing to the bottom rail (instead of the vertical stud) where the anchor bolts will further transmit the forces into the foundation. The bottom rail is then subjected to tensile load perpendicular to the grain, which can be often causes a splitting failure
The aim of this report is to present the results of three experimental studies: tensile strength perpendicular to the grain in radial and tangential direction, fracture energy with TR and RT orientations and bottom rail. The experimental programs have been conducted at two different periods and places: bottom rail tests at Umeå University in October 2012 and tensile strength perpendicular to grain and fracture energy at SP in Stockholm in June 2013.
