Field Monitoring of Vertical Movement in a Six-Story Wood-Frame Building in Coastal British Columbia

Abstract

Abstract Vertical movement was monitored for 24 months in a six-story wood-frame residential building in the coastal climate of British Columbia, Canada, from construction to service. The work was part of a long-term study to assist in the design of mid-rise wood-frame buildings. Displacement sensors were installed from the first floor to the top floor in a party wall, a hallway wall, and an interior partition wall, plus in the bottom two floors of an exterior wall to measure vertical movement, after the roof sheathing was installed. In addition, sensors were installed in the party wall and the exterior wall on the first floor to measure the moisture content of the wood, together with sensors for measuring environmental conditions in service. It was found that downward vertical movement, i.e., building shortening, occurred from construction to service and leveled off after a period of about 17 months. From the top of sill plates to the underside of roof trusses, the shortening reached approximately 34 mm at the party wall, 35 mm at the hallway wall, and 37 mm at the interior partition wall. The average shortening amount of 35 mm exceeded the predicted shrinkage amount based on a commonly used calculation method by about 25 %. The effects of loads on vertical movement should be taken into account in the design of mid-rise wood-frame construction.