In Phase I (2018-19) of this project on Prefabricated Heavy Timber Modular Construction, three major types of connections used in a stackable modular building were studied: intramodule connection, inter-module vertical connection, and inter-module horizontal connection. The load requirement and major design criteria were identified. The connections were designed and tested to quantify their performance.
Conventional methods to build timber modules based on platform construction may not be most suitable for midrise to tall stackable buildings, due to the weak compression perpendicular to grain property of wood. Balloon construction is proposed here to manufacture individual modules so that non-disruptive vertical load transfer path is maintained along the structural height. Three screwed connections were tested to evaluate the load transfer between the elements, with steel angle brackets and Laminated Veneer Lumber (LVL) blocks. Screws at 90° were found to be inadequate for this application due to the low stiffness and high variation. When screws were installed at 45°, both the steel plates and LVL blocks had high stiffness, high strength, and good ductility.