Influence of Cross-Laminated Timber Floor and Their Connections on the Robustness of Mass-Timber Building: A Case Study on Midrise Building

Mass-timber construction is becoming more prevalent in Australia and around the world. However, as these mass-timber buildings become taller, it is important to consider robust detailing against accidental damages to major load-bearing elements and thereby avoid potential progressive collapse scenarios. In order to better understand the robustness of typical mass-timber buildings, this study analyzed a typical 10-story midrise mass-timber building subjected to different progressive collapse scenarios. A scenario-independent approach was considered in the analysis, which includes the sudden removal of a load-bearing glulam column from the midrise mass-timber building. It was observed that when internal ties and bracings were provided, the robustness of the building was not affected as there was an alternative load path created. The orthogonal tie beam and diagonal bracing can transfer about 60% and 20% of the axial loads of the removed column to the adjacent columns, respectively. It was found that the building becomes vulnerable when no internal tie or bracing is available to transfer the accidental load. In this scenario, higher stiffness of the cross-laminated timber panel-to-panel joint can be adopted to improve the robustness of mass-timber building.