Fire Testing and Modeling of a Novel Hybrid Timber Floor System

To maximize the amount of carbon-sequestering mass timber and demonstrate the potential for mass timber across a range of building types and scales, DIALOG and EllisDon have developed a hybrid timber floor system (HTFS) that is composed of post-tensioned (PT) concrete beams, cross laminated timber (CLT) panels, and concrete topping connected to each other through self-tapping screws and kerf plates. This paper presents the fire performance of this novel HTFS through a combination of testing and modeling. Two mid-span sectional specimens of HTFS without concrete topping were exposed to the standard fire of CAN/ULC S101. The char depth and char rate of CLT were measured, and the temperature at specific locations were recorded to verify the design and the developed advanced finite element models. Advanced 2D models were developed to investigate the influence of steel properties and the effect from concrete spalling, and the modeling approach adopted in the refined 3D model. The developed models can estimate the char depth with difference less than 5%, and the temperature in reinforcing bars, PT duct, and concrete comparable to the average of the test results. The experimental and simulation results give an insight into the fire performance of this novel HTFS.