Effect of Edge Beam Deformations on the Slab Panel Method
Thesis DisciplineFire Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering in Fire Engineering
Previous accidental fires in multi-storey buildings and large scale fire tests have shown composite floors with unprotected steel beams had large deformations but collapse did not occur due to a mechanism known as tensile membrane action. The Slab Panel Method (SPM) was developed as a simplified performance-based design method including tensile membrane action for everyday design. As SPM has some provisions of edge beam deformations in its analysis, this research was carried out to assess how realistic these provisions are. The study was performed on SPM and VUCLAN, which is a non-linear finite element program that includes both thermal and structural analysis. The effect of various edge continuity conditions on the basic slab panel was assessed by VULCAN models and compared with SPM. 9 m x 9 m slab panel were firstly investigated, then 9 m x 6 m and 9 m x 12 m slab panels were modelled to investigate the effect of aspect ratio on SPM’s provisions. The VULCAN analyses showed that the slab panels perform better with more internal edges and edge beam deformations are always critical to the fire resistance of the slab panels. The SPM and VULCAN deflections were in good agreement in the 9 m x 9 m slab panel, but it underestimates the deflections of 9 m × 6 m slab panel and was slightly conservative on the 9 m × 12 m slab panel. It is concluded that slab continuity over the edge beams significantly enhanced the fire resistance of the slab panel. SPM provided good estimates on the fire resistance of slab panel when the edge beams are designed to be very strong or well protected, but underestimated the external edge beam deformations. It is recommended that when using the SPM in design, the external edge beams need to be designed for higher loadings than just from the yield line tributary area and that for irregular panels or high variable loading Finite Element Analysis (FEA) software is recommended to check the results.