Strength assessment of flat slabs on non-rectangular column grid

Abstract

Flat slab construction has proved efficient and large numbers have been built. Often the layout of columns is limited to rectangular grid owing to the scarcity of structural analysis tools validated by experimental evidence. Recently, to break through this barrier, two irregular flat slabs were tested at Nanyang Technological University, Singapore. However, they failed at almost twice the design ultimate load, showing the need for more work. Also, there are efforts to apply yield line analysis to flat slabs on irregular column grid. However, such efforts need validation through comparison with experimental results. To fill this vacuum, nine flat slab panels supported on non-rectangular column grid were designed and tested at Cambridge University Engineering Department (CUED). The current paper presents experimental details and analytical results of five flat slab specimens tested at CUED: three interior panel specimens and one corner panel specimen of parallelogram column layout and an irregular seven-column specimen. Failure loads are predicted using yield line analyses based on energy approach and nonlinear finite element analyses using a commercially available finite element package (DIANA). Further confirmation of predictions is made by comparisons with experimental observations.