Analytical Study of the Structural Behaviour of Thin-Shell Concrete Roofs Suitable for Low-Cost Construction in Nigeria

Thin-shell concrete roof structures offer material-efficient, structurally elegant, and potentially cost-effective alternatives to conventional beam-slab roofing for low-cost building construction in Nigeria, yet their structural behaviour under Nigerian loading conditions has not been analytically characterised. This study analytically characterised the structural behaviour of three thin-shell concrete roof forms: cylindrical barrel vaults, hyperbolic paraboloid (hypar) shells, and folded plate shells, under Nigerian loading conditions including self-weight, imposed loads, and wind pressures consistent with BS EN 1991 (Eurocode 1). Parametric finite element analysis using ABAQUS software was conducted for each shell form across span ranges of 6 to 24 metres, thickness ranges of 50 to 100 mm, and rise-to-span ratios of 1:3 to 1:8. Material properties were based on C25/30 concrete. Analysis outputs included stress distributions, deflections, critical buckling loads, and natural frequencies. Results showed that the hypar shell form exhibited the most favourable structural behaviour across the broadest span range, with the lowest material volume per unit covered area (mean: 0.039 m3/m2 at 12m span). Cylindrical shells were most efficient for spans below 10 metres. Critical buckling was not a limiting factor at thickness-to-span ratios above 1:150. Construction complexity was identified as the primary practical limitation for local adoption. The study concludes that hypar shell roofs are structurally and materially optimal for Nigerian low-cost construction contexts and recommends practical construction guide development for this shell form.

Keywords: thin-shell concrete, structural analysis, low-cost construction, finite element analysis, Nigeria