Novel Performance-Based Wind Engineering Framework for the Design of Flexible High-Rise Structures in Lagos Coastal Urban Wind Environment

Performance-based wind engineering provides a probabilistic framework for relating wind hazard to structural response and damage across multiple performance levels, offering a conceptual parallel to established performance-based earthquake engineering that has not been systematically developed for the wind-critical coastal urban context of Lagos in the South West geopolitical zone. This study develops a novel performance-based wind engineering framework calibrated to the Lagos coastal urban wind environment and applicable to flexible high-rise structures exceeding 80 metres in height, addressing a critical gap in structural design practice for Nigeria's tallest building category. The framework comprises four integrated components: a site-specific wind hazard model derived from 45 years of meteorological station data and tropical cyclone track databases; a nonlinear structural response model accounting for aerodynamic damping, gust buffeting, and vortex-induced vibration; a performance level taxonomy defining structural, cladding, facade, and occupant comfort limit states; and a risk integration module computing mean annual exceedance rates for each performance level. Four reference high-rise structures representing slender residential towers, broad commercial towers, stepped setback forms, and irregular plan configurations were analysed under the framework. Aeroelastic wind tunnel test data from 1:400 scale models provided validation for the aerodynamic load models. Results indicate that occupant comfort governs structural performance for slender towers at wind return periods of 10 to 25 years, while cladding pressure performance governs at 50 to 100-year return periods. The framework identifies a significant underestimation of ten-year return period alongwind acceleration in the current NNBC equivalent static wind force method, by a factor of 1.4 for the most slender building configuration. Keywords: performance-based wind engineering, high-rise structures, Lagos coastal, wind hazard, occupant comfort.