Integrated Structural Risk Assessment of University Lecture Theatres in Developing Countries: A Case Study of Taraba State University, Nigeria
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Abstract
This study applies the Integrated Structural Risk Assessment Framework (ISRAF) to all 12 reinforced concrete lecture theatres on the main campus of Taraba State University (TSU), Jalingo, Nigeria. ISRAF is presented as a comprehensive integrated framework adapted to the data constraints of resource-limited university environments in sub-Saharan Africa. It combines visual inspection, non-destructive testing (NDT), probabilistic reliability analysis using the First Order Reliability Method (FORM), finite element modelling (FEM), occupancy load quantification, and composite risk indexing within a single tiered workflow. The 12 theatres, constructed between 2008 and 2019, were assessed through 2,880 rebound hammer readings, 720 ultrasonic pulse velocity measurements, 60 laboratory-tested core samples, and 1,560 half-cell potential readings. Goodness-of-fit tests confirmed appropriate probability distributions for all random variables. Five theatres (42 percent) returned in-situ compressive strengths below their specified C20 to C25 design grades, and carbonation had already reached mean cover depths in four buildings (33 percent), confirming active reinforcement corrosion at structural ages as low as nine years. FORM reliability indices ranged from 1.52 to 4.34; against a Consequence Class CC2 target of βT = 3.5, four theatres were classified as Deficient and two as Marginal, while under a more demanding CC3 target (βT = 4.2) none of the theatres met the target on the governing shear limit state. Peak equivalent occupancy loads of up to 6.2 kN/m² in the most densely occupied seating zones exceeded the as-designed value by up to 148 percent. Two buildings exhibit reliability levels well below accepted targets and warrant immediate restricted occupancy and detailed specialist structural evaluation; estimated remediation costs for the six affected theatres range from approximately NGN 5 million to NGN 80 million per building. The findings establish that quality-related early deterioration in recently constructed state university buildings can produce safety deficits comparable in severity to those typically associated with decades of service
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