Development of Sensitivity based Model for Flexural Failure of Singly Reinforced Concrete Slabs Based on BS 8110: 1997

Abstract

This research presents mathematical models for checking the effect of variation in key designed parameters on the structural collapse of singly reinforced concrete solid slabs in buildings due to flexural failure based on British Standard (BS) 8110, 1997. The increasing complexity of construction process requires very high level of engineering and management skills to combat the structural collapses widely experienced globally. Most of the collapses were adjudged to be due to improper management arising from variations in structural key design parameters during construction, and this call for mathematical models to check the effect of variation in key design parameters on the structural collapse. The key design parameters considered in this research are; characteristic strength of reinforcement, grade of concrete, diameter and spacing of tension reinforcement, effective depth of tension reinforcement, applied moment. Sensitivity analysis was applied to study the effect of variation in the key parameters on the moment capacity. The results of sensitivity analysis were utilized in regression analysis to develop simplified equations for estimating the moment capacity of the slab. Computer programme was developed based on BS 8110, 1997 standard using Java to verify the model. Flexure safety factor was also checked based on BS 8110, 1997 requirements. Forty five numerical examples were taken to validate the model with the developed computer programme at 5% significance level using Chi-squared as an instrument for sensitivity-based model for flexural failure of singly reinforced concrete slab. The results show that the model is adequate at 5% significance level for checking flexural failure of singly reinforced concrete slab at construction stage based on BS 8110, 1997. It was recommended that the construction practitioners should consider the diverse effect of change in key deigned parameters during construction, otherwise the developed model should be strictly considered for quick safety check especially deflection safety of a solid slab during construction.