NUMERICAL STRUCTURAL HEALTH MONITORING OF A DISTRESSED REINFORCED CONCRETE MULTI-STOREY BUILDING

Abstract

Serviceability of reinforced concrete structures has become of much concern to engineers globally because of the failure and collapse of building frames due to inadequate member sizes and stiffnesses to resist load imposed on them. This research highlights the failure path of a typical existing three storey reinforced concrete building through the use of Orion (15.1, 2010), a reinforced concrete analysis and design software. The approach to the investigation was done in two stages. First of all, the building site was visited to take structural dimensions and measure visible deformations where possible. The second stage involved modeling of the building using the as-built dimensions: 150 mm thick slabs, 500 mm x 230 mm beams, 400 mm x 230 mm and 300 mm diameter rectangular and circular columns respectively. The application of load and analysis of the structure were carried out in accordance with BS 6399: Part 1(1997) and BS 8110; Part 1 (1997). Since deflection depends on structural stiffnesses, simulations were done when the stiffnesses of slab and beam were varied. Thus, it was easy to investigate the cause of the noted distress on the building. From the analysis and design output, the slabs were found adequately sized and reinforced resulting in deflections that were within permissible limits. However, some of the beams showed that they were not adequately sized and were under-reinforced, which led to deflections beyond the permissible limit. All columns in the building were found to be adequate in resisting the imposed load. On the basis of the simulations conducted in this study, it could be concluded that the distress on the building was initiated by excessive deflections of floor beams.