“Progressive Failure Analysis of Multi-Storey Reinforced Concrete Buildings Under Differential Settlement”.

Abstract

In recent time, progressive failure/collapse analysis of structures has become popular challenge among the structural engineers due to the progressive collapse of popular structures such as World Trade Center in New York, Ronan Point Flat in UK, Save-on- Foods Grocery Store failure in Canada, e.t.c. This research investigates the potential for progressive failure of multi-storey reinforced concrete buildings under assumed differential settlement. In this research, Alternative Load Path Method of progressive failure analysis using computer modeling is adopted for investigating the potential for progressive failure of a hypothetical 4-storey reinforced concrete building under chosen varying degrees of settlement ranging between 25mm and 150mm. The building is modeled using STAAD.Pro(2004) Structural Analysis and Design software. There are five 5-typical frame models based on the beams‟ cross-sectional dimensions. Each of the frames is analysed under the normal loads, combining with the assumed differential settlement. From the results obtained, it is discovered that the potential for progressive failure of a multi-storey reinforced concrete building increases with the increase in the degree of differential settlement. At 25mm to 75mm settlement, vulnerability to progressive failure is very low as the Demand-Capacity-Ratio (DCR) values of the component members are very small, but from 100 mm settlement and above the structure exhibits high potential for progressive failure. It is also noted that the potential for progressive failure of the structure decreases upwards the building storeys. The potential for progressive failure is higher in the lower floors than in the upper floors. Also, the rigidity of the structure helps in combating progressive failure under differential settlement