Destructive and Non-Destructive Assessment of Collapsed Structures in Onitsha, Anambra State, Nigeria
This project work identifies the incessant building failure which has been reported, resulting in the loss of lives and properties in Anambra State Nigeria. A study of some selected collapsed buildings in Onitsha, Anambra state, Nigeria is carried out in this work. The methodology includes conduct of site investigations, and site inspections, destructive testing and non-destructive testing of collapsed structural element to establish their strength by the determination of the yield strength of the reinforcements and sieve analysis of the soil at the site, the use of Schmidt hammer instrument in determining the strength of the concrete. From the results of the test carried out in the case study 1, the column strength ranges from13N/mm2 to 22N/mm2, beam ranges from 13N/mm2 to 21N/mm2 and slab strength ranges from 15.67N/mm2 to 21N/mm2. In the case 2 collapsed building the column strength ranges from 14N/mm2 to 23N/mm2, the beam strength ranges from 15.53N/mm2 to 21N/mm2 and slab from10N/mm2 to 21N/mm2.the reinforcing bars has a strength hardness value of 21.19HRC for EC, 20.22HRC for IC and 19.63HRC for SC. These values are compared with BS4449 and Nst-65-Mn standards and 24N/mm2 concrete strength at maturity in accordance to BS8110. The findings show that improper mix of concrete, the use of substandard materials and poor supervision of work, contributed to the collapse of the building.
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