HYDERABAD: The under construction multi-storied (G+6) building which collapsed in Nanakramguda in Serilingampally on December 8 was due to weak supporting structure in the form of inadequate design and excessive load on columns and foundation causing a sudden crumbling of the building.
A four-member team of professors of JNTU-H which conducted a probe into the collapse of the building which lead to the death of 11 persons and two persons getting injured, submitted a final report to Greater Hyderabad Municipal Corporation (GHMC) on Saturday.
The team which probed the incident consists of Professor and Head of Civil Engg, K Manjula Vani, associate professor of civil engineering, V Padmavathi, rector and professor of civil engineering, NV Ramana Rao and associate professor of Civil Engineering, P Srilakshmi. In the report, the members observed that the structure has been originally designed only for G+3. However on the site the builder constructed a residential building consisting of stilt+5 upper floors and a pent house.
Even the existing construction is not as per the structural drawing given by the consultant for G+3 floors. One critical column is missing in the site but is shown in the original drawing. On seeing the collapsed portions it was observed that there was meagre amount of reinforcement placed in columns. The sizes adopted for columns were inadequate and there was improper detailing of the footing and column reinforcement at the site besides plinth beams were missing leading to instability. The report mentioned that lapping procedures were ignored. The diametre of reinforcements used in the structure also appears to be inadequate for a G+6 storey building. Workmanship was also very poor.
The building foundation arrangement was highly irregular and unsymmetrical leading to further instability. The footings were too close to each other and they were eccentrically loaded, irregular in shape and highly unstable and no shear failure and lateral deformation have been observed. These arrangements of foundation led to instability of the structure and ultimately sudden collapse.
Host of mistakes
Further a deep sump was located in between two back end columns. It was noted that depth of water sump is more than the depth of foundation of adjacent column leading to instability.
The team observed that at the site, the buildings were constructed too close to each other violating the setbacks. No proper enforcement of setbacks were done at the site leading to damage of building adjacent to each other. The closeness of buildings led to foundations being too close to each other and causing excessive load on the foundation. As per the site condition, it was observed that a deep excavation was made adjacent to the building.
As per the approved drawings of the GHMC, atleast a minimum distance of 4 metres should be maintained between the building line and the excavated portion, which does not appear at the site. From the above signs it can be inferred that the adjacent excavation did not cause the collapse.