WHY THE MLOLONGO BUILDING COLLAPSED.
A six storey building collapsed in Kenya,Nairobi,Mlolongo town on Saturday 9th June 2012 at around 6pm.
I have conducted personal research on the collapse of the previous buildings collapse in Nairobi as in the links below.
Langata Southern Bypass opposite Carnivore-2011
Nairobi Kasarani Building-February 2012.
The primary reason for the Langata building collapse was because of use of poor quality sand for the beams and columns.
The primary reason for the Kasarani building collapse was use of very large spans between the beams and columns, resulting in weakness.
All the 3 buildings collapsed when the topmost floor was being constructed at the time of hoisting cement, sand and ballast for mixing.
The point localized weight of the cement, sand, ballast and water, coupled with the added force of the machine hoist that tends to pull the building at an angle during hoisting, is in my opinion the cause of the collapse in all the 3 buildings which I personally visited.
The foundation and surrounding foundations of other upcoming buildings next to the Mlolongo building was filled with water.
The type of foundation used was not suitable for an areas filled with water. The size of the columns, aprox. 250mm by 250mm in my opinion could not enable water-proofing hence easier for water to reach the steel members inside the concrete hence rust resulting to breakage.
During concrete mixing, when too much sand, cement, water and ballast was heaped at the top floor, the basement columns could have given in since the steel was eaten by rust from the swampy ground.
Also, the size of the suspended slabs was unusually thick-approx.200mm instead of a maximum of 150mm. This seemingly small difference of 5cm when quantified in tones represents hundreds of tones of added weight. With a weak basement structure, this weight was too much when added to the extra localized weight from the cement, sand and ballast being hoisted upwards.
Now that all the 3 buildings collapsed during hoisting of materials , it’s important for builders to note that their buildings have a high chance to collapse during this period so they should take precautions.
How to prevent this trend of buildings collapsing.
The responsibility to ensure buildings are safe rests squarely with the Ministry of Local Government.
It’s the work of the Ministry of Local Government to ensure that all buildings have their designs done by registered Architects and Structural engineers. In this case, the Ministry of Local Government could have ensured that the Mlolongo, Langata and Kasarani buildings submit architectural and structural drawings to them for checking. This way, when too much weight was added, the buildings could have been able to support this.
It’s the work of the Ministry of Local Government to ensure that once the design is approved, the works are supervised as per the approved drawings.
At the moment, Architects are asked to absolve the Ministry of Local Government of liabilities in case buildings collapse .This is done at the time for application for building permit.
In my opinion, I find this improper in that the architects don’t have the capacity to enforce such a role .If the building owner decides not to involve the architects, all he needs to do is not to pay the architect/engineer for his time and transport to supervise-this ensures the architect will not be able to visit the site since he can’t do this at his own personal cost.
Also, even if the architect/engineer managed to visit the site and instructed the contractor/owner to use materials as in the drawings, the architect/engineer doesn’t have mechanisms to ensure the instructions are followed. These mechanisms are within the Local Government e.g. City Court, City Askaris e.t.c who are paid by the tax payer to enforce this.
How Local Government can ensure compliance.
Local Government Engineers are few/scarce. To enable the few to work at optimum levels, an IT solution is needed. This will enable just one engineer sitting behind a computer to supervise hundreds of buildings in conjunction with practicing architects /engineers using tools such as internet, and Google earth.
I had a meeting with the PS Ministry of Local Government 2 to 3 months ago, on such a portal that I have developed. The Ministry of Local Government technical teams evaluated the portal and were ok with it.
See how the portal works at the below link
The PS recommended that I ask individual Local Authorities to buy into the idea. Any Local Authority interested in implementing this can contact www.a4architect.com for the teamwork.
Collapse of buildings in Kenya can be prevented. Local Authorities can utilize IT/internet tools such as www.a4architect.com/submit-drawings/ to work with minimum specialized labour force. With such a tool, Local Authority engineers could have seen the Kasarani building exec structural spans and advised on it online. With such a tool, Local Authority engineers could have seen the report on the type of sand being used at Langata and advised appropriately online.
With such a tool, local authority engineers could have seen the swampy grounds at Mlolongo , small sized columns and excessively sized slabs from images uploaded to the portal by the engineer and advised/enforced appropriately, all from the comfort of their offices.
The responsibility to ensure safety of buildings remains within the Ministry of Local Government and is the same in all countries worldwide. Unless the Ministry of Local Government acts, more and more buildings will continue to collapse.
Architect Francis Gichuhi Kamau.