An earthquake of magnitude 6 would bring down most recently constructed buildings in Kampala. And we are all to blame for this risk. It’s Ugandan to love the path of least resistance, a habit that makes rivers and men crooked. It’s Ugandan to love cheap at the expense of quality. We are all like passengers in a speeding car and we lack the courage to tell the driver to slow down. We are waiting for an accident to happen and we start confessing how we noticed the reckless character of the driver.
Indeed, the recent operation by UNBS against substandard steel products on the market returned sorrowful results. All our steel manufacturers except 1 have products on the market that are substandard to reckless proportions. Imagine the incident where a massive chunk of T12 steel bars sampled on our market had an average yield strength of 368 N/mm2 when the minimum allowable is 500 N/mm2. And for the T16 bars, the most failing, had an average yield strength of 379 N/mm when the minimum acceptable is 500 N/mm2. It’s T16 bars that dominate in storied residential houses. It’s T16 bars that formed most of the columns reinforcement in that apartment building you reside.
The trouble starts at the design stage. The designer follows standards that promise the strength of steel on our market to be at least 500 N/mm2. This implies that if I specify 2 bars at a bottom of a beam, my steel will be of a total carrying capacity of 1000 N/mm2. If this strength is used to design and the market provides substandard steel at yield strength of 379 N/mm2, the actual carrying capacity of my beam will now be 758 N/mm2 instead of 1,000 N/mm2. I’ve simplified engineering here for the audience to make sense of my message. But things can be more complicated. Buildings collapse in the course of construction. Indeed we recently witnessed a building collapse in Kisenyi where the causes of collapse were dominated by material quality. The buildings that survive collapse at construction stage survive under small margins of safety that a fairly strong earthquake will easily expose weaknesses. You expect a yield strength of 1,000 N/mm2 and the market gives you 758 N/mm2. Let me even go and cut my beard. Wait!
Why are we all to blame?
****************************
Apparently, the steel manufacturers are under pressure by hardware dealers to manufacture cheap steel products. Quality is cost based. So, the manufacturers play with steel feed materials to bulk the product with cheaper raw materials for volume at the expense of strength. The hardware dealers are also under pressure by their clients, property developers, to sell at cheaper prices. The developers are also under pressure by tenants to charge less rent.
What exposed engineers are doing to avoid this risk.
*****************************
Understanding the risk of poor quality materials on the market, knowing that Ugandans are mainly owner-builders that change contractors with seasons and don’t follow any quality management plans, considering that cheap is more important than quality for a typical Ugandan, structural engineers over-design. They know that the steel bars will be 300 N/mm2 instead of 500 N/mm2. So, they specify 4 bars where two of 500 N/mm2 would work. In the end, the typical Ugandan pays more money in construction than they’d have paid if the risk of choosing substandard materials didn’t exist. You can’t blame the structural engineer if the industrialist and the Ugandan hardware dealer, your friends and cousins, are submitting to your pressure and supplying substandard materials for your interest.
What the good Ugandan can do.
***********************************
It is very easy to check the quality of materials. Its very easy to design for the quality of materials and save the developer money. It starts with the developer hiring the right teams to provide construction services. Your structural engineer should know who your contractor is going to be. They should express trust in the competencies of your selected contractor. When this is achieved, your structural engineer will review the designs to eliminate excesses previously included to address contractor competence risks.
Then, you as the client should buy construction materials yourself. Purchase and supply of materials is not an engineering task. You don’t need your construction contractor to be involved in purchase of materials. You don’t need them compromised on quality and quantity of materials because they want to make a commission off materials purchases. Give the task of supplying construction materials to your house maid and let the contractor focus on the core of technical matters which are mainly at site. You’ll thank Eco Concrete Ltd later when you take this advice.
Do you have a story in your community or an opinion to share with us: Email us at Submit an Article
