I’m writing this against the backdrop of inglorious news that a building imploded in Nairobi on Monday night.
Every so often a building fails in this country. By failure I mean a building collapses, or sinks into its foundation or develops deep cracks or its columns (pillars) buckle under ordinary conditions. Building failure is dismal. It can lead injury or even death.
I wrote an earlier blog to make the case that it (building failure) is a human making, ‘that nine of ten accidents are caused, not by more or less abstruse technical effects*’, but by human carelessness.
Now I notice that nontechnical people resent when stresses and strains or any other engineering parlance is mentioned. So this write-up is demystified so that we can all understand safety in so far as building structures are concerned. We all sleep, work, study in a building. Safety is then the business of, not just the bricklayer or the structural engineer or the local authorities but all of us.
What we engineering students study is how the different elements of a structure fail. In the laboratories we exert bricks, concrete blocks, metal bars and other construction materials and we can know what mode of failure they undergo and just how much weight they can support or how long they can resist fire. We do strength calculations. We look at design charts and follow building codes. Just in case you have seen engineers refer to a book with tables and equations, it may have been a building code. Building codes keep being revised.
Building design according to clause 2.1.1 of the building code BS 8110 is to meet “acceptable probability that the structures being designed will perform satisfactorily during their intended life.” Any contravention of this leads to failure.
Long time ago living spaces were build out of mere experience, intuition and trial and error. This usually resulted in buildings being massive and certainly very costly. Later out of the discoveries of science, we have thinner structures even the size of a pane of glass being as strong as a few clay bricks.
You have probably heard glass bridges being constructed in China.
For buildings today, the strength is not in how massive the building looks. It is in the building process.
Today unlike medieval times, design is a premeditated process. The engineers visit the site, test the soil and determine what kind of foundation will be suitable. Strength calculations are done. Necessary determinations of the cement, metal bars and where they are going to placed or bent are made. Plans are drawn, blueprints are produced and verified by the local authorities.
The blueprints should be followed to detail during construction. Follow with exactness the given cement mixing ratios. Do not compromise on the thickness or type or the number or the spacing of the steel bars. Don’t be tempted to buy substandard materials for less. Do not allow the pillars to misaligned one to another even by a millimeter.
So when you are seated in a building and it does not collapse know that a meticulous process was followed. The choice, the placement and the amount of the building materials was not ambiguous. Everything was out of deliberation. A structural engineer and an architect might have argued over the size or the shape of the columns.
*Words credited to Prof E. J Gordon