Winter 2021
Communities: Private Practice
How Unregulated Engineering and Construction Put My Country at Risk
BY RIFAT BIN AHMED
Bangladesh sits atop the world’s largest river delta at close to sea level, facing both the risk posed by a quake and secondary risks of tsunamis and flooding in the quake’s aftermath. Now, unplanned and risky urbanization has been seen as to slay the slain. Since I am a practicing engineer, I can see very closely how unplanned urbanization is taking place and how it is created by such risky structure.
As the 18th most populous country in the world, Bangladesh has a population exceeding 164 million people. In terms of landmass, it ranks 92nd, one of the most densely populated countries in the world. To ensure housing for this large of a population in such a small area, building construction is increasing rapidly. But much of the growth takes place without heeding rules and regulations. Further, Dhaka, the capital and country’s largest city, is one of the riskiest cities for earthquakes in the world. And no one has to be an expert to see that Dhaka is an unplanned city.
According to the Bangladeshi public agency responsible for coordinating the city’s urban development, in 2008 the total number of buildings in the area was 1,196,412; in 2017 the total number of buildings stood at 2,146,174. A recent survey (conducted by the same authority) of 204,106 buildings found that 134,925, or 66.1%, were illegal. Most of the extended part of Dhaka city has been developed on recently filled and marshy lands. The city’s eastern and southwestern parts lie within the high to very high liquefaction susceptibility range.
These statistics show that unplanned urbanization is a significant problem. When it comes to housing throughout the whole country, houses with corrugated galvanized iron sheet supported on bamboo/concrete posts are still very common. Bangladesh is susceptible to devastating cyclones, and these houses are at great risk of having their roofs blown away due to high suction forces and to collapsing sideways.
Buildings present other challenges. The most popular type of construction in rural and urban areas in Bangladesh uses burnt clay brick masonry for the supporting walls with reinforced concrete roof slabs. These buildings are more durable against winds, but in case of earthquakes, they risk collapse if the walls are not reinforced. Although the Bangladesh National Building Code provides guidelines for making unreinforced brick masonry structures better resist earthquake forces, unfortunately these building code guidelines are rarely followed in practice.
Buildings constructed using a reinforced concrete beam-column frame system are also popular in urban and rural areas. But again, many of these buildings are constructed without following National Building Code guidelines. Many building owners don’t use the services of qualified engineers in design or construction. With the increasing popularity of multistoried buildings, not only in urban areas, but also in some rural areas, the structures are being built without following the provisions of the building code. Many owners think that the involvement of qualified engineers will likely lead to a significant increase in construction costs. However, this isn’t true. While there may be a very small increase in cost, the structures will be built according to the National Building Code, and they will be more durable and safer.
In reality, however, many owners rely on craftsmen to ensure a low-cost building. But many building technicians or craftsmen, such as masons, lack adequate knowledge to make proper decisions about quality, such as the durability of concrete. As a result, if a properly engineered and constructed structure has a life span of 100 years, the same nonengineered structure could deteriorate even after 10–15 years or less, which is an economic loss and environmentally damaging.
In Bangladesh, it is very important to change the mentality of building owners and to require regular training of building technicians, masons, rod binders, and other craftsmen. We need to ensure compliance with the National Building Code to build safer housing and structures that resist cyclone winds and earthquakes.
Today, an earthquake of a magnitude of 5.5–6.5, similar to the 1885 Bengal earthquake or the 1897 Assam earthquake, would be the worst in the history of Bangladesh, due to the widespread use of brick masonry and nonengineered and poorly constructed buildings, particularly in the capital Dhaka. Such a catastrophic event would be beyond our imagination and could even lead to abandonment of the city.
NSPE student member Rifat Bin Ahmed is a structural design engineer at Builtech Consulting Engineers in Bangladesh.