As we observed numerous houses and evaluated them, we were amazed, baffled and sometimes vexed by the ignorance of ours considering our own safety. We found every case a different one and every decision a critical one.
We were completely amazed to see few five story load bearing, mud mortar house with minor cracks only, in the locality where most of ancient monument had been destroyed. Similarly, observing a partially collapsed structure which wasn’t further damaged by the earthquake of moment magnitude (Mw) of 7.8 Mw was a sight to see.
We were literally annoyed when we saw a load bearing- mud mortar structure with cement mortar wall constructed above, such building were severely damaged by this earthquake. Again, construction of whole room or a portion of room on a cantilever area showed height of our ignorance, such buildings were also heavily damaged. Further, we found cases in which the building as whole was a combination of load bearing and framed structure; basically those building housed stair portion in loadbearing part and other dwelling portion in framed portion. What the hell, right? The worst part is that, in most of the cases the load bearing part is completely damaged and the framed portion is not.
The poor workmanship during the construction has been found to be a major cause of failure as well. Improper mixing of concrete, faulty pouring concrete leading to segregation and bleeding, haphazard spacing of stirrups, inadequate cross-sectional area of the reinforcement bars, splicing of the reinforcement bar in wrong way at a wrong place and insufficient clear cover in the beam and columns are some of many factors which have triggered the failure of the structure.
When there is inadequate number of reinforcing bars then the column cannot take the load acting on it and it fails. If there is absence of stirrups or if they are largely spaced then there is high probability of shear failure as all the shear force will not be resisted by the concrete and longitudinal steel only. The splicing of the reinforced bar at the column-beam joint and splicing of more than fifty percent rebar at the same level makes the corresponding level weak and there is risk of failure at that point. Again the splicing should be done in such a way such that the load exerted from the center line of one bar is transferred to the center line of another rebar. These things should be considered while designing the building. A Civil Engineer is a person who has specialized in the field of safe and economic construction of the structure, construction without the consultation of the engineer can have lethal consequences; most of us might have realized this by now. Whilst evaluating structures, we found many structures constructed without the technical assistance of the engineer. We came across many cases in which the structures were bought after construction by someone else; in such case we found the owner unknown about the structural features of the house. We found most of such owner raising the story without engineering consultation, so that they can rent the excess flats. Many of such houses are brutally damaged by this earthquake. These improperly constructed building have also greatly affected the neighboring house having sound structural feature. The buildings which were constructed properly following the building code, consulting engineer and using proper material have survived this earthquake with little or no damage and those buildings would have stood even if the earthquake was much greater.
Let’s take technical advice from the engineer while constructing our house, let’s get the construction supervised during the construction, and let’s be safe and happy. Yes, the engineers do charge some amount of money, but isn’t it worth for the safety of ours and the ones we love?