D. D. Derashri *
Here is an article on failures of structures written by an Engineer, having vast knowledge of his subject and long field experience – why they happen, what are the implications and how they can be reduced. The key solution suggested by the author is timely maintenance.
For engineers, there is a crucial role to play in society and they always have to find new solutions to solve new problems. We build structures so that they are able to perform for a reasonable period of time. People have faith in us as professionals and if a structure collapses or fails, the whole set up of society’s basic faith gets shaken. No one is ready to take up the failure as lightly. The pressure of accountability towards society and its reactions have severe impact on our working. Press starts criticising and demands to know that what went wrong, why did the structure could not sustain and who is responsible? Investigations are called for. Newspapers give adverse publicity ensuring political motivation. This disturbs our peace of mind. One of us feels relieved when his name is not connected with the failure. Most of us read the press coverage of the collapse and feel grateful that it was not me in the coverage. This is one of the reasons why we engineers cannot afford construction failures. But there are many failures, many times similar types of failures have repeatedly occurred.
Failures are known to have shattered morale and guilty conscience for many. An engineer has to earn his living through out his life; this is one of the reasons why very few of us like to share our experience of failure as it may cost sacrificing of our career. This is why most of us are bad communicators, and least desire to share our experience related to failure. It has become necessary now than ever before, to talk about our short comings – to share our experience as failure is not always because of our profession. There could seldom be a single cause for failure. It is always a collective contribution through many causes for which engineers are not only always responsible. It is now accepted that failures can and do occur more often than we care to admit. The direct or indirect causes of collapses of the structures are many viz.; design error, construction error, material deficiency, deferred maintenance, functional deficiency, natural hazards, sabotage, fire-blast etc.
It is interesting to note that the failures have occurred in the past, they occur today and they will continue to occur in future. Can we avoid them? Probably ‘No’. Hence the best way is to learn from past failures and adopt precautionary measures so that similar failures are not repeated. It is an established fact that every failure is a result of combination of several factors and each time the main contributor is different. This is why every failure is interesting and we can learn much from each failure as we learn more from mistakes than success.
Engineers must be shown failures so as to narrow the gap between theory and practice. As doctors see disease and handle patients, we engineers must see the problem to realise their seriousness. The process of learning from experience is a life time exercise. Hence we must learn from past failures to avoid future failures.
As an engineer we have acquired certain skills knowledge and competence with the help of education to serve society by providing it goods and services. We have the privilege of being a class of people who have been trained only to look to the progress of the society. In a lighter way it is said that a politician makes his living on the ignorance of the society. A Doctor makes his earnings on the diseases in the society – a lawyer makes his life on the quarrels of the society, but an engineer’s life depends on the progress of society. Thus it is the engineer and only the engineer who always thinks towards progress. It is a well known saying that engineers are always ready to construct any imaginative structure if some one is ready to pay the cost of it. Development of new structures is becoming costlier day by day hence whole hearted efforts are required to increase the performance and utility of existing structures – By way of proper upkeep adequate maintenance and timely rejuvenation.
Failures can be avoided by adopting a policy of timely maintenance. To have a clear idea of type of maintenance requirement it is essential to understand the ageing process. It should be made clear that no construction material in the world is maintenance free. We have to be observant to know what has gone wrong and what the relationship between deterioration and performance is. A visible deterioration of a structure is easy to demonstrate, but it is difficult to predict the loss of strength due to ageing. Thus it is preferable to reduce process of ageing by way of giving rejuvenation dosage. Regular maintenance allows one to take timely action where deterioration is observed thereby reducing its rate and prolong the useful life. To access sensible and realistic maintenance it is essential to evaluate what is happening in the system.
Diagnose the cause responsible for decay. It is very essential to evaluate that to what extent a particular structure could withstand the expected stress even after sustaining some damage.
This concept requires a positive and timely detection of damage; deformities cracks etc. received by a civil structure and warrants review of existing maintenance and structural repair practices. Hence the most important step after completion of a structure is to regularly perform condition assessment. This is done with a view to find out the extent of deterioration of a structure has received with the passage of time. The condition assessment gives an idea to decide whether it could be economical to repair and maintain the structure or to reject or declare the structure obsolete.
Presently this system of condition assessment and maintenance is badly missing. We totally overlook or forget about our own creations which later on become difficult to handle. Why this happens? What are the basic causes? Perhaps, one of the reason is the spurt in construction activities have pushed back the task of maintenance. Maintenance engineering is not considered a glamorous occupation, above all in Indian scenario; the general aptitude towards maintenance is missing. We even do not give desired attention and fail to maintain properly our personal belongings.
It is an unfortunate fact that the maintenance activities are never treated in same way as construction, secondly and probably the most genuine cause is that we are not taught for so as to become a good maintenance engineer.
The subject of structure deterioration and ageing process, with assessment of ultimate failure and reasons of such happenings needs to be introduced in our technical syllabus under “Symptomatic Diagnosis, Prognosis Engineering or simply the “Forensic Engineering”. This will certainly improve our ability to deal with the continuous ageing process, which leads to “Sick Structures”. To my view this is the right time to understand that diagnosis, treatment and rejuvenation of a sick structure is a rewarding work and requires more knowledge and skill than construction of a new structure.
The question is usually raised about the expected life of a structure. It is very difficult to pre-estimate the life as it depends upon several parameters. A civil structure is conceived when designed, born when built, alive while standing and in use, dead at old age through gradual erosion diminishing the utility of structure by way of ageing or through an unexpected accident and failure leading to total collapse.
Just as medical doctor considers health to be the norm and disease the exception and gain most of their knowledge from illness during patient examination so as the engineers must consider the structure in use to be the norm and structural failure the exception and should learn a lot from failure.
That is why I again request all fellow engineers to develop an aptitude to be interested in minutely observing every failure you come across and develop a habit of finding out technical causes responsible for failure of the civil structure. This awareness and realisation is important to our community as it would develop a skill in our minds that will certainly assist us to avoid such failures in future.
Hence we must start:
- o Communicating failure information’s to all fellow engineers to exchange the experience and to diffuse knowledge and information available to arrive at the correct failure analysis. Seniors with experience have to pass the knowledge and experience to the juniors so that they would not repeat the mistakes. I am confident if such exchange is done we can avoid repetition of failures and can arrive at a common base to decide possible approach for overall development.
- o Develop a habit of documentation, this is very important and is presently neglected. Proper documentation helps in knowing the past performance and behaviour of the structure.
- o To develop habit of regular evaluation of the performance of an existing structure.
- o To develop a full proof feed back system. In absence of feed back it is extremely difficult to actually assess the past performance and to identify how to manage better in failure. Unless we are told about the bad performance, we will keep on making the same mistakes; feed back communication implies a two way action to spell the difference between successful performance of the structure and its failure. Good monitoring and maintenance needs also must form part of our communication.
- o Not to neglect little problems or overlook minor deficiencies until they become potential hazards.
Leading to a failure we have to be observant to know that what has or is going wrong. Our efforts have to be continuous. Normal practice is this that whenever there is failure every one comes to life and becomes super-conscious about setting up a programme to avoid such a catastrophe in future. After some time, dust settles and we are back where we started and therefore similar mistakes are encountered again. This attitude needs to be curbed. It can be done only through our united and dedicated interest to safeguard the dignity of our profession by avoiding future failures. If there is any obstacle in our way or any political, economic or administrative system prevents us from doing so, it is for us to assert ourselves and in a united effort to overcome the obstacles. To achieve this we have to do some sacrifices and to develop some code of ethics to regard and assist all fellow engineers in trouble during failures.
*About the Author –
Mr. Devndra Deo Derashri (D. D. Derashri) is a retired Chief Engineer from Water Resources Department, Government of Rajasthan and is presently headquartered at Bhilwara Town of Rajasthan. He is heading a consultancy firm “Water People” and also a N.G.O. named “Panee Wale” both working in Water Resources field. Study, analysis and writing on technical & complex water related issues, is his hobby and this article is a reflexion of the same. He can be contacted at email@example.com