My main backgound as a Civil Engineer is in building things for commercial or domestic use. But as building collapses are hitting the headlines more than desirable we have to take a closer look at what we are building and what to do to keep them from prematurely collapsing.
To prevent anything from happening it is imperative that we know the cause… therefore I will dwell on the common causes of building collapses not just in Nigeria.
What has caused collapses in other countries? What have they done to prevent or reduce the risks?
I will focus on some countries where I have had personal experience, compare how they do things and learn from what they have done and then drill down to any innovative measures that I may suggest that we can adopt specifically for Project Engineers in Nigeria.
The issue of Building Collapse is not peculiar to Nigeria I found out in my searches that at one stage there were seven (7No) building control collapses in India everyday.
Main Causes Of Building Collapses
I think that even if you ask a non-professional they can tell you a few of the things in the following non-exhaustive list, pardon me if I have left a few out
1. Poor or weak foundations
2. Competence of engineers at design and construction stage
3. Building work by incompetent builders and/or artisans
4. Poor workmanship
5. Disregard of engineers detail
6. Engineering errors
7. Natural disasters (Flooding leading to landslides, earth movement)
9. Poor quality of materials/ Lack of Quality Control
10. Lack of maintenance
11. Lack of or poor supervision
12. Weak or non-existent Enforcement
13. No Regulations or Standards and Weak Enforcement
14. Sudden Impact (e.g vehicular impact)
16. Vibration from nearby explosions
17. Poor designed extensions (e.g additional floors)
18. Unauthorised change of Use (e.g from house to Nightclub)
I deliberately left out earthquakes and hurricanes which are peculiar to countries like Japan and some parts of America.
The nearest we have in Nigeria to natural disasters is from flooding but despite not having some of the more extreme natural disasters we still have a fair share of building collapses which is now becoming increasingly alarming.
Having enlisted the causes of building collapse this paper will try and focus on those factors that increase the risk of collapse that a competent Project Engineer can mitigate.
Foundations are designed based on the overall loading from a building resisted by the underlying ground reaction. The structural engineer would have considered the forces acting on the building and considered the best foundation to support the loads.
If a foundation is not built to the structural engineers specification then it will not attain its full design strength. This makes the foundation ‘weak’ from Day 1. The Project Engineer’s role is to ensure that the foundation is built as per the Structural Engineers design for it to achieve its FULL strength.
The Project Engineer must carry out his due diligence and make sure that he is familiar with the ground conditions by studying any Site Investigation (SI) reports or carry out his own trial holes. He should note the Geotechnical Engineers comments about contaminants, weak points, ground water, soil strata etc and any other risks to the foundation.
A major project over three storeys should have a SI report and if it does not the Project Engineer should wonder why not.
In UK it is common for any new building project to have a SI report, the developer may run into trouble with Insurance if not provided. For high rise buildings, SI Reports are compulsory. The foundations are designed or specified by Geotechnical Engineers who specialise in Advanced foundation design or are experienced structural engineers with post-graduate qualifications in Soil Mechanics.
Generally, the Project Engineer should satisfy himself of the following
• That the foundations are appropriate for the building
• The foundation design has been checked and approved by a regulatory authority or by an established consulting firm
• That the reinforcement in the foundation is placed properly and as per the drawings
• If piles are used they are in the correct location and rebars are left sticking out to lap with pile caps/beams etc
• Concrete is of high quality as per specification and well compacted
• Samples of concrete are taken for cube strength testing and on site mixes are of correct quality (for minor projects this is impractical, just make sure the mix is good on site)
The foundation is the most critical part of the building as such the Project Engineer has to get this stage right. If he/she does not get the foundations right, the whole project is on a slippery slope.
Bearing in mind that weak foundations are one of the highest causes of building collapse he/she has to be competent enough to match the complexity of the project.
How do we appoint a COMPETENT Project Engineer?
What makes an individual COMPETENT?
There are no fixed Golden Rules, it does depend on the Project. We cannot have COREN registered engineers on every project, that will be like using a hammer to open a groundnut, and we cannot appoint fresh Graduates as Project Engineers for a high rise building.
Its almost like a risk management…an OND graduate with a year experience could be made an assistant Project Engineer for a single storey building that has a basic foundation. If anything goes wrong, you can justify that he is competent but with adequate supervision. If we put the same person on a multi-storey car park we are in a different scenario and no justification can be acceptable if things go wrong.
Project Engineers on major projects should be members of the Civil or Structural branch of the MNSE and COREN registered. Such senior engineers can delegate roles to other less experienced or competent engineers.
A Project Engineer might have to make rapid site decisions in the absence of the project structural engineer so it is important that he is competent. He will occasionally have to step in to the role of the design engineer and provide alternative solutions/fixes.
To avoid premature collapse the project engineer is responsible for the integrity of the project at the construction phase. We have discussed the importance of the foundations, the next stage is the floors, columns, beams and walls.
He has to make sure that the materials are available on site, they are of good quality and protected from the elements. (we cannot leave cement or reinforcement bars exposed to rain or moisture)
Common weak points of any building are joints and connections. The project engineer has to take particular attention that in Reinforced concrete there is adequate lap between the foundation and column reinforcement steels. In RC the lap lengths are the strength of connection of structural elements.
Other critical joints are
• Columns to beams joints
• Beam to beam connections
• Balconies to main floor
• Cantilevers (many houses are wider at First floor with significant cantilevers) to main floor
Balconies and cantilevered floors are high risk areas for local collapse and require extra attention.
A building is in a precarious state during construction, some of the support structure takes time to reach its full structural strength. During construction the building is supported by temporary works made of timber and sometimes bamboo.
On major projects, temporary works is a defined specialist role but on minor domestic projects its fitted by experienced artisans. The project engineer has to ensure that the artisans provide safe support for structural elements such as concrete slabs when they have not attained self-supporting strength. The supports must not be removed prematurely.
Incompetent builders and/or artisans
An incompetent builder is an individual or organisation that is not able to effectively deliver the building to an acceptable standard due to lack of training, experience or knowledge. The trouble with these sorts of people is that they do not know that they are incompetent and would not necessarily agree when you point it out.
A Project Engineer has to be comfortable with and have confidence in the builder. The project engineer does not always have influence on the appointment or dismissal of the builder, you can only raise the alarm, take notes and build up evidence of your concerns.
When the errors are such that they pose a risk to the structural integrity of the project you have a professional responsibility to take severe actions. E.g Stop the work, remove defective work, dismiss the delinquent artisan
Incompetent builders are appointed by developers, architects, owners or other stake holders due to one or more of the following
• Cost; sometimes people go for the cheapest tenderer
• Corruption; The builder won the contract by means other than competence
• Misrepresentation; the individuals who were presented to do the job are not actually the ones doing it, their quality staff have been relocated to another project
• Lack of Experience; This builder has not done work on this scale before
• Nepotism; An incompetent builder being awarded the project due to personal ties
• Ignorance; an inexperienced developer cannot assess a builder
So…what do you do as the Project Engineer?
1. Provide as some technical support, take on a ‘Team’ spirit
2. Do not be quick to blame but let people know their mistakes
3. Raise alarm on defective work that poses a structural risk
4. Report shoddy work to your superiors but be professional and fair
5. Teach/train them, if they listen and improve, get on with the job
6. Be firm, dismiss persistent incompetent artisans
7. Sometimes you simply have to walk away! Its not worth ruining your reputation
With incompetent builders the building is at risk before it is occupied and might collapse during construction. Initially if the incompetence is not staggering and bearable the Project Engineer should try and assist the builder. If you cannot help then take steps to get the builder removed.
Your reputation is on the line and once you are associated with a collapsed building it will stick with you throughout your career. Jobs are not easy to come by in Nigeria and its easier said than done to just leave a job. In my experience I would start looking for another job from the time I notice that things are not right and I have no control.
How can we avoid Incompetent Builders
In UK they have so many schemes that help the naïve owner to select a competent builder examples are
• Federation of Master Builders
These are builders that have been vetted by independent professionals.
As the Project Engineer you have to deal with the builder presented to you, you can find out about them but generally you have to judge them based on YOUR experience.
It was a bit of a juggle for me deciding what is poor workmanship and what is incompetence. In my opinion, incompetence is one of the causes of poor workmanship. I see poor workmanship as the final product that an individual has produced. Is it acceptable? If not, why?
Consider two scenarios
a) Lets take a steel bar fixer who puts the main bars in the wrong place…the structure is now weaker than it should be
b) If concrete is not compacted it could lead to honeycombed concrete. This leaves reinforcement steel bars exposed potentially leading to carbonation…which could result in failure and collapse on the long run.
These are effects of Poor workmanship
As the Project Engineer you will have to step up supervision on some crucial stages.
• Bar fixing
• Cover maintenance (poor cover leaves reinforcement exposed)
• Temporary works supports and formwork
• Concrete placement
• Compaction of wet concrete
On minor buildings, as the Project Engineer, you should identify and take note of those people that are simply incompetent, lazy/slack, have bad attitude, shortcut cheats, have substance abuse problems etc etc.
Poor workmanship can be dealt with by supervision, training, discipline and rewards. Lets say you have many plasterers on a job, when you see a high quality job you reward that individual.
The scholar Maslow wrote some great theories on motivational skills, I think any aspiring Project Engineer should study Maslow. Motivated people produce quality work.
As the Project Engineer you are responsible for quality on site, you cannot be everywhere so you have to shortlist critical activities and make sure supervision is stepped up, the best artisans are on the job and mostly try and be there yourself.
Disregard of Engineers detail
This happens all over the world and it is more rampant on smaller projects. An example is when the builder simply comes up with his own detail claiming that he has more experience than those ‘book’ engineers. Yes, some builders are well experienced but if they must change anything the design structural engineer should know.
Another example is a change in a material. I have seen a builder have change a floor from timber to reinforced concrete slabs an increase in dead weight of 0.5 KN/m2 to 4.8KN/m2 (incl Screed)
This increased the dead weight of the building placing extra load on the foundations
The Project Engineer should not deviate from the engineer’s details without his approval. Most builders are more concerned with making a profit and may propose changes that make their life easier.
To err is human and mistakes can be made. The Project Engineer can spot errors in the design that could be due to incorrect assumptions revealed during construction.
Discuss with the structural engineer and rectify as early as possible.
The Project Engineer is in a good position to prevent Building Collapses by taking measures during the construction Phase. We SHOULD educate and train our Project Engineers to carry out a risk assessment just before work commences on site, identify the risk factors and mitigate them.
A simple example is a house with a large balcony. A risk assessment would enable him/her to focus on the reinforcement in this particular area and be on red alert when this task comes up.
I have tried to set a gauge on how to select the right person ‘competent’ enough to run a job based on its complexity. Of course, you will interview the candidates and check their work experience BUT a minimum level of intellectual capacity is required for the more complex jobs, as the Project Engineer might be the last safety net to identify a flaw in the structural design and correct it or improve on the design.
All said and done, we as professionals have to make a stand and say ‘You know what…I am not part of this..I am out of here’ a collapsed building is like a badge that follows you around your career. Blow the whistle, shout and if nothing changes get another job. If you are good, you will get one.
People might say that some developers, owners cannot afford a competent Project Engineer. I agree…but you can have a non-resident Project Engineer that will come and inspect/supervise the high risk elements only, that will keep costs down.
Tomi Adebayo B.Sc (Hons) C.Eng MICE