Dear Ilango:

This question begs for a simple answer, but like so many conundrums, has many unseen moving parts that cause the response to be complex and unique for each individual case. In your question, it is suggested that the lifespan of a civil engineering project or commercial building can be predicted like a 'sell by' date stamped on a perishable, manufactured foodstuff. This requires large, generalized assumptions that result in a large, generalized answer that satisfies those people interested in the general answer, not how long will a particular project will 'last'.

While a 'standard design life' is certainly required when dealing with the large herd of similar projects, to think that there is a 'standard design life' for a project picked at random is not realistic from my perspective as a practical architect. Individual project lifecycle length is affected by multiple factors during the conception, execution, and use of the project each of which act as a multiplier (positive or negative) to the length of the project lifecycle. 

I will look at selected decision points for each of these 3 project stages from both an 'Olden days' and 'Nowadays' perspective, thus illuminating my point:

Conception:  Olden days - use of materials and quantities of materials dictated by experience / rules of thumb for systems with a long track recorded (load bearing masonry walls for example, where the masonry is thick enough that moisture can not travel through the system over a season so there are little surface condensation issues) versus  'nowadays' - new materials with projected, engineered characteristics that do not have an extensive track record, thus long term consequences are not fully understood.

Execution: Olden days - things were built like the buildings that stood the test of time the longest. Nowadays - new materials require new ways of construction with unintended consequences. The failure of residential construction with the use of EIFS (exterior insulation finish system) which forces wood stud buildings to rot from the inside out due trapped water.

Project Use: Olden days - time tested materials are handled and maintained as tradition requires. Rethatching roofs on a regular basis for instance. Nowadays - New products require new ways of dealing with them, which doesn't happen with users that are ignorant of new, required ways of dealing with new materials.

In addition to these introductory points, as building cost increase, the building industries use less and less durable materials, less of them, and put them together faster, generally with little skill. Meanwhile, olden time construction techniques use more materials typically, providing a better cushion for the building to use up over time, extending the building life.

These points add to less assurity in the resilience of the completed building, thus less assurity in the projection of a given building's useful life.

We can not know the default age for these such structures from the viewpoint of use as the degrees of maintenance task as well as the misuse, leading to the short life of origin, so the periodic follow-up of the status of the building which was used is conducive to maintaining the age as planned and enable it to perform its role

Dear Llango, allow me make a contribution to your question but not generally digging deep into the issue of material components and their chemical compositions.

Can we determine the lifespan of a structure basing on the standard designs? I will answer as 'yes' and 'no'- I explain.

Yes, because the design is the basis of construction of those structures- it is upon the designs that you can then look at the materials. But before the design is formulated, many factors are put in consideration, and I specifically look at two of those: the purpose of the structure; the proposed length of time for the structure(lifespan), to be able to serve the intended purpose. Reflecting back at your question, you note that in olden days, structures were not made with composite materials and yet they lasted long unlike these days. Again, we must look at what are the underlying factors causing the recent desire for use if composite materials. Quick to note is the depletion of resources, which was not the case in the olden days, and less demand for structures. I will admit too that upon the stability(massive load baring structures), I see wastage in those old designs- so the issue of material usage and efficiency was not yet very much explored like now, still related to abanduncy of materials at their disposal. More to this I will say was in prestige as well as security, and cheap labour in construction. All these compounded, positively afforded them the pleasure and opportunity to set up massive structures, but favouring their longevity.

Fast forward to our times, scarcity of materials, a realisation of depletion of natural resources and desire for sustainability, drives material efficiency in all aspects of construction. Whereas this should not be conceived as a ticket to setting up short lived structures, it again goes back to the purpose of the structure. I would argue that if for example it is anticipated that a structure might change use several times in say 20years, why use load bearing materials in internal partitions for example? In such case I would go for fit -for - purpose materials in such light weight partitions. In such a case, then NO, the design per se will not dictate the lifespan of such a structure.

Additionally, and as a result of material scarcity and lack of cheap labour too, the cost of construction has more than doubled. These however not being the sole causes to increase in cost of construction. These situations have pushed the present designer to look at composite materials to try and bring down the cost. I will also point out that there are special challenges that face the developing world, one I grapple with in the construction industry, that of corruption. Corruption has eroded decency and honesty in the developing world to the extent that on paper, a material may be indicated with certain specifications but the industry produces a completely different one. I give you examples of timber, reinforcement materials as iron bars, cement. In designs, you might rely on the book sizes to calculate the numbers if members required for a certain structure to achieve the desired design strength; but during construction, the market gives wrong sizes, though with right numbers and so affecting the strength if your structure. Again, these are no Leeways to setting up short lived structures, but contributes to why designs alone may not determine the life span of a structure.

In all, it is no longer sufficient to rely on the design to guarantee or determine the life span of a structure.

Hope this highlights something to your querry.

In  India generally structures are designed for 50 Years. The design life of structures mainly depends on durability aspects of material. Olden structures typically constructed with a single material have long life when comparing to structures constructed with different materials say RCC. 

Dear  

Ahmed Abdelraheem Farghaly ; Aruho Tinka ; Padmanabhan Gopalakrishna Iyer

Thanks for your Answer : 

But In Structural Auditing ,

articles.economictimes.indiatimes.com › Collections › Community

Vivek Shukla, ET Bureau Sep 9, 2011, 07.59am IST

Sep 9, 2011 - A typical apartment complex or gated community comes with clubs, " The New Age customers are ... of the view that concrete apartment buildings in India last only for 30 to 50  ...

There is no doubt that given the astronomical land rates nowadays, building an independent house is increasingly becoming tough. However, experts are of the view that concrete apartment buildings in India last only for 30 to 50 years compared to the expectation of 70 to 80 years. The short life span is an economic burden for not only owners and residents but to the nation as a whole. A major factor influencing long-term service life of concrete structures is the nature of weather conditions. But it's of the view that adverse conditions like ground contamination, high temperature, humidity and fluctuating temperatures can cause damage and reduce the life span of a structure.

A important aspect which needs consideration at the design phase itself is the effect, the ambience may have on the structure, which the code may/may not consider. Service life may be predicted taking these factors into account but the predictions needs to be updated through inspection as the models themselves are not very good predictors.

Dear sir,

life span period depends on your aim and the use of the building, for example, we design the life span of houses for 20 years, but in actual use this may be 40 or more.

for important erections like dams or bridges we need to design them for 50 years or more

Thank you for activating our brain.

Faraj

Dear Sharvil Alex Faroz,

Of course,

                 In Design Phase we have to be considered all Loading parameters with Respect to "  IS or BS or some other Code and Practice can we FULFILL OUR Expectation , *******( WITH OUT IS or BS CODE PRACTICE CAN'T DO DESIGN AND ANITHINK )******

                 But In the Construction Phase also WITH OUT Code and Practice  *******( CONSIDERING IS or BS CAN MAINTAINING THE QUALITY )******* can't Follow the  QUALITY of Construction , First Fulfill the Entire Quality Then only can Expect Service Life .

Without Quality of Product HOW CAN WE Expect to Satisfaction of Use and Do Service life.   

Olden Days Expected the Life Span of Buildings,

Residential Bldg  -  50 Years

Commercial Bldg - 75 Years

Industrial Bldg     -  100 Years

But Nowadays Can be Expect ????????????

Dear Padmanabhan Gopalakrishna Iyer,

Please  Go Through Olden Structures  Like Different Type of  Buildings , Bridges etc and ALSO - Different Materials were Used in all Structure Not only """ Single Material """.

Why SIR

We are  Not Checking Durability of Materials and Use ? All ASPECTS we are Testing the materials and Using .  

Life span of structure depends on many factors such the surrounding environment around the structure and the level stresses on structural elements. The chemicals such as concrete admixtures in recycling aggregates have very little effect and can be ignored. In some cases, the environment is very severe therefore, the designer shall take care and consider in design of life span.

Life span of structure depends on many factors such the surrounding environment around the structure and the level stresses on structural elements. The chemicals such as concrete admixtures in recycling aggregates have very little effect and can be ignored. In some cases, the environment is very severe therefore, the designer shall take care and consider in design of life span.

Dear Kamal Sharobim,

Please Come from My "" First Question and Answer ""

What you type all , I Understand & Know Sir ....   

Dear Ilango,

Interesting question. I would like to comment on the numerical estimation of durability of buildings and civil engineering structures. The models that we use produce the number estimated durability. But this number has limitation due to the number of assumptions and estimation being made during the modelling since the problem is too complex and not well explored yet. The number can be used if different scenarious are compared with the same approach and /or numerical tool and under the controlled condition and assumptions.

Best regards,

Petr

Dear Ilango:

This question begs for a simple answer, but like so many conundrums, has many unseen moving parts that cause the response to be complex and unique for each individual case. In your question, it is suggested that the lifespan of a civil engineering project or commercial building can be predicted like a 'sell by' date stamped on a perishable, manufactured foodstuff. This requires large, generalized assumptions that result in a large, generalized answer that satisfies those people interested in the general answer, not how long will a particular project will 'last'.

While a 'standard design life' is certainly required when dealing with the large herd of similar projects, to think that there is a 'standard design life' for a project picked at random is not realistic from my perspective as a practical architect. Individual project lifecycle length is affected by multiple factors during the conception, execution, and use of the project each of which act as a multiplier (positive or negative) to the length of the project lifecycle. 

I will look at selected decision points for each of these 3 project stages from both an 'Olden days' and 'Nowadays' perspective, thus illuminating my point:

Conception:  Olden days - use of materials and quantities of materials dictated by experience / rules of thumb for systems with a long track recorded (load bearing masonry walls for example, where the masonry is thick enough that moisture can not travel through the system over a season so there are little surface condensation issues) versus  'nowadays' - new materials with projected, engineered characteristics that do not have an extensive track record, thus long term consequences are not fully understood.

Execution: Olden days - things were built like the buildings that stood the test of time the longest. Nowadays - new materials require new ways of construction with unintended consequences. The failure of residential construction with the use of EIFS (exterior insulation finish system) which forces wood stud buildings to rot from the inside out due trapped water.

Project Use: Olden days - time tested materials are handled and maintained as tradition requires. Rethatching roofs on a regular basis for instance. Nowadays - New products require new ways of dealing with them, which doesn't happen with users that are ignorant of new, required ways of dealing with new materials.

In addition to these introductory points, as building cost increase, the building industries use less and less durable materials, less of them, and put them together faster, generally with little skill. Meanwhile, olden time construction techniques use more materials typically, providing a better cushion for the building to use up over time, extending the building life.

These points add to less assurity in the resilience of the completed building, thus less assurity in the projection of a given building's useful life.

Personally, I think the learning curve is gonna be long and engineers will be learning parallel with what they put to practice. I agree with the question: too many of additives and new substances are added to the well-known and established theory. Some of the durability test which were accelerated in laboratory works may not represent actual degradation due to many limitations. Sometimes, are researches in construction material bring more good than harm, or are they not? Time will tell, and that will be the absolute answer. Otherwise, many will back their own different views with the state-of-the-art scientific works, but are they representative enough?

Dear Ponkumar,

Regarding your question by my opinion a relatively simple answer can be given:

That is, if everything is ideal, then YES.

You see, all chemicals added to concrete undergo certain testing if they would be harmful to any of the constituents of RC. To ensure lifespan, there are restrictions and prescriptions depending on the environment the structure is going to serve during its lifespan (such are concrete minimum strength, concrete cover, minimum cement dosage etc.).

If all above are taken into consideration, then from design point of view we are supposed to be on the safe side. BUT:

During construction mistakes are made (Those who work, make faults.) which may be unnoticed, or swept under the carpet. Saving out cement, usage of pure quality materials, over-dosage of water etc. happen daily. This is when construction supervisors come into the picture, and corruption........

Well, safety factors help a little to tackle this last, but the reason I said "IF EVERYTHING IS IDEAL" is in the paragraph.

Regarding other than structural materials the problem is much more complex, since many other factors like building physics, compatibility, durability against different environmental effects even like UV radiation etc. come into the picture. But luckily enough these are not structural problems, which would cause collapsing and as such endanger human life.

By the way, in normal case what do U mean by the life span of the structure? :-) After 30, 50 or 100 years it may collapse? Or under normal maintenance it should serve the same way as when new?

There is an other point which nobody talks about. When a material (any material) is under stress, (like humans) it will agen (corrode) faster. In case of old structures the stresses allowed (by rules of thumb) were much smaller but nowadays FEM design is much more precise, allowing higher level of utilization of strength of structural materials. But of course this is also built into the safety factors.

So if you consider all the above, then you can see that, our lifes are saved by the safety factors :-)))

Best

TS 

The design life of civil engineering structures varies from one type to another and depends on so many factors that are not common to all of them. For example in:

1.     Dams it depends on the type of the dam (arch dam, rockfill dam, earth dam, .. etc.), geology and topography of the catchment area, hydrology of the surrounding environment, sediment transport etc.

2.     In bridges, it depends on the type of the materials used for construction (steel or concrete) the fatigue life and fatigue strength of the used materials.

3.     In reinforced concrete buildings, it depends on the durability of concrete that is highly effected by the surrounding environment, temperature variations that create internal stresses, creep and shrinkage of concrete which cause redistribution of stresses inside the members and stress transfer from concrete to steel specially in columns.

4.     In liquid and earth retaining structures, it highly depends on the nature of the surrounding media and the presence of some harmful types of chemical compounds like, sulphates or chlorides.

5.    In the attached paper (Nonlinear Time Dependent Finite Element Analysis of Reinforced Concrete Beams and Columns; you can find it on the   research gate) , you will find an example of estimating the design life of R. C. column. In Figure (10) the life is effected by creep and shrinkage of concrete and is determined by the time when P=0 (strength = zero).    You can download the paper from RG.

Additional to Altaan's comments the maintenance of concrete buildings is a very important factor.  A clear example is the city of Colon, Panama.  Some buildings had no maintenance and you can see growing trees from the old concrete structures.  Nature try to recover destroying our constructions.

The mindset that once a structure is constructed, no further effort is needed, be this a conscious or unconscious series of decisions and actions, is the unspoken assumption that seems to be in the background here and is in the process of being examined in a backwards sort of way.

Any artificial arrangement is subject to the process of entropy, this evident from order/disorder paring that is part and parcel of the universe. This needs to be taken into account in the life cycle of any project. It is thought about at the design stage and will anything be done about it is a question to take into  account.

I believe that this is one of the more important points to gain from this discussion.

There are standard "Remaining Life Assessment" techniques to access the life cycle of civil and engineering structures. It involves both destructive and non-destructive methods.

Dear Sanjay Kumar ,

As per standard the life span of building during Design calculation not in construction quality & others , just i am asking that's it .