What are the major factors for a building collapse?

Bad design does not mean only errors of computation, but a failure to take into account the loads the structure will be called upon to carry, erroneous theories, reliance on inaccurate data, ignorance of the effects of repeated or impulsive stresses, and improper choice of materials or misunderstanding of their properties. The engineer is responsible for these failures, which are created at the drawing board.

All the labours may not have proper knowledge of material, kind of application, timing, importance of curing, proper covering to reinforcement etc,. . Also we notice child labours who are almost like freshers . 

In addition to design, i think various onsite factors are also responsible for deterioration of structure.

In order to save on cost, safety, durability, technical supervision etc are totally neglected.

There is total absence of technical superintendence and quality assurance.

Big time builders are hiring non technical personnel for supervision. Even PMC !!!. In medical jargon, such people are termed "quacks"!!!. They are in the field of civil Engg from a pretty long time.

If technically ignorant personnel are manning our projects, how can there by checks to ensure conformity of the materials with the specs?

Most importantly, chalta hai attitude has to go.

Civil Engineers and Civil Engg firms should desist from employing unqualified personnel. Not even for supervising curing.

I agree to all the reasons mentioned here in this ideate, but to me the most important aspect is : while designing a structure in the design stage it should go through a series of quality check, the design parameters are to be checked,if they are not passed through proper quality and parameter check how does one expect that it (structure) should stand up and avoid failure. Secondly we all agree that because of unskilled labour the structure can fail but unskilled labours appointed on the site is the  first reason for failure and we say we dont have skilled labours ---responsible the organisation, and upon that poor supervision by foremans and civil engineers on site, these guys are either short of proper knowledge of how to do and when to do and what to do sequence or are carelss or too much dependent on the UNSKILLED LABOURS, again  the responsibility is of the organisation.

Nowadays, professional practices have taken the line of business. So, the heads of professional organisations, firms, have taken the role of business heads.

And, the deliverables are depend on the employees capabilities. No one in todays trends analyse the design factors manually. They feed the input in design software & take the print out.

The softwares context & constraints are beyond the understanding of the employees who learn it & use it invariably for all situations. In fact, all the softwares are developed by foreign nationals, which may perfectly work for its intended context.

One of the major mishap is, In Indian scenario, exercising the right roles & responsibilities of professionals at various levels are missing. Everyone at their level become managers (mobilising & keeping the things moving).

So, collectively, white collar approach, lack of skill & knowledge, substandard quality - altogether causes the failure.

Since u have referred the Hyderabad building collapse at Narayanguda. I strongly feel that this is purely a case of over confidence of the Builder, basic ignorance of load assesment and strength of the Existing old structure on which 2 floors are takenup. May be the absence of SBC assesment etc., The greed of the developer to build more area and more floors without giving any thought whether the old building underneath can withstand or not. People and Authorities, Media, Intellectuals every one of us will wake up only when one incident happens. and Our memory is very short. we all discuss the issue and leave it just like that. "Chalta Hai, Chalane do" attitude will ultimately landup in this kind of situations. No one bothers about importance of structural consultant or structural aspects before start of building. People depend more on the Mason's "Knowledge and his Free advise based on his experience"than to take a paid advise from structural consultants. Even Well educated people and People in high offices are no exception to this attitude. 

Negligence in 1) Following the design 2) in using proper materials 3) use of proper procedures 4) taking into consideration all the relevant factors mentioned and advised in the design 5) not providing proper time for each process to be completed and many such reasons

Not doing the proper DUE DILIGENCE in all aspects of the building construction leads to failures.

There are many factors which contribute to a building failure, most of the time more than one such factors combine to effect the failure. Most of these have already been pointed out singly, but I shall attempt to add one or two more:

1. Starting at the begining, proper soil survey is essential before embarking on a building design. For highly seismic areas, the dynamic properties of soil and site specific response spectra are also to be established. Of course, the design offices should have qualified personnel with ability to interprete the field results.

2. Adequate design - It is important to understand the behaviour of the structure under various loading conditions and use optimum design tools to correctly model, analyze and design the structural elements and the structure as a whole. Merely using a sophisticated software is not enough, engineers should be knowledgeable enough to understand whether the results spewed out by the software are correct or not and be able to vet these results with rough hand calculations. The details in the drawings produced must also be true to the design principles applied. E.G. ductile joint detailing, bar curtailments at proper locations, etc. Knowledge of construction sequence is also very essential for a sound design. Building designs must also keep a margin for unforeseen overloads and future expansion. Concrete structures are not very amenable to changes in usage unless provisions are kept while designing.

3. Quality Construction - It is absolutely necessary to translate not only the drawings but also the design intent from the drawings to the ground. There must be tight quality control of the material & construction and adherence to the construction sequence envisaged in the design. Use of the right men, material and machine is a must for quality construction.

4. Avoid cost cutting by cutting corners - Engineers and Architects must resist pressure from developers for cost cutting by cutting corners, using cheap and inadequate materials, tools and / or personnel. Consultants trying to cut their cost by not deploying adequate (in knowledge and number) technical personnel to the job is very common and needs to be guarded against.

Be it concrete, steel, wood or any material, the work needs to be executed as it was designed to be. e.g., while placing concrete is the slump the same as it was expected to be as recommended, Are water stops placed properly and do they retain their profile while concrete is poured? In totality the work executed on site matches only 40% the procedure or method statement, due to ignorance and haste

Most of the builders/contractors are not following the QA/QC. If at any construction site properly maintaining the QA/QC means there is no collapse/loss/damage etc....

Every contractor/builder should show his professionalism by maintaining the QA/QC.

In my experience , i feel many times this. Owner will get a minor repair permit from the ULB and will replace the walls or make pillers or beams with out sufficient safety measures , although the construction is illegal and violation of rules they will do it as speedy and unhealthy and unsafely conditions.

This will leads to hazards..

The shuttering is removed before the design period to complete the project in hurry which results collapse etc. Careless during the laying of reinforcement basically supervisors don't give there full time during the  reinforcement.

The mix used /prepared on sie is not in proportion .the matrial uaed is of low standard whose testing is not carried out.The cubes sent for testing are made of seperate mix .

 also the shuttering is removed early that in wrong manner.As for cantilevers the supporting is removed from cantilever end, thus reverse stresses are indused resulting in failure.

One aspect is the materials used for construction. Are they adequate for the life expectancy and safety of the building?