Why under-construction structures collapses?

The carelessness is the sole reason for the under contruction structures to collapss. Look we have the technology and the expertise to build and run big construction structures. It has been prooved by our engineers so many times. I need not give examples of it. Carelessness is the biggest reason. Greed also creeps in sometimes or I should say most of the times. So according to me Greed and carelessness are the two biggest reasons for our underconstruction structures to collapse.

Well said Tapan, all the points you have mentioned are valid and are also major reason for the the construction collapses. We should keep in mind and then try to correct it. 

I agree what Anil said, it is because of the carelessness and improper investigation. And like to throw some light, I think we are lacking behind in technology especially in construction sector. So to overcome this issue we should adopt good technologies.  

The theory of beam  loading originated from the ideas of yester year Mathematician Euler. When beams are loaded  the weights acting on it cannot create sustained oscillations,  or over damped oscillation, instead it should be designed for "under damping" meaning loads that create oscillations must bring the started oscillation to rest as soon as possible. This is affirmed by selecting proper materials with the right "torsion" and "shear" charecteristics and deploying them at proper distances between the pillars. If this calculations go wrong "over damped" oscillations of the structure can occur and create rupture which destabilise the loading and the structure collapses.

Most construction accidents occur in the under construction structures as one of the most important aspect of construction is either being ignored or under valued.

FORMWORK.

Just like a concrete structure, form work being a temporary structure has to be properly designed by experienced designers to withstand the concrete loading and after pour behavior of concrete structures. Not only form work but also the method of assembling and dissembling the form work has to be designed properly to ensure that the concrete structure is not prematurely loaded before attaining its intended strength.

Only rarely do companies give importance to form work and this may be one of the biggest reasons for under-construction structures collapses.

As far as quality of structure is concerned, the degree of safety used for construction in india is too high that even if we use 75 % of actual materials intended to be used, still the structure will stand.

It is also a side effect of cost cutting. Mgmt wants to complet the work with new machinary with new man power with new ideas but less experties. This happens from a labour class to managerial class

1 partialy faulty design.2.poor quality control.3 proper supervision & 4.corruption in the system.

Most of the failure are due to handling machinery.Any project should start and close out with safety measures in tact.It is never meant that failure will happen but it is the only retrograde steps in construction industries.The detailed project report pay only lip service to safety.The second most important aspect is use of heavy machinery.The competency of operators and fitness of machinery are never taken care of.

Inadequate curing period of concrete structures,Lack of supervision on reinforcement 

fitment causes the structures collapses during construction.