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I have a question related to creep of construction steel under compression loading and exposed to the elevated temperatures. 

I would like to know more about the final part of the creep process until the failure. And I would like to know how it looks the final stage and form of the failure.

I would appreciate any answer and eventual instructions for the relevant literature.

I apologize that I do not have any reference material to direct you to.  However here are some factors that affect construction steels under creep conditions.  I do not have any specific expertise in the steel construction codes which will vary with the local laws and jurisdictions in any case.

If a fire happens then the factors that will be affected in a structure are the compression strength, tensile strength, and shear strength of the members and of the connections. If bolted connections are present then preloads will be reduced or lost after sufficient time at temperature, which will affect the flexibility and stability of a structure even after the fire conditions are removed.

There is often redundancy in the way that loads are handled, in other words if one area begins deforming, load will be taken up by other connected members.

Modern steel construction will often have requirements for fire/thermal insulation of steel members.  This insulation will be designed to slow the uptake of heat from a fire into the steel.  I have a recollection of construction codes being written so that the reduction of yield strength with temperature will not become a factor until the temperature is approaching the lower critical temperature of steel (724 C, 1335 F). That is in the range where short-term creep rates can begin to be significant, but as codes usually are designed around some fraction of the room temperature yield strength, the creep rate is still not that high and the time that a structure is at elevated temperature within a fire is usually not long.

A simple compression loading under creep conditions, if uniaxial, results in a shortening of a component along the axis of compression.  Internal creep damage such as intergranular void formation under short term creep, requires a fairly high amount of deformation, and would not appear until at least several percent of dimensional change has happened.  This is a lot of deformation.  One would define a "failure" by some aspect of this, either an amount of length change, or for a longer component in compression by an unstable (Euler) buckling / geometric distortion. A structure made of components will rarely be under simple uniaxial compression, there will often be a twist or shear applied to most of the components. And some components will be tension members.  Since a structure failure would occur when a certain amount of long members have distorted or buckled leading to instability of the structure, there will not be a detectable amount of creep damage other than at high stress areas which will include the buckling points of longer members and the connection details where members attach.  At connections either the welded areas or mechanical connections will be under the highest stress.  In addition the heat from a fire will not be uniformly distributed around a structure so some areas will be in a creep regime while the rest are not.

In tension the microstructural effects of creep include grain deformation, void formation, voids connecting into cracks, and reduction of cross section by necking down.  But in loading that is primarily compression you would not expect cracking except after extensive material flow.  Since there will be areas near connection points that are under both tension and shear, creep cracking (under high strain rates and relatively high temperature you will be in the "stress rupture" regime of creep) will be detectable near connection points that are hot. But again the geometric instability of a structure is what will allow failure or collapse, not strictly the amount of creep strain at any one point.  So while compression loads under creep conditions do result in deformation, the collapse of an engineered frame structure is going to be the result of distortion of the frame and failures of the connections, and creep resulting from compression loads are only a minor factor in the failure of a structure. 

In areas where the steel was exposed directly to flame, there will also be oxidation of the surface and into any cracks which form.  Under very high heat flux there may be surface checking from high expansion rates that then crack when cooled.

This was a bit of a "brain-storm" ramble but I hope it provides some value.

I have a question related to creep of construction steel under compression loading and exposed to the elevated temperatures. 

I would like to know more about the final part of the creep process until the failure. And I would like to know how it looks the final stage and form of the failure.

I would appreciate any answer and eventual instructions for the relevant literature.