Identification of Cracks

Ans.1.

a.

The mode of failure here is flexural failure which happened due to the reversal of stress during the earthquake because during the stress reversal we know that at the support top there is the tension present but during the earthquake at the support top point the structure experienced compression due to the earthquake and the bottom is still experiencing the tension due to that the stress reversal occurred.

As we observed that the top compression is managed by the slab because of the T action of the beam managed the top compression but the bottom tension was not satisfied by the type of reinforcement provided due to which the failure occured

No, the damage cannot be repaired as the reinforcement has yeilded.

b.

Here the mode of Failure is the beam pull out failure which happened due to the insufficient development length of reinforcement in joints. As we know that development length is very much essential and proper development length should be provided between the beams and columns so as to resist the loads acting due to the earthquake.

But here the insufficient development length leads to the deattachment of the beam member from the column which results in the structural failure and as we know that the horizontal movement of the structure during the earthquake make the condition more critical.

And after constructing The Beam and column if the required development length is not provided ,so the chances of repair are not possible because providing the encourage length between two existing concrete is very difficult

Hence, it cannot be repaired

c.

We observed here that the failure occurred is plastic Hinge failure which has occurred at the joints. Usually plastic Hinges failure occurred only at the joints first. Here the cyclic lateral loading and also the stress reversal at the joint are the main key loads that led to the damage.

Here also the slab has give its best to handle the tension because we can see that they are many cracks in the slab also and also observe that it has gone under tension with its flange conditions but still the damage cannot be controlled by the slab

Yes it can be repaired as it is not much critical because of the cracks happened.

ANS.2.

a.

Here the type of failure happened is soft storey failure which can also be called as plastic Hinge failure happened at the columns. As we observed that there are no infills wall to support the column at the ground floor so the plastic Hing will surely form at the top of the ground storey columns during lateral moment

Based on the servereity of the damage, it can be repairable or it can be non repairable it all depends on the development of Crush of concrete.

b.

The failure occurred here is pure shear failure in which the concrete has been completely breakdown diagonally. And also we can see that the longitudinal reinforcement are visible now due to The breakdown of concrete from the surface

Also the shear reinforcement spacing is looking more wider than the codal values so it is leading to lesser shear rebar has been provided.

It cannot be repaired as the value of shear rebars are less and also the mode of failure is severe.

c.

It is a type of short column failure because the type of that has been done is surely consisting of a slab or floor under the colum and in this type of mode of construction the inner floor of slab will experience a heavy shear force.

An additional slab or a beam connected to a column in mid height will lead to the effect of shear column failure because of the heavy experience by the column or be made the mid height.

This type of failure mostly occurs due to the unaccounted design or if the connection is unintentional

No, it cannot be repaired because it has been heavily damaged.