Identification of Cracks

1a)

This type of failure is called as flexural failure. Flexural strength, also known as modulus of rupture, bend strength, or fracture strength, is a material property, defined as the stress in a material just before it yields in a flexure test.

In this picture you can see that the concrete is ruptured and steel can been seen.Concrete spalled beyound the reinforcement which may be sign if repture.There is no cracks or damages are found at the top of the beam because of the flang advantage from slab. The crack is developed from the bottom to top means the rebar yielding occurs from the bottom.

This type of failure is formed due to reversal of stress due to earthquake.Due to stress reversal support top experience compression and the bottom experience tension.Top compression is managed by slab but the bottom tension was not satisfied by the provided reniforcement.So the failure is oocured.

1b.

The beam column joint is the crucial zone in a reinforced concrete moment resisting frame. It is subjected to large forces during severe ground shaking and its behaviour has a significant influence on the response of the structure. The assumption of joint being rigid fails to consider the effects of high shear forces developed within the joint.The shear failure is always brittle in nature which is not an acceptable structural performance especially in seismic conditions.

It is beam pull out failure due to insufficient development length of reinforcement in joints.During earthequake, the horizontal movement of structure makes this condition worse and detached the beam member from column. Providing anchorage length between two existing concrete is very difficult.

1c. Cracks are formed excatly at the joints of column and beam. This failure is called as plastic hinge failure.The damage occurres only in the joint zone first of all. Cycling lateral loading and stress reversal at the joints led to damage. Even the slab participated to its best to handle the tension(slab is severly cracked means it has undergone tension with its flange condition).But unable to control the damage.The joints can be strengthened.

2a. Concrete is damaged all over the face of the column.It is the soft story failure, due to the absence of infill wall at the ground floor, the plastic hinge forms at the top of the ground story columns during lateral movements.Based on the development of crush of concrete it can either be repairable or non repairable.

2b. The beam column joint is the crucial zone in a reinforced concrete moment resisting frame. It is subjected to large forces during severe ground shaking and its behaviour has a significant influence on the response of the structure. The assumption of joint being rigid fails to consider the effects of high shear forces developed within the joint.The shear failure is always brittle in nature which is not an acceptable structural performance especially in seismic conditions.

In the column longitudinal reinforcement are intact. It is a shear failure which is caused due to the wider spacing in the reinforcments. Inadequate shear reinforcements compels concrete takes all the shear stress.

2c.In certain building either due to the ground conditions or due to the requirement of intermediate beam there requires the construction of short columns which leads to this failure.

The short columns are stiffer compared to long columns and hence most of the earthquake forces acting on the building are taken by the short columns . More the stiffness of any structural element, less will be its flexibility to undergo any sort of deformation. Earthquake design of a building is more efficient through the flexible design of the structure.