Identification of Cracks

1. What is mode of failure or damage of beams in the figure above? Would you characterize the case as damage or as a failure? Are the damages repairable? Elaborate.

ANSWER

Beam and Column frames connection failures.

• This cracks are forming when a structure occurring undesirable seismic activity.
• The beam and column connection are poor in withstand the undesirable load acting upon the structure.
• The portal frames of beam and column joint not to designed properly by seismic load capacity.
• Therefore, formation of plastic hinges at undesirable location.
• These elements are subjected to very high shear force during seismic activity.
• If these cracks are left unattended will lead to loss of strength and collapse.
• Formation of plastic hinges must occur at the end of the beam not at the column and beam conections.
• May it is also caused due to inappropriate detailing under structural elements.

2. a)Shear Failure of column

• It follows the mechanism of week column structure under the design of seismic load action.
• The vertical or compression load acting directly through the entire column, on that process the column would designed under week condition this much of steel has buckled .
• Therefore, the structure will occur at failure during excess of load acting.
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b) Confinement failure at the column

• Formation of plastic hinges at undesired location.
• The structure required accommodate to structure while happening the inelastic deformation during seismic load acting.
• For this failure occurring due to inappropriate detailing on column.
• Under ductility response to earthquakes high compressive strain should be accepted from combined effect of axial force in bending moment.
• Therefore improper detailing difficult to transverse the load during the action, may occur the failure of column like buckling.
• Well detailed reinforcement, should avoid the failure of structure.
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c) Short column Effect

• It is caused due to influence of partial height infill increasing column shear force( short column effect).
• Short column possess high stiffness that attracts most of the forces acting on the multi-story building. Inadequate design of these forces will results in damage and shear failure.
• Since the effective height over which a short column can freely bend in small.
• May it offers more resistance to horizontal motion and thereby attracts a large force as compared to the regular column. As a results, short column sustains more damage.
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