the effect of the disproportionate effective moment of inertia caused by cracks on the seismic response of the concrete building

Concrete buildings during its service life suffer from cracks which occur due to several reasons like creeps, temperature, cyclic loading (fatigue), shrinkage, exposing to chemical material and others, these cracks affect the response of these building to the external loads and especially the seismic response, because the effective moment of inertia for the building’s elements decrease after cracking. codes like ubc97, aci318-14, and eurocode have provided formulas and structural details to estimate and control cracking procedure, and also give an estimate to the effective moment of the inertia for the cracked sections. to claim this factor, we can use values like mentioned in aci318-14, 0.7 ig for columns and 0.35 ig for beams, but we know that columns and beams in any building don’t resist the same bending moment and shear force, so it is more logical to have a special effective moment of inertia for each element, and to claim it we will use the formulas in table 2 from the aci318-14 code. the purpose of these study is to have an accurate response of the structure due to the seismic load and to prevent a failure which occur due to underestimate the whole response of buildings.