A property modifier is a change factor commonly employed in cross-sectional properties like an inertia moment, twist, and so on, assisting in reducing rigidity in concrete layers to represent cracked concrete behavior. The property modification is only used on concrete buildings as it breaks under loading.
Structures on top of other structural components are frequently studied utilizing forces that rely on the member’s stiffness. The stiffness amongst the members, or its ability to withstand distortion caused by applying the load, is defined as stiffness. These structural loads produce internal forces, leading to stress and compression within the cement fibers caused by portion cracking.
The importance of the property modifier
The term “electronic commerce” refers to the online sale of goods and services. As a result, the structural parts stiffen and attract seismic force. These stresses would then cause breaks in the tensional zone, lowering the member’s cross-section area and stiffness. As a result, the inertia moment would decrease more than the net inertial moment.
As a result, we must use a property modifier to minimize stiffness while describing structural components as fractured sections. Once cracked, property modifiers can be used to calculate the capacity necessary among the members.
Why do you need the property modifiers?
Cracking will reduce the rigidity of the structure, affecting deflection and forces. Because of the breaking in the portion, there is a fluctuating inertial moment. There is a lower inertial moment in cracking regions and a substantially larger moment in non-cracking parts. Also, as the load grows, so does the cracking. Load affects the inertia moment. This moment of inertia that changes with load renders your deflection equations non-linear concerning loading, and you cannot utilize superposition to determine load combinations.
Property modifier code recommendations
Previously, when the IS in 1893 first Part – was in use, the concept of property modifiers were not considered in structural analysis. During the period, values were obtained from several international standards by project needs.
In the most recent codal edition of IS 1893 first part, the property modifier is supplied in the particular mentioned Clause.
The inertia moment shall be used for structural analysis.
- In the RC and concrete constructions, columns account for 70% of gross, while beams account for 35% of gross.
- For beams and columns in steel constructions, gross is considered 100%.
- The code’s suggested values rely on mathematical experiments derived from many international codes. Because the column experiences axial pressure more significantly than the available beam, its property modifier is more significant.
How do property modifiers work in ETABS?
- The property modifiers in ETABS are assigned using the steps that follow:
- Navigate to “Explain,” then “Section Property,” and “Frame Section.”
- Choose the member properties you want to change.
- On the property modifiers, click on “Alter or Show Modifier.”
- Enter the Inertia moment for the two and three axes as 0.35 for the pillar and 0.70 for the section, respectively.