STIFFNESS MODIFIERS
According to IS 16700-2017- Clause no. 7.2 table no.6, UBC-97 Clause 1910.11.1 and ACI 318-19 Clause no. 6.6.3.1.1 table no.6.6.3.1.1 (a) and (b). The Stiffness Modifier values are given.
1. WHY STIFFNESS MODIFIER IS NEEDED FOR CONCRETE FRAME SYSTEM?
Concrete has an inherent property of losing itself stiffness concerning time. The age of the concrete is increasing the micro crack is developed inside the concrete by taking care of this cracked structural engineers generally applying stiffness modification factor an try to capture moment redistribution of concrete frame system and design according to it.
2. HOW MUCH STIFFNESS WILL REDUCE?
The gross moment of inertia is depending on the different structural members. The code is a suggested value for an individual structural member. You can refer to codes like IS 16700-2017, UBC-97, ACI318-19 for more clarification.
3. DOES EARTHQUAKE EVENT REDUCES STIFFNESS?
Earthquake event is dynamic in nature within a fraction of a second force is generated and the shaking of the building started. earthquake-affected stiffness directly.
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