The effect of mesh size and ACI different cracking coefficients on the responses of structures (case study: a ۲۰-story building with dual system)

In reinforced concrete structures, elements resistant to lateral forces are the moment frame, structuralwalls, or a combination of both (dual system). Nowadays, the use of a dual system in intermediate and tallerstructures is more economical and often necessary. The effective stiffness effects in dual systems (RCframe + RC structural wall) and the amount of shear absorption of each system separately are significant.The ACI Code provides stiffness reduction factors for shear walls in cracked and uncracked conditions. Italso permits the use of a reduction factor of ۰.۵ when used for other linear elements for walls in crackedand uncracked conditions. Structural control to maintain stability and achieve minimum stiffness levels isaccompanied by prescribed relationships and control of relative displacements. Applying different proposedcracking coefficients in accordance with the code to members, especially in asymmetric or irregular dualsystems, may yield contradictory and debatable responses.Furthermore, structural analysis today is often conducted using finite element methods. One of themost important aspects in finite element method is the selection of dimensional ratio and size (number) ofthe elements. Therefore, proper modeling of finite elements (mesh size) and determining the amount ofmember cracking in responses are influential.In this paper, a ۲۰-story structure with a dual system consisting of a combination of reinforcedconcrete moment frame along with reinforced concrete structural walls in the core and around the framehas been modeled and designed using ETABS ۲۰۲۰ software according to ACI-۳۱۸ criteria through linearanalysis. The effects of mesh size in walls and coupling beams in ۹ scenarios, as well as the differentproposed cracking coefficients of the code for beams, columns, and walls in structural responses, have beeninvestigated.

کلیدواژه ها:

Reinforced concrete structures ، dual system ، coupling beams ، finite elements ، meshsize ، cracking coefficients ، drift ، shear absorption.