الفهرس 
2.3 Modeling of RC framesOnly 14 pages are availabe for public view
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Abstract
Multistory RC frames and shear walls (SW) buildings with masonry infill walls (MIW) are a common construction practice according to the architectural needs in many regions of the world. The contribution of MIWs at these buildings have been investigated in-depth for more than four decades using a number of theoretical models and predictive techniques (Di Trapani et al. 2018). Many researchers proved that MIW make a major role in stiffness, and behavior of the structures (Liberatore et al. 2018, Noh et al. 2017, Asteris et al. 2011, Mehrabi et al. 1996). This role is usually based on the distribution of MIW in plane and their continuity in elevation (Cavaleri and Di Trapani 2014). In the other side, the Egyptian seismic design code, as many other national codes, neglects the contribution of MIWs in the design of RC buildings (frame and SW structural system). Nonlinear analysis of multistory RC frames and SW buildings is a challenge task because of the large number of elements, masonry behavior, and the nonlinearity. Modeling of these buildings requires reliable nonlinear models for their three main elements: 1) RC frames, 2) MIW and 3) SW.
1.1.1 RC frames
Investigating the nonlinear behavior of RC frames was the target of many experimental and numerical studies. For the experimental studies, Mehrabi et al. 1996, Dautaj and Kabashi 2018 tested one-story RC frames under pushover load. Duong et al. 2007 and Vecchio and Emara (1992) tested two-story RC under pushover load. Sharma et al. 2013 and Sharma et al. 2011 presented innovative experimental study for four-story building in three dimensional (3D) under pushover test. Other studies for investigating the nonlinear behavior of RC frames under earthquake loading (such time history as Negro et al. 1996 and Carvalho et al. 1999). For simulating RC frames, the concentrated plasticity was used in many studies to provide simple modeling with low computation cost. Alternatively, the distributed plasticity was used in others. Also, full finite element modeling with material and geometric nonlinear alternatives was introduced by Cavaleri et al. 2020; Mehrabi and Shing 1997; Shing and Mehrabi 2002; Koutromanos et al. 2011; Mohyeddin et al. 2013. The concentrated plasticity is the location of inelastic deformation is in RC elements which occur over a finite length (lp) for plastic hinge (PH). In this work, the focus is using the concentrated plasticity in modeling RC frame.
The nonlinear analysis of RC frames could be simulated using concentrated (lumped) plasticity, distributed plasticity, or full finite element modeling depending on the desired accuracy and computation cost. The concentrated plasticity is modeled using lumped plastic hinges (PH) located usually at the ends of each frame element. The nonlinear behavior of flexural PH plays a dominate role in determining the RC building response (Sunil and Kamatchi 2022, Inel and Ozmen 2006). The modeling of flexural PH depends on the ultimate curvature of element section and plastic hinge length (lp). Several formulas for estimating lp will be introduced in Table 2-1 and Chapter 3. The PH length may be affected by the shear stress and transverse reinforcements of the section (Elmenshawi et al. 2012). In this work, the focus is using the concentrated plasticity in modeling RC frame. It was worth mentioning that all these lp formulas is developed based on a one element not a complete frame. The previous studies revealed the important of introducing shear PH (Watanabe and Lee 1998), torsional PH (Park and Paulay 1975), and beam–column joint PH (Sharma et al. 2011, Pan et al. 2017 or Yu 2006.). For considering different types of deformation in special frames. A global view demonstrate that majority of previous studies simulated 2D one-story frames using lumped flexural PH.
1.1.2 Masonry infill walls (MIW)
Modeling MIW in RC frames was investigated by many experimental and numerical studies. The majority of experimented studies investigated the structural behavior of the MIW in one-story frames under pushover, cyclic or earthquake load such as Saneinejad and Hobbs 1995, Dautaj et al. 2019, Dautaj and Kabashi 2019, Dautaj et al. 2018, Mehrabi et al. 1996 and Angel et al. 1994. Experimental studies have demonstrated that MIW could develop a significant resistance against the lateral force. The modeling of MIW during earthquakes is very complex. Micromodels and macromodels have been widely used for this propose. The micromodel based on MIW discretization by finite element is a good tool to provide a more accurate results (Cavaleri et al. 2020; Mehrabi and Shing 1997; Shing and Mehrabi 2002; Koutromanos et al. 2011; Mohyeddin et al. 2013). However, micromodels is rarely used because a great computational cost is required. Conversely, macromodel needs a low computational cost with acceptable accurate results. The focus of this work is modeling MIW using macromodel. The macromodel simulates MIW using one or more equivalent diagonal struts to study the global response of infilled RC buildings. Crisafulli et al. 2000, Asteris et al. 2011, chrysostomou and Asteris 2012 and Asteris et al. 2013 are a good reference for extensive comparison between different strut numbers. Many studies were made using a one equivalent diagonal strut to develop a reliable estimation of the inelastic response under monotonic loads (Saneinejad and Hobbs 1995) and cyclic loads (Van et al. 2022; Shen et al. 2017; Mosalam and Günay 2015; Cavaleri and Di Trapani 2014; Cavaleri et al. 2005; Madan et al. 1997; Panagiotakos and Fardis 1996; Doudoumis and Mitsopoulou 1986). Only one experimental study provided investigating for MIW in four-story building were presented by Carvalho et al. 1999. For numerical modeling of MIW, the most of studies were introduced as compared between a lot of alternatives to modeling MIW in RC frame. Therefore, the location of MIW in these studies do not reflect the actual deformation for real buildings. The focus of this work is modeling MIW using macromodel with its real location based on architectural needs.