# Numerical Modeling Technique of Damage Behavior of
## 4 Numerical Verification  
Two full-scale one-story one-bay RC frame specimens with and without infill walls are utilized to demonstrate the effectiveness of the proposed modeling [58]. The geometry and design information for test specimens is displayed in Figure 8. In the test, the concrete hollow block of 390 \(\times\) 190 \(\times\) 190 mm\({}^{3}\) is used to construct the infill wall. The thickness of the bed and head joints is 10 mm. A vertical compressive load of 700 kN is firstly applied on the top of two columns and is kept constant during the test. Following this, a series of lateral reversed cyclic loads are applied on the two ends of the beam. Finite element modeling for two specimens are created in FEAP by inputting a series of parameters, such as dimensions, numbers of the reinforcement and material properties, into the programed modeling routine. The thickness of the infill panel is chosen to be two face shells of 56 mm thickness. The base of the model is fixed in all directions. The material parameters for the compressive behavior of the concrete members and masonry blocks are  
Figure 8: Geometry and design information of lightweight masonry-infilled frames (unit. mm). summarized in Table 1. The input parameters of the discrete cracks' constitutive relations used for concrete cracks, masonry cracks and mortar joints are listed in Table 2.  
To properly model the behavior of masonry-infilled RC frames, there is need of a systematic calibration process to define various parameters for the proposed finite element modeling. The compressive parameters of concrete material are determined with the data from compression cylinder tests. The tensile strength, ft, can be obtained from the tensile tests, or estimated from the compressive strength according to the suggestion of design codes. For the cohesion-softening behavior, the mode-I fracture energy \(G_{f}^{I}\) can be obtained from mode-I fracture tests, and the mode-II fracture energy \(G_{f}^{II}\) is assumed to be ten times \(G_{f}^{I}\). The material parameters controlling the evolution of the shape of the failure surface, as well as the dilatation parameters, are determined according to the recommendations in [38; 56]. The parameters of the interface elements for mortar joints in the infill wall are usually calibrated through a series of shear tests of mortar joints under different constant compressive stresses. The state parameters of the initial yielding and final failure surfaces can be determined by nonlinear fitting analyses using several groups of compressive stress and shear stress values. The mode-II fracture energy is obtained by continuously adjusting its value until the numerical shear stress displacement curves coincide with the experimental curves, and the mode-I fracture energy is then evaluated. Moreover, the dilatation parameters are calibrated by adjusting the analytical normal displacement-shear displacement curves to match the experimental results. In addition, the material properties of head joints and the frame-to-wall joints are assumed to be weaker than that of the bed joints due to the partial filling and the general poorer condition of these mortar joints. The compressive parameters of masonry unit elements are calibrated with masonry prism tests to reflect the composite properties of a masonry assembly. The parameters for tensile and shear behaviors of the masonry units are calibrated in the same way as those for the concrete material. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & **Specimen** & \(\mathbf{E}\)**, GPa** & \(\mathbf{f_{c}}\)**, MPa** & \(\mathbf{\varepsilon_{1p}}\) & \(\mathbf{\varepsilon_{2p}}\) \\ \hline \multirow{2}{*}{Concrete members} & Bare frame & \multirow{2}{*}{20.5} & \multirow{2}{*}{27.53} & \multirow{2}{*}{0.0019} & \multirow{2}{*}{0.005} \\  & Infilled frame & & & & & \\ \hline Masonry blocks & Infilled frame & & & & & \\ \hline \end{tabular}
\end{table} 
Table 1: Parameters for compressive behavior of lightweight masonry-infilled frames.