## 1 Introduction
They also demonstrated the disadvantages of the element erosion method and proposed a node split algorithm with a preprocessor for the FEM in LS-DYNA to solve the shortcoming. Using the node split technique, the destruction of the Sparkasse building in Hagen was reconstructed reasonably. Nonetheless, the findings obtained from the numerical simulations still had limits, since the abrupt separation of element connections caused by fracturing resulted in unrealistic and spurious behavior (e.g., shattering of structural parts). On the other hand, the applied element method (AEM) [6], which is an effective numerical simulation method for the nonlinear analysis of framed and continuous structures, was recently developed as a feasible alternative to the conventional FEM for modeling the progressive failure process of the RC structure. In the AEM, the fracture process of a concrete structure is simulated using normal and shear springs between rigid elements, and the stress and strain in specific portion of the structure are also calculated using the two spring types. Numerous publications exist on modeling the demolition of RC buildings using the AEM. Especially, the AEM-based commercial software \"Extreme Loading for Structures (ELS)\" is commonly used to model the collapse of RC structures. Several researchers have simulated the demolition of small-scale RC structures to evaluate the capability of the AEM to analyze the progressive collapse of the RC structure. In [7], the AEM in ELS software was applied to model 1/5 scaled three and five stories of RC structures and compared the results to experimental results. The horizontal and vertical displacements obtained from these simulation results were similar to the experimental results. The AEM in the ELS software was also used to simulate the collapse of a prototype RC moment-resistingframe building induced by seismic loading [8]. The simulation results were compared to shake table test results and found to be in good agreement. The collapse mode was thoroughly investigated, and the findings were used to train a deep neural network (DNN) to predict the collapse mode of an RC structure. Several applications of the AEM for designing demolition sequences to actual large-scale RC structure collapse can also be found. Progressive collapse analysis of high-level and shear-wall apartment buildings subjected to blast loading was also simulated to demonstrate the capability of the AEM in ELS software [9]. The simulation results showed good agreement with observed demolition behavior. The mechanism of the progressive collapse of a structural component caused by local damage was addressed in [9] using several factors such as reinforcement, axial force and moment. The progressive structural collapse of the Perna Seca Hospital building in Brazil was also simulated to verify and optimize the demolition scenario using AEM in ELS software and a fully detailed model [10]. Ground vibration caused by debris impact during the demolition process was thoroughly investigated in order to minimize damage to adjacent buildings. Finally, they compared the AEM result to the actual observation, concluding that the AEM result closely matches the actual result in terms of the structure's collapse pattern. However, in comparison to the FEM, the AEM is less accurate in the small displacement range and requires a large amount of CPU time [6; 11]. Additionally, the AEM is limited in its ability to model Poisson's effect because it is based on the assumption of rigid elements in which the deformation is not allowed. In recent years, the combined finite-discrete element method (FDEM) [12] has gained popularity as a useful numerical method for evaluating civil and rock engineering issues involving fracturing and contact processes between fragments, i.e., discrete bodies. The FDEM is able to model continuum behavior, fracturing (i.e., crack initiation and propagation) and contact between material surfaces including newly generated fracture surface.