# Damage Analysis of Reinforced Concrete Columns Based on Fiber Beam-Column Element
## 1 Introduction  
Investigation of seismic damage and experimental studies found [1; 2; 3] that the failure of reinforced concrete columns is often the main reason for the collapse of building structures. Damage analysis of reinforced concrete columns under earthquakes can provide an important basis for revealing the collapse mechanism of building structures. Currently, solid element models combined with the corresponding concrete material damage models [4; 5; 6; 7; 8] are usually used to analyze the damage of reinforced concrete members. However, due to the introduction of a large number of degrees of freedom, the computational cost is high, which makes the solid element model unsuitable for daily engineering applications. The fiber beam-column element model [9; 10; 11; 12; 13; 14; 15] can not only simulate the mechanical properties of components macroscopically, but also provide deep insights into the local nonlinear characteristics of components; it also has high computational efficiency. Therefore, it has become the most active and widely used analysis model in the field of refined simulation of the nonlinear behavior of reinforced concrete structures. However, if the fiber element model is used to analyze the damage of reinforced concrete members, it is particularly important to combine it with the damage model of concrete and steel materials.  
[PERSON] [16] proposed a damage model of reinforced concrete members based on material damage using the fiber element model. This model takes the damage index of the critical fiber of the compressive concrete in the core area and the critical fiber of the steel bar as the damage index of the section, ignoring the tensile damage of the concrete fiber. [PERSON] and [PERSON] [17] combined a 3D plastic-damage concrete model with a fiber element to analyze the damage of reinforced concrete beams and columns, but did not consider the damage of steel materials. [PERSON] et al. [18] and [PERSON] et al. [19] used the fiber element model combined with the Faria-Oliver uniaxial damage model [20] to analyze the damage of reinforced concrete members, but the damage of steel material was not considered in their analysis. [PERSON] et al. [21] developed a fiber hinge formulation wherein the corrosion-induced mechanical degradation of concrete and steel was implemented. The yield load and theultimate load of the corroded bars are calculated using the average mass loss. [PERSON] et al. [22] considered the damage and fracture of steel materials and analyzed the failure process of reinforced concrete columns under cyclic loading, but did not pay attention to the local damage of concrete, and the constitutive model of steel materials was not suitable for the simulation of members under earthquakes.  
In order to analyze the seismic damage of reinforced concrete columns with a method that takes into account both the accuracy and efficiency of the calculation, based on the previously developed Refined Simulation and Analysis Platform for Structures (RSAPS) (formerly FENAP [10]), this paper combines the previously established damage constitutive model of concrete and steel bar materials [23] with the fiber element to establish the analysis method of damage simulation of reinforced concrete members. Using this method, the overall damage distribution and damage development process of the column can be visually presented. The possible damage degree and location of the column can be quickly predicted. The RSAPS platform was used to simulate the cyclic loading test and the shaking table test of reinforced concrete columns was used to verify the effectiveness of the established simulation method. Then, the seismic damage process of the reinforced concrete column was simulated and analyzed.