# Hysteretic Behavior of Steel Reinforced Concrete Columns Based on Damage Analysis
## 7 Conclusions and Future Work  
In this paper, eight SRC frame column specimens were tested under combined axial compression and lateral cyclic load. Base on the test results, a hysteresis model was developed to simulate the hysteresis behavior of the SRC frame columns, and conclusions were obtained as follows:  
1. The failure process of the SRC column specimen experiences three stages under the cycle load, namely, the elastic stage, the inelastic with cracks stage, and the failure stage. In the elastic stage, the hysteresis behavior of the SRC frame columns is similar to the reinforced concrete frame columns. In the inelastic stage, due to the mutual constraint between steel and concrete, the bearing capacity of steel and concrete is improved. With the increase of the displacement amplitude and the number of cycles, the hysteresis loops become a plump fusiform. Especially, after the peak load, the specimens show a good anti-seismic performance. 2. With the increase of the axial compression ratio and steel ratio, the seismic performance of the frame column is enhanced. The stirrups ratio has the little effect on the seismic performance of the frame column before the peak load. However, after the peak load, the energy dissipation capacity and the ductility of the members is enhanced with the increase of the stirrups ratios. 3. Based on the comparison of the test results of the monotonic loading and cycle repeat loading, a trilinear skeleton curve model of the SRC columns can be established by simplifying the load-displacement curve under monotonic loading. According to the equilibrium of the internal force, a set of calculation equations for determining the simplified skeleton curves of the SRC columns are proposed. 4. The hysteresis loop is simplified by combining with the experimental results. Based on the seismic damage index of the SRC frame columns, the cyclic degradation index is established, which can reflect the performance degradation of the members very well. Finally, the multi-line hysteresis model of the SRC frame column is established by establishing the rule of strength and stiffness degradation of the members and the hysteresis rule. It was shown that the computed hysteresis curves are in good agreement with the experimental results, which verifies the validity of the hysteresis model. The proposed model is able to predict the cyclic response of SRC columns with sufficient accuracy. Future work will involve testing SRC specimens with embedded piezoceramic smart aggregates. During the tests, we will obtain both the sensor-based damage index and the hysteresis-based damage index and study the correlation between the two indices. If the two indices correlate well, we can use the sensor-based damage index to provide the real-time data of structural health monitoring for in-service structures with integrated sensors. Meanwhile, the proposed method in this paper has a low computational efficiency, which is not convenient for real seismic analysis of structures. Therefore, based on the cumulation damage of the material and the results proposed in this paper, we will conduct finite element analysis (FEA) of the SRC structure members in future investigations. Additionally, the stress state of concrete confined by stirrups and steel is more complicated for SRC  
Figure 14: Comparison of testing and calculating hysteretic curves. (**a**) Specimen SRC-4; (**b**) Specimen SRC-5; (**c**) Specimen SRC-6; (**d**) Specimen SRC-11. members. Therefore, to achieve the refined finite element simulation of the SRC structures, based on the cyclic constitutive model for concrete confined by transverse reinforcements [60; 61], the cyclic constitutive model of confined concrete established by considering the effect of cumulation damage will be studied in future research. [PERSON], [PERSON], and [PERSON] designed and performed the experiments; [PERSON] and [PERSON] analyzed the data; [PERSON] and [PERSON] wrote the paper.