# A Review and Future Directions on the Deterioration Evaluation of Concrete Utility Poles
## 3 The Current Status and Issues of Concrete Utility Pole
### Dynamic Characteristics and Load-Bearing Behavior  
This section discusses previous studies on dynamic and load-bearing performance of concrete utility poles [21; 22; 23; 24; 25; 26; 27; 28; 29]. Research on the dynamic performance of utility poles has mainly focused on seismic resistance and load-bearing capacity. Regarding seismic resistance, [PERSON] et al. [21] conducted a cyclic loading test on a 3.5 m concrete pole imaged Japanese prestressed concrete poles, which had been reinforced with steel after being damaged by seismic loads. The study confirmed improvements in seismic performance, such as increased bending strength due to steel reinforcement. [PERSON] et al. [22] developed an analytical model for evaluating the seismic performance of concrete utility poles. For load-bearing capacity, [PERSON] et al. [23] conducted monotonic loading tests on intentionally damaged concrete utility poles to investigate the relationship between the degree of cracking or delamination and strength. They proposed a diagnostic method for deterioration based on damage levels. [PERSON] et al. [24] examined the collapse mechanism and the impact of soil conditions on utility poles installed in soft ground in rural India through load-bearing tests and analyses simulating actual operational conditions. [PERSON] et al. [25] used full-scale H-shaped concrete poles in a push-over test. They conducted a 3D finite element analysis based on a seven-span model of utility poles to evaluate their dynamic performance. Their studies demonstrated that unexpected loads, such as gusts during adverse weather, could cause pole failures even when designed according to wind and snow load standards. They also identified weak points in utility poles and proposed measures to enhance their sustainability. [PERSON] et al. [26] analyzed seismic response using a spring-mass model of Japanese prestressed concrete poles under different transformer installation conditions. They found that earthquakes with acceleration around 200 gal did not lead to the collapse of prestressed concrete poles or the fall of transformers. [PERSON] et al. [28] conducted visual inspections and strength tests on RC utility poles in Lithuania that had been in service for approximately 30 years. While small cracks and rebar corrosion were observed, the poles met design requirements, though their resistance to torsion had decreased. Additionally, centrifugally cast RC poles showed superior durability. [PERSON] et al. [29] performed tests on full-scale prestressed concrete poles to confirm their strength, applying pure bending or combined bending and torsion loads using wires at the top. Their results confirmed that failure occurred due to concrete compression, demonstrating the effectiveness of this method for assessing concrete failure states and required performance.  
While studies on the dynamic and load-bearing performance have primarily focused on confirming seismic resistance and the effectiveness of repair and reinforcement methods, such cases are limited [21; 22; 23; 24; 25; 26; 27]. Various tests have been conducted to evaluate the dynamic performance of utility poles [28; 29], but differences in shape and the presence or absence of prestress between countries were identified. Therefore, it is necessary to perform full-scale testing on the specific concrete utility poles under consideration. Furthermore, understanding the dynamic properties of utility poles under sustained loads, such as wind loads applied over long periods, is crucial to improving maintenance and management efficiency. However, such topics have not been addressed in previous studies. Conducting load tests on full-scale utility poles to gather further data is imperative.