# A Review and Future Directions on the Deterioration Evaluation of Concrete Utility Poles
## 4 The Current Studies of Wood Utility Pole
### Deterioration Evaluation of Wood Utility Pole
[59] measured the frequency response function (FRF) from a vibration experiment based on a simulated utility pole. They developed an analytical model that can reproduce the results of this experiment. The experimental results show a change in frequency in the case of the damaged beam cable model, suggesting the possibility of confirming the presence or absence of damage if the model can be used on a full-scale utility pole. Unlike the guided waves described above, non-destructive measurement by vibration can be used to investigate the performance of the utility pole structure as a whole and, therefore, seems suitable for structural evaluation. Although it has been confirmed that the vibration characteristics change according to the degree of damage, the relationship between the two has not been fully established, and the data need to be accumulated for application to maintenance. A simulation model of utility poles is created using non-destructive evaluation methods to calculate failure probability [40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62; 63; 64; 65; 66; 67; 68; 69; 70; 71; 72; 73; 74; 75; 76; 77], following the flow shown in Figure 8. This approach evaluates replacement by calculating the probability of failure based on environmental conditions such as wind speed, service life, and dimensions. This method is widely applied to wooden utility poles. Wooden utility poles, rich in organic material, are prone to advanced corrosion. As a result, strength degradation occurs over time, and time-dependent strength degradation prediction models have been proposed [64]. In addition to these models, numerous simulations have been conducted to account for failure probability, considering factors such as wind loads from hurricanes and additional loads generated by the inclination of utility poles. Figure 7: Image of vibration response and power spectra obtained from utility poles. For example, [PERSON] et al. [70; 71] proposed a vulnerability assessment model for utility poles with parameters such as type of pole, length, years in service, number and diameter of wires, span of wires, wind speed, and wind direction. The model of a utility pole shown in Figure 9 is considered. The probability of failure is evaluated for each type of utility pole (class 1 to 7, according to US standards) using the number of years in service, length, wind speed, and other parameters, and a vulnerability assessment model is developed. The figures below summarize the relationship between wind speed and the probability of failure for wooden utility poles of classes 1 to 7, as shown in Figure 10.  
Figure 8: Image and method of evaluation methods by calculating the probability of failure. Figure 10: Comparison of wind speeds and probability of failure for different classes of poles: Height considered as a design variable (**a**), Height considered as an uncertain variable (**b**) [70]. [PERSON] et al. [72] propose two probabilistic methods for economical and efficient maintenance of wooden utility poles. The first method simulates the number of utility poles to be replaced in the future from two points of view: damage due to climate and replacement due to maintenance. The second method simulates the number of utility poles that are destroyed by a single strong typhoon. [PERSON] et al. [73,74] researched a method to calculate the probability of destruction of utility poles when subjected to typhoon wind loads. The method used the poles' service life and typhoon wind speed as variables in the simulation. [PERSON] et al. [41] are working on a framework to help reduce the cost of replacing wooden poles by combining a prediction model of age and hurricane-related damage to wooden poles with a life cycle cost analysis for a given area. Many such studies, including simulation of failure probability and cost estimation for repair, have been carried out and may be useful as an efficient cost-effectiveness assessment method for wooden poles.