# Experimental and Parametric Analysis of Pull-Out Resistance of Notched T-Perfobond Connectors
## 7 Conclusions  
Based on the pull-out tests, numerical analyses, parametric studies, and analytical work on notched T-perfobond connectors, the following conclusions are drawn:  
1. The pull-out damage modes for notched T-perfobond connectors consist of perfobond rib fracture and concrete punching damage. As the pull-out force increases, the interaction between the perforating rebar and the notched T-perfobond rib diminishes, making the connectors more susceptible to concrete damage in a wedge-shaped inverted pyramid pattern. In contrast, for un-notched T-perfobond connectors, the strong interaction between the perforating rebar and the perfobond rib, along with the anchorage effect of the concrete, leads to the fracture of the perfobond connectors. Notably, these damage modes do not exhibit the extensive fine cracks on the concrete surface that are typical of conventional concrete.
2. The proposed finite-element method is verified by comparison with the pull-out test results, demonstrating a favorable similarity to the observed pull-out damage. The analytical pull-out resistance values are 106.0% and 84.5% of the average test results for notched and un-notched T-perfobond connectors, respectively. This suggests that the finite-element model can generate rational parametric results for the pull-out performance of these connectors.
3. A total of 54 parameter simulations indicate that pull-out performance is mainly affected by flange size, connector thickness, and perfobond rib strength. Rebar diameter and strength have little effect. Concrete strength has a notable impact up to a point. Specifically, the flange thickness increases resistance from 2 to 8 mm, then plateaus. The flange width increases resistance significantly from 6 to 12 mm, then declines. The notch width has a minor influence and stabilizes beyond 16 mm. The hole height leads to a slight increase at 15 mm, then a decline. The hole length leads to an increase up to 50 mm, then a significant decrease. The perfobond rib thickness results in a dramatic increase, then plateaus. The perfobond rib length results in a linear increase up to 90 mm. The concrete strength leads to a significant increase and plateaus beyond 110 MPa. The perfobond rib strength leads to a significant linear increase. Design should balance these parameters for the desired resistance.
4. An analytical model is proposed to estimate the pull-out resistance of notched T-perfobond connectors. This model's formula for calculating pull-out resistance correlates well with test and numerical simulation results, demonstrating its utility for evaluating the pull-out resistance of these connectors.  
[PERSON] conducted the finite-element simulation and wrote the article. [PERSON] applied for project funding and made overall plans. [PERSON] completed model experiments. [PERSON] participated in formulating the experimental plan. [PERSON] and [PERSON] participated in experiments and simulations. [PERSON] participated in formulating project planning schemes. All authors have read and agreed to the published version of the manuscript.  
The research described in this paper was financially supported by Grants from the Natural Science Foundation of China (51808235), the Fujian Provincial Natural Science Foundation of China (2018)05083), the Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University (ZQN-813), the Huaqiao University Scientific Research Funding (16 BS804), and the College Students' Innovation and Entrepreneurship Training Program Project (S202310385013).  
Not applicable.  
Data Availability Statement: Data is contained within the article.  
The authors declare no conflicts of interest.