# Predicting Behavior of Grounded Dowel Connections Using Interfacial Cohesive Elements
## 1 Introduction and Background  
Grouted reinforcing bar connections, or simply grouted connections are ties having a wide variety of applications in the precast construction industry. When used in the context of precast load bearing walls, these connections are attractive owing to eliminating field welding and providing a straight force path extending along the height of a precast wall. The connection comprises a single large-diameter reinforcing bar grouted inside a corrugated metallic sleeve using a non-shrink high-strength cementitious grout with a flowing consistency. A schematic diagram of grouted connections is shown in Figure 1. Under current guidelines of the American Concrete Institute ACI 318-14 [1], grouted connections are treated as a bar in concrete and designed after the development length in tension clauses disregarding the composite action of the sleeve. The corrugated duct, which in the presence of a concrete matrix facilitates longitudinal stress transfer, exerts a uniform compressive field unto the grout, restraining it from splitting failures. Previous experimental observations [2; 3; 4; 5; 6; 7; 8; 9] highlighted this composite nature and indicated clear deviation from the assumed code treatment. Although several recently published studies provided experimental evidence for this disparity, limited information was found in the open literature addressing the numerical modeling of grouted connections, particularly on how models can be implemented into finite element simulations. Most of the proposed models were presented in relation to their respective author's experimental work without extension to other available experimental data and lacked dedicated analytical treatments to address grouted connections specifically. For instance, [PERSON] et al. [10] modeled the connections using a simple one-dimensional model, where the mechanical bearing of the bar was simulated using a series of bond springs. The model emulated the experimental results with reasonable accuracy; however, it did not physically consider the effect of the sleeve, nor did it take into consideration the interaction between the connection and the surrounding concrete. A similar approach was recently conducted by [PERSON] et al. [11], where the bond between the stainless steel and grout bound by corrugated ducts was modeled using experimentally derived phenomenological models, the results of which were implemented into a series of bond springs, and the outputs were corroborated with experimental results. [PERSON] and [PERSON] [12] and [PERSON] et al. [13] modeled precast column-footing connections using force-based fiber beam-column elements to assess their seismic post-yield behavior. In the former study, the steel bar was discretized, and bond springs were used to model slippage of the bars, whereas, in the latter, connections were modeled by modifying the steel constitutive model of the bars. No details were provided on the implementation of such models. The common factor among both studies is the scale of the model, which was more geared to mimicking the global response of the subject assemblies, while the local behavior of the connections was not the focus. Most recently, [PERSON] and [PERSON] [14] presented a three-dimensional (3D) finite element (FE) model of grouted in-line splice connectors. The complex geometry of the bars and the sleeve ribs were not modeled, and the bond-slip behavior of the bars was disregarded based on insignificant slip values observed during experimental testing. In other words, they assumed perfect bond between the bar and surrounding grout, which is not the case in grouted corrugated duct connections. Additionally, [PERSON] et al. [15] used an inverse analysis technique to derive a multi-linear bond-slip law based on FE simulations of pull-out tests. While these models compared well with their respective experimental results, several problems restrict their implementation.