## 1 Introduction  
With more than 6.8 billion pallets in circulation around the world [1] and over 80% of the current shipping volume utilizing some form of corrugated fiberboard packaging [2], it is critical to optimize pallet and packaging design. Previous research has shown that the performance of corrugated boxes is affected by the characteristics of the pallet that supports them, including factors such as deck board stiffness, gaps between the boards, unsupported box corners, among others [3; 4; 5; 6]. Additionally, pallet performance is affected by the type of storage and material handling equipment used. An extensive body of knowledge has been developed to understand pallet performance for the most common supply chain environments, for different pallet materials, and for other design characteristics [7; 8; 9; 10]. Research studies have been conducted to evaluate the pallet performance when unit loads are supported on conditions such as warehouse racing across the length, across the width, supported on forklift times, or stacked on the floor [11; 12; 13]. Research has also been conducted to understand how the characteristics of the payload affects the performance of pallets. This research has commonly shown that when a pallet carries a more rigid payload, the pallet's deformation decreases. This behavior is known as the load bridging effect and entails the redistribution of the compressive forces towards the rigid supports and away from the critical pallet components that might be more susceptive to failure [14; 15]. To characterize this effect, studies were conducted evaluating specific factors that could potentially influence the load bridging effect. Factors such as the dimensions of the packages, their contents, package stacking patterns, number of layers of packages, total height of the unit load, and load containment methods have all been evaluated [12; 13; 14; 16; 17]. This research has historically been conducted through physical experimentation with limited evaluation of the potential interactions between these factors. The load bridging effect has been measured through the change in the overall deformation of the pallet structure and by evaluating the changes in the pressure distribution across the pallet top decks [11; 12; 16; 18]. Physical experimentation for large systems, such as pallets carrying multiple packages, presents low repeatability due to the potential variation in uncontrollable factors. To account for this, simplified general models have been developed. [PERSON] et al. [19] developed a finite element model to predict the deformation of pallet top deck boards under non-uniform load applications, but this only has limited application to rigid loads. [PERSON], [PERSON], and [PERSON] [20] presented a model simulating the bending behavior of a simplified unit load segment using an implicit dynamic, two-dimensional finite element analysis approach. Unlike previous approaches, this model provides a method to generically analyze a unit load when stored on warehouse rack beam support in order to determine the predicted level of load bridging for the specific load characteristics. Seven different unit load characteristics were identified as potentially influencing the magnitude of the load bridging effect. These were: payload weight, friction between the pallet and the packages, friction between packages, box dimensions represented as the number of columns and number of layers, overall height of the unit load, and the stiffness of the pallet. Although the developed finite element model represents a robust baseline to use in studying the characteristics of a unit load and their influence on pallet performance, a full analysis of the trends and interactions of all the identified factors increases the computing requirements exponentially.