## 1 Introduction  
Skewed composite high-performance-steel (HPS) I-girder bridges are an economical solution for modern highways subject to space constraints in congested urban areas, providing roadway alignments with low environmental impact and minimal pollution for new road construction projects. However, unlike in right-angle (non-skew) bridges, where the load transfer to the support is linear, skewed superstructures create high complexity in the force flow. In such structures, the load path tends to follow the shortest route to the supports at the obtuse corners of bridge spans, as shown in Figure 1. Skewness in the superstructure leads to concentration of the reaction forces and negative bending moments at the bridge's obtuse corners, along with a small reaction and possibility of uplift reaction forces at its acute corners [1; 2; 3; 4; 5]. New types of the high-performance steel such as HPS 50 W (\(F_{y}\) = 345 MPa), HPS 70 W (\(F_{y}\) = 485 MPa) and HPS 100 W (\(F_{y}\) = 620 MPa), which became available commercially and globally in recent years, provide higher durability and strength, as well as boosted weldability. This can lead to considerable cost savings for big construction projects. For instance, Tennessee's Department of Transportation reduced the cost of building a highway bridge by nearly 17% by using HPS [6]. HPS can also be highly beneficial when designing and constructing bridges with longer and shallower spans that exceed the range of applicability defined by the current specifications [1; 7]. The critical issue limiting the wider use of HPS is our poor understanding of precisely how live loads are redistributed along a bridge's transverse and longitudinal directions and in the girders of this type of bridge under realistic vehicle loads. Prediction of load capacity of bridges under vehicle loads has been one of the most important issues in bridge engineering [8; 9]. Therefore, the concept of Load Distribution Factors (_LDF_s) has been utilized by bridge engineers ever since the 1930s, in order to predict bridge responses under vehicle loads [10]. The simple \"S-over\" method proposed in the American Association of State Highway and Transportation Officials (AASHTO) standard [11] errs on the side of caution by predicting relatively conservative values for today's bridges, especially those with skewed superstructures [12]. The more recent AASHTO LRFD specifications [13] accept the proposed _LDF_ equations proposed in the National Cooperative Highway Research Program (NCHRP) 12-26 project report [14] as an alternative to AASHTO's standard method. These equations significantly boost the accuracy of _LDF_s, although the high complexity and defined limits of applicability often compel bridge designers to perform in-depth analyses. Multiple variations in the bridge parameters force engineers to make assumptions or refine their analysis when computing _LDF_s for skewed bridges or when they exceed the defined range of applicability. Meanwhile, the accuracy of the AASHTO LRFD equations used to calculate _LDF_s for composite bridges constructed using HPS girders remains somewhat controversial. There have been many attempts to develop less complex, more accurate methods to compute _LDF_s for bridges [15; 16; 17]. Although [PERSON]'s method [18] is solely a function of the number of girders and the width of bridge roadway, it is widely used because it calculates highly conservative values for skewed bridges' _LDF_s [19]. The simplified models developed by [PERSON] and [PERSON] [15] and [PERSON] and [PERSON] [20] yield accurate results only for single or two-lane loaded non-skewed bridges, while [PERSON] et al. [21] proposed a set of equations to quantify _LDF_s for short- to medium-span composite precast inverted T-beam bridges that produce reasonably accurate results over the specified range of applicability. [PERSON] and [PERSON] [22] applied the power function method to deduce simplified _LDF_ equations for I-girder bridges that were a function of girder spacing alone.