# Influence of Construction Joint and Bridge Geometry on Integral Abument Bridges
## 1 Introduction  
### Background and Motivation  
For the last several decades, integral abument bridges (IABs) have become a preferred construction choice for short- to medium-length bridges throughout Europe and the United States owing to their lesser maintenance and construction cost and better structural and seismic performance compared with the conventional jointed bridges [1; 2; 3]. However, IABs still have unclear bridge design guidelines because uncontrollable uncertain parameters such as thermal expansion coefficient and soil stiffness cannot be determined during the design stage. In addition to the inherent uncertain parameters, bridge geometric parameters cause another difficulty in predicting bridge behavior because bridge response is nonlinear owing to nonlinear boundaries [4]. Thus, those geometric parameters have not been extensively investigated yet. Thermal loads greatly affect bridge performance, as found in the previous experimental [5; 6; 7; 8] and numerical [9; 10; 11; 12; 13; 14; 15] studies and in damage to in-service bridges [16; 17; 18]. Moreover, most previous studies [12; 19; 20; 21; 22; 23; 24] focused on substructure response corresponding to varied soil properties and pile orientations. American Society of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) (2014) [25] or other state design guidelines consider only the bridge length parameter and assume that bridge response is linearly proportional to bridge length. This linear proportionality is sometimes unreasonable under nonlinear soil boundaries. Moreover, bridge design parameters such as abutment height are strongly related to soil-structure interaction. Construction joints below girder seats can allow girder end rotation [5; 26; 27], i.e., the connection between the superstructure and the substructure is not purely rigid. Thus, abutment to backwall (AB) joints may influence the superstructure response. These critical parameters should be considered to identify IAB superstructure and substructure response. Many different analysis methods are currently available for IAB response prediction such as free expansion estimation or numerical, 2D or 3D, and static or time-history analyses [28; 29; 30; 31; 32; 33]. The simplest, but widely utilized analysis consists of idealized 2D static modeling with environmental loads from the AASHTO extreme temperature [29; 30]. Based on field monitoring, [PERSON] and [PERSON] [28; 29] demonstrated that a 2D time-history analysis including seasonal and daily temperature fluctuations, concrete time-dependent effects, and soil-structure interaction results in significantly reduced levels of response as compared with a 2D static analysis. [PERSON] et al. [15] also demonstrated that superstructure material property, i.e., thermal expansion coefficient, significantly influences bridge response thus state agencies in the United States and other countries limit the length of IABs depending on girder material [1]. Although Design Manual Part 4 by Pennsylvania Department of Transportation (PennDOT DM4) [34] limits the IAB bridge length to 180 m for concrete and 120 m for steel, [PERSON] and [PERSON] [35] reported bridge length limitation for moderate climate at 260 m for concrete and 180 m for steel girder. [PERSON] et al. [9] performed numerical analyses and found that a 457 m long concrete girder IAB with strong pile axis orientation satisfied maximum pile stress limitation. However, bridge response as a function of girder material has not been extensively investigated. Current design practice accounts for girder material only in the estimation of bridge longitudinal displacement; it does not consider the superstructure and substructure internal forces, which are also related to bridge geometry and thermal loads.