Effect of Substructure Stiffness on Performance of Steel Integral Abutment Bridges under Thermal Loads

Abstract

This paper presents a study that investigated the effect of substructure stiffness on the performance of short- and medium-length steel integral abutment bridges (IABs) built on clay under thermal load effects. Various parameters, such as pile size and orientation, pile type, and foundation soil stiffness, were considered in the study. Detailed, three-dimensional (3-D), finite element (FE) models were developed to capture the behavior of IABs. Field measurements from a IAB were used to validate the 3-D FE model developed with LUSAS software. With the use of validated models, a parametric study was carried out to study the effect of these parameters on the performance of IABs under thermal loading with AASHTO load and resistance factor design temperature ranges. The study showed that the substructure stiffness had a significant effect on the stress level induced by thermal loads in various components of the substructure and superstructure. The results also showed significant variations in displacement and stress between interior and exterior locations in relatively wide IABs. The study showed that prestressed concrete piles could form a viable alternative to steel H-piles for short-span bridges. The stress level from thermal loading in the various components of the bridge could be reduced significantly if the top part of the pile were placed in an enclosure filled with crushed stone or loose sand.

Applicability of the AASHTO’s Live Load Distribution Requirements for Integral Bridges

“…Integral bridge building in Europe was summarized by White et al in 2010 [9] and more recently in Germany by Pak and Seidl [10]. Previous research on the subject has mainly addressed the thermal load effect [11][12][13], time-dependent deformations due to creep and shrinkage [14][15][16], and seismic loading [17][18][19]. Little published work has considered live load distribution in such bridges, except for the work of Dicleli, Yalcin and Erhan, which is summarized below.…”

Study of Horizontally Curved Slab-on-Steel I-Girder Bridges with Integral Abutments Under Thermal Loading

“…Additionally, the difference is more likely attributed to the difference in the in-situ soil conditions and or change in the soil properties such as the soil density with time as the bridge undergoes cycles of thermally induced displacements. Albhaisi et al (2012) investigated the effect of substructure stiffness on the performance of short and medium length steel integral abutment bridges built on clay under thermal loading effects. Detailed 3D finite element models were developed using LUSAS software and a parametric study was carried out.…”

“…Also, the foundation soil can affect performance of the bridge especially during negative thermal loading (Civjan et al, 2007). While Albhaisi et al (2012) concluded that clay stiffness and the foundation soil have a minor effect on the displacement of the top of the abutment. Upon this contradiction about the role of foundation soil on the bridge performance, two foundation soil, namely: stiff clay and medium dense sand, were adopted to emphasize the role of foundation soil on the performance of horizontally curved IAB.…”

Simple Approach to Calculate Displacements and Rotations in Integral Abutment Bridges

“…This nonlinear behavior is simplified by using an elastoplastic curve displayed in Figure 4 with the dashed line. The elastic portion is defined with a slope equal to the secant soil modulus (E s ) and the soil modulus for clay can be calculated with the following expression: For a foundation supported by clay, the soil was approximated with elastic spring elements having a spring constant equal to E s (12).…”

“…These guidelines provide useful design examples based on experience in the design of IABs but do not provide theoretical approach for the analysis. The authors conducted a detailed parametric study to investigate the effect of substructure stiffness on the performance of steel IABs using 3-D FE models (12,13). On the basis of the results of this parametric study, a simple approach was derived to calculate the displacement and the rotation induced by thermal loading in IABs.…”