Evaluation of Passive Soil Stiffness for the Development of Integral Abutments for Railways

An integral bridge, which is constructed without expansion joints and bearings, is an economical technology that permits slender abutment and footing design to decrease the associated maintenance and construction costs. In this study, a geosynthetic reinforced integral abutment (IA) for railways and a conventional reinforced concrete abutment (CA) are modeled, considering the two types of foundations, using the finite element method. The passive soil stiffness of the foundations was evaluated through the application of a uniform horizontal load in four separate models. The passive soil stiffness of the IA model is approximately 70% of that of the CA model. Additionally, we confirmed that the passive soil stiffness was affected by changes in the thickness of the abutment, size of the footing, number of installation piles, and elastic modulus of the ground.

Skew Reduction Factors for Moment in NEXT Beam Bridges with Integral Abutments

Northeast Extreme Tee (NEXT) beams have been recently developed for the accelerated bridge construction. The skew effect on live load distribution in a NEXT beam bridge, especially with integral abutments, is not clear and shall be assessed. In this paper, various skew NEXT beam bridges are evaluated through validated finite element (FE) analyses with solid brick elements. Parameters as studied include beam section, span length, and skew angle. Per AASHTO LRFD specifications, one- and two-lane loaded cases are examined to obtain the maximum tensile strains in beam stems under the design live loading (HL-93). Unskewed bridges are used as control specimens to compute skew reduction factors (SRF) for moment from the obtained FE strains. The FE- and LRFD-SRFs for moment are compared in terms of figures, which indicate the LRFD-SRFs have good agreements with the FE-SRFs at large. For the majority of the bridges, LRFD-SFRs govern the FE-SRFs. The research findings from this paper are useful for practicing engineers to safely design a skew NEXT beam bridge with integral abutments.

Evaluation of Dynamic Characteristics of the Footbridge with Integral Abutments

The paper presents the results of dynamic field tests and numerical analysis of the footbridge designed as a three-span composite structure with integral abutments. The adopted design solution which has allowed to achieve a high resistance of the structure to dynamic loads and to meet the requirements of the criteria of comfort of use with a large reserve has been characterized. For comparative purposes, numerical analyzes of three construction variants of the footbridge were presented: F-1 - construction with integral abutments (realized variant), F-2 - construction with girders anchored in the abutments by means of tension rocker bearings, F-3 - construction with concrete side spans.