Bridge Structures - Volume 18, issue 1-2

Authors: Mahmoud, Khaled M.

Article Type: Editorial

DOI: 10.3233/BRS-220199

Citation: Bridge Structures, vol. 18, no. 1-2, pp. 1-1, 2022

Authors: Tabatabai, Habib | Nabizadeh, Azam

Article Type: Research Article

Abstract: Accidental damage to prestressed concrete bridge girders may occur due to impact by over-height vehicles on the bottom of the girder, or the top flange of the girder may be damaged during deck removal and replacement operations. Since stress checks at service loads are an important component of design for prestressed concrete beams, serviceability-based stress checks should be considered when assessing the structural condition of damaged girders. In this paper, step-by-step theoretical calculations are used to develop equations for estimating service load stress changes due to physical damage (partial loss of concrete section and strands) based on a differential approach. …The effects of lack of symmetry in the damaged cross section is considered in the calculations. A spreadsheet-based program is developed to calculate complex section property values for the damaged sections. The accuracy of the developed equations was verified using a finite element model of a prestressed beam under undamaged and damaged conditions. Reasonably good agreement was noted between the predicted stress changes and the finite element results. Show more

Keywords: Bridges, prestressed concrete, damage, over-height truck, serviceability, stresses

DOI: 10.3233/BRS-220197

Citation: Bridge Structures, vol. 18, no. 1-2, pp. 3-17, 2022

Authors: Huang, Jianwei

Article Type: Research Article

Abstract: Northeast extreme tee (NEXT) precast prestressed concrete beams have recently emerged as a promising solution to accelerate bridge construction and enhance the sustainability of bridges. To date, several studies on the live load distribution factor (LLDF) for moment and shear in NEXT F beam bridges have been reported, which indicated that using the AASHTO LRFD LLDF for moment in NEXT F beam bridges could provide a sufficient safety margin; however, a 20% increase in the LRFD LLDF for shear was recommended for the safety of shear design. This paper intended to investigate the required transverse shear reinforcements in NEXT F …beam bridges by using a factor of 1.2 for the LRFD LLDF for shear. A comprehensive study was carried out by considering various parameters, including concrete strength, beam section, bridge section, and span length. Results from this study showed that providing the minimum transverse shear reinforcement could offer a sufficient safety margin for the shear design of NEXT F beam bridges, even with an increase of 20% on the LRFD LLDF for shear. It is recommended that a factor of 1.2 be used for the LRFD LLDF for shear to ensure a safe design of NEXT F beam bridges, though the minimum transverse reinforcements will be likely to control the shear design. Show more

Keywords: Accelerated bridge construction, NEXT beam, prestressed concrete, shear design

DOI: 10.3233/BRS-220198

Citation: Bridge Structures, vol. 18, no. 1-2, pp. 19-26, 2022

Authors: Vasconez, Rosa | Kustau, Aliaksei | Najm, Husam

Article Type: Research Article

Abstract: The use of integral abutments in bridges goes back many years to the late 1930’s in the United States. Over the years, integral bridges became more popular as more and more states built those bridges and more engineers became familiar with their design and construction. These bridges are being built in Europe since the 1980’s. An integral abutment bridge acts as a frame structure with a continuity connection between the superstructure and the substructure. The substructure is typically an integral cap supported on single row of piles that provides flexibility to accommodate thermal loads and displacements. The main advantage of …integral abutment bridges is that they are built without expansion joints which eliminates maintenance costs and reduces construction costs. Because of the interaction between the soil and the integral abutment under the applied loads and the cyclic nature of thermal loads, the analysis and design of integral abutment bridges can be, in some cases, challenging especially when the designs falls outside the geometrical limits set by existing standards. This overview focus on field performance data reported in the literature and interpretation of this data. IT also highlights the needs for more test data during construction and for long term performance under cyclic thermal movements. Deck replacement requirements in integral abutments were investigated using analytical models and recommendations for deck replacement preparations are provided. Show more

Keywords: Integral abutment, soil-structure Interaction, monolithic, stiffness

DOI: 10.3233/BRS-220196

Citation: Bridge Structures, vol. 18, no. 1-2, pp. 27-43, 2022

Authors: Natalicchio, Cortney | Al-Khateeb, Hadi | Chajes, Michael J. | Wu, Zheng Y. | Shenton III, Harry W.

Article Type: Research Article

Abstract: Structural Health Monitoring (SHM) systems, in combination with controlled load tests, can provide valuable data for calibrating high fidelity bridge models, which can then be used for evaluating the long-term performance of the bridge, improved load ratings, and permit vehicle evaluation. The objective of this research was to calibrate a 3D model of the Indian River Inlet (IRIB) cable-stayed bridge, using strains recorded by the bridge SHM system during a controlled load test. The bridge was modeled in STAAD-Pro and calibrated using a pre-commercialized software platform that uses a Generic Algorithm to minimize the error between the measured and predicted …strains. The calibration parameters were the elastic modulus of groups of the main longitudinal edge girder/deck elements, which once calibrated, could be related to the measured concrete strength of the members. Four different models were investigated, using 6, 10, 14, and 18 parameter element groups of the edge girder members. Of the different models, the 14 and 18 parameter models yielded the best results. The “design” model yielded errors as high as 42% when compared to the measured strains; the error was less than 10% for the majority of measurements for the 14-parameter model. Including the effect of the traffic barriers in the model, the weighted average concrete strength of the calibrated model was within 4% of the measured weighted strength. The calibration was shown to be insensitive to measurement noise and was validated using several unique single and multi-vehicle load cases that were heavier and more offset from the centerline of the bridge. The calibration procedure was able to capture the variability in flexural stiffness of the edge girders due to the variability of the concrete, resulting in significantly better agreement between the live load measured strains and the model predicted strains. Show more

Keywords: Calibration, cable-stayed bridge, concrete, concrete strength, strain, load test, structural health monitoring, system identification

DOI: 10.3233/BRS-220195

Citation: Bridge Structures, vol. 18, no. 1-2, pp. 45-62, 2022