Sponsors: Sponsored by ACI Committees 342, Evaluation of Concrete and 343, Concrete Bridge Design (Joint ACI-ASCE) Editors: Benjamin Z. Dymond and Bruno Massicotte In recent years, both researchers and practicing engineers worldwide have been refining state-of-the-art and emerging technologies for the strength evaluation and design of concrete bridges using advanced computational analysis and load testing methods. Papers discussing the implementation of the following topics were considered for inclusion in this Special Publication: advanced nonlinear modeling and nonlinear finite element analysis (NLFEA), structural versus element rating, determination of structure specific reliability indices, load testing beyond the service level, load testing to failure, and use of continuous monitoring for detecting anomalies. To exchange international experiences among a global group of researchers, ACI Committees 342 and 343 organized two sessions entitled “Advanced Analysis and Testing Methods for Concrete Bridge Evaluation and Design” at the Spring 2019 ACI Convention in Québec City, Québec, Canada. This Special Publication contains the technical papers from experts who presented their work at these sessions. The first session was focused on field and laboratory testing and the second session was focused on analytical work and nonlinear finite element modeling. The technical papers in this Special Publication are organized in the order in which they were presented at the ACI Convention. Overall, in this Special Publication, authors from different backgrounds and geographical locations share their experiences and perspectives on the strength evaluation and design of concrete bridges using advanced computational analysis and load testing methods. Contributions were made from different regions of the world, including Canada, Italy, and the United States, and the technical papers were authored by experts at universities, government agencies, and private companies. The technical papers considered both advanced computational analysis and load testing methods for the strength evaluation and design of concrete bridges.

In 2006 in Quebec, a skewed cantilever solid concrete slab bridge without shear reinforcement collapsed due to a shear failure, which highlighted the need to improve the assessment of this type of structure. A large experimental program was carried out to test three decommissioned solid slab bridges to failure. In parallel, an extensive nonlinear finite element analysis study was performed with the aim of better understanding the failure mechanisms, the degree of load redistribution, and to gain insight into the ultimate shear capacity of these structures. A beam shear failure mode was expected for the first two bridge tests, but a flexural failure mode was observed. This paper focusses mainly on the last field test of a simply supported solid slab bridge having a 40 degree skew. The load position and the loading protocol were established with the objective of causing a shear failure at the obtuse corner of the slab where high shear forces develop. The main test motivation was to illustrate that simply supported solid slab bridges would normally not be prone to shear failure due to an intrinsic redundancy. The paper presents experimental techniques that could help bridge owners in assessing the performance of their bridges. The test results also provide valuable information for calibrating nonlinear element models that can be used for assessing the carrying capacity of existing concrete bridges. Although the actual bridge conditions were worse than anticipated, a global shear failure mode occurred near the obtuse corner at a maximum load of 1400 kN, which significantly exceeded the factored shear force due to the maximum traffic load. The failure was followed by a gradual load redistribution toward undamaged portions of the slab. This field test confirmed the assumption of non-fragility for this type of bridge, where support conditions enable development of an intrinsic redundancy. Despite these observations, nonlinear analyses carried out in parallel to the testing program indicated that this beneficial effect diminishes with an increase of slab thickness.

Several of the first prestressed concrete segmental bridges in North America were built in Quebec, Canada. The Rivière-aux-Mulets bridge was one of them. Built in the early 1960s, this bridge experienced several disorders due to inadequate design criteria enforced at that time. Despite a structural strengthening in the late 1980s, a bridge behavior follow-up has been required to ensure reliability. The structural health monitoring program implemented to track structural disorders, along with results from modal analysis and diagnostic load tests, is presented with a focus on the instrumentation and the data analysis. A three-dimensional finite element model was developed and calibrated using the frequencies and mode shapes detected under ambient traffic conditions. Data analyses showed that the expansion bearings were frozen, causing bending of the associated piers, which generated axial forces in the deck and decompression of concrete in the area surrounding active cracks. This process enables premature failure of prestressing tendons in the vicinity of these cracks, especially those located in the top flange, which is a corrosion-friendly environment. Development of cracks and associated prestress loss caused a reduction in the bridge load-carrying capacity. Analyses of health monitoring data led to acute assessment of the overall bridge structural performance.

During bridge construction, the concrete finishing machine weight, along with other dead and live loads, affects the stability of the structure during construction and the service life of the bridge. These eccentric unbalanced loads lead to torsional moments in the exterior girders of the bridge, deflection of the overhang, and excessive rotations in the exterior girders. In skewed bridges, the finishing (screed) machine can be oriented parallel to the skew or perpendicular to the girders during construction. This study focused on evaluating different orientations of the machine along the span of skewed bridges. Finite element models of bridges with different skew angles were developed using SAP2000 to simulate construction conditions. These bridge models were then subjected to different machine orientations to form a better understanding of this phenomenon and to find the most effective method to operate the concrete finishing machines. The results showed that moving the screed machine parallel to the skew angle led to rotations that were more balanced between the exterior girders compared to moving it perpendicular to the girders. Therefore, a more leveled concrete surface can be obtained when running the machine parallel to the skew.

Concrete columns in curved bridges have reportedly showed high interaction between bending and torsional moments when subjected to design-level earthquake loading. In order to accurately evaluate the performance of curved bridges under earthquake loadings, it is necessary to incorporate the interaction behavior into computational models. However, very limited work has been reported in the literature, which includes finite element models involving threedimensional solid elements and user-developed fiber elements in open-source computing tools; the former involves significant computational effort when multiple levels of earthquake records need to be considered, while the latter is not widely available in analysis tools like OpenSees. This study developed a modeling technique to simulate the interaction between bending and torsional moments in bridge columns through the discretization of the column into longitudinal, transverse, and diagonal elements. In this study, the developed modeling technique was validated against experimental data from a previous study, and case studies on typical curved bridges were presented to show its efficiency in seismic simulation.