International Concrete Abstracts Portal

The aging reserve of bridges in the United States needs load rating assessment to ensure sufficient load-carrying capacity and safety. Bridges without sufficient capacity to carry the legal loads are load posted. These load limits reroute traffic that may result in traffic congestion and longer routes and, thus, impose inconvenience to travelers and significant cost to society. This paper investigates the potential for improvement in the load rating process for simple-span concrete slab bridges. Such bridges are load rated by the Texas Department of Transportation using simplified load rating procedures, which are intended to be conservative and can have varying degrees of accuracy compared to the actual behavior of bridges. Finite element modeling was conducted to simulate the expected behavior of a representative concrete slab bridge, and the model was calibrated using experimental test data. The equivalent width results were compared with estimates from established design specifications and empirical guidelines. The methods developed for concrete slab bridges with integral curbs provided accurate estimates of moment demand for curb sections. In addition, an established analytical approach in the literature accurately predicted the moment demand for interior slab sections under one-lane loading, while the equations in current design specifications performed well for the two-lane loading case.

To promote the application of fiber-reinforced polymer (FRP) bars reinforced ultra-high-performance seawater sea-sand concrete (FRP-UHPSSC) structures in marine construction, four-point static bending tests were carried out on 16 FRP-UHPSSC beams with different reinforcement ratios, height of cross-section, and type of FRP bars to investigate the ultimate load-carrying capacity, the midspan deflection, and the failure modes of the beams. The experimental results show that all the test beams are brittle failures, and the failure mode of the beams is shear failure when the ratio of the actual reinforcement ratio to the balanced one is higher than 2.73. Increasing the reinforcement ratio and the beam section height both improve the bending moment at ultimate load and the flexural stiffness at the service limit state. The Steel-FRP composite bars (SFCB) reinforced UHPSSC beams have the maximal bending moment at ultimate load, and the basalt fiber reinforced polymer (BFRP) bar reinforced UHPSSC beams have the optimal ductility. The deviation of ultimate bending moment and midspan deflection obtained by the proposed calculation method is reduced from 7.5 to 2.8%, and from 15 to 3%, respectively, compared with current specifications for FRP-reinforced concrete structures.

Current design assumptions for precast, prestressed concrete piles embedded in cast-in-place (CIP) pile caps or footings vary across states, leading to inconsistencies in engineering practices. Previous studies suggest that short embedment lengths (0.5 to 1.0 times the pile diameter) can develop approximately 60% of the bending capacity of the pile, with full fixity potentially achieved at shorter embedment lengths than current design specifications due to confinement stresses. This study experimentally evaluates 10 full-scale pile-to-cap connection specimens with varying embedment lengths, aiming to investigate the required development length for full bending capacity. The findings demonstrate that full bending capacity can be achieved at the pile-to-pile cap connection with shallower embedment than code provisions, challenging existing design standards and highlighting the need for more accurate guidelines for bridge foundation design.

This paper presents the effectiveness of various reinforcing schemes in the end zones of prestressed concrete bulb-tee girders. The default girder, provided by a local transportation agency, includes C-bars and spirals intended to control cracking, and is analyzed using three-dimensional finite element analysis. The formulated models are used to evaluate the breadth of end zones, strain responses, cracking patterns, damage amounts, and splitting forces, depending upon the configuration of the end-zone reinforcement. The number of C-bars is not influential in developing strand stress along the girder. The maximum principal stresses exceed the conventional limit within h/4 of the girder end, where h is the girder depth; however, the 3h/4 limit adequately encompasses the stress profiles, particularly in the web of the girder. The maximum tensile strain in the concrete varies with the elevation of the girder and the inclined strands cause local compression in the C-bars, while spiral strains are independent of the number of bars. By positioning the C-bars, the vertical strain of the concrete decreases by more than 15.9%, which can minimize crack formation. Whereas the short-term crack width of the girder may not be an immediate concern, its long-term width is found to surpass the established limit of 0.18 mm (0.007 in.). In this regard, multiple C-bars should be placed to address concerns about undesirable cracking. The splitting cracks in the girder, resulting from the strand angles and eccentricities, can be properly predicted by published specifications within the range of 0.2h to 0.7h, beyond which remarkable discrepancies are observed in comparison with a refined approach. From a practical perspective, two to three No. 6 or 7 C-bars spaced 150 mm (6 in.) apart are recommended in the end zones alongside welded wire fabric.

Engineered cementitious composites (ECC) represent a significantinnovation in construction materials due to their exceptionalflexibility, tensile strength, and durability, surpassing traditionalconcrete. This review systematically examines the composition,mechanical behavior, and real-world applications of ECC, with afocus on how fiber reinforcement, mineral additives, and micromechanical design improve its structural performances. The present study reports on the effects of various factors, including different types of mineral admixtures, aggregate sizes, fiber hybridization, and specimen dimensions. Key topics include ECC’s strain hardening properties, its sustainability, and its capacity to resist crack development, making it ideal for high-performance infrastructure projects. Additionally, the review discusses recentadvancements in ECC technology such as hybrid fiber reinforcementand the material’s growing use in seismic structures. The paper also addresses the primary obstacles, including high initial costs and the absence of standardized specifications, while proposing future research paths aimed at optimizing ECC’s efficiency and economic viability.