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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 952 Abstracts search results
June 30, 2020
Sarah De Carufel and Hassan Aoude
This paper presents the results from tests examining the blast performance of columns constructed with ultra-high-performance concrete (UHPC) and high-performance reinforcement (high-strength steel or stainless steel). As part of the study six columns with square cross-sections were tested under simulated blast loads using a shock-tube at the University of Ottawa. Parameters investigated include the effects of concrete type, longitudinal reinforcement type and longitudinal reinforcement ratio. The results demonstrate that the use of UHPC increases the blast performance of reinforced concrete columns by increasing blast capacity and improving control of maximum and residual mid-span displacements by an average of 30% and 40%. Substitution of normal-strength bars with high-strength or stainless steel bars in the UHPC columns resulted in further reductions in displacements, which ranged between 18-43% for maximum deformations and 38-66% for residual deformations. The failure mode of all columns with low steel ratio of 1.24% (4 – No.3 bars) was tension bar rupture, regardless of steel type. Increasing the steel ratio from 1.24% to 1.84% (6 –No.3 bars) increased blast capacity and delayed failure. The use of increased amount of stainless steel bars was particularly effective, and transformed the failure mode from bar rupture to fiber pullout. The analytical study confirms that dynamic inelastic SDOF analysis can be used to reasonably predict the blast response of UHPC columns reinforced with varying steel types.
Mostafa Tazarv and M. Saiid Saiidi
Current seismic codes prevent bridge collapse under strong earthquakes. For conventional reinforced concrete (RC) bridges, this performance objective is usually achieved through confinement of ductile members such as columns. When an RC bridge column undergoes large displacements, its reinforcement yield and sometimes buckle, the cover concrete spalls, and the core concrete sometimes fail. Damage of reinforcement and core concrete is not easy to repair. Advanced materials and new technologies are emerging to enhance the seismic performance of RC bridge columns by reducing damage, increasing displacement capacities, and/or reducing permanent lateral displacements. Two types of advanced materials, shape memory alloy (SMA) bars and engineered cementitious composite (ECC), are the focus of the present study. SMA bars are viable reinforcement for concrete structures since they resist large stresses with minimal residual strains. Furthermore, ECC, which is a type of fiber-reinforced concrete, shows significant tensile strain capacities with minimal damage. SMA-reinforced ECC bridge columns are ductile with minimal damage and insignificant residual displacements under extreme events. A displacement-based design method for NiTi superelastic SMA-reinforced ECC bridge columns is proposed based on large-scale experimental and extensive analytical studies. A summary of the proposed guidelines, background information, and supporting studies are presented for this novel column type to facilitate field deployment. Finally, the details of the world first SMA-reinforced ECC bridge constructed in Seattle, USA, is discussed.
June 1, 2020
Yang Yang and Ruili He
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.
April 1, 2020
Raymon W. Nickle and Yail J. Kim
With over 80 years of history, it is only in the last 20 years that the use of fiber reinforced polymer (FRP) materials has become feasible for bridge applications in part due to the ever increasing requirement to make structures last longer, with the current American Association of State Highway Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications requiring that structures be designed for a 75 year design life; but also in the development of cost effective production techniques, and the introduction of FRP materials, which bring the cost and strength of FRP materials closer to traditional steel reinforcement. Published documents provide comprehensive recommendations on design methodology, predictive equations, and recommendations for strength and service limits states. In this paper, the background of FRP-prestressed concrete bridges is discussed and trial bridges are designed. Research needs to advance the state of the art are identified and delineated.
Santosh Timilsina, Nur Yazdani, Eyosias Beneberu, and Abel Mulenga
Fire is a possible hazard on highway bridges which causes significant economic damage, and it is also one of the least investigated of all hazards. There is a lack of knowledge on the long term performance and structural integrity of fire damaged and fiber reinforced polymer (FRP) laminate retrofitted bridges. One such rare in-service bridge was selected for this study. The fire damaged cast-in-place non-prestressed girders were previously repaired with mortar and strengthened with FRP wrapping. The girders were instrumented with strain gages and displacement transducers, and a non-destructive live load test was carried out to evaluate the structural response. The results from the load testing were used to compare two identical girder spans with and without CFRP strengthening. A full-scale non-linear finite element model of the overall bridge superstructure was created, and the test results used to calibrate the model. The carbon (CFRP) strengthened girder exhibited similar stiffness compared to the undamaged girder as evidenced by almost equivalent mid-span deflection. The girder moment capacity decreased significantly due to fire damage, and the CFRP strengthening plus mortar repair was successful in restoring the moment capacity. The finite element model provided good correlation with load test results.
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