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International Concrete Abstracts Portal

Showing 1-5 of 864 Abstracts search results

Document: 

SP342

Date: 

July 17, 2020

Publication:

Symposium Papers

Volume:

342

Abstract:

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.


Document: 

SP-341-11

Date: 

June 30, 2020

Author(s):

Ahmed Ibrahim, Sabreena Nasrin, and Riyadh Hindi

Publication:

Symposium Papers

Volume:

341

Abstract:

The spiral reinforcement is a special detailing technique used for reinforcing columns in regions of high seismic activities because of its ability in energy absorption and ductility. In this paper, the results of the experimental testing on cross spiral confinement in reinforced concrete columns are presented. The experimental results were verified by nonlinear finite element analysis as well as an analytical model. The developed analytical model was based on the octahedral stress criterion and compared with other models available in the literature. In the Finite element model, the concrete damage plasticity and steel yielding criterion were used in the constitutive equations. The finite element showed very good prediction of the ultimate load and failure strain for various spiral reinforcement ratios. Analytical stress-strain models have been developed and compared to the experiment results in the literature and found work well in predicting the columns behavior under monotonic axial loads. The authors see that the proposed technique is a very good potential of industry implementation and provides a more seismic resiliency to structures.

Such detailing technique could be used as a mitigation system for columns in high seismic zones.


Document: 

SP-341-08

Date: 

June 30, 2020

Author(s):

Ruchin Khadka, Mustafa Mashal, and Jared Cantrell

Publication:

Symposium Papers

Volume:

341

Abstract:

Recently titanium alloy bars (TiABs) have been gaining popularity in civil engineering applications. They offer good deformation capacity, better fatigue performance, high-strength-to-weight ratio, lighter weight (60% that of steel), and excellent corrosion resistance. Recently, TiABs were used in the strengthening of two bridges in Oregon to increase the shear and flexural capacities of the concrete beams. The research in this paper quantifies some common mechanical properties of TiABs using experimental investigation. This is done to explore suitability of the material for wider applications in civil infrastructure. The four types of testing conducted in accordance with ASTM standards included tension, hardness, Charpy V-Notch, and galling tests. Samples of 150 ksi (1034 MPa) high strength steel were also tested for comparison. Test results showed good performance of TiABs. Analytical models are proposed for stress-strain and toughness-temperature relationships.


Document: 

SP-341-04

Date: 

June 30, 2020

Author(s):

Mahmoud Aboukifa, Mohamed A. Moustafa and Ahmad Itani

Publication:

Symposium Papers

Volume:

341

Abstract:

Ultra-High Performance Concrete (UHPC) is a versatile building material as it is characterized by very high compressive strengths reaching 30 ksi [200 MPa], ductile tensile characteristics, and energy absorption. Currently, UHPC is commonly used in limited structural applications, such as joints and connections between precast structural elements. To extend the use of UHPC in full structural elements, a better understanding of the structural behavior and failure mechanism of such elements is needed. One potential application of UHPC for structural elements is columns, which is the focus of this study. This paper presents an experimental investigation of the behavior of UHPC column subjected to combined axial and lateral loading. A large-scale UHPC column is tested under axial and quasi-static cyclic lateral loading at the Earthquake Engineering Laboratory at the University of Nevada, Reno. To establish a comparison with conventional columns, a normal strength concrete (NSC) column with same dimensions and design as the tested UHPC column is analytically modeled and analyzed under similar loading protocol using OpenSEES. The experimental response of the UHPC column is evaluated and compared to the analytical response of the NSC column. Both global and local behavior are presented and discussed to include damage progression, failure type, peak moment strength, stiffness degradation, and displacement and curvature ductility.


Document: 

SP-342_07

Date: 

June 1, 2020

Author(s):

Qiang Gui and Zhongguo John Ma

Publication:

Symposium Papers

Volume:

342

Abstract:

Research on the seismic performance of unreinforced concrete railroad bridge substructures is presented. The restraining effect of a continuous rail track structure, which is considered to contribute to better seismic performance of railroad bridges compared with highway bridges, was investigated. A numerical modelling scheme that takes into consideration the nonlinear properties of the ballast and bearings as well as steel and concrete materials was proposed and validated using previous full-scale field testing. The equivalent spring stiffness of the rail track system was obtained and used in the subsequent small-scale shaking table experiment, which investigated the dynamic response of column-shaped rigid body specimens with a spring restraint on the top. Several parameters were considered in the test matrix such as the stiffness of the restraint spring, the height/breadth ratio, the ground excitation, and single-body or multi-body configurations. Discussion regarding the testing results are also presented.


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