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Showing 1-5 of 2036 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-341-07

Date: 

June 30, 2020

Author(s):

Maher AL-Hawarneh, AHM Muntasir Billah, and M. Shahria Alam

Publication:

Symposium Papers

Volume:

341

Abstract:

In recent years, shape memory alloys (SMA) have drawn significant attention and interests among researchers and structural engineers for diverse civil engineering applications. Superelasticity, shape memory effect, and hysteretic damping are the three major characteristics of SMAs that make them appropriate for bridge engineering applications in high seismic zones. Recent earthquake events have shown the most devastating earthquake loading that structures could experience are the near-fault ground motions. On the other hand, the ground motion duration effect on structural response has attracted a lot of interest over the last decade. This study aims to evaluate the comparative seismic fragility of concrete bridge piers reinforced with SMA rebars and steel rebars in the plastic hinge region under long duration and near-fault earthquakes. The bridge pier is assumed to be part of a lifeline bridge located in Western Canada and has been designed following a performance-based design approach. Fragility analysis has been conducted considering uncertainty in the material properties and the seismic hazard of the site location. Fragility curves are developed using suits of long duration and near-fault motions where each suite contains 20 ground motions. The vulnerability of the SMA-RC bridge piers and steel-RC bridge piers has been evaluated in terms of maximum drift and residual drift as the demand parameters. The outcome of this study indicates how the performance of the SMA-RC bridge pier and steel-RC bridge pier are affected by the duration of ground motion and fault location.


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-341-06

Date: 

June 30, 2020

Author(s):

Mostafa Tazarv and M. Saiid Saiidi

Publication:

Symposium Papers

Volume:

341

Abstract:

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.


Document: 

SP-341-05

Date: 

June 30, 2020

Author(s):

Yu-Chen Ou, Samuel Y.L.Yin, Yi-Qing Liu, and Jui-Chen Wang

Publication:

Symposium Papers

Volume:

341

Abstract:

The use of unstressed Grade 1860 (MPa) seven-wire steel strands as longitudinal reinforcement in columns has the advantage of reducing the cost of steel as compared with conventional Grade 420 (MPa) deformed steel bars. A preliminary experimental study was conducted to investigate the performance of a column with unstressed seven-wire strands as longitudinal reinforcement. Large-scale column specimens were designed and tested using double-curvature lateral cyclic loading under a constant axial load. Test results showed that the column with strands as longitudinal reinforcement (RH1) showed less and wider cracks and less energy dissipation than the column with deformed bars as longitudinal reinforcement (ORH1). Despite this, RH1 showed a slightly higher drift capacity than ORH1 even when the strands used in RH1 had a much lower ultimate strain than the deformed bars used in ORH1.


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