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  • 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.

International Concrete Abstracts Portal

Showing 1-5 of 425 Abstracts search results

Document: 

SP-340-07

Date: 

April 1, 2020

Author(s):

Sary A. Malak and Neven Krstulovic-Opara

Publication:

Symposium Papers

Volume:

340

Abstract:

This paper provides an overview of simplified methods for dynamic blast analysis of structural members. The presented approach focuses on the use of a general simplified non-linear single degree of freedom dynamic model commonly used for typical flexural members such as slabs, beams or columns. The presented approach also allows modeling of members retrofitted against blast loading using fiber composites. The fiber composites considered in this paper include conventional Steel Fiber Reinforced Composites (FRC) as well as High Performance Fiber Composites (HPFRC). HPFRC’s include Short Steel Slurry Infiltrated Concrete (SIFCON), Long Continuous Slurry Infiltrated Steel Fibers Mat Concrete (SIMCON), and Fiber Reinforced Polymers (FRP). The model identifies different material parameters that affect the response of the structure. The effect of the material properties on the composite response is discussed within the framework of the existing blast-resistance guidelines and standards. Different retrofit techniques for existing concrete structures using fiber reinforced composites and the effect of varying the composite material properties on the response is presented. Final conclusions and recommendations are provided in terms of composite material’s properties, modeling performance and response. Specific limitations on their use is also discussed.


Document: 

SP-340-14

Date: 

April 1, 2020

Author(s):

Raymon W. Nickle and Yail J. Kim

Publication:

Symposium Papers

Volume:

340

Abstract:

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.


Document: 

SP-340-10

Date: 

April 1, 2020

Author(s):

Santosh Timilsina, Nur Yazdani, Eyosias Beneberu, and Abel Mulenga

Publication:

Symposium Papers

Volume:

340

Abstract:

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.


Document: 

SP-339_02

Date: 

March 1, 2020

Author(s):

Saeed Fathali, Bret Lizundia, and Francisco Parisi

Publication:

Symposium Papers

Volume:

339

Abstract:

This paper summarizes the benefits and challenges of implementing performance-based seismic design (PBSD) for two concrete buildings of the Lower Sproul Plaza Redevelopment Project in one of the busiest areas of the UC Berkeley campus. The project included new construction of Eshleman Hall and the additions to Martin Luther King (MLK) Hall, and the seismic retrofit of the existing MLK Student Union as a result of the expansion. The peer-reviewed PBSD implemented three-dimensional nonlinear response history analyses at two levels of seismic hazard. The analytical simulations using pairs of near-fault ground motions, scaled to match the site-specific spectrum, were intended to establish the expected seismic behavior of the buildings under rare and frequent earthquakes. The choice of PBSD over code-prescriptive procedures was prompted by multiple layers of complexity of the project. Several challenges including those related to the horizontal and vertical irregularities, or connecting new and existing concrete buildings with different lateral force-resisting systems would have made a code-prescriptive design a cumbersome analytical endeavor without providing reliable insight about the expected seismic behavior of the buildings. The PBSD, however, proved a powerful framework to design for a reliably predictable seismic behavior with sufficient ductility, and a designated ductile hinge zones with sufficient confinement and shear capacity. The PBSD methodology also enabled the designers to avoid unnecessary conservatism to deal with the complexities, when designing drift- and acceleration-sensitive elements including the cladding system. Finally, the PBSD methodology allowed the design to consider all potential modes of failure of concrete elements retrofitted by FRP material including the debonding failure between FRP material and substrate.


Document: 

SP333

Date: 

October 9, 2019

Author(s):

Yail J. Kim, John J. Myers, and Antonio Nanni

Publication:

Symposium Papers

Volume:

333

Abstract:

Concrete bridges play an important role in the efficiency and reliability of transportation civil infrastructure. Significant advancements have been made over the last decades to enhance the performance and durability of bridge elements at affordable costs. From an application perspective, novel analysis techniques and construction methods are particularly notable, which have led to the realization of more sustainable built-environments. As far as the evaluation and rehabilitation of constructed bridges are concerned, new nondestructive testing approaches provide accurate diagnosis and advanced composites, such as carbon fiber reinforced polymer (CFRP), have become an alternative to conventional materials. This Special Publication (SP) contains nine papers selected from two technical sessions held at The ACI Concrete Convention and Exposition – Spring 2018, in Salt Lake City, UT. The objective of the SP is to present technical contributions aimed to understand the state of the art of concrete bridges, identify and discuss challenges, and suggest effective solutions for both practitioners and government engineers. All manuscripts were reviewed in accordance with the ACI publication policy. The Editors wish to thank all contributing authors and reviewers for their rigorous efforts. The Editors also gratefully acknowledge Ms. Barbara Coleman at ACI for her knowledgeable guidance in the development of the SP.


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