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International Concrete Abstracts Portal

Showing 1-5 of 212 Abstracts search results

Document: 

SP-355_18

Date: 

July 1, 2022

Author(s):

Renee T. Rios, Francesca Lolli, Katelynn Schoenrock, Kimberly E. Kurtis

Publication:

Symposium Papers

Volume:

355

Abstract:

Performance-based specifications (PBS) may increase concrete quality and sustainability by facilitating innovations in material selection and proportioning. This is particularly relevant now with increased interest in a broader set of minimally processed minerals for use as supplementary cementitious materials (SCMs) or fillers; these are often industrial and agricultural byproducts and with limited performance history in concrete. This study compares traditional largely prescriptive concrete design, following practices currently allowed by the Georgia Department of Transportation, with three new concrete designs which do not comply with current specifications but offer increased sustainability. Three metrics are assessed for each mixture: the associated cradle-to-gate CO2 emissions, a metric that incorporates the environmental burden of concrete, compressive strength at 28 days, and surface resistivity measurements taken weekly from 28 to 56 days. A framework is proposed to statistically analyze compressive strength data to pre-qualify mix designs, which can be broadly applied to reduce time-consuming iterative testing and to help meet sustainable development goals. The aim is to foster innovation in material use and mixture design towards an increased durability and performance, while reducing environmental impact and minimizing risk.

DOI:

10.14359/51736027


Document: 

SP-343_33

Date: 

October 1, 2020

Author(s):

Ranjbarian, M.; Mechtcherine, V.

Publication:

Symposium Papers

Volume:

343

Abstract:

The structures subject to dynamic loading demand more ductile materials to prevent catastrophic failure. The results of investigations on strain-hardening cement-based composites (SHCCs) distinguished this group of materials – due to their highly ductile behaviour – as a suitable alternative for structures with high resistance against seismic, impact and cyclic loadings. While mechanical properties of SHCC are determined mostly by bridging behaviour of dispersed fibres crossing cracks and properties of fibre-matrix interface, the dependency of these mechanisms on the loading regime is pronounced. Specifically, under cyclic loading, the number of cycles to failure decreases dramatically when SHCC is subject to alternating tension-compression regime. Degradation of fibres compressed between the crack faces and deterioration of their bridging capacity are responsible for such early failure and necessitate further investigations at the micro level. The article at hand presents the influence of loading history in cyclic tension-compression regime on the bridging capacity of the single PVA microfibre embedded in cementitious matrix. A novel double-sided single fibre pull-out setup is used for the experimental investigations. First the test setup, material composition and testing procedure are explained. Next, the results of double-sided pull-out specimens, tested under monotonic and cyclic tension-compression regimes, are discussed. It is shown that the deterioration of fibre bridging capacity can be assessed by applying cyclic loading in post-cracking stage, followed by pulling the fibre out of the matrix. Possibility of a change in pull-out behaviour of PVA microfibre from “fibre rupture” to “fibre pullout”, also a change of behaviour in post debonding regime from “hardening” to “softening” are also observed. Eventually, the results of microscopic analysis are presented and discussed, which show the specific phenomena responsible for changes in pull-out behaviour.


Document: 

SP-343_14

Date: 

October 1, 2020

Author(s):

Winterberg, R.; Rodrìguez, L.M.; Cámara, R.J.; Abad, D.S

Publication:

Symposium Papers

Volume:

343

Abstract:

Fibre reinforced concrete (FRC) is becoming widely utilized in segmental linings due to the improved mechanical performance, robustness and durability of the segments. Further, significant cost savings can be achieved in segment production and by reduced repair rates during temporary loading conditions. The replacement of traditional rebar cages with fibres further allows changing a crack control governed design to a purely structural design with more freedom in detailing. Macro synthetic fibres (MSF) are non-corrosive and thus ideal for segmental linings in critical environments. Although fibre reinforcement for segments is relatively new, recent publications such as the ITAtech “Guidance for precast FRC segments – Volume 1: Design aspects” or the British PAS 8810 “Tunnel design – Design of concrete segmental tunnel linings – Code of practice” have now given more credibility to this reinforcement type and the basis for design. This paper presents and discusses the design methodology for precast tunnel segments and in particular the tasks associated with the use of MSF reinforcement. Temporary loadings as well as long term load behaviour will be addressed. A case history from the Santoña–Laredo General Interceptor Collector, currently under construction in northern Spain, will illustrate the specific benefits of MSF reinforcement for segmental linings.


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.

DOI:

10.14359/51725816


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.

DOI:

10.14359/51724690


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