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Showing 1-5 of 176 Abstracts search results

Document: 

SP348

Date: 

March 19, 2021

Publication:

Symposium Papers

Volume:

348

Abstract:

Sponsors: Sponsored by ACI Committee 351 Editor: Carl A. Nelson This special publication grew out of the Technical Session entitled “Application of ACI 351-C Report on Dynamic Foundations,” held at the ACI Spring 2019 Convention in Québec City, Québec. Following this event, Committee 351 decided to undertake a special publication with contributions from those session participants willing to develop their presentations into full-length papers. Three papers included in the current publication were contributed by these presenters and their coauthors, with six additional papers provided by others. All but one of the papers deal with the subject matter of ACI 351.3—Foundations for Dynamic Equipment—updated in 2018. The one exception (the paper of Wang and Fang on wind turbine foundations) provides valuable information to engineers dealing with a lack of consistent design criteria among various codes for reinforced concrete foundations subjected to high-cycle fatigue loads. I would like to thank the members of ACI Committee 351 for their support, in particular the current main Committee and Subcommittee C Chairpersons Susan Isble and Dr. Mukti L. Das, respectively. I also wish to express my gratitude to the authors for their perseverance through the difficult circumstances of 2020, and to the reviewers who generously contributed their time and expertise to this publication. Last, but not least, I want to thank my wife Cindy for tolerating me (and the growing piles of paper) over the past several months as the deadline approached. Carl A. Nelson On behalf of ACI Committee 351 Minneapolis, December 2020


Document: 

SP-347_07

Date: 

March 1, 2021

Author(s):

Andrew D. Sorensen, Robert J. Thomas, Ryan Langford and Abdullah Al-Sarfin

Publication:

Symposium Papers

Volume:

347

Abstract:

The impact resistance of concrete is becoming an increasingly important component of insuring the durability and resilience of critical civil engineering infrastructure. Design engineers are not currently able to use impact resistance as a performance-based specification in concrete due to a lack of a reliable standardized impact test for concrete. An improved method of the ACI standard, ACI 544.2R-89 Measurement of Properties of Fiber Reinforced Concrete, is developed that provides a resistance curve as a function of impact energy and number of blows (N) to failure. The curve provides information about the life cycle (N) under repeated sub-critical impact events and an estimate of the critical impact energy (where N=1), whereas the previous method provided only a relative value. The generated impact-fatigue curve provides useful information about damage accumulation under repeated impact events and the effectiveness of the fiber-reinforcement. In this paper, the improved method is demonstrated for three fiber types: steel, copolymer polypropylene, and a monofilament polypropylene. Additionally, the analytical solution for the specimen geometry is given as well as the theoretical considerations behind the development of the impact-life curve. The use of a specimen geometry provides a path to generalize the test results to full-scale structures.


Document: 

SP-345_01

Date: 

February 1, 2021

Author(s):

Arne Spelter, Juliane Wagner, Manfred Curbach, and Josef Hegger

Publication:

Symposium Papers

Volume:

345

Abstract:

Carbon reinforced concrete (CRC) is a material composed of a high-performance concrete and a carbon reinforcement (textile grids, lamellas, rods). Composite materials with reinforcements of other fiber materials are called textile reinforced concrete (TRC). The investigations of CRC started more than 20 years ago and the continuous development as well as research findings have opened many fields of application. Today, the use of CRC includes the strengthening of reinforced concrete elements as well as the realization of new elements such as facades, shells and even bridges.

Some of these structures require knowledge of the fatigue behavior due to cyclic loading (e. g. bridges). In a collaborative project of the Institute of Structural Concrete of the RWTH Aachen University and the Institute of Concrete Structures of the TU Dresden, the uniaxial tensile fatigue behavior of two carbon textile reinforcement types was systematically investigated. The specimens were subjected up to 107 loading cycles and stress ranges up to 261 ksi (1,800 MPa). The influence of the maximum load and amplitude were investigated as well as fatigue curves for these two reinforcement types derived.


Document: 

SP-343_17

Date: 

October 1, 2020

Author(s):

Juhasz, K.P.; Schaul, P.

Publication:

Symposium Papers

Volume:

343

Abstract:

In the past decade macro synthetic fibre reinforcement has become widely used for concrete track slabs including tramlines. By using macro synthetic fibres as a reinforcement in concrete slabs both the casting time and manual work will decrease, while the concrete’s ductility will increase. In addition the durability will be higher with using synthetic fibres, and the carbon footprint will be lower compared to steel mesh or fibre reinforcement. In most cases the steel reinforcement can be omitted entirely from the structures using macro synthetic fibres. The uniformly distributed fibres in the concrete can increase the residual flexural strength of the concrete independently from the location. This makes it possible to use the fibres in both cast in situ and precast elements used for tramlines. The calculation process for these structures always has to comprise of both the static load, the dynamic load and the effect of cyclic loading, i.e. fatigue. These load calculations can be handled using advanced finite element analysis software, which is specialized for concrete and fibre reinforced concrete structures. The paper will present the opportunities for using macro synthetic fibres together with the process of designing fibre reinforced concrete tramlines.


Document: 

SP-343_31

Date: 

October 1, 2020

Author(s):

Poveda, E.; Ruiz, G.; Cifuentes, H.; Yu, R.C.; Zhang, X.X.

Publication:

Symposium Papers

Volume:

343

Abstract:

This work proposes a new strain-based failure criterion for compression fatigue in steelfiber reinforced concrete. It is based on the Spark and Menzies’ relationship between the logarithm of the secondary strain rate per cycle and the specimen life expressed as the logarithm of the number of cycles until failure. This relationship permits calculating the critical strain at the failure of the specimen as the sum of two terms. The first one is the maximum strain in the first cycle due to the maximum compression stress. The second term is the increase of strain due to the remaining cycles until failure. Thus, failure occurs when the strain reaches a critical level during fatigue loading. On the contrary, the material continues resisting while its accumulated strain is lower than the critical one. This criterion is validated against a series of low-cycle fatigue tests in five types of concrete with different amounts of fiber that share the same concrete matrix. Besides, the experimental results show that the fibers delay the deformation and deterioration processes caused by fatigue. They also show that there is an optimum fiber content that maximizes fatigue life.


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