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International Concrete Abstracts Portal

Showing 1-5 of 162 Abstracts search results

Document: 

SP-343_06

Date: 

October 1, 2020

Author(s):

Juhasz, K.P.; Schaul, P.; Winterberg, R.

Publication:

Symposium Papers

Volume:

343

Abstract:

The design of fibre reinforced shotcrete (FRS) hard rock linings is commonly based on the Q-System or Barton charts. This performance based design approach assess the results of experimental tests, carried out on panel specimens according to existing standards or guidelines. This is different to the general methodology to assess and determine the performance of fibre reinforced concrete (FRC) using standardized beam tests. Panel and beam test results yield significantly different information on the performance of FRC and it is problematic to correlate them. The beam test yields a stress-strain relationship for a small displacement range only. Based on the significantly different working and failure mechanisms, structural tests to evaluate the post-crack performance and the ductility of FRS linings are typically conducted on different types of panels rather than on traditional beams. As a consequence, test results based on beam tests may lead to an overestimation of FRC performance in panels and vice versa. In order to avoid uneconomic designs the most appropriate material must be found using the most appropriate test methodology. This paper discusses the difficulty in correlating test results obtained from beams and panels as well as the discrepancy in performance of different FRC using different test methodologies and aims to provide guidance on materials, testing and design.


Document: 

SP-343_24

Date: 

October 1, 2020

Author(s):

Bernard, E. S.

Publication:

Symposium Papers

Volume:

343

Abstract:

Numerous investigations of the effect of fibre addition on the seismic performance of conventionally reinforced concrete members have been published. These generally show that fibres can improve robustness and survivability during reverse-cycle loading, but the dosage rate of fibre required to achieve significant improvements in performance is substantial. Recently, pure FRC members have increasingly been used in structures such as tunnel linings, including both fibre reinforced shotcrete and pre-cast FRC segments. Concerns have been raised about the absence of data on the seismic resistance of such members given that all previous research on seismic performance has essentially involved hybrid members incorporating both steel reinforcing bars and fibres. The present investigation has focused on the reverse-cycle flexural performance of FRC members in the absence of conventional steel reinforcing bars. Laboratory testing was performed on plain, bar-reinforced, and steel fibre reinforced concrete members, and their performance was compared. The tests indicate that steel fibres provide a small improvement in flexural capacity under reverse-cycle loading compared to plain concrete, but that the robustness of pure FRC members is relatively poor compared to steel bar-reinforced members incorporating steel stirrups. The data suggest that, when used at practical dosage rates, large hooked-end steel fibres cannot be relied upon to provide seismic performance in flexure comparable to steel bar reinforced concrete members.


Document: 

SP-330-02

Date: 

September 26, 2018

Author(s):

Zhenping Sun, Chao Chen, Yanliang Ji, Xu Yang, Yuansong Sun, and Lelin Wu

Publication:

Symposium Papers

Volume:

330

Abstract:

The objective of this study was to evaluate the influence of alkalinity on the properties and acceleration mechanism of the accelerated cement pastes. Properties of cement pastes relating to its setting time and the strength development as well as its hydration behavior were experimentally tested. XRD and SEM analysis were also performed on the cement pastes to identify the hydration products and their structures.

Results showed that with the increase of alkalinity, the hydration rate and the early compressive strength of cement paste with both alkaline and alkali–free accelerators were accelerated and the setting time was shortened. However, it is harmful for the long-term compressive strength. XRD analysis disclosed the existence of more ettringite with the increase of the alkalinity. However, it appeared no difference between the formation of the ettringite in the cement paste with different alkalinity.


Document: 

SP326-99

Date: 

August 10, 2018

Author(s):

Viktor V. Granev, Nikolay G. Kelasiev, Emil N. Kodysh, Nikolay N. Trekin, and Ivan A. Terekhov

Publication:

Symposium Papers

Volume:

326

Abstract:

The paper considers a structural concept for multistorey buildings with free floor plan and the new type of large-size load-bearing structures. The characteristic of the structural concept is that the main spatial reinforcing member for adjacent storeys in building is a steel truss.

Such approach makes it possible to organize large-span space through the floor and it can be used for different purposes, for example, for shopping area, ice or roller-skating rinks, open space offices.

The authors designed structural node connections including resting of floor slab on truss chords, as well as joining of steel truss to shotcrete filled rectangular tubes.

Parameters of the most cost-efficient cast-in-place floor slab by corrugated deck have been determined.


Document: 

SP310-04

Date: 

March 17, 2017

Author(s):

Christopher K. Y. Leung

Publication:

Symposium Papers

Volume:

310

Abstract:

Research and applications of fibre-reinforced concrete (FRC) started in China during the early 1970’s, and have grown substantially over the last few decades. The first design guideline for fibre-reinforced concrete structures was developed in 1992 and subsequently updated in 2004. The design guideline focuses on steel fibre concrete, which is most commonly used in practical applications, but also has provisions for the use of synthetic fibres. In this paper, a general overview of the guideline will be provided. The design concepts for both serviceability and ultimate states are presented first. Various applications covered in the guideline, including fibre-reinforced structural or semi-structural components, pavements, bridges, hydraulic structures, shotcrete (for tunnel and repair) as well as waterproofing will then be described. By providing a concise summary of the guideline, we hope to convey an idea about the current state of fibre-reinforced concrete design in China.


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