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International Concrete Abstracts Portal

Showing 1-5 of 11 Abstracts search results

Document: 

SP245

Date: 

April 1, 2007

Author(s):

Editors: Raafat El-Hacha and Sami H. Rizkalla / Sponsored by: ACI Committee 440

Publication:

Symposium Papers

Volume:

245

Abstract:

Fiber-reinforced polymer (FRP) composite materials have been proposed for use in lieu of steel for prestressing applications. The use of FRP has been growing rapidly in recent years. FRP provides options and benefits not available using traditional materials. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. In 2005, ACI Committee 440, Fiber Reinforced Polymer Reinforcement, published ACI 440.4R-04, “Prestressing Concrete Structures with FRP Tendons,” as one of several guides in ACI’s Emerging Technology Series to provide recommendation for the use of FRP materials based on available test data, technical reports, and limited field applications. The aim of this document is to help practitioners implement FRP technology while providing testimony that design and construction with FRP materials systems is rapidly moving from emerging to mainstream technology. In addition to this publication, ACI Committee 440 organized a special technical session entitled “Case Histories and Use of FRP for Prestressing Applications” at the ACI Fall 2006 Convention in Denver, Colorado, on November 8, 2006. The session provided a worldwide state-of-the-art forum for researchers, civil/structural engineers, contractors, consultants, practitioners, and regulatory authorities to exchange recent advances in both research and practice. The technical papers presented at the session and published in this volume included the most recent analytical and experimental research work as well as selected field applications, design, and construction guidelines. The session was well attended, and generated substantial technical discussion and exchange of new technology. This Special Publication consists of 10 papers, some of which were presented in the special session sponsored by ACI Committee 440 at the ACI Fall 2006 Convention. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-245

DOI:

10.14359/18613


Document: 

SP245-10

Date: 

April 1, 2007

Author(s):

Z. Wu, K. Iwashita, and X. Sun

Publication:

Symposium Papers

Volume:

245

Abstract:

Fiber reinforced polymer (FRP) composites have been widely used as externally bonded reinforcements to strengthen or rehabilitate deteriorated concrete structures. However, premature debonding failure due to the limitation of bond at the FRP-concrete interface is often encountered which limits FRP material potential for flexural strength increase. To minimize debonding failures and mechanical damage such as vehicular traffic and impact, etc., near surface mounted (NSM) FRP technology has emerged as another structural rehabilitation method. This study aims at evaluating a new strengthening using prestressed NSM carbon fiber reinforced polymer (CFRP) tendons. Although NSM FRP tendons are less susceptible to debonding than externally bonded FRP laminates, the load-carrying capacity of RC structures with NSM reinforcements is still likely to be governed by "premature" debonding failure. An experimental program with design variables such as prestress level and bonding agents was carried out to study the strengthening performance in terms of stiffness, cracking behavior and load-carrying capacity. The experimental results are presented and discussed in this paper. Experimentally validated bonding method is also proposed in this study.

DOI:

10.14359/18768


Document: 

SP245-03

Date: 

April 1, 2007

Author(s):

M.M. Reda Taha, K.-K. Choi, M. Tait, and S.L. Lissel

Publication:

Symposium Papers

Volume:

245

Abstract:

This paper summarizes the experimental and analytical research work for simulating a recently built retaining masonry wall post-tensioned with carbon fiber reinforced polymer (CFRP) tendons. A group of creep and shrinkage experiments on masonry prisms similar to that used in the masonry diaphragm wall is discussed. A theoretical investigation using numerical models to describe the time-dependent deformations of the masonry diaphragm wall was performed. Creep coefficients based on the experiments are compared to common creep values based on other research investigations and on well established code models. A finite element model of the masonry diaphragm wall was developed incorporating the non-linear time-dependent properties of masonry to investigate the long-term deformations and stress redistribution in the walls over time. Deformations of the walls are compared to observations from a continuous monitoring system observing the lateral deformations and strains and stresses of the wall.

DOI:

10.14359/18761


Document: 

SP245-04

Date: 

April 1, 2007

Author(s):

K. Soudki, A. Al-Mayah, and A. Plumtree

Publication:

Symposium Papers

Volume:

245

Abstract:

A new design concept, experimental assessment and numerical simulation of a wedge anchor system for prestressing CFRP rods are presented. This compact and reusable anchor required no presetting load and was capable to carry the full design strength of the rod. It consists of an outer cylinder (barrel), a number of wedges, and a soft metal sleeve. The contacting surfaces of the wedges and barrel have a circular profile along the length of the anchor. Monotonic tensile testing was carried out. The relationship of the tensile load and displacement of the rod was established. A three dimensional finite element model was developed to simulate the anchor components. Contact pressure on the rod surface for different presetting distances was low at the loading end of the rod and increased at the free end. Tensile load and displacement relationships was found and compared to that of the experimental investigation.

DOI:

10.14359/18762


Document: 

SP245-02

Date: 

April 1, 2007

Author(s):

C.C. Choo, I.E. Harik, and H. Gesund

Publication:

Symposium Papers

Volume:

245

Abstract:

An analytical investigation was conducted to study the long term effects in the strength interaction (Pn-Mn) behavior of non-slender concrete columns prestressed with fiber reinforced polymer (FRP) tendons. Two long term concrete stress-strain behaviors were used and compared to the instantaneous or short term load. The expressions for the strength interaction of FRP prestressed concrete columns are derived from the strain compatibility and equilibrium conditions and are presented herein. Based on this preliminary investigation, it was concluded that the long term loadings and the tensile creep rupture of FRP tendons considerably influence the column strength. The results of the column cross sections considered herein show that disregarding long term effects may be conservative provided that rupture of FRP tendons does not occur in the columns.

DOI:

10.14359/18760


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