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International Concrete Abstracts Portal

Showing 1-5 of 92 Abstracts search results

Document: 

SP228

Date: 

June 30, 2005

Author(s):

Editor: Henry G. Russell

Publication:

Symposium Papers

Volume:

228

Abstract:

SP-228CD This CD-ROM of Special Publication 228 contains the papers presented at the Seventh International Symposium on the Utilization of High-Strength/High- Performance Concrete that was held in Washington, D.C., USA, June 20-24, 2005. The symposium continued the success of previous symposia held in Stavanger, Norway, (1987); Berkeley, California (1990); Lillehammer, Norway, (1993); Paris, France, (1996); Sandefjord, Norway, (1999); and Leipzig, Germany, (2002). The symposium brought together engineers and material scientists from around the world to discuss topics ranging from the latest applications to the most recent research on high-strength and high-performance concrete. In the years since the first symposium was held in Stavanger, there has been worldwide growth in the use of both high-strength and high-performance concrete. In addition to more research and applications of traditional types of high-performance concrete, the use of self-consolidating concrete and ultra-high-performance concrete has moved from the laboratory to practical applications. This publication offers the opportunity to learn the latest about these developments.

DOI:

10.14359/16471


Document: 

SP228-57

Date: 

June 1, 2005

Author(s):

J.F. Davalos, I. Ray, Z. Sun, and T. Hong

Publication:

Symposium Papers

Volume:

228

Abstract:

Overlay systems have been used by many states for the protection of bridge decks, but the premature delaminations and failures have been observed in many cases. A comprehensive study was recently defined to investigate overlay performance in collaboration with the West Virginia Department of Transportation-Division of Highways (WVDOH). As part of a comprehensive program, the present study is concerned with the properties of four types of overlay mixtures and the interface bond strengths between the overlays and substrate concrete. All the materials used are of interests to WVDOH. Four overlay types were: silica fume modified concrete, latex modified concrete, fiber reinforced concrete and slag modified concrete. With these overlays, statistical design of experiments were conducted for the evaluation of the influences on bond strength of four factors: aggregate types, surface preparations, use of bonding slurry, and substrate age using a recently developed direct shear test apparatus. Results show that except for bonding slurry, all the parameters had strong influence on shear bond strength. The results of this study will serve the purpose of screening and selection of overlays from a large number of variables, and will finally help to develop guidelines by WVDOH for future implementations of concrete overlays in the field.

DOI:

10.14359/14512


Document: 

SP228-46

Date: 

June 1, 2005

Author(s):

J. Hegger, A. Sherif, and S. Gortz

Publication:

Symposium Papers

Volume:

228

Abstract:

The shear capacity of stirrup-reinforced concrete elements consists generally of a portion modeled by a truss Vtruss and an exceeding concrete contribution Vc. Recent research results assign a portion of the concrete contribution to the effect of aggregate interlock. After shear cracking, a relative displacement of the crack edges occurs activating friction forces upon the rough crack edges with increasing load. In such a model the concrete contribution is considered solely by a more flat strut inclination , and accordingly a truss model can describe the whole shear-capacity. In addition, the shear behavior of high strength concrete is different than ordinary concrete, presumable due to the different shear transfer mechanisms across the shear cracks. However, the experimental and theoretical investigations conducted show that the truss model only describes a part of the whole shear capacity. There is an exceeding remaining load-bearing system. Based on the research results a design model for shear is developed which is applicable for high performance as well as ordinary concrete.

DOI:

10.14359/14501


Document: 

SP228-39

Date: 

June 1, 2005

Author(s):

D. Konstantinidis

Publication:

Symposium Papers

Volume:

228

Abstract:

The present research evaluates the performance of reinforced concrete buildings made of high performance materials in earthquake prone areas through the parametric analysis of twenty-two buildings using a finite element approach. The concrete strength in the buildings varied from 50 MPa to 90 MPa and the reinforcement consisted of 500 MPa, 800 MPa and 1200 MPa steel. Among the building combinations considered, there were two that involved varying concrete strengths between the beam and column elements and different combinations of reinforcement steel. The design of the buildings was carried out for peak ground acceleration 0.25g according to the Eurocodes 2 and 8 for both ductility class ‘’Medium’’ and ‘’High’’. The nonlinear static (pushover) analysis technique was employed to assess the behavior of the RC buildings. The performance of the buildings designed for ductility class ‘’Medium’’ and ‘’High’’ under the design earthquake level corresponding to 0.25g and a selected collapse prevention level corresponding to 0.50g was very satisfactory. Considering the financial benefits resulting from the use of mixed concrete strengths in the beams and columns and their general performance under the two seismic events, the construction of RC buildings incorporating different material strengths appears to offer several potential benefits.

DOI:

10.14359/14494


Document: 

SP228-37

Date: 

June 1, 2005

Author(s):

E. Canbay, Z.B. Koru, G. Ozcebe, and U. Ersoy

Publication:

Symposium Papers

Volume:

228

Abstract:

Three series of tests were carried out to investigate the behavior and strength of high and normal strength concrete spiral columns under uniaxial compressive loading. Five columns with normal strength and fourteen high strength spiral columns were tested. Normal strength and high strength steel were used as spiral reinforcement. The main variables investigated were; (a) volumetric ratio (varied from 0.008 to 0.038) and spacing of spiral reinforcement, (b) ratio of gross to core area (varied between 1.05 and 1.45), and (c) strength of spiral reinforcement. Strength increase and ductility due to the presence of spiral reinforcement were investigated. When high strength concrete is used, the minimum spiral reinforcement required by ACI 318-02 results in extremely small spacing as the ratio of the gross to core area increases. Spacing of the spiral reinforcement can be increased to reasonable values if higher strength steel is used. During the tests it was observed that the columns having high strength spiral reinforcement behaved well, and had adequate ductility.

DOI:

10.14359/14492


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