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International Concrete Abstracts Portal

Showing 1-5 of 17 Abstracts search results

Document: 

SP231-04

Date: 

October 1, 2005

Author(s):

W.N. Marianos, Jr.

Publication:

Symposium Papers

Volume:

231

Abstract:

The growth of prestressed concrete development in the United States wasgreatly influenced by the publications available to practicing engineers. A number ofthe early books and publications on prestressed concrete are reviewed and discussedin this paper. Pioneers of prestressed concrete development are viewed through theirpublications and the role they played in promoting prestressing. Two key conferences(in 1951 and 1957) are also considered. Figures include samples of important passagesfrom the texts considered. Through all of these, some of the flavor and personalities ofthis important period can be experienced.

DOI:

10.14359/14920

Document: 

SP231-16

Date: 

October 1, 2005

Author(s):

R.W. Furlong, Ph.D., FACI, HonMASCE

Publication:

Symposium Papers

Volume:

231

Abstract:

Career highlights are presented regarding Ned H. Burns, now recognized asa “Legend of the Prestressed Concrete Industry.” Dr. Burns’ childhood, family,marriage, military service, and education are described briefly. His development inresearch and teaching is chronicled as awards began to accumulate. Leadershippositions are indicated while awards continued in recognition of his excellence instructural engineering education and practice.

DOI:

10.14359/14932

Document: 

SP231-05

Date: 

October 1, 2005

Author(s):

K.W. Kramer

Publication:

Symposium Papers

Volume:

231

Abstract:

A survey of the first uses of precast, prestressed or post-tensioned foldedplates roofs show that this structural system start in the 1950’s and end in the 1970’s Ahistoric perspective of this structural system will be presented starting in the 1950’s andending in the 1970’s. While prestressed concrete was making a break-through in theUnited States with the Walnut Lane Bridge in Philadelphia, PA, Europe was usingprestressed concrete in various types of structural systems. One of these systems wasthe folded plate roof system. Approximately a decade later in the United States, theCloverleaf Lanes Bowling Alley in Dade County, Florida used the same application inwhich the corrugated slab spanned 120 feet and extending transversely 286 feet. In1962, this system of folded plate shells went from long span structures to being used inroof structures for dormitories at Washington State University. The main beams for thedormitories were pretensioned in a factory, while the secondary beams were post-tensioned on site. During the 1970’s, precast folded plate structures were beingconstructed throughout the United States for various types of buildings, one notablestructure is the Hangar for Allegheny Airlines at Logan Airport, Boston, Massachusetts.Then they disappeared in the United States. Some Possible reasons why folded plateconstruction stopped are numerous but the two main factors are the architecturalsolution, and the lack of understanding of folded plate structures on the part ofengineers and architects.

DOI:

10.14359/14921

Document: 

SP231-08

Date: 

October 1, 2005

Author(s):

P.R. Gupta

Publication:

Symposium Papers

Volume:

231

Abstract:

Friction losses contribute about 50% of the total losses in post-tensionedconstruction. The original loss coefficients that were derived for earlier post-tensioningsystems are still being used in the ACI recommendations for unbonded construction.Some of these systems have not been used in the industry for almost 30 years.This paper presents a review of the current ACI recommendations of friction losses inunbonded construction. The paper also describes the theoretical development of asimple field technique to determine the curvature and wobble coefficients under fieldconditions. Results from initial testing are compared with the ACI recommendations andindustry practice.

DOI:

10.14359/14924

Document: 

SP231-07

Date: 

October 1, 2005

Author(s):

A.E. Naaman

Publication:

Symposium Papers

Volume:

231

Abstract:

Assuming the prestressing force remains constant with applied externalload, the analysis of beams prestressed with unbonded tendons under service loads,where the section is uncracked, is no different than the analysis of beams with bondedtendons. However, after cracking, significant differences emerge, the most importantof which is that the stress in the unbonded tendon is member dependent, that is, itdepends on the deformation of the member, while the stress in the bonded tendon issection dependent, that is, it depends on the curvature of the section. This causes thestress in unbonded tendons to be significantly smaller than that for bonded tendons,and that is particularly important at nominal bending resistance.This paper summarizes the analysis procedure for beams prestressed with unbondedtendons at service and ultimate limit states; it focuses in particular on three problems:1) how to analyze a beam in the elastic uncracked range of behavior; 2) how to analyzea beam in the elastic cracked range of behavior; and 3) how to analyze a beam atnominal bending resistance.

DOI:

10.14359/14923

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