International Concrete Abstracts Portal

International Concrete Abstracts Portal

The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Showing 1-5 of 23 Abstracts search results

Document: 

SP120-19

Date: 

June 1, 1990

Author(s):

Michael E. Kreger Gregory L. Fenves, and Kamal C. El-Habr

Publication:

Symposium Papers

Volume:

120

Abstract:

A nonlinear finite element analysis was conducted to examine the full range of behavior of segmentally precast box girder construction with external post-tensioning tendons. A primary objective of the study was to examine the effect of dry joints (without epoxy) on the strength and ductility of box girder construction. A secondary consideration was the influence of supplemental bonded internal tendons on the behavior of the structure.

DOI:

10.14359/2859


Document: 

SP120-20

Date: 

June 1, 1990

Author(s):

Jeanne M. Nagele, Sankar C. Das, and Reda M. Bakeer

Publication:

Symposium Papers

Volume:

120

Abstract:

The purpose of this investigation was to examine the forces developing in the dome of a prestressed concrete nuclear containment structure due to prestressing of vertical tendons. A computer program was developed for personal computers to evaluate the effect of prestressing forces. A parametric study was conducted, using the program, to examine the effects of dimensions, prestressing force, properties of tendons, etc. on the resulting stresses in the dome.

DOI:

10.14359/2862


Document: 

SP120-21

Date: 

June 1, 1990

Author(s):

Eilhard WoelfelI

Publication:

Symposium Papers

Volume:

120

Abstract:

In the near future, prestressed concrete structures will be designed in Europe according to Eurocode 2 (EC 2). The EC 2 principles governing the design of structures with bonded tendons and with external tendons are given in this paper, and a comparison is made between the structural behavior of the two different types of structures. It is shown that the reliability of both is comparable if the characteristic strain due to prestressing is introduced in the calculations.

DOI:

10.14359/2865


Document: 

SP120-22

Date: 

June 1, 1990

Author(s):

A. S. Nowak, A. E. Naaman, and S. C.Ting

Publication:

Symposium Papers

Volume:

120

Abstract:

Evaluation of existing bridges is an important part of the strategy of dealing with the deteriorating infrastructure. Load and resistance parameters are random variables because of uncertainties in load components, material properties, and dimensions. Therefore, the reliability of a structure is a convenient measure of its performance. The load and resistance models are first summarized. The major load components in bridges are dead load and live load. The live load model is based on the weigh-in-motion studies. Girder distribution factors are derived using special computer procedures for bridge analysis. Behavior of composite girders is considered using a nonlinear model. The basic characteristic of the section is the moment-curvature relationship. The reliability is measured in terms of the reliability index. The approach is demonstrated on evaluation of a prestressed concrete girder bridge. Three cases are considered: original design condition, damaged with corroded strands, and repaired by external prestressing. The load components and load-carrying capacities are evaluated and then the reliability indexes are calculated for the three cases.

DOI:

10.14359/2868


Document: 

SP120-14

Date: 

June 1, 1990

Author(s):

B. G. Rabbat and K. Sowlat

Publication:

Symposium Papers

Volume:

120

Abstract:

The behavior of two segmental concrete girders incorporating external tendons was compared to that of a similar girder with internal tendons. The girders were 31 ft long and consisted of 11 match-cast segments. Test variable was the location of the tendon ducts. In the first girder, the ducts were embedded in the girder cross section. The ducts of the second girder were external to the concrete cross section except at pier segments and intermediate deviation diaphragms. The third girder was similar to the second except that portions of the external ducts were embedded in a second-stage concrete cast. The segments included multiple shear keys and were dry jointed. All ducts were grouted. Each girder was simply supported over a 30-ft span and loaded statically to destruction under a two point load. The first and third girders attained their respective flexural strengths predicted by the classic bending theory for monolithic girders with bonded tendons. The second girder exceeded the flexural strength predicted by the provisions of the AASHTO specifications for members with unbonded tendons.

DOI:

10.14359/3248


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