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International Concrete Abstracts Portal

Showing 1-5 of 17 Abstracts search results

Document: 

SP133-05

Date: 

September 1, 1992

Author(s):

B. Vijaya Rangan

Publication:

Symposium Papers

Volume:

133

Abstract:

The paper presents a summary of treatment of serviceability design in the current Australian Code, AS 3600-1988. The backgrounds to the code rules with regard to control of deflection and crack widths are presented. The provisions for durability design of concrete structures are also discussed.

DOI:

10.14359/3148


Document: 

SP133-03

Date: 

September 1, 1992

Author(s):

M. Z. Cohn an Z. Lounis

Publication:

Symposium Papers

Volume:

133

Abstract:

An approach that integrates serviceability control with the ultimate limit state (ULS) design is presented. Each serviceability limit (SLS) is related to an amount of moment redistribution that corresponds to the permissible values of the crack widths, deflections, and stresses under service conditions. A design that simultaneously satisfies the specified ULS and SLS criteria may be obtained if the assigned moment redistribution percentages y do not exceed the recommended redistribution limits for serviceability control. The proposed approach integrates all relevant design criteria via the moment redistribution percentage y, and may be used within the framework of ACI 318-89 or other standard codes. The approach allows a direct extension to existing nonlinear, multicriteria, and optimal design methods.

DOI:

10.14359/3143


Document: 

SP133-02

Date: 

September 1, 1992

Author(s):

Andrew Scanlon and Ross B. Corotis

Publication:

Symposium Papers

Volume:

133

Abstract:

The American Concrete Institute, Standard 318, Building Code Requirements for Reinforced Concrete have permitted the design of reinforced concrete structures in accordance with limit state principles using load and resistance factors since 1963. A probabilistic assessment of these factors and implied safety levels is made, along with consideration of alternate factor values and formats. A discussion of issues related to construction safety and safety of existing structures is included.

DOI:

10.14359/3138


Document: 

SP133-01

Date: 

September 1, 1992

Author(s):

Edward G. Nawy

Publication:

Symposium Papers

Volume:

133

Abstract:

This paper presents the state of the art in evaluating flexural crack development and control of macrocracking. It is based on extensive research over the past five decades, in the United States and overseas, in the area of macrocracking in reinforced and prestressed concrete beams and in two-way action slabs and plates With the advent of limit states theories that generally lead to economic proportioning of members, control of cracking has become essential to maintain the integrity and esthetics of concrete structures. The trend is stronger than ever in better utilization of current concrete strengths, use of higher strength concretes that include super-strength concretes of 20,000 psi (138 MPa) compressive strength and higher, and increased application of prestressed concrete concepts. All these trends require closer control of serviceability requirements in cracking and deflection. Design expressions are given for the control of cracking in reinforced concrete beams and thick one-way slabs; prestressed, pretensioned, and post-tensioned flanged beams; and reinforced concrete two-way action structural floor slabs and plates. In addition, recommendations are given for the maximum tolerable flexural crack widths in concrete elements.

DOI:

10.14359/3131


Document: 

SP133-07

Date: 

September 1, 1992

Author(s):

Stephen J. Sopko

Publication:

Symposium Papers

Volume:

133

Abstract:

Reinforced concrete floor systems must be analyzed for deflections to minimize serviceability problems such as excessive deflections. Member depths should be based on serviceability requirements as well as stress, especially when long-term deflection must be considered. The ACI equations for member depth may not always be adequate to prevent excessive long-term deflections of reinforced concrete floor members where heavy sustained loads are present. Two case studies are presented focusing on floor systems which have exhibited excessive deflections. From this investigation and analysis, proper design, detailing, and construction practices will be discussed to minimize serviceability problems. Care must be taken in analyzing and designing floor systems which support heavy sustained loadings or masonry.

DOI:

10.14359/3159


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