International Concrete Abstracts Portal

Showing 1-5 of 11 Abstracts search results

Document: 

SP183-01

Date: 

May 1, 1999

Author(s):

S. Simmonds

Publication:

Symposium Papers

Volume:

183

Abstract:

The justification for using elastic frame analogies to determine design moments in two-way slab systems is discussed. A brief history of two-way reinforced concrete slab design leading to the current code procedures is presented. This history includes a description of the various elastic frame analogies that have existed in past codes, the reasons for changes and the research leading to improved frame analogies. This is followed by a critical review of the Equivalent Frame Method in the current code with suggestions for improving and simplifying provisions for elastic frame analogies in future codes.

DOI:

10.14359/5531


Document: 

SP183-02

Date: 

May 1, 1999

Author(s):

S. Woodson and T. Krauthammer

Publication:

Symposium Papers

Volume:

183

Abstract:

Traditionally, U.S. Government agencies have developed and maintained manuals for the design of structures to resist severe dynamic loads, I.e. blast effects. However, such manuals have been primarily directed toward structures of a military nature, and relatively little attention has been given to the design of civilian buildings to resist blast effects. The lack of concern for the blast resistance of buildings is no surprising in that the threat has been minimal. Although some design guidance for blast resistance has been available to the general public, the primary users have been petro-chemical industries that are aware of potential accidental explosions related to their normal operations (I.e., chemical plants). Historically, general design guidance, such as that of the American Concrete Institute's Committee 318 (ACI, 1995) (1) has served the public well. However, two recent events, the World Trade Center and the Alfred P. Murrah explosions, have heightened awareness in the United States of the potential need to consider blast effects in the design of some buildings. The discussion presented herein summarizes existing blast-resistant design approaches and addresses issues that are critical to the development of buildings with improved resistance to severe dynamic loads. Emphasis is given to the design and behavior of reinforce concrete structures.

DOI:

10.14359/5532


Document: 

SP183-03

Date: 

May 1, 1999

Author(s):

S. Megally and A. Ghali

Publication:

Symposium Papers

Volume:

183

Abstract:

Design of connections of columns to flat slabs to ensure safety against punching failure is presented. The connections transfer shearing forces and moments between the columns and slabs. The objective is to cover the design procedure in most practical situations including: interior, edge and corner columns, prestressed and nonprestressed slabs, slabs with openings and slabs with shear reinforcement. The ACI 318-95 code requirements are adhered to where applicable. The designs are demonstrated numerical examples. Design of shear reinforcement in raft slabs, footings and walls subjected to concentrated horizontal forces is also discussed.

DOI:

10.14359/5533


Document: 

SP183-04

Date: 

May 1, 1999

Author(s):

W. Gamble

Publication:

Symposium Papers

Volume:

183

Abstract:

The yield line theory for the determination of the ultimate load for slab structures is a well documented method of analysis. The basics of the method, which can be implemented using either equations of equilibrium or virtual work equations, are briefly reviewed, using a rectangular panel with all edges supported. A more complex single panel is then considered, followed by a brief review of multi-panel failure mechanisms. The potential importance of in-place forces, both compression and tension, is noted. These forces, which can be thought of in arch or dome terms for compression and catenaries for tension, have led to slab failure loads much greater than can be explained on the basis of flexure alone in many test. This phase of behavior is seldom usable for normal design of civil structures, but may be very useful and helpful in trying to understand the behavior of and design structures to resist blast loadings.

DOI:

10.14359/5534


Document: 

SP183-05

Date: 

May 1, 1999

Author(s):

S. Simmonds

Publication:

Symposium Papers

Volume:

183

Abstract:

This paper review the requirements of the upper-and-lower-bound theorems of plasticity as they apply to continuous reinforced concrete slabs. The background and assumptions leading to Johansen's yield line theory (upper-bound) and Hillerborg's strip methods (lower-bond) are presented and the advantages and disadvantages of these two methods are discussed. The segment equilibrium method proposed by Wiesinger is described and presented as an alternative procedure. It is concluded that the theory of plasticity provides a practical solution for the design of continuous reinforced concrete slabs, particularly for slab systems with irregular support geometry.

DOI:

10.14359/5535


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