International Concrete Abstracts Portal

Showing 1-5 of 13 Abstracts search results

Document: 

SP161-08

Date: 

April 1, 1996

Author(s):

M. A. Bhatti, B. Lin, and J. P. Idelin Molinas Vega

Publication:

Symposium Papers

Volume:

161

Abstract:

The usual design practice for analysis of reinforced concrete slabs with openings is to neglect holes if their area is less than 10- 12% of the total slab area. This practice is based in part on studies conducted in early sixties regarding the effects of holes on the elastic behavior of plates. A literature survey revealed no specific studies regarding the effects of holes on deflection and strength of reinforced concrete slabs with openings. This paper presents a numerical study of the effects of openings of different sizes on the behavior of reinforced concrete slabs. A nonlinear finite element model for reinforced concrete slabs is developed using three dimensional brick elements taking into account cracking and crushing of concrete, and plasticity of both reinforcement and concrete. Distributed and concentrated loads are applied to slabs until collapse. Results show that when slabs are subjected to uniformly distributed loads, the openings do not have much effect on their strength and serviceability. The openings should be considered, however, when designing slabs subjected to concentrated loading where the opening ratios are larger than 2.5% .

DOI:

10.14359/10055


Document: 

SP161-01

Date: 

April 1, 1996

Author(s):

Russel S. Fling

Publication:

Symposium Papers

Volume:

161

Abstract:

An 8000 sq ft (740 sq m) portion of an industrial building was load tested and vertical movements measured to an accuracy of 0.0043 in. (0.11 mm). Measured deflections were compared to those estimated before testing and to revised estimates after testing. Using simplified procedures and judicious estimates of design parameters, computed deflection normally should be within 40 percent of actual average deflection; the coefficient of variation should be less than 50 percent. With a complete and accurate selection of design parameters, the accuracy and statistical variability can be improved to 15 and 40 percent, respectively.

DOI:

10.14359/1436


Document: 

SP161-02

Date: 

April 1, 1996

Author(s):

H. Solanki

Publication:

Symposium Papers

Volume:

161

Abstract:

Presents American and European design provisions for the control of deflections. Both minimum and computed versus allowable deflections of CEB-FIP Model Code (MC 1990) and ACI Code (ACI 318-89) are considered. The methods in both codes for predicting deflections and applying span/depth-thickness ratio are evaluated in design examples. Based on the simplified method for computing the long term deflection, no significant difference is found between the codes.

DOI:

10.14359/1437


Document: 

SP161

Date: 

April 1, 1996

Author(s):

Editors: Edward G. Nawy and Debrethann R. Cagley

Publication:

Symposium Papers

Volume:

161

Abstract:

SP-161 All the papers presented in this publication were reviewed by recognized experts in accordance with the ACI review procedures. It is hoped that designers, constructors, and codifying bodies will be able to draw on the material presented in this volume in conjunction with the ACI 435 Committee Report "Control of Deflection in Concrete Structures", in improving the long-term deflection behavior and performance of concrete constructed facilities.

DOI:

10.14359/14201


Document: 

SP161-03

Date: 

April 1, 1996

Author(s):

I. N. Robertson and C. J. Ambrose

Publication:

Symposium Papers

Volume:

161

Abstract:

The effective beam width method is used extensively for two- and three-dimensional analysis of flat plate structures subjected to combined gravity and lateral loading. Typically, the member stiffnesses are assumed constant throughout each span. This approach is shown to produce unreliable estimates of lateral drift and slab bending moments when compared with the results of a previously reported experimental program performed by researchers at the University of California at Berkeley. This paper presents a two-beam effective width model in which different section properties are used in negative and positive bending regions of the slab. Proposed slab stiffnesses for use in this model are based on a correlation between the experimental data and analytical analysis results. The application of the two-beam model using the proposed slab stiffness factors to a typical flat-plate structure is demonstrated in a worked example.

DOI:

10.14359/1439


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