ABOUT THE 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.

International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

Document: 

SP210-08

Date: 

April 1, 2003

Author(s):

C. Kassem, E. El-Salakawy, and B. Benmokrane

Publication:

Symposium Papers

Volume:

210

Abstract:

This paper presents the test results of 14 full-scale concrete beams. The beams were 3300 mm long with a rectangular cross-section of 200-mm width and 300-mm depth. Twelve beams were reinforced with carbon FRP composite bars and two reinforced with steel as control. Two newly developed types of CFRP bars with different surface textures were considered: the sand-coated ISOROD bars and the ribbed-deformed C-BAR. The beams were tested to failure in four-point bending over a clear span of 2750 mm. The results presented focus on the deflection behaviour of beams reinforced with CFRP bars, which have different bond, elasticity modulus, strain, and strength characteristics. The test results were compared to the predictions of some of the available models (ISIS-M03-01 design manual, ACI 440.1R-01 guidelines, and Razaqpur model). Based on the findings of the study, the validity of the design guidelines and the effectiveness of using the new CFRP bars as reinforcement for concrete beams were established.

DOI:

10.14359/12578


Document: 

SP210-10

Date: 

February 1, 2003

Author(s):

J. R. Yost, S. P. Gross, and D. W. Dinehart

Publication:

Symposium Papers

Volume:

210

Abstract:

Deflection behavior of high strength concrete (HSC) flexural members reinforced with glass-fiber polymer bars (GFRP) is investigated. Because serviceability plays a significant role in establishing design acceptance for GFRP reinforced concrete beams, accurate modeling of flexural stiffness is critical and he effect of influencing parameters must be considered. This study accounts ofr variations in reinforcement ratio ( r ) for HSC beams. Experimental results from twelve simply supported concrete beams reinforced with GFRP bars are compared with published deflection models to establish analytic accuracy. All samples have a hear-span-to-depth ratio of 9.4 and are overreinforced with respect to a balanced strain design. Results show that the ACI 318 and ACI 440 effective moment-of-inertia expressions greatly overestimate flexural stiffnes, with the degree of inaccuracy dependent upon on reinforcement ratio.

DOI:

10.14359/12580


Document: 

SP210

Date: 

February 1, 2003

Author(s):

Editor: NJ Gardner

Publication:

Symposium Papers

Volume:

210

Abstract:

SP-210 This Symposium Publication contains papers presented during the 2002 ACI Spring Convention in Detroit, including six papers related to predicting the deflections of concrete members reinforced with fiber-reinforced polymer (FRP) reinforcement: one paper describes two field investigations, two unique laboratory investigations, a paper on estimating the errors in calculating deflections of high-performance concrete slabs, and a comparison of the ACI and EC2 deflection provisions. This volume should be read in association with Symposium Publication SP-203, Code Provisions for Deflection Control in Concrete.

DOI:

10.14359/14020


Document: 

SP210-03

Date: 

February 1, 2003

Author(s):

S. Teng and Tavio

Publication:

Symposium Papers

Volume:

210

Abstract:

A procedure for calculating the instantanious deflections of irregular reinforced concrete flat plate floors is presented. The method is applicable throughout the entire loading stages from the uncracked state to the fully cracked state and even up to the ultimate limit state. Based on the familiar effective moment of inertia approach, the proposed procedure also uses the ACI Direct Design Method with some generalization. The total static moment in a particular design strip will be distributed to the midspan and support sections according to the distribution coefficients of the ACI Direct Design Method, taking into account column sizes and irregularity of slab geometry around the edge slab-column connections. At high loads, the modulus of elasticity of the concrete can be reduced to better reflect the nonlinear behavior of concrete slabs. The definitions of effective span, width of design strips, torsional rigidity of transverse torsional members, and column sizes and orientations will be generalized as far as practical. The accuracy of the proposed procedure has been compared with measured deflections of two multiple-panel irregular flat plate floors tested at Nanyang Technological University - Singapore. The comparison between the calculated deflections and the experimetnal values show that the proposed procedure is reasonably accurate.

DOI:

10.14359/12573


Document: 

SP210-04

Date: 

February 1, 2003

Author(s):

M. M. Reda Taha and M. A. Hassanain

Publication:

Symposium Papers

Volume:

210

Abstract:

Although limit state design blends both serviceability and strength limit states, most engineers tend to be less confident in serviceability limit states than in strength limit states, especially when deflections of reinforced concrete slabs are considered. A major source of the lack of confidence is the existence of many uncertain variables in calculating slab deflections of reinforced concrete slabs are considered. A major souce of this lack of confidence is the existence of many uncertain variables in calculating slab deflections such as concrete properties (e.g., modulus of elasticity, modulus of rupture), creep coefficient, curing regime and duration, and the existence of construction loads. The absence of any reliability ocefficients in deflection calculations or deflection limits gives the impression that engineers are expected to evaluate the exact deflection that will take place on site. To make matters worse, the introduction of high-performance concrete (HPC) has increased the uncertainty about concrete properties. While HPC enhances the overall material's performance, it is usually reported to have higher shrinkage strains, and it is more susceptible to plastic shrinkage than normal-strength concrete (NSC). The possible reduction of curing periods from the recommended one week to two or three days due to tight construction schedules can result in substantial microcracking which would significantly reduce the concrete modulus of rupture. Therefore, serviceability performance is dependent on many inter-related factors that the engineer cannot control in the design assumptions. Unless the band of errors in deflection calculations is known to the engineer, the lack of confidence in deflection claculations will always be there. This paper describes a mathematical model utilizing the theory of error propagation to predict the error in the calculated deflections of simply-supported, one-way reinforced concrete slabs. Parametric studies have been carried out to examine the effect of changing the concrete properties as a result of changed site conditions on the accuracy of the estimated deflections.

DOI:

10.14359/12574


123

Results Per Page