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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 19 Abstracts search results
Document:
SP246
Date:
September 1, 2007
Author(s):
Editors: John Gardner and Mario A. Chiorino
Publication:
Symposium Papers
Volume:
246
Abstract:
SP-246CD This CD-ROM is a collection of papers prepared for a session held at the ACI 2007 Fall Convention in Puerto Rico on the effects of shrinkage and creep of concrete. The papers are organized into four groups: 1) design, construction, and behavior of bridge structures; 2) effect of concrete shrinkage and creep on the design and construction of tall buildings; 3) deflection and cracking serviceability of slabs, beams, and walls; and 4) other problems and basic questions.
DOI:
10.14359/18914
SP246-12
I. Ujike, R. Sato, I. Maruyama, M. Tanimura, and M. Suzuki
The effect of shrinkage on short-term and long-term flexural deformation and crack width of structural concrete members is investigated numerically and experimentally. The numerical analysis was performed by solving simultaneous differential equations relating to bond slip based on bond stress-slip relationship. The equations were formulated for an element between adjacent two cracks, taking shrinkage, creep, time dependent of bond and tension softening based on fictitious crack model into consideration. To verify the present method, load tests were carried out on structural concrete members with 200mm wide x 250mm high section made of conventional high shrinkage concrete and expansive high strength concrete, in which curvature and crack width were measured in a constant bending moment zone with 800mm length. In addition to this, creep and shrinkage tests were also performed. The following conclusions are drawn from the present study; (1) Tension in concrete at a cracked section contributes dominantly to decreasing the stress in a tension reinforcing bar resulting in enhancing the flexural stiffness and in decreasing the flexural crack width, when the stress in the tension reinforcing bar is below 150 N/mm2 and the tension reinforcing bar ratio is below 1.5%. (2) Flexural crack widths increase with time after the application of sustained loading mainly due to loss of tension stiffening at cracked section, which is caused by shrinkage. (3) The above conclusions are explained by the present method.
10.14359/18987
SP246-08
W.F. Baker, D.S. Korista, L.C. Novak, J. Pawlikowski, and B. Young
The Burj Dubai tower, which is currently under construction, will be the world’s tallest structure. This paper addresses the structural system utilized for the Burj Dubai tower and the structural design implications of creep and shrinkage of the high performance reinforced concrete vertical load carrying elements.
10.14359/18983
SP246-09
J.I. Lee, A. Scanlon, and M.A. Scanlon
This paper describes laboratory tests on nine simply supported one-way reinforced concrete members subjected to immediate live load and sustained load. The specimens are 12 ft (3.66 m) long supported on an 11 ft. (3.35 m) span, 12 in. (304.8 mm) wide, and 5 in. (127 mm) deep with two #3 bars at an effective depth of 4 in. (101.6 mm) providing a reinforcement ratio of 0.0046. The specimens were moist cured for up to seven days. Three specimens each were removed from the forms and subjected to immediate live load at three days, seven days, and twenty eight days followed by sustained load due to self weight. Each specimen was subjected to immediate full live load again after six months. Applied load and mid-span deflections were recorded under immediate live load and sustained load. The test results demonstrate the effect of shrinkage restraint provided by embedded bars on the flexural cracking of the specimens under applied load, as well as effects of early age loading on time-dependent response. Calculated deflections based on effective moment of inertia for immediate deflection and long time multipliers for time-dependent deflection are compared with measured deflections.
10.14359/18984
SP246-10
P.H. Bischoff and R.D. Johnson
This paper investigates the influence of shrinkage on tension stiffening in flexure and subsequent effect on short-term deflection in beams and slabs. While shrinkage is typically thought of as being a long-term effect, it can also have a significant effect on the initial short-term response (particularly for beams tested in the laboratory that are used to develop and validate theoretical models for predicting deflection). Shrinkage that takes place before the beam is loaded is locked into the member response, having the effect of reducing the cracking moment (caused by tensile stresses that develop in the concrete from restraint to shrinkage by the reinforcement) and causing a shift in the bare bar response of the cracked transformed section. The lower cracking moment and shift in the cracked member response both work together to increase the immediate (short-term) deflection of a member loaded in flexure. Neglecting this influence leads to a perception of reduced levels of tension stiffening and also affects comparison of theoretical deflection models with experimental results.
10.14359/18985
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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.
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