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Home > Publications > 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.
Showing 1-5 of 22 Abstracts search results
Document:
SP284
Date:
March 1, 2012
Author(s):
Editors: Peter H. Bischoff, Eric Musselman, Shawn Gross, and Hani Nassif / Sponsored by: ACI Committee 435 and ACI Committee 348
Publication:
Symposium Papers
Volume:
284
Abstract:
This CD-ROM contains 21 papers that were presented at sessions sponsored jointly by Committee 435 & 348 at the ACI Fall 2011 Convention in Cincinnati, Ohio. The papers encompass a broad overview on the important issues related to serviceability and safety of structures from both a theoretical and design perspective. There are 15 papers on serviceability related to deflection and cracking, an additional 5 papers on topics related to various aspects of safety, and 1 paper on sustainability issues. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-284
DOI:
10.14359/51683715
SP284-18
Jonathan Hirsch, Flora Calabrese, Eamonn Connolly, and Allan Bommer
Today’s slab designers face a quandary – economic efficiency demands the use of very thin slabs; however the deflection performance of these slabs is difficult to predict. Exacerbating the situation is that the construction methods and sequences to be utilized are unknown at the time of design. This paper looks at the predictions of several deflection calculation methods and then compares them to actual measured deflections in both the laboratory and field. The variability of deflections and the reasonable range of predictions are also discussed concluding with recommendations for design practice utilizing off-the-shelf software.
10.14359/51683813
SP284-19
Robert L. Vollum
The thickness of reinforced concrete slabs is usually governed by the need to limit deflections in service to avoid damage to finishes and partition walls. Deflection control has become more important over recent years due to requirements for longer spans and more economic use of materials as well as design method developments. It is well established that long-term slab deflections can be increased by early age construction loading and cracking induced by restrained shrinkage. The author has previously shown that long-term slab deflections in the European Concrete Building at Cardington were governed by construction loading. This paper examines the influence of short term peaks in loading on long term curvatures in slabs subject to sustained loading. A simplified method is proposed for taking account of the effects of construction loading in deflection calculations with Eurocode 2. The method is validated using laboratory data from tests on simply supported slabs carried out at Imperial College London.
10.14359/51683814
SP284-15
Admasu S. Desalegne and Adam S. Lubell
The ACI 318-08 design code provides a direct computation method for deflection control of slender reinforced concrete beams. This method is based on the Navier-Bernoulli theory where shear deformations are presumed to be minimal. Using a database of twenty slender reinforced concrete beams with shear reinforcement, this paper reports on an analytical study which compared the service deflection predictions from the ACI 318-08 model, with predictions from a proposed MCFT-based sectional analytical deflection model and two MCFT-based numerical models, namely Response-2000 and VecTor2. The MCFT-based models all consider the deflection resulting from shear deformations in addition to the Navier-Bernoulli deflections. Emphasis in the study was placed on deflection predictions at the equivalent serviceability limit state for slender concrete beams longitudinally reinforced with either conventional or high strength steel and transversely reinforced with conventional stirrups. The results indicate that the ACI 318-08 deflection model can underestimate the service deflections by a large margin, especially for members with high transverse reinforcement ratios. The MCFT-based models gave results in better agreements with the test values for the full range of parameters studied. The average test-to-model deflection ratios were 1.77, 1.44, 1.50 and 1.09, and coefficients of variation were 23% 17%, 14% and 18%, for the ACI 318-08, Response-2000, VecTor2 and proposed MCFT-based sectional deflection models respectively.
10.14359/51683810
SP284-16
Peter H. Bischoff and Mohammadali Darabi
A generalized design approach is presented using an effective moment of inertia to compute deflection of steel and fiber reinforced polymer (FRP) reinforced concrete. Realistic estimates of short term deflection are obtained by taking proper account of tension stiffening after cracking, shrinkage restraint, preloading from construction loads, and the variation in member stiffness along the member span. A simple slab example is used to demonstrate how account of the preceding effects can give a more flexible response and increase computed values of deflection four-fold. Long-term effects related to shrinkage and creep are also considered separately for computation of time-dependent deflection. Shrinkage is shown to affect both the short and long-term response of flexure members, and a slab example is used to demonstrate how the effects of shrinkage and creep can be considered separately in a rational manner to compute deflection.
10.14359/51683811
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