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International Concrete Abstracts Portal

Showing 1-5 of 9 Abstracts search results

Document: 

SP226-06

Date: 

March 1, 2005

Author(s):

K. Itzler, P.E. and A. Nelson

Publication:

Symposium Papers

Volume:

226

Abstract:

A general overview of the approach to the design of autoclaved aerated concrete (AAC) structural walls and floor/roof panels is presented. Variations in design approach from concrete and masonry, and design equations specific to AAC are discussed and provided. Design examples illustrate the proposed approach.

DOI:

10.14359/14393


Document: 

SP226-07

Date: 

March 1, 2005

Author(s):

C. Shi, Y. Wu and M. Riefler

Publication:

Symposium Papers

Volume:

226

Abstract:

The use of lightweight concrete has many advantages over conventional concrete. The reduced self-weight of lightweight concrete will reduce gravity load and seismic inertial mass. The lightweight concrete reported here has compressive strengths from 8 to 50 MPa with dry densities from 800 to 1400 kg/m3, which is strong enough for any load-bearing and non-load-bearing applications. The compressive strength to flexural strength ratio increases as the compressive strength of the concrete increases. The introduction of a small amount of fiber does not affect the flexural strength and drying shrinkage of the concrete, but improves the ductility and handling properties of the product very significantly. The lightweight concrete has a higher moisture loss during drying, but a lower shrinkage than the normal weight concrete due to the buffer effect of the moisture in the lightweight aggregate. Properly designed fiber-reinforced ultra lightweight concrete can be easily cut, sawed and nailed like wood.

DOI:

10.14359/14394


Document: 

SP226-05

Date: 

March 1, 2005

Author(s):

R. E. Klingner, J. E. Tanner, and J. L. Varela

Publication:

Symposium Papers

Volume:

226

Abstract:

This paper summarizes the final phases of the technical justification for proposed design provisions for AAC structures in the US. It is divided into two parts. The first part describes the design and testing of a two-story, full-scale AAC shear wall specimen that was designed and tested at The University of Texas at Austin, under reversed quasi-static loads representative of those experienced in a strong earthquake. The specimen withstood repeated reversed cycles to story drifts of about 0.3%, and displacement ductility ratios of about 3. The specimen conformed with the two main objectives. Those objectives were: 1) to show that the behavioral models developed for the shear walls also govern in a building; and 2) to demonstrate that a squat wall can exhibit failure governed by flexure. The second part describes the development of R and Cd factors for seismic design of AAC structures. The seismic force-reduction factor (R) specified in seismic design codes is intended to account for energy dissipation through inelastic deformation (ductility) and structural over-strength. The factor (R) is based on observation of the performance of different structural systems in previous strong earthquakes, on technical justification, and on tradition. For structures of autoclaved aerated concrete (AAC), the force-reduction factor (R) and the corresponding displacement-amplification factor (Cd) must be based on laboratory test results and numerical simulation of the response of AAC structures subjected to earthquake ground motions. The proposed factors must then be verified against the observed response of AAC structures in strong earthquakes. The objectives of this paper are: (1) to present a general procedure for selecting values of the factors (R) and (Cd) for use in the seismic design of structures; and (2) using that procedure, to propose preliminary values of the factors (R) and (Cd) for the seismic design of AAC shear-wall structures. The general procedure is based on comparing the predicted ductility and drift demands in AAC structures, as functions of the factors (R) and (Cd), with the ductility and drift capacities of AAC shear walls, as observed in quasi-static testing under reversed cyclic loads. Nonlinear numerical simulations are carried out using hysteretic load-displacement behavior based on test results, and using suites of natural and synthetic ground motions from different seismically active regions of the United States.

DOI:

10.14359/14392


Document: 

SP226

Date: 

March 1, 2005

Author(s):

Editors: Caijun Shi and Fouad H. Fouad

Publication:

Symposium Papers

Volume:

226

Abstract:

SP-226 Since its inception more than 80 years ago, autoclaved aerated concrete (AAC) has enjoyed a reputation for excellent thermal insulation, acoustic, and fire-resistant properties due to its low density and cellular structure. The production and use of AAC in the United States, however, did not start until the mid 1990s. To promote and encourage the use of AAC and other ultra-lightweight concrete, ACI Committee 523, Cellular Concrete, and ACI Committee 229, Controlled Low-Strength Materials, organized a technical session on "Controlled-Density/Controlled-Strength Concrete Materials at the 2003 ACI Spring Convention in Vancouver, Canada, and a session on "Aerated Concrete - An Innovative Building Solution" at the 2003 ACI Fall Convention in Boston. Thirteen papers were presented at these two technical sessions covering a wide range of practical case studies and research projects on different types of ultra-lightweight concretes, with particular focus on AAC. These papers should be of interest to the practicing engineers, educators, and researchers in that they demonstrate the effective use of AAC as well as other types of ultra-lightweight concrete materials. This special publication (SP) contains eight of the 13 papers presented at the session. Six of the papers deal with AAC and cover a wide variety of topics including material properties, structural design, seismic performance, and design examples. The other two papers address the acoustic and structural properties of foamed and/or aerated lightweight concretes cured at room temperature.

DOI:

10.14359/14359


Document: 

SP226-01

Date: 

March 1, 2005

Author(s):

F. H. Fouad and J. Dembowski

Publication:

Symposium Papers

Volume:

226

Abstract:

Autoclaved aerated concrete (AAC) is a lightweight uniform cellular material, first developed in Sweden in 1929. Since that time, AAC building components have been widely used in Europe and other parts of the world. Until recently, however, AAC was relatively unknown to the United States precast construction market. Today, AAC is gaining rapid acceptance in the United States due primarily to increasing energy cost and environmental concerns. Although AAC is a well-recognized building material in Europe, very little research work has been done on American-produced AAC components. The goal of the testing program was to further develop the database of the material properties and structural behavior of American-made AAC by testing plain AAC elements from three different manufacturers. Manufacturers and designers will be provided with information that will help to promote AAC as a reliable engineered construction material in the U.S. Tests performed on the plain AAC consisted of compressive strength, flexural tensile strength, shear strength, and modulus of elasticity.

DOI:

10.14359/14388


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