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Showing 1-5 of 17 Abstracts search results

Document: 

SP226-04

Date: 

March 1, 2005

Author(s):

R. E. Klingner, J. E. Tanner, J. L. Varela, M. Brightman, J. Argudo, and U. Cancino

Publication:

Symposium Papers

Volume:

226

Abstract:

This paper summarizes the initial phases of the technical justification for proposed design provisions for AAC structures in the US. It is divided into two parts. The first part gives general background information, and presents an overall design strategy. Autoclaved aerated concrete (AAC), a lightweight cementitious material originally developed in Europe more than 70 years ago and now widely used around the world, has recently been introduced into the US construction market. AAC elements can contain conventional reinforcement in grouted cores, either alone or with factory-installed reinforcement. To facilitate the use of AAC in the US market, an integrated seismic-qualification program has been carried out, involving general seismic design provisions, specific element design provisions, and material specifications. The second part describes the design and testing of a suite of 14 AAC shear wall specimens, with aspect ratios from 0.6 to 3, under in-plane reversed cyclic loads at the University of Texas at Austin. The results of these tests have been used to develop predictive models and reliable design equations for AAC shear walls, the primary lateral force-resisting element of AAC structural systems.

DOI:

10.14359/14391


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: 

SP226-03

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, plain and reinforced 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 prefabricated elements are gaining rapid acceptance in the United States due primarily to increasing energy cost, environmental concerns, and the ease of construction using AAC elements. Although AAC is a well-recognized building material in Europe, very little research work has been done on U.S.-produced AAC products. The primary objective of this work was to study the structural behavior of U.S.-made reinforced AAC elements. The laboratory test program included most commonly used reinforced AAC elements: floor panels, lintels, and wall panels. Two U.S. manufacturers supplied the AAC elements. Floor panels and lintels were tested in bending, whereas the wall panels were tested under axial or eccentric loading. The ultimate load capacity, cracking, deflection, and failure mode were observed and recorded for each test. The results provide a database that will be used to refine the analytical methods for the structural design of reinforced AAC elements. This information is needed to enhance AAC design methodologies and lay the foundation for establishing AAC as a reliable engineered construction material in the U.S.

DOI:

10.14359/14390


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: 

SP226-02

Date: 

March 1, 2005

Author(s):

R. E. Barnett, J. E. Tanner, R. E. Klingner and F. H. Fouad

Publication:

Symposium Papers

Volume:

226

Abstract:

This paper is a summary of ACI 523.5R, which is a guide for using autoclaved aerated concrete panels. Its design provisions are non-mandatory, and are a synthesis of design recommendations from the Autoclaved Aerated Concrete Products Association, and from the results of research conducted at the University of Alabama at Birmingham (UAB), the University of Texas at Austin (UT Austin), and elsewhere. This paper discusses the design equations associated with the various typical structural uses of autoclaved aerated concrete. Those uses include flexural, axial compression, shear, bearing, bond and development of reinforcement and special seismic design provisions. The design provisions of this Guide are not intended for use with unreinforced, masonry-type AAC units. Design of those units is covered by provisions currently under development within the Masonry Standards Joint Committee.

DOI:

10.14359/14389


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