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International Concrete Abstracts Portal

Showing 1-5 of 40 Abstracts search results

Document: 

SP-347_01

Date: 

March 1, 2021

Author(s):

Iurie Curosu, Viktor Mechtcherine, Daniele Forni, Simone Hempel and Ezio Cadoni

Publication:

Symposium Papers

Volume:

347

Abstract:

Synopsis: Strain-hardening cement-based composites (SHCC) represent a special type of fiber reinforced concretes, whose post-elastic tensile behavior is characterized by the formation of multiple, fine cracks under increasing loading up to failure localization. The high inelastic deformability in the strain-hardening phase together with the high damage tolerance and energy dissipation capacity make SHCC promising for applications involving dynamic loading scenarios, such as earthquake, impact or blast.

However, the main constitutive phases of SHCC, i.e. matrix, fibers and interphase between them, are highly rate sensitive. Depending on the SHCC composition, the increase in loading rates can negatively alter the balanced micromechanical interactions, leading to a pronounced reduction in strain capacity. Thus, there is need for a detailed investigation of the strain rate sensitivity of SHCC at different levels of observation for enabling a targeted material design with respect to high loading rates.

The crack opening behavior is an essential material parameter for SHCC, since it defines to a large extent the tensile properties of the composite. In the paper at hand, the rate effects on the crack opening and fracture behavior of SHCC are analyzed based on quasi-static and impact tensile tests on notched specimens made of three different types of SHCC. Two SHCC consisted of a normal-strength cementitious matrix and were reinforced with polyvinyl-alcohol (PVA) and ultra-high molecular weight polyethylene (UHMWPE) fibers, respectively. The third type consisted of a high-strength cementitious matrix and UHMWPE fibers. The dynamic tests were performed in a split Hopkinson tension bar and enabled an accurate description of the crack opening behavior in terms of force-displacement relationships at displacement rates of up to 6 m/s (19.7 ft/s).


Document: 

SP-348_07

Date: 

March 1, 2021

Author(s):

Pericles C. Stivaros and Pablo A. Bruno

Publication:

Symposium Papers

Volume:

348

Abstract:

This paper presents a case study involving the structural analysis and design of an elevated foundation plinth to support multiple pieces of rotating machines with different operating weights and speeds. The equipment is used to operate a high-speed balancing testing facility for turbines and rotors that are located within an adjacent testing chamber. This project comprised of several layout and design challenges, including vibration and resonance concerns, effects of multiple operating frequencies, plinth shape, and pile foundation effects. Major concern was to maintain the high precision and strict tolerance limitations required by the high-speed balancing operations. Elevated machine foundations integral with other structures possess many natural frequencies, both locally and globally. The traditional design rules-of-thumb are not adequate for analyzing and designing elevated machine foundations. A computer-based finite element analysis method is required to identify the multiple natural frequencies of a complicated foundation structure. The strength design of a machine foundation can become very challenging when trying to implement code requirements that are mostly applicable to building elements and not to massive concrete foundations. This study recognizes the need for the development of a design standard to include special design requirements for mass concrete machine foundations.


Document: 

SP-343_30

Date: 

October 1, 2020

Author(s):

Aoude, H.; Li, Y.; Bastami, R.; Ibrahim, F.M.

Publication:

Symposium Papers

Volume:

343

Abstract:

This paper presents the results of a study examining the effect of synthetic fibers on the flexural and shear behaviour of beams tested under quasi-static and blast loading. In total, ten beams built with normal-strength concrete and synthetic fibers are studied, with five specimens tested under quasi-static four-point bending and a companion set of five beams tested under simulated blast loads using a high-capacity shock-tube. Test parameters include the effect of concrete type (plain vs. fiber-reinforced concrete), fiber type (two types of macro-synthetic fibers) and transverse reinforcement (in plain and fiber-reinforced concrete beams). Under slowly applied loads, the provision of synthetic fibers is shown to improve the residual shear capacity of beams built without stirrups, while the combined use of synthetic fibers and stirrups is found to improve flexural ductility. The effect of synthetic fibers on blast capacity is examined by comparing the mid-span displacements, failure modes and damage of beams tested under gradually increasing blast pressures. The results show that the use of synthetic fibers increases the blast capacity of beams built without transverse reinforcement, delaying shear failure. When combined with stirrups the use of synthetic fibers is shown to enhance damage tolerance and allow for better control of residual mid-span displacements at equivalent blasts.


Document: 

SP338

Date: 

April 27, 2020

Author(s):

Bruce A. Suprenant and Oscar R. Antommattei

Publication:

Symposium Papers

Volume:

338

Abstract:

Ward R. Malisch spent most of his 50-year career addressing issues related to concrete construction, specifically to problems that concrete contractors deal with daily. His civil engineering training began at the University of Illinois at Urbana-Champaign where he received his BS, MS, and PhD in 1961, 1963, and 1966, respectively. During his time at Illinois he also carried out research on concrete durability and taught courses on plain concrete. Following that, he taught courses in concrete construction at the University of Missouri-Rolla (now Missouri University of Science and Technology) where he received several awards for outstanding teaching. During his time there he took a leave of absence to work in quality control for the prime contractor building Missouri’s first nuclear power plant. This experience spurred his interest in how specification requirements and tolerances affected contractors’ abilities to build both simple and complex structures. Malisch was able to reach the construction industry more directly when he joined the staff of the World of Concrete seminar program and later became editor of Concrete Construction magazine. He was then able to teach at a national level by further developing a seminar program and editorial content that featured how-to-do-it information on concrete technology, with an emphasis on contractor-related topics. During his tenure with the magazine, he began answering questions on a telephone hotline service offered by the American Society of Concrete Contractors (ASCC), and gave advice on problems related to unrealistic concrete tolerances, inadequate knowledge about plastic concrete properties, ambiguous specifications, and a wide range of other construction-related topics. In subsequent years, Malisch served as director of engineering and later as senior managing director at the American Concrete Institute. There, while supervising the engineering, marketing, and education departments, and serving as publisher of Concrete International magazine, he also interacted with other concrete-related organizations, serving on the Research, Engineering, and Standards Committee of the National Ready Mixed Concrete Association and on the ASCC Board of Directors. Along with the ACI Strategic Development Council, ASCC, and Construction Technology Laboratories, he helped to organize an Inter-Industry Working Group on Concrete Floor Issues that brought together leaders from several construction and flooring industry groups. One outcome of this group’s activity was publication of ACI 302.2R-06, “Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials.” Upon retirement from ACI in 2008, he was named technical director of ASCC. He was active again in forming an Inter-Industry Working Group on Reducing the Cost of Tolerance Compatibility Problems along with eight other co-sponsoring groups. He later served as principal investigator on two construction related research projects dealing with contractor-related problems. Dr. Malisch’s awards include: • 1986— Elected Fellow of the American Concrete Institute • 2004— Arthur Y. Moy Award, ACI Greater Michigan Chapter • 2006— Silver Hard Hat Award, highest award given by the Construction Writers Association • 2008— Richard D. Gaynor Award, Highest technical award given by the National Ready-Mixed Concrete Association • 2009—One of Concrete Construction magazine’s Most Influential People • 2010— Arthur R. Anderson Medal, ACI, given for outstanding contributions to the advancement of knowledge of concrete as a construction material • 2011— ACI Construction Award, given to the author of any paper of outstanding merit on concrete construction practice • 2011— ASCC Lifetime Achievement Award, ASCC’s highest honor, acknowledging recipients for their body of work within the industry and their service to ASCC • 2013— ACI Honorary member, given to a person of eminence in the field of the Institute’s interest or one who has performed extraordinary meritorious service to the Institute • 2019—Roger H. Corbetta Concrete Construction Award, ACI, given to an individual that has made significant contributions to progress in methods of concrete construction. For his dedication to the concrete construction industry, this Special Publication is a tribute to his work and is sponsored by the ACI Construction Liaison Committee. Sixteen presentations, distributed in four sessions named “Ward R. Malisch Concrete Construction Symposium,” were given at the 2017 ACI Fall Convention in Anaheim, CA. The quality of the presentations was highlighted by the participation of four former presidents of ACI: David Darwin, Terry Holland, Ken Hover and Mike Schneider. The nine manuscripts presented in this Special Publication are significant in that each paper represents authors that have been previously published in ACI. Thanks are extended to the many ACI members who reviewed the manuscripts and provided helpful technical and editorial comments which enhanced the authors’ papers. This Special Publication is but one small token of appreciation and gratitude to the more than 50-year service of Ward R. Malisch to concrete construction. He has been a source of inspiration to many as well as an example of honesty, integrity, and dedication. He has built the foundation for others to build upon in serving the concrete construction industry.


Document: 

SP-338_09

Date: 

March 1, 2020

Author(s):

Eldon Tipping and Bryan M. Birdwell

Publication:

Symposium Papers

Volume:

338

Abstract:

This is the third of a three-part series, the goal of which is to provide the designer and contractor with tools necessary to produce level deflected slabs on metal deck. This third part provides the designer and contractor with strategies for producing level deflected slabs on metal deck. An approach by which elevation tolerances can be successfully imposed on the erected steel frame is presented. The method requires that the designer first provide the contractor with desired relative elevation of splice points at each floor level and flexible column splice details. This information, provided by the designer, enables the contractor to establish desired relative elevations that can assist in achieving those tolerances. An effective cambering strategy that recognizes the differing behavior of members framing to columns and those that connect to girders is presented and discussed. The paper finally presents a floor construction/monitoring program that identifies frame behavior during construction and provides both the designer and contractor with the resources necessary to produce level deflected slabs. The program includes pre- and postplacement surveys of structural steel frame, utilization of a controlled method of striking off the concrete, a survey of the completed slab surface, and use of the collected data to respond to unexpected structural behavior. Other tools, including the selective use of “loose shores” or a secondary placement can enable the contractor to produce deflected slabs on metal deck with 80% or more of the surface within a 3/4 inch (19 mm) deep envelope.


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