International Concrete Abstracts Portal

To minimize thermal cracking, specifications for mass concrete often state a maximum allowable temperature difference, ΔT, between the hottest interior location (usually the center) and surface of the mass concrete section in the days following placement. Section 8 of ACI 301-05, “Specifications for Structural Concrete,” did not set such a limit, but the recent revision, ACI 301-10, sets a default value of 35F for the difference (see box). The 35F difference is based on experience with unreinforced mass concrete dams where the consequences of cracking and subsequent water leakage were critical. For mass concrete in mat foundations, large piers, and thick walls, 35F may be unduly conservative.

Editors: Kyuichi Maruyama and Andrew W. Taylor

The First American Concrete Institute (ACI) and Japan Concrete Institute (JCI) joint seminar was conceived as a vehicle for promoting collaboration and cooperation between two organizations that are dedicated to the global advancement of concrete technology. In September 2012 ACI President James Wight, and ACI Executive Vice President Ronald Burg, visited the headquarters of JCI and discussed ways to promote collaboration between ACI and JCI with JCI President Taketo Uomoto and JCI Executive Directors. A joint ACI and JCI technical seminar was proposed as a way to share knowledge and foster collaboration between the two organizations. Subsequent discussions between Ronald Burg and JCI Executive Director Kyuichi Maruyama led to a joint seminar planning meeting, held at the ACI convention in Minneapolis, Minnesota, in April 2013.

This volume contains the technical papers presented at the First ACI & JCI Joint Seminar, held in Waimea, Island of Hawaii, Hawaii, July 16 to 18, 2014. The theme of the joint seminar was “Design of Concrete Structures Against Earthquake and Tsunami Disasters.” Five papers were presented by authors from ACI, and five papers from JCI. Three papers are related to tsunami loads and structural design requirements, and seven are related to seismic analysis and design.

The three papers on tsunami effects included a summary by Nakano of structural design requirements for tsunami evacuation buildings in Japan; an overview by Chock of the new tsunami load and design requirements in the United States; and a study by Maruyama et al. on the evaluation of tsunami forces acting on bridge girders.

The seven papers on seismic effects addressed topics ranging from seismic design standards to innovative methods of construction for seismic retrofit. Parra-Montesinos et al. presented the results of experiments on fiber-reinforced coupling beams, as well as design guidelines. Teshigawara discussed JCI contributions to the ISO Standard for seismic evaluation and retrofit of existing concrete structures. A summary of a project on the use of high-strength reinforcement for seismic design was presented by Kelly et al., including findings that are based on extensive prior research on high-strength reinforcement in Japan. Shiohara described the results of a study that supports the new Architectural Institute of Japan (AIJ) Standard for Seismic Capacity Calculation, with a focus on beam-column joints and collapse simulation. Matamoros presented a study of factors that affect drift ratio at axial failure of nonductile reinforced concrete buildings. A study of the seismic response of reinforced concrete bridge piers, including the effects of interaction between piles and soil, was presented by Maki et al. Finally, French et al. discussed an overview of lessons learned from laboratory testing of reinforced concrete shear walls.

The day after the joint seminar a meeting was held between ACI and JCI officials to discuss future collaboration and joint seminars. Representing ACI were President William E. Rushing, and the ACI Executive Vice President, Ronald Burg. Representing JCI were President Hirozo Mihashi, and Chair of the JCI Committee on JCI-ACI Collaboration, Kyuichi Maruyama. It was resolved to hold a second joint seminar, to be hosted by JCI in Tokyo, in conjunction with the 50th anniversary celebrations of the founding of JCI on July 13, 2015. In addition, subsequent discussions between ACI and JCI led to plans for the third joint seminar, to be hosted by ACI at the ACI Convention in Anaheim, California, in October 2017.

It is hoped that this collection of papers will serve to advance the state of analysis and design of concrete structures against earthquakes and tsunamis in both the United States and Japan, and that it will serve as a model for future collaboration between ACI and JCI.

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-313

Editor: Riadh Al-Mahaidi

This CD contains 8 papers that were presented at a session sponsored by Joint ACI-ASCE technical commttee 447 at the ACI Fall Convention, October 2011 in Cincinnati, Ohio. The papers cover the modeling for strengthening for flexure, shear, torsion, and confinement of concrete. Where applicable, the papers cover comparisons of modeling results with experimental tests performed around the world.

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-301

This paper presents Finite Element (FE) model to predict and analyze the cyclic loading response of reinforced concrete (RC) beams strengthened in shear with Carbon Fiber Reinforced-Polymer (CFRP) and Near-Surface Mounted (NSM) reinforcement. Four FE models were developed based on experimental tests conducted in a previous study. The first specimen was unstrengthened to serve as a control beam while the other two beams were strengthened with NSM CFRP bars with different spacing arrangements. The last beam specimen was strengthened with larger diameter CFRP bars. The developed FE models employed different nonlinear constitutive material modeling laws and techniques such as concrete cracking, steel yielding, bondslip between CFRP bars and epoxy resin, and debonding between the epoxy resin and concrete surfaces. The predicted and measured load-deflection response envelop curves along with the associated hysteresis loops for each specimen were used as platforms to validate the accuracy of the developed models. The results indicate that there is a good match between the predicted results and measured data. It is concluded that the developed FE model is a suitable tool to predict the behavior of such strengthening systems when subjected to cyclic loading and could be used in lieu of expensive experimental testing especially in design-oriented parametric studies.

Fiber-reinforced Polymer (FRP) started to find its way as an economical alternative material in civil engineering from the early 1970s. The behavior and failure modes for FRP composite structures were studied through extensive experimental and analytical investigations. While research related to the flexural behavior of FRPstrengthened elements has reached a mature phase, studies related to FRP shear strengthening is still in a less advanced stage. In all proposed models to predict the shear capacity, the constitutive behavior of concrete and FRP was described independently. The true behavior, however, should account for the high level of interaction between the two materials. In this research, new constitutive relations for FRP-strengthened reinforced concrete elements subjected to pure shear are developed. In order to generate these relations, large-scale tests of a series of FRPstrengthened reinforced concrete panel elements subjected to pure shear are conducted. The University of Houston is equipped with a unique universal panel testing machine that was used for this purpose. These constitutive laws are implemented into fiber-based finite element models to predict the behavior of externally bonded FRP strengthened beams. The newly developed model proved to provide a good level of accuracy when compared to experimental results.