In May of 1993, approximately twenty researchers and five representatives from construction firms met in Kyoto, Japan, for the First Multilateral Meeting on Structural Performance of High-Strength Concrete in Seismic Regions. Four countries (United States, Japan, New Zealand, and Australia) were representated at the meeting. The 3-day meeting divided into eight sessions covering current research programs and applications of high-strength concrete in the respective countries. The objectives of the meeting were to exchange information and to develop a coordinated program for further information exchange, evaluation of information, and development of design guidelines for the use of high-strength concrete in seismic regions. The follow-up meeting was held in November 1994 in Honolulu, Hawaii, and was attended by twenty seven participants from the US, Japan, Canada, New Zealand and Hong Kong. The Second Multilateral Meeting on Structural Performance of High-Strength Concrete in Seismic Regions consisted of thirteen sessions. Six of the sessions concentrated on the following behavioral topics: bond and anchorage, confinement, flexural members, axially-loaded members (columns and walls), beam-column joints, and shear and torsion. An additional session was devoted to presentation and discussion of design concepts and applications of high-strength concrete (HSC) in seismic regions. The remaining six sessions consisted of large and small working group sessions. During the small group sessions, participants were divided into groups of five to ten members to discuss the results of the previous sessions. Summaries of the small working group were then presented to the entire group fro additional comments and conclusion during the large working group sessions. This ACI Symposium Publication comprises selected papers which were the outcome of the Second Multilateral Meeting on Structural Performance of High-Strength Concrete in Seismic Regions. The working group discussion summaries are also included in this special publication. The editors are appreciative of the eforts of the authors and reviewers of these papers. The cooperation of the authors in the careful revision of their papers in accordance with the reviewers' comments is greatly appreciated. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP176

This paper presents an overview of the provisions for anchorage and development of reinforcement in concrete for New Zealand concrete design code : NZS 3101: 1995 (1). These provisions take into account the nature of high strength concrete (compressive strength f’c > 55 MPa (8000 psi)) and the expected performance under seismic loading. The criteria for development lengths for straight reinforcement (with specific surface deformations) and those for bars terminated with hooks are largely based on recent studies of Sozen and Moehle and ACI 318: 1989. Simple, conservative equations are presented along with less conservative equations of more complexity.

This paper discusses briefly, the major applications of high-strength concrete in seismic regions. The advancement of material technology and production has led to higher grades of concrete strengths. These concretes can be produced using conventional production procedures, The use of high-strength concrete is becoming popular in the USA and other countries. The reduced member sizes obtained through the use of high-strength concrete will develop reduced inertial loads under seismic excitation. Strength and ductility are the most important design considerations for a structure to behave satisfactorily under these conditions. These aspects relevant to high-strength concrete members are summarised in the paper.

The state-of-the-art on recent experimental research in Japan on beam-column joints with high-strength materials subjected to seismic loads is introduced. Previous experimental studies on beam-column joints in reinforced concrete frames for seismic resistance is outlined for the shear strength of beam-column joints and the deformation characteristics of subassemblages including beam-column joints. Analytical research using FEM microscopic models and macroscopic models have been done in order to deepen the understanding of the experimental results and to investigate the shear resisting mechanisms of the joints with high-strength materials. Recent analytical research on joints using high-strength materials is introduced.

Synopsis: Recent research on confinement of high-strength concrete (HSC) is reviewed. The emphasis is placed on the effects of confinement parameters and related experimental research. A review of analytical models proposed for HSC is also presented. The results indicate that for similar strength and deformability, HSC requires higher confinement pressure than normal-strength concrete. The level of lateral pressure required can be provided by increasing the volumetric ratio and grade of continement reinforcement. The effkiency of pressure can be improved by reducing the spacing of lateral reinforcement in both the longitudinal and cross-sectional planes. When properly confined, HSC exhibits ductile stress-strain characteristics. The analytical models developed for normal-strength concrete cannot be used to describe stress-strain characteristics of HSC. A number of models have been proposed for HSC that produce good correlations with experimental data.