■　On June 13th-15th, NDT team leader and senior scientist Dr. Tomoki Shiotani and research fellow Dr. Dimitrios Aggelis had presentations at 2006 the International Conference "Structural Faults and Repair".

On June 13th-15th, 2006 the international conference "Structural Faults and Repair" was held in Edinburgh, Scotland. The sessions took place at the "Assembly Rooms" the historic venue built in 1787. More than 200 participants from 30 countries were gathered. Tobishima Corporation, Research Institute of Technology was represented by NDT team leader and senior scientist Dr. Tomoki Shiotani and research fellow Dr. Dimitrios Aggelis. Tobishima participated to the conference with 3 papers: ・DAMAGE QUANTIFICATION OF AGING CONCRETE USING NDTS, T. Shiotani and D.G. Aggelis ・DAMAGE EVALUATION ON CONCRETE MATERIALS USING ELASTIC WAVES, D.G. Aggelis and T. Shiotani ・SEISMIC TOMOGRAPHY WITH EVOLUTIONAL WAVE VELOCITY DISTRIBUTION, Y. Kobayashi, H. Shiojiri and T. Shiotani The conference is considered one of the top world events of the civil engineering due to attendance by numerous professors, engineers and publishers and the high level of scientific announcements. The main topics of the conference concerned concrete durability, assessment by nondestructive techniques, concrete repair, masonry arch bridges, timber structures, advanced composites for repair. Dr. Shiotani served as chairman at the session concerning "nondestructive testing of concrete and advanced composites". Also during the conference dinner, Dr. Shiotani was invited to the top table among, the organizer Prof. M. Forde from the university of Edinburgh, Prof. M. Ohtsu from the Kumamoto university, Prof. Buyukozturk from MIT, and Prof. Binda from the university of Milan. The 3rd RILEM* TC-ACD committee meeting on 'Acoustic Emission and Related NDE Techniques for Crack Detection and Damage Evaluation in Concrete (chairman: Prof. Ohtsu of Kumamoto University)' was held at the Infrastructure & Environment Institute in University of Edinburgh, UK on the 16th of June. Prof. Forde of Edinburgh Unversity organized the venue and Dr. Shiotani, NDT team leader and senior scientist, attended the committee meeting serving as secretary. The main purpose of the committee is to establish the standards on AE monitoring for concrete materials; at present round robin activities have been performing among the participating institutes world wide. *International Union of Laboratories and Experts in Construction Materials, Systems and Structures

Dr. Tomoki Shiotani		Dr. Dimitrios Aggelis

Dr. Tomoki Shiotani was invited to the top table(the 4th from the right)

The 3rd RILEM TC-ACD committee meeting

DAMAGE QUANTIFICATION OF AGING CONCRETE STRUCTURTES BY MEANS OF NDT Tomoki Shiotani & Dimitrios G. Aggelis Tobishima Corporation ■ ABSTRACT Aging concrete structures are increasing remarkably, and to sustain those with a proper repair method the evaluation of the structural integrity is a crucial issue. NDTs appear to contribute to this paramount issue since they are non-destructive and are a variety of testing corresponding to the objective measurements. The NDTs might also provide momentous information on repair effectiveness when repeating the test after the repair work. In the paper, such NDTs as seismic tomography and acoustic emission were applied for the damage quantification of a concrete structure. The tests were conducted both before and after repair work. Distribution of velocity and AE activity were carefully examined. Consequently the followings are found: the velocity variations reflected well with the repair effect; and damage indices obtained from AE activity showed in good accordance with structural integrity. DAMAGE EVALUATION ON CONCRETE MATERIALS USING CHARACTERISTICS OF ELASTIC WAVES Dimitrios G. Aggelis & Tomoki Shiotani Tobishima Corporation ■ ABSTRACT A commonly used repair technique is the injection of repair agent into boreholes with high pressure, ensuring that, at a high percentage, the system of interconnected cracks and voids is eliminated. A certain question rising refers to the estimation of repair effectiveness. Due to the time dependent properties of the repair agent, post monitoring using stress waves can lead to false conclusions before full hardening of the material takes place. Therefore, a theoretical investigation was undertaken with multiple scattering theory in order to highlight the role of properties of filler material that after filling the cracks, acts as scatterer in the concrete matrix. Additionally, an experimental series of pulse velocity measurements has been conducted in laboratory using specimens of the same grouting material. The specimens were cured at the same conditions with the site material, in order to evaluate the evolution of mechanical properties at any time, while porous concrete specimens examined after impregnation with grout, exhibited decrease in pulse velocity, highlighting the role of fresh grout in wave propagation in the actual structure. DAMAGE IDENTIFICATION USING SEISMIC TRAVEL TIME TOMOGRAPHY ON THE BASIS OF EVOLUATIONAL WAVE VELOCITY DISTRIBUTION MODEL Yoshikazu Kobayashi*, Tomoki Shiotani**, Hiroo Shiojiri* *Nihon University, **Tobishima Corporation ■ ABSTRACT Seismic tomography has been studied as a way of identification. This technique aims to compute the distribution of elastic wave velocity from combination of ray-trace technique and first travel time that is observed at in-situ or model tests. However, it is difficult to apply this method to a model that has many degrees of freedom due to the difficulties of settlement of initial condition that defines parameters on algorithms of identification such as covariance of state variables. In this paper, a method that the extent of damage area evolves in the progress of identification is presented. This method is characterized by the assumption of the elastic wave velocity distribution that is illustrated as superimposition of functions. These functions are invented from result of experiments and defined from some parameters that characteristic of probability is easily determined. The difficulties on the determination of covariance for each degree of freedom are mitigated since this assumption, and the number of variables is drastically reduced as well. This method is applied to a simple example model. The result shows that the presented method correctly identifies the parameters of the example model.