Atsushi Hattori

STRUCTURAL PERFORMANCE OF SLENDER REINFORCED CONCRETE COLUMNS USING ULTRA HIGH STRENGTH CONCRETE WITH COMPRESSIVE STRENGTH OF 300 N/mm 2

This study deals with structural performance of slender reinforced concrete columns using concrete with compressive strength of 300 N/mm2. From structural experiments and geometric nonlinear analyses, it is found that the columns of which the ratio of length to depth is 15 to 30 have the horizontal displacement capacity of 1/50 rad. or more in drift angle under the axial load ratio of 0.33, although these columns don’t resist horizontal force. From these analyses, it is also found that the buckling occurred under antisymmetrical moment in case which the ratio of the length to the depth is 40 or more.

COMPRESSIVE BEHAVIOR OF JOINT MORTAR ON PRECAST CONCRETE COLUMNS

A compression test for concrete-mortar-concrete specimens has been developed to investigate the compression behavior of the joint mortar between two ultra-high-strength precast concrete columns. A method for estimating the compressive strength from the strength values of constituent materials is proposed. Long-term loading tests confirmed that the joint mortar remains stable over a long period of time even under high stress. The compression test was also used as a joint mortar strength control test for a practical building. The test results indicate that the newly developed test can be used to obtain reliable strength test results under accuracy conditions of specimen fabrication and precise loading.

Transition of grasses and management of river dike

Evaluation of protective function of grasses covering a river bank against erosion due to flood flow is important for grasses to be used for the protective measures instead of concrete armoured bank. On the real river, however, transition of grasses takes place and the preffered kind of grasses may change from the turf being planted at the construction time. Thus the understanding of transition process is very important in such an evaluation of protective function of grasses. This study aims to investigate this transition process of grasses through a field observation in the Iwai River in Iwate Prefecture. Annual change in covarage rate of grasses was observed at river banks of various stages after the construction.

Field Experiment on Erosion-Resistance of Embankment of Ichinoseki Flood Detention Basin against Overflow.

Erosion resistance of a river bank slope with variety of plants was exeperimentally investigated. The experiment was carried out on a natural embankment of Ichinoseki Flood Detention Basin under rapid overflow condition. It is found that erosion resistance of embankment is governed by not only difference of distribution of plants but also mole holes in the bank.