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We have developed a new seismic reinforcing method that combines aramid fiber sheets and steel plates for existing RC columns. In order to investigate structure characteristic of RC columns retrofitted with this technique, cyclic lateral loading test was carried out. As a test results, the tendency of hysteretic loops were generally similar for all specimens;longitudinal bar was yielding at drift angle of 1/100rad, the strength started to decrease when the maximum strength was achieved at drift angle of about 1/50rad. Flexural cracks after the test were observed at the top and bottom of column. However, the strength decrease was very small and cracks was few. Furthermore, it was found that this method can be used for enhancing the flexural strength compared with RC columns retrofitted only by aramid fiber sheets. Therefore, the calculated values by current ultimate flexural capacity formula were underestimate test results. This paper was discussed about the flexural strength and the ductile behavior obtained form the skeleton curve, which was converted into the elastic-plastic restoring force characteristics based on principle of the ultimate energy equilibrium. In conclusion, the experimental evaluation methods of seismic performance for columns retrofitted with this technique was estimated considering the increasing effect of flexural strength and equivalent viscous damping factor.

Reviewing the modern knowledge of Tribology and the past experimental data on friction, the coefficient of friction between wood and steel is not well known especially under a high contact pressure. Thus, a new testing method named compression-pullout test is introduced to measure the sliding coefficients of static and kinetic frictions between wood and steel plates under heavy loading. The most important finding is that the friction is categorized into complete and incomplete frictions. The former is the case that the relative displacement between wood and steel is identical to the sliding as a rigid body, while the latter is that plastic deformation due to shear yielding of wood is associated with the sliding. Heavy contact especially with rough steel is apt to bring incomplete friction, in that the coefficient of friction is smaller than that of the complete friction under light contact. This means that the Amontons-Coulomb's law is not valid in the entire range from light to heavy contact.

Even in the region with less snowfall, snow accretion to exterior wall surface and structural members of high rise building in Tokyo metropolitan region has frequently occurred. Concern about human damage produced by snow blocks falling including snow accretion has been pointed out. Therefore, it is important to build method of countermeasures against snow accretion for buildings. To accumulate technical data for countermeasures against snow accretion, the authors studied basic characteristics of snow accretion on structural members both observationally and experimentally. First, field observation for snow accretion on structural members was performed in Sapporo of Hokkaido. When the snow accretion occurred during the observation, daily mean wind speed was more than 3.0 m/s. The snow accretion occurred around the stagnation of wind, which was formed in the vicinity of structural members. Next, wind tunnel test, for usual shape members such as steel pipes and flat plates, was performed. The snow accretion amount on the steel pipe increased with the diameter and it depended on the surface roughness in case of the steel pipe 216mm in diameter. The snow accretion amount on the steel plates decreased with attack angle. Through the observation and the wind tunnel test on snow accretion characteristics, technical data of countermeasures against snow accretion for buildings was obtained.

Concrete fine powder that is residue after aggregates recycling of demolished concrete and acid water that is used for acid cleaning of rusted steel plates are the wastes thrown away as valueless substances. However, there is possibility for obtaining some valuable materials from the two wastes by applying chemical reaction between them, because the former is alkaline substance and the latter is acid solution. In this paper, the production process of obtaining valuable materials from the wastes was developed. Silica and calcium carbonate of more than 95% in purity could be successfully obtained through the developed process.

A new type of moment resisting timber joint has been developed. The joint is made up of steel plates, bolts and cotters. The plates and the bolts are embedded with timber element of frame structure. By combining those elements with steel cotters, moment resisting joints can be constructed easily. Static loading tests of the joint have been performed, and results of the tests made it clear that the joint have rotational rigidity and strength required from constructing moment resisting joint. In this report, three kinds of racking tests were performed to simulate the moment-rotational angle. “A tests” were prototypes, and “B tests” and “C tests” had each kinds of joint. The simulation results of moment-rotational angle curves by three kinds of tests agree with the prototype tests results.

Tests on shear corrugated steel plates were carried out to examine effect of section shape, thickness and boundary condition on shear buckling behavior and post buckling behavior. Based on the test result, previous shear buckling strength formulas were reviewed. Furthermore, tension-field action model were proposed through observation of plastic deformation after shear buckling, and design formulas were derived from the strength model. Comparison with the test results showed that the design formulas provided appropriate strength estimation for shear buckling and post buckling behavior.

A new-type hysteretic damper composed of a slitted steel plate and buckling-restraining wood panels is proposed. Cyclic loading tests on five damper element specimens, including one without buckling restraining panels, are conducted. The buckling-restrained specimens behave in a stable manner with the equivalent viscous damping ratio ranging from 0.3 to 0.4, while the hysteresis loops after the ultimate strength are pinched due to the steel plate's local buckling in the vicinity of slit ends. In the specimen with the thinnest wood panels, large kinks are formed close to corners of the steel plate, and in another specimen, where cracks are formed between the slits, strength deterioration is observed. Associated FEM analyses that represent the specimens show good agreement with the test results.

Tests on shear corrugated steel plates were carried out to examine effect of shape and thickness of cross section on end failure action that may occur at the ends of flutes in shear diaphragms. Based on the test result and observation obtained through this research, previous deformation model for stiffness estimation were reviewed, and the deformation model were developed into strength model with application of yield line hinge. Strength design formulas were derived from the strength model using a limit analysis technique. Comparison with the test results showed that the derived formulas provided appropriate stiffness and strength estimation.

Seismic performance of 72 two-story wooden houses build in Sapporo was grasped from seismic diagnosis that considered snow depth on roof. Photos and drawings of the wooden houses for seismic diagnosis were obtained from an outside walls renovation company. Seismic reinforcement for the wooden houses was estimated from evaluation of the seismic diagnosis. The results indicate as follows: for the seismic diagnosis as the snow depth 0m, the evaluations in lots of the wooden houses were more than 1.0. As the snow depth more than 1.0m, the evaluations were small so that the seismic reinforcement is needed. Reinforcement for capital and column base by steel plates was assumed as the seismic reinforcement. To have improvement effect for the wooden houses having poor seismic resistant in the seismic reinforcement was clarified.

The RC framed shear walls are popular to resist the earthquake loads efficiently. The recent past earthquakes reveal that they are vulnerable to large seismic excitation. To satisfy the demand of high energy absorption in large earthquake, it is necessary to retrofit the existing framed shear walls with converting the failure mode from shear to flexural or uplift one. Considering this fact, the retrofit technique of utilizing additional concrete sandwiched by steel plates and PC bar prestressing is proposed here. The proposed retrofit technique is experimentally investigated and analytically evaluated. The seismic performance of the specimen is also discussed here.