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Utsunomiya-shi, Japan

Iwase T.,Niigata University | Horiguchi Y.,Niigata University | Yasuoka H.,Center for Better Living
20th International Congress on Acoustics 2010, ICA 2010 - Incorporating Proceedings of the 2010 Annual Conference of the Australian Acoustical Society

Concrete is useful and indispensable material for the construction of modern buildings. However, it contracts after drying and causes cracks on its surface and in structure body. Moreover, long use period after construction make the crack deeper and wider. These bad states will cause peeling off and falling accidents. To prevent the accident, diagnose of the crack is necessary. Famous detection method for crack depth using ultrasonic wave was not used for inspection of concrete wall with wide area because there were faults with high cost and severe test condition as using grease. Therefore, authors tested other detection techniques for the crack depth, and then we found that the air column resonance being caused by a crack is similar to a wind instrument. It can be understood that the length of 1/4 of the wavelength of the first order resonance sound wave corresponds almost to the depth of air column with one end closed and the length of 1/2 of wavelength also to the depth with both ends open. We propose the method of nondestructive detecting crack depth based on the resonance phenomena. It has been understood that it would be able to detect for the width within 1mm on concrete wall in typical building by the spectral analysis peak at frequency of several hundred hertz. Under assumption of expanded use for special concrete constructions with very thick wall, we made some detection experiments by the addition. If depth increased, and width narrows, it became difficult to detect by the first order resonance as at frequency lower than one hundred hertz. Fortunately, higher order resonance phenomena, as at frequency several hundred hertz, were found and were able to be clearly caught in the experiments. It is possible to detect even by deep depth of about 1m with width of about 1 and 2mm. In the paper, principle and measurement ways of diagnosis based on the sound resonance are introduced, and the examination results are described. Copyright© (2010) by the International Congress on Acoustics. Source

Yasukawa M.,Waseda University | Yasui N.,Waseda University | Suzuki A.,Obayashi Corporation | Hasemi Y.,Waseda University | And 5 more authors.
AIJ Journal of Technology and Design

Fire resistance tests were conducted on loaded beam and post-beam joints of heavy hardwood (ZELKOVA) designed for traditional temple buildings. The tests revealed the followings: (1) predictability of the structural fire resistance of ZELKOVA beam with safety margin by the assessment of the bending buckling. (2) applicability of the traditional beam and post-beam joint designs to the Quasi-fireproof construction. Source

Kawabata Y.,Shinshu University | Nakagomi T.,Shinshu University | Sakino Y.,Osaka University | Hattori K.,Center for Better Living | Tobori K.,Tomi City Office
Journal of Structural and Construction Engineering

The weld defect of the welded beam-to-column joint in steel structure causes the brittle fracture and has possibilities to reduce the deformation capacity. It is considered that the effect of the weld defect on the deformation capacity from the difference of between shop and site welding beam-to-column joints is different. Therefore it is important to understand this difference. In this paper, full-scale welding test was done it were shop and site welding beam-to-column joints. Then, the effect of the deformation capacity of test specimens caused by the difference of the position of welding defects between two joint methods was studied. As the results, the deterioration ot deformation capacity caused by the welding delect was low using shop welding beam-to-column joints. and high using site welding beam-to-column joints. Source

Nakagawa T.,Japan Building Research Institute | Kawai N.,Japan Building Research Institute | Okabe M.,Center for Better Living
AIJ Journal of Technology and Design

In this study, bending tests of continuous footing foundation reinforced by the several kind of seismic retrofit constructions were carried out. The retrofit constructions used in this study were made by additional concrete casting and carbon fiber sheet reinforcing. The tests were carried out by the three-point bending that has 3.6m length spans. The specimens whose beam and footing retrofitted by the additional casting had equivalent seismic resistance as the reinforced concrete foundations. But the other specimens didn't have enough seismic resistance. Source

Okabe M.,Center for Better Living | Okabe M.,Gifu University | Yasumura M.,University of Shizuoka | Kobayashi K.,University of Shizuoka | And 3 more authors.
World Conference on Timber Engineering 2012, WCTE 2012

Structural performance of shear walls to resist against wind and seismic loading is evaluated by applying static or cyclic load testing. IS021581 specifies the static and cyclic lateral load test for shear wall. ISO defines two method of lateral load test. Method 1 shows the boundary conditions are designed to produce mainly the shear response of the wall. Method 2 shows the boundary conditions are designed to produce mainly the rocking (rigid body rotation of the wall) or combined shear-rocking response of the wall reflecting the intended actual construction details of joints connecting the wall to bottom and top boundaries. Cross Laminated Timber panels (also known as CLT or X-LAM) are relatively new building material and high rigidity and strength compared to sheathing materials. It is possible to apply to low-rise residential buildings from the multi-story timber buildings. In Japan manufacturer has been already trying to produce Sugi CLT. Sugi (Cryptomeria japonica) is most popular softwood in Japan. In this report shows effect of vertical load based on IS021581 method 2 under cyclic lateral load test of Sugi CLT. Vertical load applied three condition, 15kN/m, 30kN/m and without vertical load. Stiffness of CLT wall panel against horizontal load shows higher on vertical load. However maximum strength increase due to vertical load was smaller than the stiffness. Source

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