北守 顕久

<title>Abstract</title>In this study, the columns with interior notches in traditional Japanese timber frames were selected as the research object, and static bending tests were performed to investigate the effect of interior notches on the flexural properties of columns. First, the bending behaviors of columns under three-point and four-point load configurations were compared to obtain a suitable referenced strength of a column without notches. The reduction in the load-bearing capacity of columns with different types of interior notches in traditional Japanese timber structures was determined through experimental tests and statistical analysis. The results indicated that the mean bending strength of columns with three different notch types was consistent with those without notches, the continuous timber on both sides of the notch had a beneficial effect on maintaining a higher strength and reducing the stress intensity around the notch. The fracture position and the standard deviation of the bending strength were affected not only by the notch depth, but also by the notch width on the tensile side of the column.

<title>Abstract</title>The pretensioning force in bolted joints enhances the lateral strength of the connections, and causes the embedment of metal washers into wood. Despite the significance of embedment behavior in the design of bolted joints, its mechanism has yet to be fully understood. In this study, the mechanism of the embedment of a metal washer into wood along the radial direction was examined through three-dimensional nonlinear finite-element analysis (FEA). The FEA results were validated by comparing them with experimental results for nine metal washers with different geometries. Moreover, the sensitivity of embedment stiffness and yield load to wooden material constants was also investigated. The numerical results showed good qualitative and quantitative agreement with the experimental results. In addition, the embedment stiffness and yield load were sensitive to the yield stress and Young’s modulus of wood in the radial and tangential directions. The determination of these mechanical properties of wood through material testing is important for reproducing the behavior of the embedment of a metal washer into wood and accurately estimating the yield load and initial stiffness using FEA. This will play a significant role in designing bolted joints.

The study deals with the damage control system of wooden houses using wood friction-based dampers subjected to earthquake motion. In this study, wood friction joints were developed to introduce damping into wood shear walls. Shaking table tests were also conducted to investigate the seismic performance of two-story timber structures composed of plywood shear walls, plasterboards and timber shear walls using high damping devices. The purpose of this study is to propose an estimation method of the required quantity of the friction damper to satisfy the restriction value of the story drift angle for the continued use after earthquake motion.

To investigate the effects of tightening speed on the torque coefficient in lag screw timber joints with steel side plates, tightening tests were conducted on main timber members made from Cryptomeria japonica, Chamaecyparis obtusa and Pseudotsuga menziesii, under four tightening speed conditions (1, 4, 10, and 20 rpm). Major stick-slip behavior was observed in C. obtusa based on the relationship of tightening angle with clamp force, tightening torque, and thread torque at tightening speeds of 1 and 4 rpm. In addition, tightening speed’s effects on the torque coefficient (K) varied depending on the wood species of the main member. In P. menziesii, K was not affected by the tightening speed: the ratio of torque expended on tightening was 25% on average, and the ratio of torque expended on bearing surface friction was higher than the ratio of torque expended on thread friction.

This study empirically examines the relationship between clamp force and pull-out strength in lag screw joints of timber members, using data obtained in tightening tests and pull-out tests. Maximum clamp force per unit screw length as determined from the tightening tests was lower than the lower bound for the 95% tolerance range for pull-out strength per unit screw length as determined from the pull-out tests. Moreover, X-ray CT (computed tomography) observations of anchor members from both tests revealed that failure behavior clearly differed between the tightening test and the pull-out test: tightening caused damage to the wooden, female thread in addition to major splitting damage in the wood perpendicular to the grain near the tip of the lag screw.

A method for calculating plastic clamp force from tightening torque was presented by considering a bi-linear model obtained from experimental tightening torque-clamp force relationships. The practical applicability of the calculation method was verified by tightening tests of Cryptomeria japonica bolted joints using metal washers of various sizes. Results were as follows : It was found that a ratio of side length (diameter) to thickness of metal washers ranging from 7.8 to 16.0 did not affect the torque coefficient. In addition, the ratio of maximum plastic torque coefficient to maximum elastic torque coefficient, gamma(max) and the ratio of minimum plastic torque coefficient to minimum elastic torque coefficient, gamma(max), which are elements of the calculation method, tended to increase depending on embedment into timber of metal washers in side-length (diameter) to thickness ratios of 10.0 (washer size : 32 x t 3.2 mm), 10.9 (washer size : 35 x t 3.2 mm) and 7.8 (washer size : 35 x t 4.5 mm). Furthermore, calculated tightening torque values were verified by tightening tests using a digital torque wrench. As a result, plastic clamp force values obtained by experiment agreed with calculated values ranging from minimum clamp force F-min to maximum clamp force F-max. However, the method of reducing variation in gamma(max) and y(min) remained to be investigated.

Due to major recent major earthquake, many traditional Joglo buildings have been damaged. In order to preserve Javanese wooden house against earthquake attack, as tangible culture, an evaluation and improvement of timber structures is indispensable. Joglo is the most complicated and sophisticated roof type in terms of the construction and techniques of Javanese wooden houses. The Joglo use teak wood as the primary construction material for both the building's structure and the ornaments. The house is use a knock down construction method, using mortise and tenon. Joglo-style for high-class society e.g., sultan place. The Joglo structure consists core and side structure. In term vertical and horizontal direction, they have different proportion and performance against lateral force. Structural proportion has role with seismic vulnerability. Here, investigation of the structural proportions of Javanese wooden house was carried out associated with earthquake structural damages. It shows the level of vulnerability of Joglo buildings against earthquake attack. A total of 29 Joglo buildings were estimated; the estimation can be used for earthquake mitigation in the future. In this paper, we report the results of investigation and objective to verify the contribution of structural proportion to the damage level of Joglo. (C) 2015 The Authors. Published by Elsevier B.V.

Six scaled-specimens of glued-acacia beam were tested in bending and effectiveness of non-metal repair of damaged beam by epoxy adhesive-vacuumed method was investigated. Two failure modes of glued-acacia beams by bending test were crack in bottom center and split from edge. Different covering method was used for them. MOE of type A showed fairly good recovery after repair. However in comparisons both specimens between bending strength before and after repair remarkable degradation. The epoxy adhesive-vacuumed method in full cover condition was thought to be appropriate and bending strength has possibility to increase more. The reason is adhesive is difficult to permeate the crack inside of the beam, they can permeate mostly from the surface. (C) 2015 The Authors. Published by Elsevier B.V.

本研究では、インドネシアジャワ島の代表的伝統木造建築物である、Joglo形式の建物の地震被害について論じた。2006年の地震被害調査結果と関連づけ、Jogloの規模および構成する部材の寸法比率と、被害規模に明確な関連性を見出した。これにより特定比率以下の建物の耐震補強の必要性を提言した。

Many Javanese traditional timber structures have been destroyed by major earthquake. A lot of them tend to be dismantled due to a high cost of reconstruction and a demand for more reliable structures. In order to preserve this disappearing building as valuable and tangible culture, a deeper understanding on these traditional timber structures is necessary. Especially the restoring force of the traditional joints, which are the major earthquake-resisting elements has to be investigated. The static characteristic of these structural components has been investigated experimentally. A total of 12 full-scale specimens of 2 types made from glued Acacia-mangium were tested. The specimen simulated joint at middle part, which is a joint of column-tie beams interlocked each other. The horizontal cyclic load was applied on the specimen placed in pin joint frame from two mutually perpendicular directions. The cyclic loading protocol consists of 7 increasing target deformations from 1/200 radian to 1/15 radian, and finally until failure. As the test result, failures were caused by embedment, crack, and split in beams parallel to the load direction. All crack of beam started from corner of beam mortise and resulted in the split. From the curve of load and rotational relationship, occurrence of initial slip leaded to the larger deformation. It revealed the importance of joint tightness against future earthquake. (C) 2014 The Authors. Published by Elsevier B.V.

直交集成板（以下，CLT）の面圧および端部せん断強度と，その繊維角度依存性を評価するための予測式を誘導し，面圧実験およびいす型せん断実験を，荷重方向に対する繊維角度を実験条件として行った。予測式の誘導では，各層が独立とした上で以下の仮定を用いた。（a）CLTの面圧強度は各層の面圧強度の平均で表される。（b）荷重に対して繊維角度が傾いた層の面圧および圧縮強度はハンキンソン式を用いて表される。さらにせん断に対しては（c）荷重に対して繊維角度が傾いた層では，圧縮降伏，または繊維に沿ったせん断破壊のいずれかが生じる。（d）CLTのせん断強度は，荷重に平行なせん断面（見かけのせん断面）の面積で，荷重を除した値で表される。得られた応力-角度関係は，実験値と同様の傾向を示し，値は安全側となった。

A shear wall composed by prefabricated mud wall units (PMWU) was studied. Mud panels reinforced by bamboo laths are enclosed in wooden frame, combining mud material's high energy absorption and stiffness of wooden frame. Among the advantages are workability and quality control before and after assembly. The PMWU's performance related to the number of frames’ connectors was analyzed. Digital speckle photography (DSP) was used to measure strains and finite element method (FEM) to validate the results. The shear stiffness of PMWU varied due to rotation of the panels. The stress transmission was influenced by the number of connectors via shear and contact between frames.

In this study, glulam beams were strengthened by inserting compressed wood (CW) blocks into the pre-cut rectangular holes with one-thirds of the beam depth from the top of the beams. This practice was to make use of moisture-dependent swelling nature of the compressed wood which was conditioned with the moisture content significantly lower than the ambient one. The test results showed that a pre-camber was produced in the mid-span of the beam reinforced due to expansion of the compressed wood blocks on the top part of the beam. As a result, significant initial tensile and compressive stresses were generated on both the top and the bottom extreme fibres of the beam, respectively. Subsequent bending tests revealed that the initial stiffness and load carrying capacity of the pre-stressed beams were increased significantly in comparison to the beam without pre-stressing. (C) 2011 Elsevier Ltd. All rights reserved.

本研究では、木質製材品を有効に活用するために、これらを接合具で緊結することで大断面化した柱・梁部材を作製し、またそれらを組み合わせた門型架構を作製してその面内せん断耐力性能を評価した。特に接合には圧密木材製の接合具を用いることで、解体・廃棄が容易な構法として提案を行った。