Naoya Shojo

Wall clay test specimens using different mixing ratios and materials were fabricated using Kumamoto (Yatsushiro, Taragi, Aso, and Amakusa), Saitama, and Kyoto’s new soil and some reused soil. To understand the mechanical properties of the mud wall, a compression test and a double shear test were conducted. Then, multiple regression analysis was performed using this data to calculate the estimation formula of compressive strength (σ_max) and shear strength (τ_max). First, the compression test of a 150×150×60 mm block and the double shear test of a 60×60×180 mm block were conducted, and the following items were confirmed. In the new soil of Yatsushiro,  ･As the compression specimen size decreased in size to a 100×100×60 mm block, the σ_max and its dispersion increased.  ･The σ_max of the second coating soil was higher than that of the first coating soil, but τ_max slightly varied. In addition, the second coating soil displayed brittle fracture behavior, but the first coating soil had a relatively higher degree of toughness.  ･The σ_max of some reused soil was higher than that of new soil, but σ_max and τ_max did not increase even when these soils were mixed.  ･Even when the straw content was increased from 5% to 8%, σ_max and τ_max remained approximately unchanged.  ･In the matured period from 7 to 90 days, σ_max and τ_max increased by 1.2–1.3 times.  ･Even when the quantity of sand in the second coating soil increased, σ_max, Young's modulus, and shear stiffness decreased.  ･When the specimens were classified into coarse-grained soil and fine grained soil, the σ_max of the coarse-grained soil was higher than that of fine-grained soil. However, the τ_max/σ_max of the coarse-grained soil and the reused soil were 0.6–0.7, that of the fine-grained soil was 0.8–1.0, and their strength ratios were classified into two groups.  ･The influence of soil appeared to be significant in the new Kyoto soil.  The following results were obtained using multiple regression analysis:  ･The σ_max of the first and second coating soil had the highest correlation with the clay mass percentage and the water content of the mud plaster (correlation coefficient R = −0.9). τ_max had the highest correlation with the plasticity index and the air-dried water content of the wall clay (R = −0.85).  ･It was possible to estimate σ_max using the explanatory variables of (1) and (2), where (1) is the fine sand mass percentage and density and water content of mud plaster of first and second coating soil, and (2) is the coarse fraction mass percentage, plastic limit, and air-dried water content of first coating soil.  ･τ_max could be estimated by explanatory variables of mud plaster density, fine sand mass percentage, plasticity index, and air-dried water content of first coating soil, but it could be also estimated by the average of σ_max, which is classified as coarse-grained or fine-grained soil.  However, these multiple regression equations have a relatively low degree of general versatility because the specimen shape, the type of material, and mixing ratio are limited. In the future, we will further increase the soil type and derive a multiple regression equation of high general versatility.

In this paper, the bending experiment on the wooden members with partial loss of sectional area was done. This bending experiment has three parameters such as the minor side of member, the direction and the length ratio of partial loss. Moreover, the influence of the partial loss of sectional area was modeled with the rotational spring, and the formula for the rotation rigidity was derived from the experimental results. The formula for the rotation rigidity was obtained from the length and the flexural rigidity in the partial loss of sectional area. Then the bending experiment on the specimens with the partial loss of sectional area to assume the post-Sashigamoi joint was done. And the effectiveness of the formula for the rotation rigidity was examined from these experimental results.

This paper presents the tension test of the pegged, mortise and tenon joint (column-sashigamoi joint) in the sashigamoi construction method. And, the tension test results are compared with the European Yield Theory (EYT). As a result, when the specimens consist of large and high Young's modulus column members, the maximum and yield strength rise. There are three failure types: Splitting failure of the column, shear failure of the peg, and shear failure of the tenon. When this joint is designed, the calculation of the yield strength is possible with EYT.

In this paper, the static loading experiment on the two story timber frame structure using drift pins are reported. The experiment was carried out in two construction stages. The first stage is the one in which the columns, the beams and the floors were constructed, and the second stage is the one in which the bearing walls were added to them. The contribution to the stiffness of this wooden structure by the frame and the bearing walls are examined experimentally.

In this paper, three types of moment resisting joints using drift pins are modeled into the three springs, and the relations between the moment and the rotation angle are calculated. The spring elements relating to the moment transfer consist of the connecting elements with the drift pins and the round bar of the tension side and with not only the same drift pin element but also the compressive strain inclined to the grain of compression side. The characteristics of the springs are evaluated by the experimental results in each element. The results calculated by the spring models are compared to the experimental results shown in reference 1). Furthermore the full-scale static loading experiments of the timber frame structure are carried out. Comparing the results obtained by the experiment to the results calculated by the spring models, the validity of the numerical modeling is confirmed sufficiently.

The purpose of this study is to examine the mechanical characteristics of the moment resisting joints in the performance of timber frame structures, and to certify the influence of each element upon the moment transfer, through the bending experiments of three types of joints. As the result of this examination, it is clearly confirmed that the element relating to the moment transfer is the connecting elements by the drift pins and the round bar in the part of the tension side, and not only the same drift pin element but also the compressive strain inclined to the grain in the part of compression side. By this modeling of the joint, the derivation of the calculation formula in the rotation rigidity and the yield moment are shown in this paper. Next, the rigidity and the yield moment of the compressive strain inclined to the grain and the drift pin element are evaluated. Comparing the experiment results of the three types of joints and the numerical results obtained by the calculation formula, the validity of this calculation formula is confirmed.

In this paper, the dynamic characteristics of a timber frame structure subjected to microtremor measurements are reported. The microtremor was measured in two construction stages. The first stage is the one in which the columns, the beams and the floors were constructed, and the second stage is the one in which the bearing walls were added to them. Not only the microtremor measurement but also the free vibration experiments were carried out, and the magnitude of damping factor was obtained. Moreover, the natural frequency obtained by this microtremor measurement was compared with the one calculated by static experiment and, furthermore, compared with the analytical solution obtained by using the rigid bar element with the springs for bending in both edges.

In this study, rotation rigidity and strength of the joint were evaluated through bending experiment of the joint using round bars and drift pins. Next, rotation rigidity (necessary rotation rigidity) of the joint of the timber frame structure which satisfied story deformation angle restriction of 1/200 and distortion angle restriction of 1/300 of the deflection of the beam was quantitatively grasped, and it was examined for the joint proposed here.

The purpose of this study are to know and to compare the shear strength of conventional dado and dove-tail joints with metal connectors system using LVL for timber structures by the experimental test. In this paper, we discuss the mechanical behavior regarding these 2 types of joints by the compressive strain inclined to the grain. Based on these experimental results, we propose a mechanical model for the calculation of the stiffness and strength in these connections.