In this study, the suppression effect of Ground granulated blast furnace slag on hexavalent chromium elution during initial hydration and after carbonation was examined. It was revealed that Alkali-Activated Ground granulated blast furnace slag reduced leaching of hexavalent chromium by the effect of reduction and immobilization, and increased sulfur components showed an initial reduction effect more as added Ground granulated blast furnace slag increased. The hexavalent chromium elution from hardened cement after carbonation was suppressed by the reduction effect of alkali-activated Ground granulated blast furnace slag even when cement hydrate, which could immobilize hexavalent chromium, decreased.

The authors evaluate the effect of size on the brittle fracture initiation properties using proportionally sized specimens with 4:2:1 geometry, with the aim of clarifying the relationship between geometric shape (size) and brittle fracture properties. Three-point bending tests are conducted on eight types of specimens with different sizes and notch depths. Interpretations using simple beam theory or the traditional fracture mechanics parameter, crack tip opening displacement (CTOD) shows a large scale dependence. It is evident that an appropriately improved local approach is proposed to interpret the experimental results.

The clearance of the buckling-restrained brace is a factor that has a significant influence on its failure mode and mechanical behavior. In this study, the clearance adjustment construction for the buckling-restrained brace using steel mortar planks is improved. Further, the clearance adjustment construction of partially pasting fluororesin sheets or butyl rubbers to a core plate or spacers is proposed. The requirements for workability, cost performance, reliability for fabrication, and structural performance for safety is examined. Finally, based on a comprehensive evaluation, it is verified that the practicality of the proposed clearance adjustment construction.

　Floor covering is used for various purposes. For example, it is used in hospitals, logistics facilities, production facilities, etc. In recent years, the cases are reported that the problems with the floors occur. One of the problems is a wrinkle that is caused by the dynamic load when the equipment runs on the floor. In this study, we examined to set up a test method for wrinkle durability to these dynamic loads.

　As a result, we developed a testing machine that could be a standard testing method from the viewpoint of wrinkle durability, and confirmed its validity.

In this paper, a generalized method is extended to estimate story stiffness of wooden residential houses considering non-structural walls based on microtremor records of multiple building structures. The proposed method can estimate wall standard stiffness, effects of wall opening or wall shape as unknown model parameters to minimize the estimation error of eigen frequency. The validity of proposed method is examined by using actually measured microtremor records and drawing information, i.e. wall types and wall length, of 19 wooden residential houses.

The relational equation of the inhomogeneity of the subsurface soil and the propagation distance of the ground motion with the spatial variation of the ground motion between adjacent points is constructed based on the scattering theory. By applying the relational equation to the response wave of the seismic simulation using the three-dimensional heterogeneous soil model and the observation records on the Chiba array, heterogeneous parameters of subsurface soil and the depth 𝐿_c which affects the spatial variation of the seismic motion were estimated.

Structural health monitoring is attracting attention as an effective means to understand the functional continuity of a building after an earthquake. Previous studies have reported that continuous use of buildings was restricted after damage to their foundation structures despite minor damage to the buildings themselves. We propose to identify soil springs using the subspace method as one of the indirect monitoring methods; then, this approach is verified via numerical analysis using the sway rocking model. Furthermore, the proposed method is applied to measured data from a large shaking table test of a pile foundation to detect damage to the piles.

In general, eigenvalue analysis for beams considering rotatory inertia and shear deformation is not trivial, even in the case of uniform beams. In this paper, a practical method is proposed for calculating natural bending frequencies of uniform elastic beams considering rotatory inertia and shear deformation. The proposed method is based on the modified Timoshenko beam theory, which is more rigorous and realistic than the traditional Timoshenko beam theory. It is shown that the proposed method calculates the natural frequencies of an arbitrary order-vibration mode for beams of arbitrary cross-sections with a high level of accuracy, similar to numerical analysis.

The purpose of this study is to clarify the bending deformation of the surrounding members caused by the compressive resistance of the board wall, and to clarify the resulting change in the rotational embedment of the board wall and its resistance force by experiments. Based on the results, we proposed an equation for estimating the restoring force characteristics due to the rotational embedment of board walls when beams and columns are deformed in bending, and the estimated values represented the experimental values with good accuracy.

The shear design method of the panel-zone at the beam-to-column connections with lag-screw bolts is presented in this paper.

The average shear stress around the center of the panel-zone is evaluated using the wire frame model. The external forces subjected to beam-to-column connections, i.e. the axial force of lag-screw bolts and the compressive force from beams are considered to calculate the average shear stress around the center of panel-zone.

The calculated values are approximately the same as the values calculated by FEM analysis, regardless of the distance of the lag-screw bolts from the beam edge.

Work in this paper is to conduct experiments on hybrid steel bar (rebar)-timber beams under long-term loading during high-temperatures in order to determine allowable upper temperature of the beam at fire-resistant temperature environments and to reveal creep deflection of the beam under high temperature in Summer. The results are summarized below.

i) The rebar drastically reduces bending deflection component of creep of the beam during the temperatures in summer.

ii) The previous proposed equation could have predicted the bending component even under the high temperatures.

iii) The allowable temperature for the beam also was 110℃ at the fire temperature environment.

The purpose of this series of studies is to propose a design flow of connection in wooden wall structure calculated on allowable stress design and to verify its validity. In this paper, the perspective of the design flow is introduced and experimental and analytical research related to calculation modeling of shear wall is reported. From the results of wall analysis, the load contribution of connections to shear performance of wall was confirmed quantitatively. By comparing the results about joint between wall test and joint test both in experiment and analysis, the difference of stress distribution of joint was indicated.

The present study investigates the seismic performance of twelve-story RC buildings focusing on the structural effects of flat walls which are commonly neglected in design practice. Two-span moment-resisting frame was numerically modeled considering three analytical cases: Case 0 of beam-column subassembly, Case 1 with conventional flat walls, and Case 2 with damage control flat walls which were proposed in the authors’ previous study. Comparing the seismic performance of the three models based on the analytical results, the damage control flat walls were found to contribute to enhance both the serviceability and safety limits of the subassembly.

This study's primary purpose is to analyze channel member's distortional buckling behavior based on the energy method. A non-conventional mechanical model and displacement functions that simulate the distortional buckling behavior were proposed, and the contradictions of Hancock's model and Schafer's model were described. An evaluation formula for the distortional buckling that directly reflects the channel member's parameters was proposed via the proposed mechanical model. Also, an approximate formula is proposed. The proposed formulae's reliability and effectiveness are shown by comparing finite element analysis results and conventional evaluation formulae.

The damped outrigger system is in widespread in seismic area as a damping modification system. However, the relationships between the exact damping performance and its seismic response reduction effect has not been deeply investigated yet. This paper investigated the non-linear dynamic response characteristic of single-damped outrigger systems with oil dampers or elasto-plastic dampers considering design earthquake levels. The optimal damper design equations to maximize 1st mode damping ratio were proposed, and validated through the application example of a Japanese super-tall building, and a design algorithm to translate the optimized single damped outrigger to quad damped outrigger systems is proposed.

The purpose of this study is to verify the applicability of the equation discovery method proposed using mode extraction via singular value decomposition to the problem of finding a simple mathematical expression representing an input/output system of numerical analysis results. In this study, the derivation of equations for skeleton curve of steel beam was verified as an example. First, the outline of equation discovery method and the example problem are explained. Then, the results of the equation discovery are shown, and the applicability of the method is verified.