This paper investigates the effect of dynamic soil-pile-structure-interaction on the nonlinear seismic responses of super high-rise RC buildings to pulse-like input motions. Dynamic soil springs and foundation input motions of pile foundations were evaluated for various types of input waves considering nonlinearity of surface soil. The effects of kinematic and inertia interaction on the seismic responses of buildings to pulse-like ground motions were comprehensively investigated by using sway-rocking models. Compiled results of the SSI effects on super high-rise RC buildings were validated using observed records including the 2018 northern Osaka earthquake (M_J6.1) and the 2021 northwestern Chiba earthquake (M_J5.9).

The author has estimated a broadband source model of the 2022 off Fukushima prefecture earthquake (M_J 7.4) by the back-projection and the empirical Green’s function methods using S-net, K-NET and KiK-net records. Five strong motion generation areas (SMGAs) do not overlap the aftershock area. Two SMGAs are located at shallow area in oceanic crust and the other three SMGAs are located at deep area in oceanic mantle. The two SMGAs at shallow area contribute largely to strong motions at land. The short period spectral level is larger than the previous equations for intraslab earthquakes.

The occurrence of earthquake ground motions exceeding the assumed design level may lead to plasticization of the superstructure of seismically isolated buildings. It is known that the plasticization of the superstructure is accompanied by a rapid development of deformation (quasi-brittle). In this paper, the relationship between the D_s value and the ductility factor is determined using incremental dynamic analysis, and the nature of quasi-brittle is quantified by formulating this relationship. Furthermore, seismic safety evaluation method for the limit state of seismic isolation layer and superstructure in seismically isolated buildings is proposed using this relationship.

This paper proposes a method of uniform response of an equivalent shear-spring model with viscous dampers. First, we propose an equivalent stiffness to evaluate the effect of the Maxwell model and confirm the validity of the results of eigenvalue analysis by using the equivalent stiffness in the primary mode. Next, to uniformize inter-story drift angle responses that envelop the maximum values of time history analyses for multiple earthquakes, we apply the equivalent stiffness to a method using closed-form representations of the primary mode. The results confirm that the method of controlling viscous damping via the equivalent stiffness is effective.

In this paper, a new load-bearing wall system is proposed which is composed of curved wooden member unit. This system can control both the stiffness and strength independently by changing the unit size, sectional size or curvature. The performance based design method is also proposed based on an inverse problem. By applying this system to old traditional wooden buildings, it becomes possible to design load bearing walls that can follow high deformation performance of the building structures. Furthermore, it is possible to change the appearance without changing the performance. The validity of the proposed method is examined through numerical examples.

In recent years, examples of adoption of steel plate structures are increasing. If a curved steel plate wall can bear vertical loads, the number of existing structural columns can be reduced. It is important to clarify the relationship between the shell shape and the strength in order to make it possible to use a curved steel plate wall as a structure.

In this study, we theoretically examined curved shells with two types of curvature and formulated the buckling strength. Furthermore, several analyses were performed to verify the validity of the evaluation formula.

When soil liquefaction is evaluated by numerical analysis, effective stress analysis is often used. In this paper, we propose a new method for estimating model parameters used in effective stress analysis. In our proposed method, liquefaction strength curves and pore water pressure curves obtained from laboratory tests are used as targets of the inverse analysis. It was confirmed that the parameters obtained by our method could not only reproduce both the liquefaction strength curve and the pore water pressure curve with high accuracy, but also the effective stress path, which was difficult by the existing method.

It is important to estimate an appropriate lateral load acting on piles of pile foundation during earthquake. The lateral load consists of an inertial force of structure and ground deformation. This paper describes the equivalent seismic coefficient of the foundation used in the pseudo-static analysis for piles design which are evaluated rationally by using seismic observation records. The evaluated seismic coefficients of the foundation were significantly smaller than the observed maximum accelerations divided by gravity accelerations. The reasonable evaluation method of the seismic coefficient was proposed considering the phase difference between oscillation of the superstructure and the foundation.

When the functional of the mixed finite element method based on the Hellinger-Reissner principle is applied to structures that cause large displacements, obtained solution has not a little error. By applying the augmented Lagrangian method to the principle of minimum potential energy with constitutive law, a new functional is presented. A formulation using this functional was developed and applied to several models causing link motion. Then, appropriately convergent solutions are obtained. This functional has the function to eliminate errors that occur when nonlinear equilibrium equations are linearized for analysis. However, the mixed method does not have this capability.

We conducted pull-out experiments on test pieces that imitated "komisen" joints of traditional wooden buildings and examined the fracture mechanism and conducted material tests on the test piece sets based on the fracture mode observed in the pull-out experiment to obtain basic data on the material properties. In addition, we evaluated the yield strength by the existing EYT formula and compared with the experimental results, and considered the applicability of the existing formula. Also, we constructed two-dimensional FEM models that simulate the pull-out fracture of the joints and compared the experimental results with the analysis results.

The purpose of this study is to establish a design method for the splitting strength of glued laminated timber beam with two round holes. In this paper, a design method for splitting strength is proposed by formulating the ratio of the maximum tensile stress perpendicular to the grain acting around the hole as the distance between the holes decreases, using finite element analysis. Then, a three-point bending tests were conducted on a glued laminated wood beam with two round holes, and the experimental and calculated values were compared to confirm the validity of the proposed design method.

It has become a very important issue to establish a rational reinforcement method for transmission towers, since the increase of assumed loads resulting from revision of design standards. However, some methods have been established for replacing and reinforcing brace members, it’s very difficult to replace the main post members.

In this study, we propose a reinforcement method in which reinforcement members are added to the existing main post angle members, and confirm the effectiveness of the reinforcement and its range of application by member compression tests.

In order to realize the buckling-restrained brace (BRB) with high energy absorption performance, it is important to prevent premature local bulging failure of the restraining part. In this study, the strength of BRB to resist local bulging failure of the restraining part is considered to be the minimum value of the strength of the steel plate considering the influence of the effect of filling materials and the strength to resist bearing failure of the filling materials. Local bulging failure is prevented by the value to resist local bulging failure larger than the force acting in the out-of-plane direction.

This paper is concerned with the effect of the bracing stiffness on the elastic buckling strength of H-shaped members subjected to axial force and end moments. The member is fixed to out-of-plane at both ends and discrete lateral bracing and torsional bracing are attached. The buckling equation is derived by using the Rayleigh-Ritz method. The relation between elastic buckling strength and bracing stiffness are presented when the bracing is attached at the midspan of the member. The equation for the required bracing stiffness in order to obtain the buckling strength when the deflection and the torsion are restrained.

The statistical procedures employing the Weibull distribution in the above paper for calculating the embedding stiffness parallel to wood grains seem contradictory to the theory of statistics. The assumption that the embedding stiffness results from the compressive deformation of the damage zone generated by cutting operation seems suspicious. Other miscellaneous problems which may be related to the reliability of the relevant paper are pointed out.

We are grateful for Prof. Kuwamura’s discussion to our paper. In this answer, we will give our opinions on questions about the statistical procedures employing the Weibull distribution and the relationship between damage zone and embedding stiffness parallel to the grain.