In reinforced concrete structures, drying shrinkage strain and creep deformation occur continuously over a long period of time. When concrete members are anchored to other structural members, stresses are generated and cracks may occur, adversely affecting the serviceability and durability of the structure. In this study, some examples of continuous frame models assuming reinforced concrete rigid-frame structures were created, and elastoplastic analyses were conducted over a long period of time by applying drying shrinkage strain and applying the FEM analysis software that simulates creep analysis to evaluate the damage that occurs in the entire structures, and to evaluate the damage that occurs in the entire structures. The objective of the study was to evaluate the extent of the restraining spring against the tensile axial force of the beams proposed in previous research. The following results were obtained.

The frames model exhibited shear-lag deformation behavior due to drying shrinkage, resulting in tensile axial forces in the beams at the first level and shear forces in the columns at the ends of the structure. Shear failures occurred when drying shrinkage were applied, and fractural cracks occurred at both ends of the beams when large bending moments were applied to the beams.

The degrees of the restraining spring for the axial force acting on the beam in the first layer section were distributed according to the shear-lag deformation and were not significantly affected by the number of layers in the model.

In this study, a series of static cyclic loading tests were conducted on serially connected two RC walls to investigate the shear stiffness degradation of the walls under varying axial load. The shear forces carried by the two walls were measured by the load cells independently located at the two bases. The shear resistance at the tensile-side shear walls decreased down to nearly zero in inelastic range, while the compressive-side wall carried nearly all of the total shear force. The shear distribution could not be simulated by the frame analysis using the conventional three vertical line element wall model, where the shear stiffness reduction is assumed to be same with the two walls regardless of the axial load level. A new model, called axial-shear model, was proposed to evaluate the shear stiffness degradation of the central line element including the varying axial load based on the stress-strain constitutive relation of the plane strain element, from which the shear distributions measured in the tests could fairly be simulated.

This study experimentally investigates the effect of the wing wall transverse bar ratio and axial force ratio as parameters on the shear strength of RC column with a wing wall on Either One Side. Next, the accuracy of the evaluation formula for the shear strength of the current RC column with wing wall is examined by comparing the experimental results with the calculation results in which tensile bars are defined for each of the positive and negative directions. Furthermore, the applicability of the replacement section method, which evaluates the shear strength of a column with a wing wall on either one side by replacing it with a rectangular section, is examined.Finally, the applicability of the analytical model is discussed by comparing the experimental results with the analytical results obtained from a stable convergence algorithm applicable to columns with a wing wall.

This paper focuses on low-rise RC buildings and presents a simplified method for calculating the distribution of the required wall ratio to ensure continued use after an earthquake. The method is based on energy balance and considers not only the main shock but also the largest foreshock or aftershock, aiming to keep the damage level below minor. The study estimates the distribution of wall ratios that would result in minor or less damage after multiple occurrences of extremely rare earthquake, as stipulated in the regulations, and provides guidelines useful for performance design. Nonlinear time-history response analyses were conducted to confirm the applicability of this method to strong seismic responses.

In general, the width of precast pile caps is often set at 2.5D (D：pile diameter ). Numerous experiments on specimens with 2.5D have also been reported in previous studies. Furthermore, according to the literature from the Architectural Institute of Japan, the effect of shear reinforcement cannot be considered in the design formula of the pile head embedded portion. In this study, bending shear experiments were conducted using specimens with a pile cap width of 2.0D to present the damage process of the pile caps and the influence of various parameters on the experimental results. Additionally, by considering the effect of shear reinforcement, a proposed formula is presented to evaluate the maximum strength of the pile head embedded portion.

Japan is one of the most volcanic countries in the world, and ensuring the safety of structures against disasters such as volcanic cinder impact is an important issue. Therefore, the safety of evacuation shelters and other structures against volcanic cinder impacts is being verified.Analytical studies on the phenomenon of volcanic cinder impact have been conducted using the finite element method and the difference method. However, the finite element method and difference method use differential quantities in space, which may lead to calculation failures.

In this study, a numerical analysis of a steel evacuation shelter subjected to volcanic cinder impact is attempted using Peridigm, a fracture analysis system based on the Peridynamics theory, which discretizes the integral equation without using the differential quantity of space. Strain-rate effects are taken into account in the analysis, and the application of strain-rate effects is also analyzed.

In structural health monitoring, one key objective is to assess the integrity of buildings by observing their seismic response. Due to the limitations in the operation of monitoring systems, it is often impractical to monitor all stories, and the number of observed stories is typically limited. To predict the seismic response of unmonitored stories, we propose a method that translates the entire building into an equivalent shear model without relying on prior information on eigenmodes. The proposed method adjusts the top acceleration transfer function assumed to be derived by observed data to account for differences in higher-order natural circular frequencies between the frame model and the shear model. By fitting the transfer function, the stiffness and damping factors of the shear model are identified, enabling the estimation of maximum inter-story drifts and the absolute acceleration responses of the unmonitored stories. In a numerical example, the proposed system identification method is applied to a 20-story three-dimensional frame model, and the identification accuracy and effectiveness of the method are demonstrated.

This study deals with bending analysis that takes into account the slipping displacement at the joint surfaces of composite cross-section beams with arbitrary cross-sectional shapes, arbitrary material properties, and arbitrary number of joint surfaces. In this paper, the analysis method to take into account the effects of shear deformation are developed. In this paper, the following points are clarified.

1. A finite element analysis model is proposed for Timoshenko beams with any cross-sectional shape, any material properties, any number of layers at the joint surfaces, and any adhesion coefficients at the joint surfaces.

2. Several numerical analysis examples are carried out, and it is shown that the proposed analytical model is effective.

3. An elastic analysis method that evaluates shear deformation by taking into account the effect of sliding displacement on the joint surfaces of laminated beams is presented.

In recent years, the use of structural members of buildings with arbitrary laminations has been increasing. When performing detailed analysis, it is necessary to appropriately consider the influence of bond slip deformation on the joint surfaces. It is desired to develop an analytical model that can perform buckling analysis.

In this paper, an analytical model for buckling analysis of a laminated column member with arbitrary number of joint surfaces, arbitrary cross-sectional shape, and arbitrary structural characteristics is proposed, and then a finite element equation is presented. The analysis example shows that by performing buckling analysis of a column member having arbitrary adhesive coefficients, the elastic buckling load can be appropriately determined, and the buckling mode can also be appropriately determined.

Flying characteristics of wind-borne debris were investigated using two one-cell tornadic models. Wind-borne debris was assumed to be released at 961 points at each of 21 different heights. Fluctuating wind speed was considered and the fluctuating components were generated from the power spectral density with a constant power. From the analyses, it was found that the effect of tornadic models on flying characteristics was large. But, the effect of fluctuating wind speed was found to be small. It was also found that many release points from various heights need to be examined.

Authors discuss the characteristics of eddy current dampers composed of a magnet and a copper plate with magnetic material. Differential integral equations governing both eddy current and magnetization were derived from the Maxwell’s equations and some phenomenological laws. The equations were simplified into a linear simultaneous equation. The results of a shaking table test validated the damping effect and the calculation method of electromagnetic force. Through numerical analysis, the size of the eddy current damper to be applied to a seismically isolated detached house was estimated, and the attractive force acting between the magnet and the steel plate was identified.

This study investigates Large Deformable Elastic Plates (LDEPs), which exhibit significant elasticity and can return to their original shape even after large deformations. The concept of Large Deformable Elastic Braces (LDEBs) is applicable and explores the elastic properties of LDEPs, which minimize residual deformation of the model. This study conducts both experimental tests and finite element method (FEM) analyses to find the performance of LDEPs under tensile loads for conditions of material and geometric non-linearity. However, topology optimization of four-column formulation methods has been established, and the findings demonstrate the significant potential of LDEPs in improving earthquake resistance. This study also focused on the considerable effect of residual stress and material hardening due to laser cutting. The final key conclusion is to develop an equation for yielding deformation and yielding force of LDEPs, verified by numerical analysis and experimental test results. The practical application of these components underscores their suitability in earthquake-prone regions.

A piece-wise linear modal analysis method is developed for analyzing seismic uplifting responses of multistory buildings modeled as uniform shear-beam on rigid ground. Classical modal analysis is applied to calculate responses for two phases: contact phase and uplift phase. Two sets of modes corresponding to the two phases are converted to each other at the incipient of uplift and the instant of landing. The assumption of complete plastic collision is adopted at landing instants. After showing the validity of the method by comparison with experimental results, examples show the effect of damping and vertical seismic motion.

This is a review of journal papers on additive manufacturing, also known as 3D printing, published until April 2024 with a focus on structural engineering including material, design, fabrication, construction, education and sustainability issues. The AM-related articles have been increasing exponentially since around 2013, now piling up to astronomical figures in the world. Despite this enormity, the author is brave enough to select only 177 articles which must reveal the basic movement of AM for structural engineers, being urged by the current state that such a review paper has never been published in Japan. The readers of this paper will find that many challenging research topics are advancing and further that a variety of digital technologies are playing in the AM world.

Load and resistance factors design is widely used in structural codes for reliability-based limit state design. Among various design methods, third-moment methods are widely used because they do not require double iterations based on the derivative and the probability distribution of random variables. However, the accuracy of the existing third-moment methods restricts the skewness to a narrow range, which does not satisfy the structural design under the large range of the skewness. This paper proposes a simple and accurate method for determining the target mean resistance and load and resistance factors based on the newly proposed exponential reliability index, which eliminates complex iterations and expands the applicability of existing third-moment methods. Several examples are provided to demonstrate the applicability and accuracy of the proposed method for determining load and resistance factors.

This study addresses shape optimization and maximum bending strain energy design problems with bending strain energy as the objective function, subject to a constant amount of shape modification for shell surfaces. The difference between the maximum and minimum bending strain energy ratios is defined as the variation range. Based on the magnitude of this variation range, we investigate the sensitivity of the bending strain energy ratio to shape modification. By examining shells with various boundary conditions and openings, our results show that, for example, axisymmetric dome-shaped shells and trumpet-shaped shells exhibit high sensitivity to external forces in the vertical direction, but low sensitivity to external forces in the horizontal direction.

A wire rope is a material consisting of many steel wires bound together, and is characterized by high strength, flexibility, and long length. Recently, cables have come to be used in a wide variety of ways. Under these circumstances, detailed analysis of wire stress through numerical analysis is required to verify the safety of wire ropes. Based on the above, this paper performs an analytical study with the aim of understanding in detail the stress of the wires when the cable is subjected to simple tension, local bending, and lateral local pressure.

A hybrid string structure is a structure that combines a frame with bending rigidity and strings (non-compression-resistant straight members). This structure is characterized by the ability to control deformation and stress by intentionally introducing tension into the cables. For this reason, when designing a hybrid string structure, it is important to determine the appropriate string arrangement and initial tension. In recent years, examples of hybrid string structures with various shapes have been seen. Taking these circumstances into consideration, this paper aims to establish an optimization method for hybrid string structures, and focuses on a plate string structure to examine a method for optimization of topology and tensile force.

The ceiling surface of the gapless ceiling buckles by receiving compression force by inertial force from the wall. In this paper, two buckling modes and their corresponding strength prediction formulas were examined. One is the buckling between hanging bolts, where the gypsum board and the joist receiver buckle together. The other is the buckling between joists, where the gypsum board buckles out-of-plane and the joist receiver buckles in-plane. We revise the strength prediction proposed by a previous study and investigate its validity using new test specimens. The causes of the discrepancies in the predicted results are examined. Additionally, the axial force distribution of joist receivers and gypsum boards in the joist receiver direction of gapless ceilings is investigated.

This paper presents a method for predicting dominant vibration modes using neural networks to calculate the static seismic loads of single-layer cylindrical reticulated shells with various support conditions. In order to represent the structural features of these shells, such as support conditions and aspect ratios, in neural networks, this study introduces a method of expressing the displacement distribution in a fixed-length three-dimensional array, similar to image data. The three-dimensional array is fed into a neural network with convolutional layers and is used to predict the dominant vibration modes. Machine learning was applied for training, validation, and testing based on the vibration analysis results from 37,293 shells. The results demonstrate that the proposed method can accurately predict the dominant vibration modes.

In the seismic design of secondary systems (SS) such as nonstructural components, the effect of torsional vibrations of structural frames due to asymmetric properties are not explicitly considered. The effect has been investigated for relatively small SS, but not for large ones. In this paper, seismic response of symmetric large SS installed in continuous broad areas in single-story asymmetric buildings are investigated through response history modal analysis. The torsional response of symmetric SS and the correlations between modal responses are discussed. From the results, peak responses of large SS are shown to be almost equal to those of corresponding small SS.

Structural health monitoring (SHM) is one of the most effective methods for estimating building damage immediately after an earthquake. However, this method generally requires the installation of expensive sensors in buildings, which makes it often difficult to implement and maintain. In this paper, a simple damage estimation method for RC buildings is proposed assuming next-generation gas meters are installed. Using time history response analyses, changes in the natural period of the building due to damage were evaluated using data from next-generation gas sensors, and the relationship between the changes in the natural period and the damage was developed.

On January 1^st, 2024, an earthquake occurred in the Noto region of Ishikawa Prefecture. This earthquake caused damage to many buildings, mainly in the northern part of the Noto Peninsula. It is necessary to clearly determine the destructiveness of earthquake motions. In the previous research, collapse base share coefficient (Cc) spectra to prevent buildings from being collapsed by the earthquake motions were proposed as a method for evaluating the destructiveness of earthquake motion.

In this study, in order to consider the destructiveness of the ground motions of the Noto Peninsula Earthquake, seismic response analyses were performed, and the Cc spectra were obtained. There were general correlations between Cc spectra and building damage. By comparing the Cc spectra of the 1995 Hyogo-ken-Nanbu Earthquake (JMA Kobe), the characteristics of the destructiveness of the Noto Peninsula earthquake were considered.

Recently, as a measure against huge earthquake motion, the design methods using the dampers and deformation-control devices are supposed. This design methods would suppress the story drift angles for huge earthquake motion, but could increase the floor acceleration for small or medium earthquake motion. Therefore, in this paper, the hysteresis characteristics of the dampers and the deformation-control devices on story drift angle and floor acceleration at different earthquake ground motion levels are investigated by time history response analysis.

In high-rise steel structures, electroslag welding (ESW) is used for joining box-shaped columns and H-shaped beams. The slit at the ESW joint raises the risk of brittle fractures due to tensile stress and large heat input. Studies using experiments and finite element analysis (FEA) showed a strong correlation between maximum principal stress near the slit and brittle fracture occurrence. To prevent such fractures, cyclic loading in FEA is essential. Common models like Chaboche & Rousselier's cannot account for strain amplitude dependency of cyclic hardening, unlike Chaboche's memory surface model. This study compares these models' impact on ESW joint stress-strain states.

In the Tohoku Pacific Coast Earthquake (2011), long-period earthquakes are attracting social attention in the point of disaster prevention. In the Hyogo-ken Nanbu Earthquake (1995), ruptures in the beam end welds near weld access holes were reported.

Regarding this damage, countermeasures have been taken to prevent early fracturing, but existing buildings have same detail. It is important to evaluate deformation capacity of these steel beams.

In this paper, test and FE analysis were carried out to investigate the effect of thin beam webs on the deformation capacity of H-shaped beam with weld access hole subjected many cyclic loadings.

In this paper, the sliding properties of high-strength bolt friction joints with slot holes are investigated by slip tests and FEM analysis. This paper focuses on one-sided friction joints. First, slip tests were conducted to investigate the effects of each parameter: bolt hole shape, plate thickness, and stiffening plate shape on the slip coefficient. Next, FEM analysis is performed to investigate the effects of other parameters such as joint strength ratio, slot hole direction, thickness and shape of stiffening plate, and plate width on the slip coefficient. As a result, it was found that even if the stiffening plate is one size smaller than the base metal, it has little effect on the reduction of the slip coefficient. The effect of joint strength ratio and slot hole direction on the slip coefficient is also significant, and it is considered necessary to design the joints in consideration of these factors.

In this study, the effective length factor was calculated using the SI method. Three analytical models were analyzed using the type of column bases, number of stories, number of spans, beam stiffness ratio, stiffness ratio reduction factor and story shear force distribution (Case I, Case II) as analytical parameters for a relatively even non-uniform frame, a frame with severely disturbed column stiffness and a frame with severely disturbed column axial forces, and the effective length factor obtained by the SI method was compared to the effective length factor obtained by the buckling slope-deflection method, and the validity of the SI method was investigated. The results showed that the SI method was able to evaluate the correct value of the effective length factor within an error of about 5% for both analytical models, regardless of the story shear force distribution.

In recent years, Buckling-Restrained Braces (BRB) used in high-rise buildings have increasingly required high strength brace. Therefore, it is necessary to verify the feasibility of Buckling-Restrained Braces using Steel Mortar Planks (BRBSM) that are capable of handling larger sizes. In this study, we fabricated a full-size BRBSM based on a trial design of the largest size and its corresponding reduced-size test specimen. Structural test on the reduced-size specimen confirmed stable restoring force characteristics and energy absorption performance. Additionally, a fabrication test using the full-size specimen verified its feasibility by meeting the established quality control standards.

For seismic retrofit steel frame buildings, on-site welding and drilling for bolted joint often can not be applied because of fire safety concerns, overly thin plate and section loss. The authors have proposed a welding-free joint method for existing steel pipe members consisting of adhesive and non-adhesive bonding connections.

This paper shows the mechanism of the proposed welding-free joint method, the results of cyclic loading tests, and a simplified method to evaluate the joint capacity. The cyclic loading tests were conducted to clarify the effect of the existing steel pipe size and the joint geometry on the load-carrying capacity of the joints. The simplified evaluation method of joint capacity was established to estimate the stress condition of the adhesive bonding joints and to evaluate the joint capacity with several assumptions. Furthermore, good correspondence could be confirmed by comparing the simplified evaluation method and test results.

The seismic intensity is recognized as the scale of earthquake motion in Japanese society. In this paper, I discuss the maximum displacement responses on strong motions with intensity 6. In order to discuss this issue, the restoring force characteristic of non-structural wall and the input angle of strong motion is also considered. Wooden houses are classified according to the sufficiency ratio of resistant wall and eccentricity ratio based on the wall mass and other criteria (enforced in 2025). In this case, the sufficiency ratio is considered for both Method 1 and Method 2. The results may be summarized as follows: the maximum base shear coefficient is more highly correlated with the sufficiency ratio by method 1 than the with the one by method 2. The eccentric factor diminishes the distribution of maximum displacement response efficiently. The relation between the seismic intensity and the maximum displacement response of houses is shown.

Plywood, due to its high workability, has the potential to be used as a structural seismic wall with unreinforced openings, offering flexible design possibilities. In this study, we define a "Non-Uniform Lattice Patterned Plywood Seismic Wall" that features an opening pattern surrounded by straight members of various widths and angles, as an example of a free shaped, unreinforced opening. We experimentally verify its mechanical performance and propose two numerical evaluation methods: a simplified calculation technique that models the wall as a frame of beam members, and a detailed calculation method that models the wall as an orthotropic plate element. We also propose a shape generation method using optimization techniques. Finally, we outline the design flow for these seismic walls, integrating the proposed numerical methods and shape generation techniques.

The objective of this study is to verify whether the addition principle can be used to evaluate the seismic performance of temples and shrines combined with several types of seismic elements. Static loading tests were performed on several types of wooden frame specimens with columns, a kashira-nuki, an uchinori-nuki, an ashigatame-nuki, wooden siding walls and mud walls. From the test results, the load-deformation angle relationships and damage situations were clarified. By comparing the load-deformation angle relationships of different types of specimens, the relationship between the number of seismic elements and load increase ratio were determined.

To clarify the presence or absence of local buckling suppression effect and confining effect due to the interaction between the metal pipe and the wood, a short column test was first conducted by simultaneously compressing both the wood and pipe sections of a square steel tube with knotty wood inserts. The results showed that the relationship after reaching the maximum compressive force between compressive stress and strain in these short columns under the conditions of this experiment is a superposition of the relationships obtained in tests with only the steel tube and only the wood. Following this, a short column test was conducted using a method where the compressive force was applied directly only to the knotty wood inserted in square steel and aluminum square tubes. Consequently, there was no confining effect of each metal tube on the compressive strength of the knotty wood. Simultaneously, a confining effect on behavior during the stress descending portion was observed.

This study is to propose a timber-steel hybrid beam string structure with local lumbers of general distribution. The proposed system is that local constructors can handle locally grown lumber without special materials or techniques. We obtained the structural performance of this unique construction method through bending experimental tests of individual assembled upper-string members and structural tests and structural analysis of the timber-steel hybrid beam string structure. Findings through this study include the following：

・The bending performance of the joints of the upper chords of laminated timber under wind loads at blowdown and unbalanced snow loads was determined through structural tests.

・An elastic analysis with replacement of beam and spring elements was performed to obtain specifications of sections and joints for various loading conditions.

・Through bending experimental tests on the timber-steel hybrid beam string structure, we considered that the analytical results are compared and the validity of the experimental results.

To expand the use of timber in steel structure buildings, it is essential to employ wooden members not only for slabs but also for wall components. The authors proposed using CLT as support members for seismic panel damper sys-tems integrated into steel structures.

The authors used a lag-screw-bolt (LSB) as a shear connector and hexagon head bolts to connect the steel members and CLT panels. Push out shear test and horizontal cyclic loading test were carried out in order to investigate hyste-resis behavior of shear panel with CLT as support members. From the test results, the shear panel exhibited stable behavior and large energy dissipation under the condition of yield shear strength of LSBs more than ultimate shear strength of shear panel.

In this study, static loading tests were conducted using 40% scale test specimens to examine the structural performance of one-story, one-bay reinforced concrete (RC) moment-resisting frames infilled with CLT panels. The tests investigated three parameters: the presence of CLT infill, CLT panel thickness, and division numbers of CLT infill. The experimental investigation revealed the following findings:

1. The presence of CLT infill significantly increased the initial stiffness and strength of RC moment-resisting frame. Additionally, it caused the main rebar in the beams to yield earlier.

2. Increasing the CLT panel thickness significantly contributed to increase the initial stiffness of the overall frame, while its impact on to the overall mechanism strength was limited.

3. Increasing the division number of CLT infill reduced the overall structural strength. The aspect ratio of the CLT panels affected the rocking behavior.