Influences of energy level of artificial ground motions on characteristics of response spectrum are discussed. The 10%-damped energy spectra and 10%-damped acceleration response spectra are computed in various frequency bands using artificial ground motions with equivalent phase properties and different energy characteristics. As a result, though all artificial ground motions are compatible with a 5%-damped design acceleration response spectrum defined in Japan’s code, tendencies for the acceleration response spectrum to decrease as the level of the energy spectrum increase are observed in almost all frequency bands. Consequently, it is recommended that designers consider the characteristics of the energy spectrum, as well as the phase properties of design artificial ground motions.

In previous studies, the dam-break type hydraulic experiments and computational fluid dynamics have been conducted to clarify the characteristics of tsunami loads acting on a building with an upstream obstruction. We found that the tsunami force acting on the model behind the obstruction is smaller than that acting on the isolated model, while the tsunami force acting on the model parallel to the obstruction is larger than that acting on the isolated model. However, the effect of downstream obstructions on the tsunami force of the building was not discussed. It is possible that the tsunami force acting on the building decreases in the case of the building structure with downstream obstructions, because that the tsunami water enters between the building and obstructions, and then the water height behind the building raises, exerting the force from rear to push the building. Therefore, this paper investigates the fundamental characteristics of the tsunami force acting on the building with downstream obstructions by using hydraulic experiments and computational fluid dynamics.

Aerodynamic and response characteristics of a square- and rectangular-plan tall building models with various aspect ratios were investigated through a series of wind tunnel tests under the flow conditions representing the suburban area. The cross-sectional areas were designed to be the same and the aspect ratios were changed from 2 to 9.5. It was found that the effect of the side ratio on mean and fluctuating force coefficients in X-direction was found to be small. But, clear differences were found on force coefficients in Y-direction, showing larger values for the square-plan model. From the Den Hartog criterion, an aerodynamic instability could occur for the square-plan models with the aspect ratio larger than 3 and the rectangular-plan models with the aspect ratio larger than 2 for the wind direction which is normal to the long side of the model. Correlation length scale increases with the aspect ratios, showing larger values in X-direction than those in the Y-direction. Lastly, tip displacements and peak accelerations were calculated based on a spectral modal method. Both responses increase with the aspect ratio and the tip displacements of the square-plan model become larger than those of the rectangular-plan model when the aspect ratio is larger than 6.5. However, peak accelerations of the square-plan model were larger than those of the rectangular-plan model for all the aspect ratios.

This study proposes a new representation method of an input ground motion model as a non-stationary stochastic process based on the short-time Fourier transform (STFT). The inverse STFT of the product of a deterministic amplitude function concerning time and frequency and the Fourier transform of a Gaussian white noise gives the input ground motion model. This definition implements the ground motion model as an evolutionary process and delivers the expression of the non-stationary power spectral density function. The sample waveform functions generated numerically from the stochastic model keep expected well-designed characteristics. Furthermore, a method of random response analysis of an elastic SDOF system excited by the input ground motion model is carried out and used to estimate its maximum response. Some numerical simulations demonstrate the effectiveness and accuracy of the proposed method.

Effect of inter-period correlation of spectral accelerations on seismic risk reduction was examined. At first, authors introduce the measure, that is the ratio of probable maximum loss (PML) of portfolio of buildings to the some of PMLs of individual buildings, in order to quantify the reduction in seismic risk. The multi-event model that is often employed for the seismic risk analysis of the portfolio of buildings located in the different places was utilized to handle the inter-period correlation. Three buildings whose natural periods are 0.3 s, 1.0 s and 3.0 s, respectively, were selected as the model buildings for trial calculation. It is noted that the damage functions and fragility curves were developed analytically in advance. Remarkable results related to seismic risk reduction are summarized as follows;

1. the lager the natural periods of buildings are separated, the bigger the effect on the seismic risk reduction is,

2. the number of buildings in the portfolio affects the seismic risk reduction, and,

3. the magnitude of inter-period correlation of spectral accelerations gives the large effect on the seismic risk reduction.

Estimating the performance curve and evaluating the damage level in structures is essential but challenging. This paper proposes a characteristic point method and a scaling method for updating performance curves and current damage levels based on observed records and analytical models. A single-degree-of-freedom system is proposed to verify the applicability of the methods. First, a trial calculation is carried out to verify the performance of the proposed methods compared with the condition without applying the methods. Then, a series of cases is considered to investigate the applicability of the proposed methods by 1) limiting the observed range to a maximum ductility factor between 0 and 4, and 2) introducing artificial error in the analytical model by modifying initial stiffness and yielding stiffness using factors between -40% to 40%, and cracking strength and yielding strength using factors between -20% to 20%. For both methods, the estimation of characteristic points, performance curve, and damage level reaches reasonable accuracy when the maximum observed ductility factor exceeds 1.2. The characteristic point method is better if the observed data contains the yielding point, but if observations are limited to contain only data prior to yielding, the scaling method produces more accurate results.

In this study, I carry out following three series of experiments: series A: hanging walls with horizontal slit at the bottom of the beam, series B: mud walls with horizontal slits at the top and the bottom of the wall and walls without beam and series C: mud walls with various opening. The following findings were clarified from the experiments: If the story deformation angle is 1/30 rad or less, the presence or absence of slit of the hanging wall would be irrelevant to the stiffness and strength. When there are the slits on the top and bottom of the wall, both the stiffness and strength would decrease by 0.75 times compared to when there is not slit.

This study proposes a structural system and analysis model of passive controlled shear wall for mid-rise wooden construction with high damping rubber damper and cross laminated timber using drift-pin joint. In this paper, to verify the validity of the proposed analysis model and the effectiveness of the shear wall, cyclic loading tests of high damping rubber damper and full scaled shear wall specimens ware conducted. Test results ware simulated by analysis model using elastic-plastic pushover analysis. Calculation results simulated by proposed analysis model showed that the analysis results reproduced the experimental results accurately.

The feasibility of mid-to-high-rise timber buildings was examined and proven from the following 2 aspects:

1. A hybrid structural system using CLT walls and steel frames, that can utilize the high strength and stiffness of CLT, was proposed, and full-scale steel frame-CLT wall test showed high performance.

2. Practical structural analysis model was developed and validated by full-scale steel frame-CLT wall test, and it was found that the strength and stiffness could be evaluated with high accuracy.

In order to evaluate the wind resistant performance of the roofs of conventional wooden houses appropriately, the present paper focuses on the lifting strength of the rafter to pole-plate joint, which is regarded as the weakest point of roof structures. Pulling-up tests are conducted using full-scale test specimens of the joints with different connecting methods, roof slopes, and wood species. Based on the results, the effect of each parameter on the strength is made clear. Furthermore, in order to evaluate the strength of the joint where different connecting methods are used together, element tests are also conducted for these connecting methods. The results indicate that the strength of the joint with each connecting method can be reasonably evaluated by the formulas specified in the current design standard. It is also found that even when different connecting methods are used together, the connection strength can be evaluated by these formulas. Considering that the strength is significantly affected by wood deterioration, an accelerated deterioration test is carried out on the wood specimens. The results of the present study may provide useful information for developing a model for predicting the wind-induced damage to the roof structures of existing wooden houses.

This study is to propose a parallel string truss construction system with local lumbers of general distribution. The system consists of arrangement characteristics of the species processed on standard lines of residential pre-cutting machines, and it is easy to assemble as a parallel string truss. In order to verify the workability of this system and to obtain basic data on structural performance for practical use, joint element experiments and full-scale experiments were conducted. The results of these experiments were obtained as follows ;

- The elemental joint experiments were confirmed the mechanical properties of the different species of wood, number of screws, and shape of the specimen.

- The joint performance was considered to improve arrangements of the drift pins or screws.

- The full-scale experiments of 4.4m and 11m span were carried out. The mechanical properties have some differences performances for species of wood or truss span.

The objective of this study is to evaluate the seismic performance of the column-to-kashiranuki connection used for temples and shrines considering a vertical axial force. Static loading tests were conducted on timber frame specimens with a kashiranuki and columns. From the test results, the load-deformation angle relationships and damage situations were clarified. The evaluation formula for the column-to-kashiranuki connection was proposed and compared with the test results to evaluate its accuracy.

This paper presents time history response analysis of two-dimensional models of a simple gable frame. Several frames with different structural types and yielding mechanisms are analyzed to investigate the differences in vertical response due to frame yielding. The S1 beam yielding model has a vertical deformation in the collapse mechanism, so the response increases with larger input earthquake motion. In other models, the vertical displacement is caused by the disappearance of the roof thrust. These vertical displacements and accelerations are predicted by hand calculations, and it is shown that some correspondence can be found with the numerical results.

FRP materials that have superior material properties, e.g., high weight strength ratio and corrosion resistance, have been widely applied to industrial, aerospace, and construction use in recent. In the construction field, the repair and strengthening method using FRPs has been strongly researched and developed. Almost all methods adopt the adhesive bonding method to apply FRPs to the existing structures. This paper shows a new strengthening method and mechanism using thin FRP restrainers. We propose the use of slitted thin FRP pipes for strengthening. The FRP pipes are wrapped with rotational lamination around the existing pipe member to increase the bending stiffness and buckling load. Because of the high elastic deformation performance of FRP, the plastic band-like application method can be used for the wrapping. As a result, the proposed strengthening method is demonstrated successfully, and it is clearly shown that the bending stiffness and buckling load are increased by the present method.

In recent years, advancements in construction technology have led to the construction of many free-form lattice shells with complex curvatures. As a result, there is a growing need for research on the buckling strength of these structures. This paper focuses on various free-form lattice shell models with distinct mesh patterns and boundary shapes, investigating their buckling behavior in response to initial shape imperfections. We aim to clarify the impact of these differences on the sensitivity of elastic buckling loads to imperfections. Additionally, we will conduct reduced stiffness (RS) buckling analysis, a method for predicting the lower limit of buckling load in the presence of imperfections and analyze its relationship with elastic buckling analysis.

The present study investigates an approximate FEM buckling analysis method for H-section beams, in which the effects of torsional and warping rigidity are included using traditional beam-column elements, followed by its application to materially and geometrically nonlinear buckling analysis of an arch structure and a unit dome. The approximate-beam model consists of three parallel beam-column elements deforming independently which enables the model to express lateral torsional buckling deformation of members. The validation of the proposed beam model is confirmed by both beam theory's solutions and 3-D FEM analysis. The present approximate-beam model, applied to an arch structure and a unit dome, proves its efficiency in buckling analysis. The results show that the torsional and warping deformation of H-section beams are relatively large and cannot be neglected in buckling load evaluation. The present model based on the compound use of traditional three-beam elements is concluded to be capably applied to H-sections under nonlinear torsional and warping deformation.

In the biomechanics field, tensegrity structures are considered to be similar to the human skeleton and the joint. Oh proposed a bio-tensegrity model that mimics the human spine and presented a shape control strategy, which leads to the optimization problem with the lengths of the tensile members corresponding to the muscle and tendon as design variables. It has been pointed out that this model has low initial stiffness and buckling occurs during shape control to avoid obstacles. In this study, a method for modifying the shape and self-equilibrium stress so that the minimum eigenvalue of the stiffness matrix in the initial state becomes the specified value is presented. Furthermore, with constraints on the eigenvalues of the tangent stiffness matrix, we extend to a shape control method that avoids obstacles without buckling.

TMD (Tuned Mass Damper) is fit for the vibration control of a spatial structure because it is possible to install the TMDs by a single supporting point. Therefore, there are many studies on the vibration control for a spatial structure by TMDs. However, the effects of degrees of connections at joints between roof structure and supporting substructure on the vibration modes controlled by installing TMDs are not examined. In addition, depending on the half open angles of roof structures, multiple TMDs are concentrated at a single node by the antinodes of multiple controlled modes overlapping. As a results the stresses of members near that node may increase. Therefore, this paper is intended as an investigation of the effects of changes in degrees of connection between roof structure and supporting substructure and the effects of distributed installation of multiple TMDs installed on roof structure and supporting substructure for purpose of dispersing loads at nodes of roof on the response reduction effects by TMDs for cylindrical lattice shell roofs.

In the structural optimization problem determining the placement of dampers on a building, an appropriate structural model is desired to evaluate the structural seismic response and the performance of the dampers. Although the structural optimization based on the time-history analysis using large-scale frame model can be performedrecently, it is preferable to use a simple structural analysis model to reduce computational time in optimizations. This paper proposes a simplified modeling method to efficiently perform the structural optimization problem installing stud-type high rubber damper in frame model. The simplified model is a shear model with damper considering the performance degradation of damperswhere supporting spring is allocated as Maxwell model.The proposed formulation is aimed to determine the stiffness of supporting spring based on direct stiffness method for frame model.

This paper discusses a multi-objective optimization problem with robustness in truss structures subjected to uncertain loads. Variations in characteristic values due to uncertain structural parameters are calculated by sensitivity analysis. The displacement, strain energy, and mean compliance in the structure are then often selected for the characteristic values. In this study, the stress variation caused by uncertain loads was chosen as the characteristic value to solve a robust optimization problem. In allowable stress calculations in structural design, it is necessary to ensure that the stresses are within the allowable stress. Therefore, it is reasonable to choose the variation of stress as the characteristic value. Since the objective function in this multi-objective optimization problem is set to the stress variation and the mass of the truss, the two objective functions are in a trade-off relationship, and it is necessary to find a set of Pareto optimal solutions. This set of Pareto optimal solutions is obtained using mPSO with a slight modification of the particle trajectories in Particle Swarm Optimization (PSO).

The present paper deals with a prediction method for axial force distribution of optimal topology using neural network (U-Net) and truss topologies data. By reducing design variables based on following predicted data, we also propose a method which is more computational efficient than conventional optimization methods. In this paper, we use a truss topology optimization problem, which is to find the cross-sectional area of truss members, such that both the structural volume and compliance are minimized as examples. U-Net trained with the optimal solutions by optimization method can predict optimal truss topology even from untrained data. Moreover, optimal or quasi-optimal solutions are obtained by solving optimization problems with truss members exceeding a certain value as design variables. The applications of the proposed method are illustrated in numerical examples with discussion on effectiveness of the proposed method and computation efficiency.

Authors suggest a base-insulation system using a permanent magnet and a displacement control material made of a compound geomaterial for reducing seismic response of small buildings. The electromagnetic theory provided a method for calculating magnetic force and revealed its important properties such as nonlinearity and negative stiffness. A shaking table test and a finite element analysis demonstrated the response reduction by the magnetically levitated foundation. The analytical study clarified that the restoring force of the displacement control material canceled the magnetic negative stiffness and governed the impedance of the foundation for the seismic response.

In this paper, the hysteresis models of the dampers using bent steel plates are proposed, and the influence of hysteresis characteristics of the dampers on the seismic response of seismically isolated buildings is investigated by time history response analysis. Furthermore, the applicability of response prediction methods from previous studies to the seismic response of seismically isolated buildings with the dampers also be discussed.

Residual deformation can potentially impact the seismic behavior of base-isolated buildings. Although the presence of residual deformation in tall base-isolated structures during typhoons is well-documented, there remain several unresolved aspects in this regard. Thus, the objective of this study is to establish a connection between the response of a 3D model and a MDOF model using long-term wind forces generated from typhoon simulations. Through a wind-induced responses analysis encompassing along-wind, across-wind, and torsional effects, it has been clarified that the input of multi-directional wind forces is imperative for accurate residual deformation estimation. Furthermore, the study also discussed the effect of torsion on the base isolation layer when using the 3D model.

The evaluation method of equivalent element length was presented, and the effect of equivalent length on the response of RC columns was discussed with respect to three parameters and the mesh sensitivity index. The findings obtained are as follows;

1. When comparing the presented method to the conventional one, the presented method contributes to improve the accuracy of member capacity. For Lp = 0.5D, the accuracy with the presented one was improved by 9% .

2. The presented method contributes to improve the ductility. For Lp = 0.5D, the accuracy was improved by 15%.

3. The region beyond the drift of 2%, the impact of equivalent can be observed, and the presented method can alleviate the issue of size effect in the frame element by up to 17%.

In this study, we used FEM software that enables creep deformation analysis and elasto-plastic analysis when a linear spring is installed at both ends of the beam to restrain it in the axial direction, and drying shrinkage strain is applied while applying a vertical load. Long-term properties were evaluated. Furthermore, in order to clarify short-term properties such as during earthquake motion, Pushover analysis was performed after long-term analysis. As a result, the following findings were obtained.

1) Long-term analysis showed that axial force was generated in beams when cracks did not occur due to drying shrinkage, but axial force decreased when cracks did not occur. In addition, when cracks occurred, the stress of the main reinforcement on the tension side at the end of the beam increased as the degree of beam restraint increased or as the drying shrinkage strain increased.

2) As a result of short-term analysis, the bending strength of the products with drying shrinkage was almost the same as those without restraint, and the products with no cracks were almost the same as those without restraint. However, when cracks occur, the bending strength is greatly reduced. However, bending stiffness decreased in all models.

Lateral load tests were conducted with crushed dimensions as experimental variables for the purpose of investigating the maximum lateral strength and bending moment equation for RC columns in demolition.

1. Percentage of Maximum lateral strengths tended to decrease as the amount of crushing in the depth direction increased.

2. Experimental values of the maximum Lateral strength at disassembly can be estimated using the proposed bending moment calculation equation. When calculated using the average of the crushed cross sections and the length of the neutral axis of RC columns determined by theory, the proposed bending moment equation adequately evaluates the experimental values.

3. The length of the neutral axis of RC columns determined by theory tended to increase with increasing depth of crushed for the same crushed height direction. Those values ranged from 43% to 57% of the column depth.

Non-structural components account for a big ratio of the seismic repair cost in a building, and their influence is considerable in the evaluation of reparability performance based on seismic loss estimation. In this study, we focused on the seismic damage of LGS partition walls among the nonstructural members and investigated a method to evaluate the reparability performance of nonstructural members of RC buildings by calculating their seismic repair costs for multiple earthquake scenarios that may occur during the service period. In particular, the effect on the seismic repair cost was examined when the fragility curves of nonstructural members are sequentially optimized by image monitoring for multiple earthquake scenarios during the service life of the building.

In AIJ CFT Recommendations, the full plastic flexural strength is used as the ultimate flexural strength of the rectangular CFST beam-columns using the concrete strength reduction factor of _cr_u = 1.0. Currently, the maximum limiting value of the strength of the steel is 440 MPa and that of the concrete is 90 MPa. Besides, the limiting value of the width-to-thickness ratio for the steel tube of CFST members is 1.5 times the value of that for the steel structures. The ultimate flexural strength calculated using CFT Recommendations may overestimate the beam-columns’ maximum flexural strength when the concrete strength is more significant than 60 MPa and/or the width-to-thickness ratio of the steel tube is larger than the limiting value. In addition, the use of high tensile strength steel may cause the overestimation of the maximum flexural strength of the beam-columns. However, the effect of the combination of these experimental parameters on the applicability of the full plastic flexural strength has not been examined.

This study discussed and investigated the limiting value and effect of various parameters on the ultimate flexural strength of the rectangular CFST beam-columns analytically.

In AIJ CFT Recommendations, the full plastic flexural strength is used as the ultimate flexural strength of the CFST beam-columns. The ultimate flexural strength of rectangular CFST beam-columns is calculated using a concrete strength reduction factor of _cr_u = 1.0, and that of circular CFST beam-columns is calculated considering the confined effect between the filled-concrete and steel tube. However, when the loading condition of the CFST beam-columns are pure bending, the design ultimate strength may overestimate the experimental values even if all experimental parameters are within the scope of the CFT Recommendations.

For the practical beam-columns subjected to flexural shear, the lateral load carrying capacity may increase by around 10% due to the end constraint, and other conditions. Therefore, it can be evaluated on the safe side under flexural shear loading condition, even if the flexural strength ratio between the experimental value and design strength is 0.9 under pure bending condition. However, the increase in flexural strength due to the end constraint under flexural shear condition has not been examined.

This study discussed the effect of end constraint on ultimate flexural strength of concrete-filled steel tubular beam-columns.

The purpose this study is to produce square CFT columns that do not exhibit degrading behavior due to local buckling. From this, the authors thought placing steel tubes around the perimeter through grout on the critical sections of square CFT columns to suppress degradation behavior caused by local buckling. To further prevent an excessive increase in resistant load due to stiffening, internal voids decided to place within the filled concrete. Therefore, in this study, first conducted compression tests on these stiffened CFT short columns. As a result, the following findings are obtained. i) After reaching the maximum compressive strength, the stresses in the stiffened CFT remained as stable as those in the unstiffened CFT. ii) It is not possible to assess the degradation behavior of stiffened CFT solely for the maximum compressive strength and the compressive stress that stabilizes after reaching it. iii) To conduct a detailed examination of the effects of stiffening effect, it is necessary to improve the construction and quality accuracy of the grout.

The effective concrete width of 13 beam-through type reinforced concrete column-steel beam joints with a cover plate was analyzed in this study, it was found that the factor of effective concrete width of test specimens decreased with the increase of column-to-beam width ratio when the column-to-beam ratio was less than 3.2. Based on the analysis, the factor of effective concrete width was proposed, and it was found that the shear strength of the test specimens is better agreement with test results than AIJ Recommendations for Design Mixed Structurers Composed of Reinforced Concrete Columns and Steel Beams and formula proposed by Sakaguchi Noboru.

The use of quasi-statically admissible states in plastic analysis brings about such a great advantage that closed formulae for the limit loads or the plastic collapse loads can be presented. Thus, we are released from tedious procedures of numerical calculations which are generally required for finding the limit loads by use of either statically admissible states or kinematically admissible states. However, the application of the quasi-statically admissible states is associated with such a serious objection that we cannot know how reliable the approximate solutions are, in other words, to what extent the solutions are conservative or radical in comparison to the exact ones. A general answer to this question seems impossible, because a variety of quasi-statically admissible states can be chosen even for a unique problem. Then, this paper presents a method to examine the preciseness of the solutions resulting from the quasi-statically admissible states in the example of axisymmetric annular plates.

Deformation capacity of steel beam-end connections has been evaluating based on methods proposed in correspondence with loading history, which was employed for the experiment. However, the relationship between the evaluation methods, and their accuracies have not been sufficiently investigated. In this study, an experimental database of steel beam-end connections subjected to constant amplitude cyclic loading, increasing incremental amplitude cyclic loading was established. Based on the experimental database, evaluation methods that are independent on loading histories and their accuracies were discussed. In addition, experimental results of beam-end connections carried out by the authors were used to verify the accuracy of the evaluation methods.

A lipped-channel member is a steel member made of thin steel strip, and it sometimes occurs a local buckling before reaching its maximum strength. The current design code considers the effect of local buckling by employing the effective width method, and the effective cross-sectional area is evaluated using the yield stress of the steel material. However, when the lippedchannel member reaches its maximum strength under axial compression, the maximum stress at the cross-section is typically lower than the yield stress due to the effects of global buckling and distortional buckling. Therefore, this paper investigates the effective cross-sectional area of axially compressed lipped channel members. Through axial compression tests, we found that the effective area of axially compressed lipped channel members can be more accurately assessed by using the maximum stress at the cross-section compared to that based on the yield stress.

Metal panels formed by bending metal plates are widely used as non-structural exterior walls. They must be able to follow the story drift during earthquakes without losing important functions and falling out. This paper describes two in -plane cyclic loading tests: one-unit of metal exterior wall with one metal panel and multiple-unit of metal exterior wall attached to one-story, one-bay steel frame. Experimental results showed that the deformation limit for continuous use of the wall is story drift angle of 1/120 to 1/100 rad, and that the deformation limit for falling out of the wall is story drift angle of 1/33 to 1/25 rad.

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 by widening the beam end flanges, etc., but existing buildings have many details similar to those that suffered fracture damage. It is important to evaluate deformation capacity of steel beams with weld access hole under cyclic loading.

In this paper, structural 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.

In the construction of cast-in-place concrete piles, the concrete is cast after inserting a rebar cage into the holes previously drilled into the ground. Generally, confirmation of the finished shape after concrete placement is frequently omitted by confirming the shape of the drilled hole using ultrasonic measurements. Recently, the requirement for quality confirmation has increased. Therefore, we devised a new evaluation method using an electromagnetic wave radar in the form of a borehole survey to evaluate the finished shapes of cast-in-place concrete piles. This paper presents the method and experiments conducted to verify the feasibility of the method.

Here, a calculation formula was derived for wall ratio and yield base shear coefficient of a low-rise reinforced concrete structure in which walls and rigid-frame structure coexist, based on the correlation between seismic input energy and acceleration power (square integral of ground motion acceleration) and energy balance. Wall ratio indicates the wall cross-sectional area per total floor area. Using the calculation formula, the calculated value generally corresponded to wall ratios of actual buildings damaged by earthquakes and the Ds values of earthquake resistance regulations. These indicators are described as being a useful guideline for seismic performance targets in performance design.

Aluminum alloys have the characteristic that they can be easily manufactured in a cross-sectional shape that is more flexible than steel materials. Normally, in aluminum structural material, the beam is increased in beam height to improve bending rigidity, while reducing the plate thickness to achieve both strength and weight reduction. In the case of extremely thin plate materials, there is a concern that the strength of the beam material will be significantly reduced due to plate buckling. In this paper, the authors propose beam models with the new shape of reinforcing material and verify the relationship between buckling strength and weight reduction using numerical analysis.