Segregation resistance tests were conducted on concrete with electric arc furnace oxidizing slag fine aggregate (ES) or normal fine aggregate (NS) and, segregation index was evaluated. In addition, a method of estimating segregation index was investigated based on mix proportion and flesh test. As a result, coarse aggregate is floated in concrete with ES, and coarse aggregate is settled in concrete with NS due to the difference of density between mortar and coarse aggregate. Furthermore, the possibility estimating segregation index is shown based on density difference between mortar and coarse aggregate and arrival time of 200mm flow of mortar.

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 show that it is possible to predict the occurrence of blistering by using the caster load, hardness, and edge radius.

In this study, PIV and wind pressure experiments were carried out under tornado-like wind flow affected by surface roughness. The authors discussed the effects of swirl ratio and roughness density on the velocity field and the pressure deficit characteristics near the surface. It was confirmed that the velocity field structure gradually transitioned by changing swirl ratio and roughness density. Next, the pressure deficit characteristics showed that the measured pressure was the lowest when the roughness density was 0.014 at any swirl ratio. In the above discussion, the models on the radial velocity distribution and the pressure deficit distribution were proposed.

Under extreme ground motions, such as long-period ground motion and pulse-like ground motion, laminated rubber bearings can be subjected to large shear deformation. In the case of their shear strain beyond 250%, they can exhibit hardening behavior. This study verified the effectiveness of semi-active control using an MR damper applied to base isolation systems with the hardening of laminated rubber bearings. Moreover, the dual real-time hybrid (DRTH) simulation was conducted to evaluate the semi-active control performance. DRTH simulation is a seismic response simulation method with a combination of numerical computation and physical testing of two specimens by excitation devices.

This study investigates seismic response characteristics of a high-rise RC building with the composite foundation of wall and pile group. The building under investigation has maintained a dense, long-term array of strong-motion observations for over 25 years, including data during the 2011 Great East Japan earthquake. Simulation analyses with input motions in the NS and EW directions are performed. The effective input motion is evaluated from seismic records, and axisymmetric FEM analyses are performed for several cases with the foundation type as a parameter, and influences of foundation types on structural responses are discussed.

In the previous study, the author proposed a new flare-like structure with the aim of improving buckling property, and evaluated the ultimate properties of a high-damping rubber bearing with the proposed structure. In the case of a flare-like structure, the structure is more complex than conventional structures, resulting in more design parameters. In recent years, machine learning has drawn attention as a method for predicting the characteristics of products with many parameters. In this study, a method for predicting the buckling property of natural rubber bearings using machine learning is proposed.

I present a new formulation for the wave obtained by performing an inverse Fourier transform to spectrums in sufficiently narrow frequency bands. Here, these sufficiently narrow frequency bands can be assumed phases of the spectrums change linearly in them. I studied the nature of the formula. Then, I concluded as follows.

1. The time characteristics of this wave are directly related to phase information and amplitude information in the sufficiently narrow band.

2. This wave is represented by the product of the envelope term and the vibration term.

3. The formula agrees with previous studies and actual earthquake records.

This paper proposes an algorithm that utilizes Bayesian optimization to generate spectrum-compatible time history waveforms. This algorithm aims explicitly to prevent interference among mutual corrective waveforms. It dynamically adjusts the total number of corrective waves based on the expected improvement in the objective function. This capability effectively minimizes the objective function, even when generating simulated ground motions using observed phase characteristics. The algorithm is also designed to fit multi-damping target spectra accurately. The effectiveness of this approach is demonstrated through the generation of simulated ground motions compatible with four multi-damping target spectra using observed phase characteristics.

This paper attempted to understand the vibration performance of RC arches under various conditions by impact vibration tests. In addition, we derived an evaluation formula for the vibration performance of arch structures. As a result, it was shown that it is possible to evaluate the natural frequencies of RC arches with deterioration or repair. Furthermore, specimen with many cracks tended to have lower natural frequencies and higher damping coefficients than that without cracks. And it was confirmed that the natural frequencies tend to be high and the damping coefficients tend to be small by the inside pressure hardening method.

We conducted loading tests using steel plate-inserted joints with drift pins at the beam ends of glulam beams. The ultimate strength formulas for these joints are the splitting and shear resistance, but their applicability is unclear.

We observed the fracture properties during the tests and defined each fracture type’s characteristics. Material experiments were conducted for each fracture property, and the 5% lower limit was applied to the current standard equation. A positive correlation was observed between the calculated and experimental values. Additionally, using the proposed values in this study improved the accuracy of determining the fracture properties.

Instead of the expensive, high-performance hardware employed in CLT panel construction methods, we propose a structure utilizing cost-effective residential hardware. This system is designed to ensure no damage under moderate seismic events while relying on restoring forces to prevent collapse during massive seismic events. single-story full-scale CLT building equipped with existing residential hardware was subjected to deformation exceeding 1/3 rad. The experimental results confirmed the addition of lateral resistance by hardware, a consistent negative slope of restoring forces, and collapse limit displacement of over 910mm. Furthermore, it was observed that rocking behavior caused the weight concentration on the CLT walls.

In order to continue using the load-bearing parts of wooden structural members after a fire, it is necessary to understand their mechanical performance after exposure to fire. Equilibrium moisture content, Young’s modulus, and bending strength were measured on sugi specimens that were once exposed to elevated temperatures of 60-210°C. Results revealed that Young’s modulus and bending strength increased with temperature history of up to 150°C, presumably due to a decrease in equilibrium moisture content. The heating times were 30 minutes and 8 hours, and above 180°C, the longer the heating time, the greater the decline in mechanical performance.

This study proposes a novel method for evaluating the ultimate shear capacity of precast prestressed concrete columns post-tensioned by unbonded tendons. Through loading tests, the shear behavior of the columns under high compressive axial forces was investigated. Observing axial collapse near maximum load capacity led to the development of a truss-arch mechanism-based evaluation method, assuming axial force balancing. This method accurately evaluates the maximum load capacity of specimens in this study within a range of -5% to +12% with standard deviation of 0.051, aligning with the actual failure mode.

Loading tests have been conducted on subassemblage with wide composite beams to investigate the bearing capacity degradation of composite beams due to slab damage in the large deformation range. The experimental results show that the slab transfers stress over a wide range and that the axial force acting on the beam affects the occurrence of local buckling. Furthermore, an analytical model is proposed that takes into account its bearing capacity degradation characteristics.

The purpose of this study is to clarify the influence of loading history on ductile crack growth in order to study the influence of loading history on the deformation capacity of steel members under large cyclic deformation. Cyclic loading tests are conducted to confirm the influence of the change of loading amplitude on the change of tensile load occurred from ductile crack growth. Then, FEM analysis which reproduces ductile crack growth is conducted in order to confirm the plastic strain distribution ahead of ductile crack. From these, the influence of loading history on ductile crack growth is clarified.

This study suggests a new hybrid seismic resistant wall constructed of steel stubs sandwiched between plywoods with steel joint hardware, and each wall panel is arranged in a checkered pattern. Here, to investigate the resistant mechanism and restoring force characteristics, horizontal loading tests are conducted as parameters with composition of hybrid panel. From the test results, the combined effect of bending resistant of steel stub and embedded plywood is confirmed, and this effect is influenced by the steel joint hardware. Furthermore, the analytical method of strength is proposed, and it can estimate the test results.