In this study, to construct an expansion prediction model for expansive additive (EA), we conducted experiments to obtain the basic properties of EA-mixed cement paste using ettringite quicklime complex (CSA type) EA. For cement pastes with EA replacement ratio of 2.6 to 12.9%, expansion strain measurements and some mechanical tests were performed to construct model functions. In addition, the state of EA after hydration was observed using a micro-CT scanner and a scanning electron microscope. From test results, we confirmed that the hydration mechanism of EA changes when the replacement ratio exceeded 6.4%.

The carbonation progress of aged reinforced concrete buildings, where a negative correlation appears between the thickness of the finishing material such as mortar and the carbonation depth of concrete, was analyzed based on a steady diffusion model. As a result, the carbonation progress could be predicted by calculating the carbonation rate coefficient of concrete, the carbonation rate coefficient of mortar, etc., the ratio of the carbon dioxide diffusion coefficient of concrete and mortar, etc., and the ratio of the calcium hydroxide content of the finishing material and concrete through regression using the least squares method.

This study aimed to improve the compressive material properties of wall clays by analyzing the material composition of swallow nests. Uniaxial compression tests were conducted to evaluate the effects of fiber orientation, fiber length, fiber diameter, fiber content, and mucin as a solidifying agent. The results revealed that fibers-oriented perpendicular to compressive forces improved the compressive material properties. When the fibers contained in wall clays had shorter lengths, larger diameters, and lower content, these properties were enhanced. Additionally, mucin derived from swallow saliva demonstrated its effectiveness as a solidifying agent.

The 3-, 5- and 10-story coupled shear-flexural-beam (SFB) models with various flexural stiffness of the continuous columns (C.C.) are analyzed for the 20 SAC near-fault ground motions. It is found that drift response is sometimes significantly influenced by the inelastic behavior and drift concentrations in particular stories due to insufficient flexural stiffness of the C.C. The coupled SFB models with large flexural stiffness of the C.C. exhibit almost identical response to the equivalent SDOF model. The stiffness and strength required for the C.C. to mitigate large drift concentration in particular stories and to maintain the elastic state are quantitatively estimated.

For two adjacent buildings connected by a joint damper, an inverse problem is formulated based on the pole allocation method in control theory. Each building is simplified as a single-degree-of-freedom lumped-mass damped shear model, and the joint damper is represented by the Maxwell model that consists of a dashpot and joint spring in series. The model is useful for understanding the realistic effectiveness of vibration reduction. The previous study considers only a dashpot as the joint damper, while the present study considers the dashpot and joint spring. The difference between the two models is discussed under the same control target.

This paper proposes a method for evaluating the bending moment and curvature relationship of steel composite concrete (SC) piles. Analytical simulations are conducted using actual pile specifications and varying axial force as a parameter. The resulting relationships are modeled using a multi-linear model. Verification through fiber analysis and component experiments on SC piles confirms that the proposed method provides sufficient accuracy for use as a design model.

Although the number of FRP applications for civil structures has increased in recent years, the use of FRP in the architectural field remains limited. CFRP offers lightweight, high rigidity, and reasonable elasticity, with strength comparable to other structural materials. Therefore, CFRP has the potential to enable the construction of lightweight spatial structures. This study aims to clarify the mechanical characteristics of CFRP pipes manufactured by the VaRTM method using an outer mold. Mechanical testing at the material and component levels will be conducted, and the results are expected to contribute to the development of structural design.

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. In previous studies, analytical investigations have been conducted ambitiously. However, no studies have been conducted with TMDs installed in full-scale buildings. In this study, the response reduction effect of double TMDs on the roof surface of the target structure is investigated by large shaking table tests on a 1/4-scale model of a gymnasium.

This paper focuses on roof structures consisting of radially arranged cables placed between the inner tension ring and the outer compression ring. Although many examples of the adoption of this structure have been reported outside Japan, no actual examples have yet been reported in Japan. Therefore, the authors are conducting this study with the aim of preparing structural design documents. In this paper, a study is conducted to propose structural behavior and wind load assessment methods for this structure in strong winds, taking into account roof deformation, and to expand basic design documents.

The physical behavior of semi-rigid timber frame structures with panel zone joint metals connected to beams and columns yielded by shear is discussed in this paper.

The specifications of panel zone joint metals with easy construction has been developed. Those performances were confirmed through experimental and analytical studies.

The structural design procedure of timber frames with panel zone joint metals is suggested.

The four-story building is designed following the suggested design procedure and the mechanical characteristics of the frame are studied.

We studied nonlinear pull-out behavior of Lagscrewbolt (LSB) using a newly developed nonlinear analysis method based on a classical analysis of mechanical joint. To verify the nonlinear analyses, we conducted various full-scale pull-out experiments using LSBs with thread diameters of 30 and 35 mm and embedded depths of 150, 300, 450, and 600 mm in Larch and Sugi glulam. The results showed that, while current LSB design manual tends to give conservative assessments, the nonlinear analyses could predict the load-slip behavior more realistically, and there was a clear proportional relationship between the embedded depth and the pull-out strength.

The purpose of this paper is to investigate the effect of vertical ground motion input on horizontal seismic responses of two-story wooden houses with sliding base systems. The two-dimensional frame model of a two-story wooden house was developed in OpenSees, and time history response analysis was conducted with/without vertical ground motion input. The maximum sliding displacement increased by 10 cm due to the decrease of friction force at a sliding base caused by vertical ground motion. The story drift angle and horizontal acceleration of the superstructure increased when the strong vertical ground motion inputted during the sliding motion.

This paper investigates the impact of beam axial tension on the cyclic performance of beam-to-column connections consisting of RHS column and H-beam. Five specimens were tested under cyclic loading with the column thickness and the presence and magnitude of beam axial tension as test variables. FEA was also conducted to quantify the degree of damage at the fracture initiation point. From experimental and numerical results, when the strength of the beam-end connection is determined by the out-of-plane bending capacity of the column wall, a significant reduction in plastic deformation capacity was observed, with an increase in beam axial tension.

This paper summarizes how the effective length factors calculated by the G-factor method can be utilized based on previous papers. First, 1) proposed evaluation formulas for effective length factors are summarized in Tables. Furthermore, it is shown that 2) the effective length factors by the G-factor method give the factors related to story buckling, 3) the G-factor can be used to calculate the moment amplification coefficients due to the P-Δ effect in a uniform frame, and 4) the effective length factors of multi-story, multi-span frames can be calculated by using the concept of story buckling loads and buckling-associated stories.

This paper investigates the collapse modes of local buckling in I-shaped beam members subjected to monotonic loading, aiming to enhance the accuracy of structural performance evaluation. Parametric finite element analysis explores the influence of member geometry and stress state on collapse modes of local buckling. Index P_FB and α_p are proposed to classify the collapse modes of local buckling that develop after plasticization. Furthermore, a novel structural performance evaluation index W_Fp is presented, which utilize the proposed index. This index W_Fp enables more precise structural performance assessment by considering the local buckling collapse modes associated with various member geometries.