In this paper, in order to identify the modal properties of a structure based on the ambient vibration monitoring, an innovative method for modal identification, called Hybrid Time and Frequency Domain Analysis, is described and a full scale test is presented. The method consists of frequency domain analysis for natural frequencies and modal shapes identification; and time domain analysis for the damping estimation. The methodology was tested in a 5 story steel frame structure constructed at the Disaster Prevent Research Institute, Kyoto University, Japan, using ambient vibration testing. The dynamic response was measured with simultaneous sensors in every floor, including ground. The modal shapes results were compared with the FEM and with previous results obtained from monitoring under forced vibration. For the damping estimation, free vibration results were compared with the ambient vibration test. The system identification obtained under ambient vibration tests are in very good agreement with the forced and free vibration tests and with the analytical results.

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  The aim of this study is to characterize the mechanical behavior of connections timber-to-timber joist hangers with specific nail fasteners. The methodology proposed by technical design standards is based on the hypothesis of an elastic and linear joint behavior. However, the local behavior of joint is semirigid characterized by the ductility of wood material in embedment and the non linear behavior of the nail fasteners in bending. Hence, in this study, the combination of a comprehensive experimental setup and a numerical approach is developed to analyze the evolution of the forces in the joint. Firstly, various tests are realized on specific nail fasteners, using different glulam species, in accordance with European test standards. They concern the withdrawal push-out test, the single plane shear and the yield bending moment. Besides, the adequacy of the methodology proposed by Eurocode 5 for dowel-type fasteners is discussed. Secondly, a similar investigation is carried out on a whole timber-to-timberjoint, with nailed tridimensional metal plates. Considering the hypothesis of a semi-rigid behavior of the joint, the stiffness of each fastener is identified in tension and shear slips. Finally, a finite element model is applied and discussed considering the fasteners represented by bi-directional mechanical springs. The stiffness of each spring is considered as the slip modulus of each fastener defined by tests. A semi-rigid formulation was adopted and the overall joint behavior is apprehended numerically.

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  From the viewpoint of protective design for the construction of concrete structures, this study is to present an estimation method of local damage in concrete plate due to high velocity impact of rigid projectiles. The method of evaluating local damage is a method which compares the calculated maximum impact load and the critical load at occurrence of scabbing. To calculate the penetration depth, a theoretical model is modified by considering both the strain rate and constitutive model. Also, to predict the local damage modes of concrete, the existing punching shear formula is modified. By using this modified model, it can be obtained the agreeable results with test results. Finally, the utility of this estimation method is verified by comparing with the past test results.

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  Since flutter phenomenon is catastrophic oscillation, its stabilization is very important subject in the design of long span bridge girders. Authors reported that flutter characteristics obtained by step-by-step analysis and Complex-Eigen-Value analysis showed perfect agreement. In this study, by using step-by-step analysis, three kinds of torsional divergence instability are clarified, and physical meanings of flutter branch are discussed in relation to fundamental flutter modes. Then, basing on step-by-step analysis in torsional branch characteristics, similar form of Selberg's formula, which evaluates flutter onset velocity, is described.

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  To evaluate earthquake-resisting capacity of existing bridges located in Tokyo lowland, dynamic interaction among piers of bridges, pile foundations and ground should be considered. The Sway Rocking model (SR model) is a simple model to take into consideration. We have studied an analytical method to identify the elastic constants and the damping coefficients using the observed earthquake motions at the top of pier and on the surface of ground. In this paper, the validity of identification analysis method according to SR model is verified using dynamic centrifugal model test from relationship between natural period of ground and pier, and the setting method of the elastic constants and the damping coefficients is proposed. Whether the dynamic analysis according to SR model using the elastic constants and the damping coefficients set by the method is applicable in level 2 earthquake motion is examined. As the result, it is proven that the simplified dynamic response analysis according to SR model reproduced the response of pier in two-dimensional FEM analysis approximately.

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  This paper aims to propose the methods for evaluating the seismic performance of stiffened steel box members in consideration of hysteresis. The previous study pointed out that the seismic evaluation results on the basis of strain are affected by the hysteresis. In this paper, the curvature or the intersectional force is focused on as proper parameters for evaluating seismic performance of steel members. Then, the seismic evaluation methods by using the curvature or the intersectional force are proposed because the curvature or the intersectional force is hardly influenced by the hysteresis. The validity of proposed methods was confirmed by comparing with experimental data and analysis data in the previous studies. Furthermore, the possibility of applying the proposed method by using intersectional force to the steel members under 2 axis bending moment or torsion is indicated.

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  This study investigated the effect of large cities on wind systems over Kanto plain when heavy rainfall occurred in Tokyo, by using a meso-scale atmospheric model. Two types of land-use distribution, the actual land-use and virtual land-use where cities were converted to the forests, were prepared to simulate an actual heavy rainfall event. Also, a generalized heavy rainfall event was simulated by using the upper air observation of Tateno. The results indicated that the effect of large cities on wind systems over Kanto plain was trivial, however, the convergence area of wind was enhanced around the urban area. These led to new finding that cities changed wind around the urban area and developed convergence of wind. The generalized simulation did not reproduce the easterly wind from Kashima-nada which is important for the outbreak of the heavy rainfall event in Tokyo. The reason is explained by the fact that the easterly wind from Kashima-nada was originated from the pressure gradient around the Pacific Ocean. Since this easterly wind did not appear in the simulation without data assimilation, we come to the conclusion that this easterly wind developed with a process other than the sea breeze circulation or the heat island circulation.

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  In recent years, it is increasing to be replaced instead of re-repairing for the deteriorated RC slabs. This selection is appropriate from the viewpoint of life cycle costs. Also, in the case that a slab is replaced partially, the newly installed deck should be easily connected to the existing one and weight increasing is prohibited. A steel-FRP-concrete composite deck for satisfying such demands was developed by the authors. However, the structure of this deck is complicated due to the composite structure of FRP, steel tubes, reinforcing rods and concrete. In this study, the structural characteristics and durability of this deck were confirmed by a series of experiments such as material tests, beam tests and slab tests of static and fatigue loading. Especially, the requirement of the joint was filled by the improvement of structural detail. This paper is showing the research process for one of composite decks and expressing these research results.

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  Concerning the wake galloping of the tandem circular cylinders, the response of the leeward cylinder, steady and unsteady pressure are measured, and the mechanism of the vibration is investigated. The steady pressure measurement clarify that the lift force acting on the leeward cylinder is basically dominated by the pressure field in the wake of the windward cylinder and that the flow switching to the gap flow generates a peaked lift. The peaked lift is also generated while the cylinder vibrates. However the peaked lift itself is not the cause of the vibration. The variation of the lift force shows that the phase lag in the lift force makes the cylinder unstable and the peaked lift acts to suppress the vibration because it makes the phase lead.

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  This study is aimed at developing a cyclic elasto-plastic constitutive model for a structural aluminum alloy, which is expected to exhibit excellent inelastic behavior for seismic dampers in steel structures. To determine various model parameters used in the modified two-surface model that has been extensively utilized to simulate the elasto-plastic cyclic behavior of steel structures, a series of cyclic tension-compression tests have been carried out under various loading conditions. The model parameters have been decided in reference with the previous studies for steels. The simulation to verify the validity of the developed model has also been executed for random loading experiments.

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  Recently, with the spread of application of steel twin girders bridges, PC slab has become to be generally used and its span is getting longer. In construction of the New Tomei Expressway, we studied the most suitable shape and estimate of bending moment of PC slab which span length is over 6m that is limit of specifications for highway bridges.
  In this study, we calculated the bending moment of long span PC slab caused by B-class live load, using FEM analysis. We considered influence by the loading condition of the live load and anisotropy of PC slab. In addition, we suggested new design moment for long span PC slab, by analyzing the results of other bridges which calculated by similar technique.

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  In this paper, we carried out numerical analyses on pounding superstructures, which consist of expansion joint, concrete floor slab and steel girder, by using the 3-dimensional finite element method. To be more precise, the damage level of the expansion joint and concrete slab is simulated. From the numerical analyses, the finger part of the expansion joints is lifted up from about 20mm to 200mm. The serviceability for the emergency car is also investigated by using the vertical gap between the expansion joints. From the result, it is found that the emergency cars are necessary to traverse in low speed when the impact velocity is larger than 2.0m/sec.

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  An analytical model focused characteristic cracks in surface of concrete structures damaged by ASR was applied to brace of bridge pier. By comparing the analysis results and candidate structure in terms of behavior of cracks, the applied model was roughly able to reproduce the behavior. Additionally, this study took particular note of steel break which should be heeded in recent years and an analytical model was proposed in order to entertain strength degradation due to chaps which occurred in bent corner of reinforcement. Then, it was clarified that reinforcement was wreaked rapid strength degradation even if bent corner of reinforcement had tiny chaps. By comparing strain in bent corner in reinforcement simulated by applied model and strain simulated by proposed model, it was indicated that steel break occurred on high probability in near boundary with different reinforcement ratio.

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  In seismic design for railway structures, it is essential to evaluate the effects of the subsurface structure appropriately. In order to estimate the ground structure, the boring investigation is mainly used. The boring investigation, however, may be difficult in case of certain circumstances, such as the soft ground condition, the deep engineering bedrock, the space condition for investigation and so on. In such cases, it is necessary to estimate the ground structure using other estimation methods. In this report, the authors presented another estimation method using microtremor and gravity survey. Moreover, we clarified the importance of structure estimation by calculating the ground motions based on the estimated subsurface structure.

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  For the analyses of fatigue cracking problems of complicated welded steel structures of highway bridges, simulation analyses of vehicle loadings are employed to count stress cycles due to random running of vehicles after prepared influence surfaces of stresses by 3D FEM analysis. But the ordinary methods to make the influence surface require a huge computing time and much cost. The authors propose to apply Muller-Braslau's theorem to 3D FEM analysis to get it by one computation. The paper shows some examples with the accuracy and some examinations regarding fatigue problems.

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  The XFEM is the numerical method which employs the approximation including priori knowledge of the solution by using the concept of enrichment in a local area. In this paper, reproducibility of priori knowledge in the standard XFEM and the PUFEM-based XFEM (PU-XFEM) reformulated by authors for the crack analysis is evaluated, respectively. The results show that there is a significant reduction in the reproducibility of priori knowledge in the local enrichment area near the crack tip for the standard XFEM. On the other hand, it is shown that the priori knowledge can be accurately reproduced in the PU-XFEM.

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  If small fatigue cracks initiated at welded structures are retrofitted by closing crack surface, it would lead to improving structural integrity with less cost. Fatigue tests were carried out on notched bead-on plates to develop a surface fatigue crack. Then, the sides of the crack were plastically deformed by impact tool to close the crack surface. With this treatment no fatigue crack growth was observed over ten million cycles of loading, otherwise only around two million cycles were needed for the crack to penetrate to plate thickness. The technique, named as Impact Crack Closure Retrofit Treatment, or ICR Treatment, may open the way to retrofit welded joints with small fatigue cracks.

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