It is known that iterative procedures are always needed when the capacity spectrum methods based on the equivalent linear systems are employed to estimate the maximum deformation of existing structures. In addition to inefficiency, it has been shown that the existing method sometimes leads to the lack of convergence and accuracy. Besides, the problem of multiple solutions is encountered in many cases, and it is hard to decide which one is the best. To overcome these problems, this paper presents a non-iterative capacity spectrum method using a varied version of the equivalent linear methods for determining the maximum displacement demands of existing structures. A trustworthy single value will always be obtained by the procedure.

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The functionalities and energy dissipation capability of Displacement dependent semi-active hydraulic damper, DSHD are analyzed and discussed with complete experiment which involves the factors to affect time-delay of DSHD, and the reasons to cause sliding of the oil cylinder under the dynamic state. The test results show that 1) Time-delay occurs in unloading period because of the hysteresis phenomenon. Herein, Kelvin solid is approved to simulate this process and shows that stiffness of the brace and damping coefficient of oil will lead time-delay; 2) It's important to avoid sliding of the cylinder, caused by insufficient oil pressure and residual air in the oil cylinder and pipe, for achieving excellent performance of DSHD. These phenomena can be improved by applying appropriate pre-pressure to the oil tank.

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An elastic beam bending theory for analysis of prestressed concrete girders with corrugated steel web is derived by the application of the variational principle. The theory is a shear deformable beam theory which is based on three displacement fields and is similar to the classical Timoshenko beam theory. A two-node linear finite element with full and reduced integration of the theory is provided. It is then used to analyze simply supported and continuous I- and box-girders. Their predicted results are found in good agreement with those by the 3D finite element analysis. A simplified theory which is similar to the proposed theory by Kato et al. (2002) is also discussed and included in appendix.

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Wave scattering in the Biot's poroelastic media is investigated using a numerical method based on the boundary integral formulation. The formulation adopts the fundamental solution derived with a direct manner and traction operators for physically meaningful boundary conditions. Some numerical examples for wave incidence on a spherical scatterer is presented. In the examples, coupling effects of solid and fluid are parameterized with coupling parameters and the boundary conditions. The results show that scattered fields, especially pore pressure, are highly influenced by the coupling effects with the conversion of the fast longitudinal wave to the slow one.

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A report of 1995 Kobe earthquake showed that impact damage at ends of girders and fails of supports can impede traffics of rescue works. To precisely analyze the behaviors of bridges with poundings and evaluate the effectiveness of pounding mitigation measures, a 3D model for whole bridge structures including pounding and pounding mitigation devices is constructed. A three-span steel elevated bridge has been chosen for a case study. In addition, the peak gap size between girders and maximum relative displacements of supporters are employed for serviceability evaluation.

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The ultimate behavior of various types of metal bridge bearings under seismic loading is studied experimentally using real-size models, and their behavior is evaluated analytically. Firstly, material tests of several types of steels, used in the bearings, are conducted, and their ductility and strength are clarified. Secondly, detailed experimental methods of the bearings are described. The loading methods, which simulate the behavior of the bearing under actual loading conditions, are proposed. Based on the experimental results, the ultimate behavior of the bearings is presented. The seismic capacities of the bearings calculated by the standard design procedure are also evaluated by the experimental results. Finally, the two types of the bearings are analyzed by the 2D finite element method, and the models are found to agree well with the experimental results.

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A feedback control technique of vortex shedding behind a circular cylinder is investigated through two- and three-dimensional numerical simulations. Periodic velocity excitation is applied from the cylinder surface to the separated shear flows with a time delay and feedback gain for the fluid velocity at a downstream sensor location. It is shown that the feedback excitation can suppress the vortex shedding considerably. However, the suppressing effect on the vortex shedding becomes lower if the time delay is fixed between the feedback excitation and the fluid velocity at the sensor location or the sensor is located downstream of the formation region of the vortices behind the cylinder. This is because the change of the vortex shedding frequency and the wavelength resulting from the suppression of the vortex shedding alters the phase delay between the vortex shedding and the feedback excitation.

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Traffic vibration of highway bridges often leads to fatigue cracking at the bases of tubular columns with signboards. This paper deals with the application of carbon fiber sheets and non-shrinkable mortar to improve the fatigue life at the tubular column bases. Fatigue experiments are completed on the tubular column bases with CF sheets and/or NS mortar provided. It is shown that CF sheets improve the life when cracks propagate under CF sheets, while NS mortar increases the life until cracks reach CF sheets.

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Long-term cumulative damage by traffic loads causes fatigue problems which are primary defects in steel bridges. For this reason, it is necessary to monitor the traffic loads continuously for effective maintenance. In order to measure the traffic loads, the system called W. I. M. (Weigh-In-Motion) has been used. However, the conventional W. I. M. has not been a system which can continuously monitor the traffic loads for a long term.
In this study, the remote monitoring system of automatic real-time W. I. M. was developed. This system was applied to three existing bridges. The traffic loads on the bridges has been monitored continuously for long term and the characteristics of the traffic loads were analyzed.

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The shear performance of high damping rubber bridge bearings is influenced by low temperature. Therefore, getting to know the internal temperature of rubber bridge bearings and the relation with ambient temperature has an important meaning to the design of bridge structure. In this paper, two kinds of full-scale rubber bridge bearings were tested and checked at four different type ambient temperatures. Comparison of the experiments and results of transient heat conduction analysis was performed, and it was checked that the accurate estimation of internal temperature is possible by the numerical analysis. Furthermore, it was also shown that these results could be estimated by simpler numerical formulation.

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As the corrugation on rail surface brings some practical problems about vibration or noise, it is important to investigate and clarify the formation and growth mechanism of the rail corrugation. In this study, the dynamic behavior between wheel and inner-rail is examined using a numerical simulation model and a new simple analytic model for the vehicle running on steep-curved track. It is concluded that both the wheel attack angle and the wheel load fluctuation makes a periodic movement between wheel and rail, i. e. the stick/slip motion, with increasing the rail tilting vibration, and that a small unevenness on the rail surface grows to the corrugation which has a constant wavelength decided by the running speed and the tilting natural frequency of inner-rail. Also, a global corrugation formation process is shown by parametric analyses.

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Recently, many fatigue cracks were found in the beam-to-column connections of steel bridge frame piers in metropolitan expressway bridges. It was pointed that high stress concentrations occurred at the corner of beam-to-column connections, and caused fatigue cracks. In order to improve the fatigue performance of the beam-to-column connections, we proposed rib-installation. Effects of rib-installation were evaluated by the Finite Element Analyses and fatigue tests. As a results, it was found that the rib-installation was effective to reduce stress concentration at the corner of the beam-to-column connection, and rib-installation could improve fatigue performance of beam-to-column connections.

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For predicting the low cycle fatigue life under variable strain amplitude, Mini's rule has been accepted as a simple and effective idea. In extreme large strain field corresponding to the fatigue life of less than ten cycles, however, the accuracy of Miner's rule has not been verified yet. In this study, by means of a newly developed testing system, low cycle fatigue tests under variable strain amplitude in extreme large strain field was conducted. The test results showed Mine's rule always predicted longer fatigue life than actual life. As another idea for predicting low cycle fatigue life, we proposed a simple model introducing the damage mechanics concept and examined its validity.

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