In order to clarify the rationality of restoring force characteristics of steel pipe column filled with PUFA, the cyclic loading tests were conducted for three types of steel pipe columns, i.e. column with concrete, column with PUFA and steel column only. Then, the effect of smearing polymer on the inner side of steel pipe and the difference of skelton under three kinds of loading, such as one-cycle loading, three-cyclic loading and push over loading, are investigated. Furthermore, the skelton, the hysterical loops, the equivalent stiffness reduction ratio and the equivalent damping ratio of steel pipe column filled with PUFA are proposed. Finally, the buckling phenomena and the seismic performance of steel pipe column filled with PUFA are discussed.

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We develop an analysis method, which is named “global-local finite cover method (global-local FCM)”, for the analysis of local crack growth in overall structure, and apply it to numerical simulations of propagating cracks in concrete due to reinforcement corrosion. First, we formulate the global-local FCM in conjunction with the hierarchical mesh for a kind of multi-scale analysis of RC structure. Secondly, numerical implementations for the FCM analysis of multiple cohesive crack growth are explained. Thirdly, the performance of global-local FCM is assessed for the approximation of mechanical behavior of hierarchical heterogeneity including local crack propagations. Finally, we apply the proposed method to global-local numerical simulations of propagating cracks in RC structure due to reinforcement corrosion.

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Corrosion is typical damage on steel bridges, but evaluation method for strength of steel member with corrosion has not been made clear sufficiently. In this study, following examinations have been performed in order to examine a parameter for arranging tensile and yield strength of corroded steel plate and method for evaluating the strength using the parameter. They are observation of plate sureface onfiguration with corrosion, tensile tests on corroded steel plate extracted from actual steel bridge, and three-dimensional elastic-plastic finite element analyses.

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Slip coefficient of friction type of high strength bolted connections is well known to depend on the condition of contact surfaces. However, the coefficient is determined as 0.4 in the Japanese specifications for steel highway bridges, in which contact surfaces are to be rough without mill scale or have inorganic zinc rich paint. If the coefficient higher than 0.4 can be applied, the number of bolts and size of splice plates can be reduced. In this study, slip resistance tests on the joints with various contact surface conditions have been done, and a lot of existing data have been collected and assembled. On the basis of above examinations, slip coefficient is proposed in consideration of contact surface conditions.

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In Japan, a steel-plate concrete composite deck which is connected concrete and a steel-plate with shear studs, is called Robinson type. In order to decrease deflection of the steel plate when fresh concrete is casting on, the steel plate is stiffened with steel strips. In recent years, the composite deck is applied to many high way bridge decks. Its predominant failure mode was detected as the punching shear by repetition of wheel loads. In this paper, the authors have derived punching shear strength formulas for fatigue strength evaluation. These formulas were induced by the concrete cracking pattern and failure mode of mid span part between supporting girders and overhanging part specimens for wheel trucking tests.

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The ultrasonic testing has been applied to the quality control of welded joints of steel bridges. By the ultrasonic testing, one probe technique has been applied conventionally. Sometimes, however, detection of planar defects such as crack, incomplete penetration was di.cult by the one probe technique. Recently, phased array transducers have been developed. A phased array transducer consists of many small elements that can focus and change the refraction angles by controlling the excitation time of the elements. This study aims at the accurate non-destructive evaluation by the use of two phased array transducers. The testing system could reconstruct the image of side holes in a specimen of complicated shape very clearly. The testing system could detect an incomplete penetration and gave very accurate result of size estimation.

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This paper presents a concept and an implementation of hierarchical sensor network for sensing of civil infrastructures. As an example, implementation of hierarchical localization method applicable for large scale sensor network is presented. This system consists of parent nodes with a low priced L1 GPS receiver and child nodes with an acoustic ranging device. Relative positions between child nodes are estimated based on acoustic ranging through a distributed scalable algorithm, called inverse Delaunay algorithm. Relatively localized child sensor nodes are given global coordinates with the help of centimeters accuracy GPS on parent nodes.

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This study attempts to develop a new impact acoustic method by introducing Attractor analysis based on Chaos Theory for the purpose of improvements of the ordinary method investigating Frequency domain. The proposed method detects exfoliations inside the steel-concrete composite slabs by evaluating the difference of convergence process of attractors reconstructed from acoustic signals. The efficiency and applicability of the proposed method is discussed in comparison with the ordinary method through several field experiments. As a result, the proposed method could catch effectively the difference between intact part and damaged parts that could not be recognized by the ordinary method.

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Typical approaches to estimate analytically average characteristics of composites may be the Hashin-Shtrikman upper/lower bounds and a method based on the Mori-Tanaka theory. These take into account microscopic geometry and local equilibrium. Within the elastic framework, we proposed a similar averaging approach which includes the classical methods and these modern methods. The method deals with 3-phase materials, but the matrix has zero volume fraction as a limit. The predictions have some characteristics similar to those by Hill's self-consistent method, and explain experimental results better than the Hashin-Shtrikman bounds. We here apply the same approach to elastoplastic materials under general loading conditions. The results are compared with pre-existing experimental data to show precision and feasibility of the method.

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The linearized inverse scattering method reconstructs the shape of flaw by low frequency wave data obtained by ultrasonic measurement. It is possible for this method to be a practical NDE method for concrete structures. Performances of the two-dimensional inversion formulae have been studied by both numerical simulation and experimental measurement. In contrast, no experimental shape reconstruction by three-dimensional inversion formulae has been studied. In this study, numerical simulation is used to discuss the effects of scattering the amplitude's wavenumber on reconstructed shapes of flaw models. Cement paste specimens are prepared based on the numerical simulations, and backscattered waveforms from all directions surrounding a flaw model are obtained. The wave data are fed into inversion formulae, and performances of the method are verified by comparison with X-ray CT scan images.

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In recent years, high-voltage transmission towers received severe damage due to typhoon and earthquake in Japan. Steel pipes for transmission towers have radius-to-thickness ratio of 10-25, and slenderness ratio of 20-80, and belong to relatively thick cylinders. Transmission towers have been considered to be designed with enough wind-resistance performance, however, it is necessary to reexamine the current estimation methods from the point of load carrying capacity to improve the structural integrity. The purpose of this paper is to investigate the buckling strength of the steel pipes for main leg members of transmission towers experimentally and analytically, and to provide the buckling strength estimation formulae under eccentrically axial compression. Furthermore, coefficient of effective buckling length of main leg members is investigated and the possibility that conventional value can be rationalized is clarified.

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In this paper, an analytical method for obtaining natural period of a rectangular plate with an interface crack between two dissimilar elastic half planes is proposed. A process zone is formed along the interface between the physical crack and the continuous part. Then, the support type of right-angled two edges in the interface is simple support, and parallel two edges in it are support type of three modes (simple support, fix support and free). Features of the obtained theoretical solution for a plate are that only the deflection has a gap of the finite term Fourier series shape along a crack line, and the deflection continues along the other line. From some numerical calculation examples, an estimated formula that can convert the length of the process zone under the natural period constancy condition to the equivalent crack length is presented.

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This paper discusses the corrosion shapes and measurement method of steel angle member under oceanic exposure which measured precisely with two types of laser equipment. From the measurement result, the distribution of remaining thickness and property of corrosion shapes are obtained. We also compared the measured thickness by a laser equipment with the past data which measured by a micrometer.

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A circular hole which removes weld defect or is mistakely drilled is usually repaired by welding. This portion may have various defects. Instead of the welding, we are interested in expansion fit of the round steel bar into the hole as a repair method. This method may realize stress transmission through the hole position due to bearing-pressure.
This study aim at making clear the strain properties and fatigue strength of steel plate with circular hole filled by expansion fit steel round-bar. For this purpose, we have performed strain measuring tests, fatigue tests and stress analyses by finite element method on model specimens.

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