It is essential to know the stresses generated in pipelines in order to maintain their safety from external forces. The highest stresses often occur in bent rather than straight sections. Two methods have been developed for non-destructively measuring stresses occurring in bent pipes: one is a method of non-destructively measuring stresses occurring in bent pipes using the principle of magnetostriction and the other is a method which uses the ovalization which occurs when an external load is applied to a bent pipe. Tests have confirmed that both of these methods are fully practical and capable of measuring stresses with sufficient precision.

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For global monitoring of large-scale civil infrastructures, it requires direct and accurate macro-deformation measurements to characterize the different performances of entire structural element. The conventional “point” static strain measurements are difficult to provide sufficient information for structural damage identification due to their localized behavior. In this regard, a novel packaging method for practical adaptation of long-gage FBG strain sensors in large-scale structures is proposed. Some static tests are carried out to verify the ability of the proposed FBG sensor for macro-strain measurements by comparing with that of foil strain gauge. Combined with a parametric identification method based on static macro-stain measurements, the applicability of the distributed long-gage FBG sensors in structural parameter estimation and damage detection is discussed. An experimental study of a beam specimen shows the advantage of the proposed sensor for structural identification over traditional strain gauge.

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A supersonic method and an elastic impact wave method are mentioned to the typical thing of a non-destructive test method. However, by the supersonic method, since the input is small, it is said that the depth of the investigation becomes very shallow. Theoretically, if it becomes possible to input vibration of a supersonic domain into concrete with a high output directly, the investigation of the deep investigation depth and the high precision will be attained. In this research, it is aiming at building of the supersonic investigation system which input the vibration by the piezo-electric ceramics which gave it the voluntary waveform of the high voltage. In this paper, the result of foundation experiment by the AE transducer is shown.

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Scattering analysis of Lamb waves in perpendicularly bent plates with and without a crack is presented. Single cracks on the inner or outer surface of a bent part with various lengths are considered. The scattering behaviors of Lamb waves in the bent plate with or without a crack are discussed in order to investigate the potential of Lamb wave ultrasonic method for characterizing cracks in a bent part. Experimental results are also carried out to verify the numerical results.

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Failure behavior of RC beams flexural reinforced with fiber reinforced polymer (FRP) sheet will be influenced by several factors, such as dimensional characteristics, material properties, and reinforcing conditions. This study is devoted for numerical investigation on influences of main rebar yielding on failure behavior of RC beams flexural reinforced with FRP sheet. In this study, two kinds of reinforcing material were used as main rebar: deformed steel bar and aramid FRP rod. Numerical analysis was carried out by using three-dimensional finite element method, in which, discrete crack approach is employed to take the geometrical discontinuities into account. From this study, it can be confirmed that main rebar yielding gives a significant influence on failure behavior of RC beams flexural reinforced with FRP sheet, and there is no tendency for FRP sheet to be peeled off in case that main rebar without yielding is used.

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This paper aims to investigate interfacial resistance and to propose a constitutive material model of the interface between concrete and polymer-cement mortar (PCM) in tile systems. The interfacial resistance of the concrete/PCM interface is evaluated in terms of interface fracture toughness based on an interface fracture mechanics method. The experiment is conducted under pure tension and mixed mode conditions (tension and shear) by using four-point bending tests. It is found that the interface fracture toughness is low especially at high mixity of shear stress, and that the tendency of the interface fracture toughness is different from the one of the concrete I fiber reinforce concrete (FRC) interface that is used to be the representative of the concrete/cementitious material interface in this study. Moreover, two models of the interface fracture toughness are derived from a cracking criterion, a linear cracking criterion and an elliptic one respectively, by assuming linear softening behavior. The model derived from the elliptic cracking surface shows good agreement with the experimental result of the concrete/PCM interface fracture toughness.

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The purpose of this study is to investigate the flexural strengthening effects of RC beams with hybrid FRP sheets consisting of high modulus type of continuous carbon fibers. Based on a preliminary hybrid design by following rules of mixture for the hybridization of high strength and modulus types of carbon fibers, the hybrid fiber sheets are used to strengthen RC beams. Throughout a series of investigations on beam specimens under three point bending, it is clarified that the hybrid fiber sheets consisting of high modulus type of carbon fibers as an externally bonded reinforcement can be used to enhance effectively. The service ability performances of structures such as cracking load and other resistance behavior, stiffness and steel yielding load etc. Moreover, through a rational design of hybrid fiber sheets, the controlling of stress drops due to the gradual ruptures of fibers and the sufficient ductility by avoiding premature debonding can be realized practically. Finally, some indices for evaluating the strengthening effects with hybrid fiber sheets and the optimum mixture are also suggested and discussed in the paper.

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For the reliable design of a structure, it is very important to clarify the dynamic soil-structure interaction effects on the nonlinear response situation due to earthquake. Since the damage of structure may be closely related to the earthquake input energy, it is necessary to carry out the damage assessment by means of the energy evaluation. The dynamic soil-structure interaction effects on the damage evaluations are examined in the present study. The soil-structure interaction is represented with the sway-rocking model and the nonlinear characteristics on the pier are dealt with the bi-linear model. It is suggested that for the damage evaluations of soil-structure interaction system due to seismic motions, it is very important to account for the relations between the dominated frequency of the soil-structure interaction systems and the seismic input motions.

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A simplified model of 3-degree-of-freedom system composed of single mass element and sway-rocking element is studied to evaluate earthquake-resisting capacity of existing bridges. Elastic constants and damping coefficients of soil-structure interaction are calculated from observed earthquake motions at the top of pier and on the close ground by structural identification techniques based on inverse analysis. The identified parameters are compared with these values simulated according to the specifications for highway bridges. As results, the parameters according to the specifications for highway bridges would not always lead secure solutions under the condition of the inelastic response analyses of the 3-degree-of-freedom system in level2 earthquake motions.

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For the civil engineering structure of framed structures, it is important to clarify the combined effects of axial forces and bending moments to severe seismic motions. In the present study, the seismic performance evaluations are carried out using the seismic response energy due to the seismic motions. The influences with respect to the axial force are caused for the response quantities as well as the energy distribution. It is shown that coupling effects of the bending moment and the axial force give important role on the seismic response evaluations of framed structures.

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This study aims to evaluate the pile-group effects of the pile foundation structure analytically under level2 earthquake motion in a bridge structure. The analytical method adopted is a simplified 3-D analysis. This method is 2-D frame model for a pier-system with a pile foundation, 2-D FEM model for the ground separately, and connects the nodes of soil and the nodes of pile with the interaction spring in consideration of the 3-D effects. By this model a dynamic analysis and a monotonic loading analysis were conducted. Major findings from these analyses are as follows:(1) The pile rows and the soils deployed perpendicular to the load direction show a different displacement (2) The difference is proportional to the spacing of pile rows perpendicular to the load direction, and has more influences on a rocking displacement mode as compared with a sway displacement mode of a structure-foundation system.(3) These are considered to be the causes of the pile-group effects, and it not only affects behaviors of the pile-foundation, but they affect the force responses of a bridge pier.

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In the present paper, the impact response in the field test on the railway jointed track is simulated using the wheel-track vibration model with the finite element method. The simulated results on the dynamic response are discussed in terms of railpad force, sleeper-ballast interaction force, sleeper acceleration and ballast acceleration. The ballast and substrate are modeled as 2D elastodynamic bodies. The accuracy of the vibration model is investigated based on the comparison with in-situ measurements. In the railpad force and the sleeper-ballast interaction force, the impact responses are accurately simulated; the post-impact responses obtained bythe present model have the differences in terms of period and amplitude in contrast to the measurements. The sleeper acceleration has the different peaks in the spectral space between the numerical results and the measurements; the intensity of the response shows good agreement in the frequency range under 200Hz. The ballast layer is an assemblage of crushed hard stone, of which the particle action influences to the macroscopic dynamic response of the ballast layer. Therefore, though the present model can evaluate the maximal acceleration level, it may simulate the spectrum distribution sufficiently.

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For accurate evaluation of the wave response for a semi-submersible type floating structure, the viscous damping force must be evaluated and included in the analysis. The present study thus aims to identify the viscous damping force acting on a floating body of a semi-submersible type by the forced oscillation experiment. The particular shape of the floating body examined here is the one that has been considered for possible application to a floating runway in Tokyo bay. The viscous damping force has been assumed to be represented by a drag force component as usual, and the drag coefficient, C_d, has been identified by the forced-oscillation experiment to be around 5.0 depending on the Keulegan-Carpenter number.

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