Showing papers in "Doboku Gakkai Ronbunshu in 1988"
TL;DR: In this paper, a new kind of damper, Tuned Liquid Damper (TLD) relying on motion of shallow liquid in a rigid cylinder, is experimentally studied, where prototype-sized circular containers with diameters 40cm and 60cm and partially filled with water, are attached to a single-degree-of-freedom structural model with natural period of 2sec.
Abstract: A new kind of damper, Tuned Liquid Damper (TLD) relying on motion of shallow liquid in a rigid cylinder, is experimentally studied. Prototype-sized circular containers with diameters 40cm and 60cm and partially filled with water, are attached to a single-degree-of-freedom structural model with natural period of 2sec. The damper effect is measured in terms of the increase in the logarithmic rate of decrement of free oscillation of the main structure. The structural displacements range from 8cm down to 0.25cm. It is seen that, for large damping effect at small amplitude of structural vibration, it is necessary to tune the fundamental sloshing period of the liquid to the natural period of structure; hence the name Tuned Liquid Damper. Breaking of surface waves, which is dependent on structural vibration amplitude, appears to be a major mechanism of energy dissipation in the range of displacements considered. Also investigated are the effects of: ratio of liquid frequency to structure frequency; liquid viscosity; container bottom roughness; container roof height; ratio of liquid mass to structure mass; and container diameter.
114 citations
TL;DR: In this paper, the relationship between stress and deformation of segments-joints system, both for axial force and for bending moment, are formulated into the form of "equivalent stiffness", i.e., the stiffness of uniform beam having the same stress-deformation relation as that of segments joints.
Abstract: This paper presents a practical method to evaluate the longitudinal stiffness of shield tunnel linings which is of great importance in the seismic response analyses of shield tunnels. Linings of shield tunnels are constructed assembling a number of segments and joints, and have structural discontinuity in the longitudinal direction. In this paper, relationships between stress and deformation of segments-joints system, both for axial force and for bending moment, are formulated into the form of “equivalent stiffness”, i. e., the stiffness of uniform beam having the same stress-deformation relation as that of segments-joints system.Modeling the lining into a uniform beam with the equivalent stiffness, it makes possible to analyze behavior of shield tunnels by means of seismic deformation method as well as other pipe-like underground structures. Parameters which have influence on the equivalent stiffness are also discussed.
60 citations
42 citations
TL;DR: In this article, it was found that a method which also uses curvature information in the so-called most likely failure point usually is preferable to the alternatives if an update of first-or second-order estimates is necessary.
Abstract: First-and second-order reliability methods have turned out to be efficient practical tools in structural reliability for direct probabilistic design or for the development of probability-based design codes. These methods are approximate but certain Monte Carlo techniques with importance sampling can make reliability estimates arbitrarily accurate. Three different methods are presented and tested at a suitable example with respect to their numerical efficiency. It is found that a method which also uses curvature information in the so-called most likely failure point usually is preferable to the alternatives if an update of first-or second-order estimates is necessary. However, that method becomes inadequate for very high problem dimensions and/or large failure probabilities.
40 citations
TL;DR: In this paper, a new framework for evaluating probability distribution models used in hydrologic frequency analysis is proposed, where the variance (standard deviation) in estimation of T-year events (quantiles) obtained by the model is incorporated as an evaluation criterion as well as some goodness-of-fit criteria; resampling methods such as the jackknife and the bootstrap are also incorporated to quantify the variance.
Abstract: This paper proposes a new framework for evaluating probability distribution models used in hydrologic frequency analysis. In the framework, the variance (standard deviation) in estimation of T-year events (quantiles) obtained by the model is incorporated as an evaluation criterion as well as some goodness-of-fit criteria; resampling methods such as the jackknife and the bootstrap are also incorporated to quantify the variance. Using the existing extreme data (annual maxima of κ-day precipitation, κ=1, 2, 3), the authors reveal the insufficiency of the conventional model evaluation which is based on only the goodness of fit. The proposed framework evaluates ten distributions with two or three parameters. Additionally, the relation between the amount of data and the variance (estimation accuracy) is investigated through bootstrap-type resampling.
26 citations
TL;DR: In this paper, a series of dynamic loading tests with use of large-scale reinforced concrete bridge piers was conducted to investigate an effect of number of load reversals with the same displacement amplitude.
Abstract: A series of dynamic loading tests with use of large-scale reinforced concrete bridge piers was conducted to investigate an effect of number of load reversals with the same displacement amplitude. The specimens were subjected to a series of step-wise increasing symmetric displacement with n cycles, in which number of cycles n was varied from 3 to 10 as a parameter to be investigated.It was understood from the study that although deterioration of the specimen progresses, as a general trend, in accordance with increase of the number of inelastic loading cycles, for specimens which failed in flexure, effect of the number of loading cycles between 3 and 10 is less significant at the loading displacement smaller than or equal to the displacement at which the maximum load was developed.
20 citations
TL;DR: In this article, a finite element method based on the velocity correction method is presented, which employs the linear interpolation functions based on quardrilateral isoparametric elements.
Abstract: In this paper, a finite element method based on the velocity correction method is presented. However there arise difficulties about the boundary conditions which have been used for the solution of the pressure Poisson equation. For example, in the calculations of the conventional analysis, uniform pressure (P=O) or normal gradient of pressure equal to zero (∂P/∂n=0) has been adopted especially on the open boundary which is artificially introduced as the limitation of the calculation domain for the sake of analysis convenience. However, these boundary conditions are false because the pressure on the boundary can not be prescribed in general for the time-dependent problems. In order to improve these boundary conditions, a new approximation method is proposed in which the boundary pressure Poisson equation is solved for each time step.The method presented in this paper employes the linear interpolation functions based on the quardrilateral isoparametric elements.
19 citations
TL;DR: In this paper, the authors presented a numerical calculation model to predict longitudinal behaviour of the shield tunnel and compared with results of prototype test and calculation model on longitudinal behaviour, it was found that the calculation model could give results consistent with the prototype ones.
Abstract: As well known, a shield tunnel is one of typical long structures. Its lining has many segment joints in the cross section and in longitudinal direction. For rational design of a shield tunnel subject to strong earthquake motion or ground subsidence, it is essential to evaluate its longitudinal structural characteristics accurately. Namely, effects of the joints should be taken into account in structural calculation.This study shows approaches to evaluate the effects of the joints for longitudinal tunnel design. For this purpose, the authors present a numerical calculation model to predict longitudinal behaviour of the shield tunnel. In this model, joint elements are introduced so as to evaluate segment joints.Compared with results of prototype test and calculation model on longitudinal behaviour of a shield tunnel, it was found that the calculation model could give results consistent with the prototype ones.
18 citations
18 citations
TL;DR: In this paper, an inverse procedure for the source characterization of acoustic emission was proposed based on a generalized theory of AE, and numerical experiments were performed on the surface observation of AE.
Abstract: Based on a generalized theory of acoustic emission which we previously proposed, an inverse procedure for the source characterization of AE is discussed. To determine the source kinematics (crack type and crack orientation), a moment tensor representation is introduced. It is clarified that the eigenvalue analysis of the moment tensor can afford essential information on the kinematics of crack movement. Then, an deconvolution analysis provides the kinetics of crack motion as a source-time function. To confirm the applicability of the source inversion procedure, numerical experiments are performed on the surface observation of AE. By employing simulated AE waveforms, source characteristics are inversely solved and determined. Results demonstrate a great promise of the proposed procedure for the source characterization of AE.
14 citations
TL;DR: Wang et al. as mentioned in this paper proposed 3D simplified Bishop method, simplified Janbu method, and Spencer's method to analyze 3D slope stability, which is more accurate and reasonable than 3D simple slice method proposed in the authors' previous study.
Abstract: In order to analyze three-dimensional (3-D) slope stability, new 3-D methods are proposed by extending the simplified Bishop method, the simplified Janbu method and Spencer's method to three dimensions. It is shown that these methods are more accurate and reasonable than 3-D simple slice method proposed in the authors' previous study. Next, the approximate equations of 3-D safety factors for 3-D simplified Bishop method and Janbu method are presented and their limits of applicability are discussed.
TL;DR: In this article, an arc length control algorithm for tracing smooth equilibrium paths of nonlinear structures is developed utilizing curvature of the paths, and an example on a reticulated space elastic truss structure is presented to demonstrate the efficiency.
Abstract: An automatic arc length control algorithm for tracing smooth equilibrium paths of nonlinear structures is developed utilizing curvature of the paths. An example on a reticulated space elastic truss structure is presented to demonstrate the efficiency of the proposed algorithm.
TL;DR: In this paper, the dynamic response of offshore structures to random sea waves and strong earthquake motions is investigated, where Bretschneider's wave energy spectrum and ground motions are represented by Kanai's power spectrum.
Abstract: Dynamic response of offshore structures to random sea waves and strong earthquake motions is investigated. Sea waves are modelled by Bretschneider's wave energy spectrum and ground motions are represented by Kanai's power spectrum. Governing equation of motion is obtained by the substructure method. Response analysis is carried out using frequency-domain random vibration approach. Wave responses are found to be generally larger whereas seismic responses are smaller when soil-structure interaction effects are considered. Reliability studies show that earthquake loadings provide comparable results to those of wave loadings, but the latter have more significant effects on response evaluations because of the longer duration time.
TL;DR: In this article, the effect of initial curing periods in water, the replacement ratio of fly ash and binder content on the depth of carbonation of concrete under accelerated carbonation condition is evaluated to predict the depths of carbonations under natural exposure condition.
Abstract: The effect of initial curing periods in water, the replacement ratio of fly ash and binder content on the depth of carbonation of concrete under accelerated carbonation condition is evaluated to predict the depth of carbonation of concrete under natural exposure condition. The depth of carbonation depends on these factors and it can be predicted by the effective water-binder ratio or compressive strength of concrete cured in water for 28 days. The test results of the accelerated carbonation test are compared with those of the natural exposure test. The depth of carbonation of concrete exposed indoors for 15 years has a good correlation with the calculated values by the equations proposed in this study. The depth of carbonation of concrete under natural indoor condition can be predicted by the accelerated carbonation test.
TL;DR: In this article, the influence of different types of cement, cement content per unit volume of concrete, and concreting temperatures on adiabatic temperature rise were evaluated during this study.
Abstract: The influence of different types of cement, cement content per unit volume of concrete, and concreting temperatures on adiabatic temperature rise were evaluated during this study. The Adiabatic temperature rise was measured with a new testing apparatus, with high reliability that has been confirmed through comparison with time-dependent temperature changes in mass concrete structures. Before the evaluation, the most suitable equation for approximating the adiabatic temperature rise as a functional formula of time was selected based on the experimental results. Further, comparison of the above approximate values with standard values proposed by JSCE or JCI was done, and problems involved in these standard values were pointed out.
TL;DR: In this paper, several vehicle tests were executed on a remolded silty loam terrain of 30% water content by use of a small tracked vehicle of 3.55kN weight, 71cm contact length and 20cm width of track belt.
Abstract: To clarify the trafficability and the traffic performance of a bulldozer operating on a weak terrain at driving and braking state, several vehicle tests were executed on a remolded silty loam terrain of 30% water content by use of a small tracked vehicle of 3.55kN weight, 71cm contact length and 20cm width of track belt. From the measured relations between driving and braking force, drawbar-pull and effective braking force, sinkage and slip ratio, it is clarified that the largest drawbar-pull is obtained at 3.2 grouser pitch height ratio and the locomotion resistance increases with the increment of slip ratio at driving state, and the sinkage under the rear sprocket at driving state is larger than that at braking state due to the large amount of slippage and the large eccentricity.
TL;DR: The field test shows that the fuzzy controler can control shield machine as well as skilled operators and the optimum controller can be obtained when the performance index is minimized.
Abstract: This paper deals with the construction of the fuzzy controller for shield tunnelling and the result of the field test. The fuzzy controller has two functions. One is controlling shield jack speed and rotation speed of screw conveyer for pressure regulation at a muck chamber, the other is making choice of shield jack patterns for direction control of a shield machine. This fuzzy controller has a parallel circuit structure. By this way it can control complex systems by a few control rules founded on the know-how which skilled operators have obtained through their experiences. The fuzzy controller aims at shield machine control by skilled operators. So the root mean square of the diviation in operation between skilled operators and the fuzzy controler is defined as the performance index. The optimum controller can be obtained when the performance index is minimized.The field test shows that the fuzzy controler can control shield machine as well as skilled operators.
TL;DR: In this paper, the erosional process of soft muds is studied experimentally and theoretically, and a model for the behaviour of muds was developed to simulate the errosional process, well describing the changes of suspended solids concentration and vertical distributions of solid fraction in uneroded remaining muds.
Abstract: The erosional process of soft muds is studied experimentally and theoretically. Mud erosion is classified to three types according to water content of them. These characteristics are distinguished by the range of the slump value. The erosion tests of soft muds show that the critical shear stress of erosion τce is expressed as a function of solid fraction of muds at the surface layer and the initial erosional flux as a function of non-dimensional bed shear stress τ/τce-1. The erosional fluxes at constant shear stresses decrease in an hour after the start of experiment because of the hardening of muds by the shear deformation which accompanies the reorientation of mud particles.On the basis of these experimental results, a model for the behaviour of muds is developed to simulate the erosional process. This model well describes the changes of suspended solids concentration and vertical distributions of solid fraction in uneroded remaining muds.
TL;DR: In this article, a total of 47 model slabs whose scale was about 1/3 to a typical deck panel between adjacent main girders of an existing steel-concrete composite girder bridge were tested under the repetition of a wheel load using a wheel tracking machine originally developed by Osaka City University.
Abstract: A total of 47 model slabs whose scale was about 1/3 to a typical deck panel between adjacent main girders of an existing steel-concrete composite girder bridge were tested under the repetition of a wheel load using a wheel tracking machine originally developed by Osaka City University. The tests were confined with a low cycle fatigue range in which the repetition of a wheel load was less than 2×104 times. The numerous data obtained in the tests are used to reveal the low cycle fatigue characteristics of bridge deck RC slabs. Besides, assuming that such characteristics may also significantly control the high cycle characteristics of the slabs, a method for estimating fatigue strength and fatigue life of bridge deck RC slabs is proposed.
TL;DR: In this paper, the authors proposed estimation formulae of ground settlement during earthquakes focused on lifeline earthquake engineerings, which were obtained by regression analysis using 404 data of the ground settlements in the past major five earthquakes.
Abstract: The present paper has proposed estimation formulae of ground settlement during earthquakes focused on lifeline earthquake engineerings. The proposed formulae were obtained by regression analysis using 404 data of the ground settlements in the past major five earthquakes. The maximum ground settlement is given by the function of height of sandy soil layer, embankment height, maximum ground surface acceleration and N-value of sandy soil layer. The estimation formulae were given for two cases of geological soil conditions; embankment and plane site. The proposed formulae were compared with following two results by other researchers to ensure the accuracy. The formula for embankment settlement was applied to other data of ground settlement observed on back fills around abutments, and also the ratio of the maximum ground settlement to the height of sandy soil layer at plane site settlement was compared with laboratory experimental results as to volumetric strain. They showed pretty good agreement.
TL;DR: Probabilistic safety analysis methods for structural systems involving spatially variable material properties are studied and Monte Carlo simulation, based on the stochastic field simulation technique, is recommended because its accuracy is guaranteed irrespective of the number of random variables.
Abstract: Probabilistic safety analysis methods for structural systems involving spatially variable material properties are studied. For the cases to which the first-order second-moment methods cannot be applied well, two different Monte Carlo methods are employed in conjunction with the finite element technique. “Monte Carlo simulation”, which is based on the stochastic field simulation technique and the safety judgment for each trial, is recommended because its accuracy is guaranteed irrespective of the number of random variables. On the contrary, the accuracy of “Monte Carlo integration”, where a numerical integration of the joint density function of the random variables is carried out by means of sample-mean Monte Carlo method, goes down dramatically as the number of random variables getting large. Numerical examples verify the above argument and reveal the effects of correlation parameters on the local and system limit state probabilities.
TL;DR: In this paper, the authors present characteristics of the ultimate strength of steel plate panels under uniform shearing stress on the basis of the elasto-plastic finite displacement theory.
Abstract: In the case of design for steel plates under in-plane combined loading, it is important to clarify the ultimate strength of steel plate panels in shear, although many studies on load carrying capacity of plate girders in shear have been carried out using experiments and plastic analysis. Moreover, evaluation of the ultimate strength is essential to promote the ultimate limit-state design method.This paper presents characteristics of ultimate strength of steel plate panels under uniform shearing stress on the basis of the elasto-plastic finite displacement theory. The ultimate shear strength curves also proposed, to represent the theoretically obtained ultimate strength.
TL;DR: In this paper, the deformation capacity of reinforced concrete bridge piers under earthquake was investigated, and a method capable of calculating the ductilities for quantitative evaluation of deformation capacities of the piers was proposed.
Abstract: In order to find deformation capacity of reinforced concrete bridge piers under earthquake, cyclic horizontal loading tests were carried on the specimens of bridge piers for which span ratio, tensile reinforcement ratio, web reinforcement ratio and axial compressive stress have been modified, and the effect due to these factors against deformation capacity has been identified.Furthermore, a study was made on the method to obtain ductilities for quantitative evaluation of deformation capacity of the reinforced concrete bridge piers, and a method capable of calculating thereof relatively accurately was proposed.
TL;DR: Raliability-based rating criteria in the form of load and resistance factor rating (LRFR) code are presented in order to show the direction of the development of rating codes.
Abstract: This study is directed for the evolution of rational approaches to the systematic evaluation of the load carrying capacity of bridges based on the practical and advanced second moment reliability methods. Raliability-based rating criteria in the form of load and resistance factor rating (LRFR) code are presented in order to show the direction of the development of rating codes. Furthermore, an approach using the reliability index as a measure of rating of an existing bridge is suggested.
TL;DR: In this article, the authors summarized and presented fatigue crackings in 180 steel bridges as a data base in personal computers, including the histories of bridge, details of structure, types of cracking, causes of cracking and retrofitting methods.
Abstract: Fatigue crackings in 180 steel bridges are summarized and presented as a data base in personal computers. This data base includes the histories of bridge, details of structure, types of cracking, causes of cracking and retrofitting methods. By using the reference function of data base, the service life and occurrence of crack of bridges, typical cracks and their causes in various bridge details, and the fatigue strengths of connections are discussed.
TL;DR: This study is an attempt to develop a forecasting method of population attributes by zone in a metropolitan area using a micro-simulation technique, which can chase individuals' behaviours and can provide flexible aggregation.
Abstract: This study is an attempt to develop a forecasting method of population attributes by zone in a metropolitan area. Random utility models are used to formulate each event of household related to individual's life cycle and residential relocations. As the forecasting method, a micro-simulation technique, which can chase individuals' behaviours and can provide flexible aggregation, is employed. The validity test and policy tests proved the advantages of the model, compared with existing models.
TL;DR: In this article, an analytical model is proposed to predict the load-deformation response of reinforced concrete elements subjected to pure torsion, which is capable of predicting not only the strength but also the angle of twist, the steel strains and the concrete strains throughout the loading history.
Abstract: In an effort to predict the load-deformation response of reinforced concrete elements subjected to pure torsion, an analytical model is proposed in this study. In this model, compressive stress-strain curve and tensile stress-strain curve of concrete struts between diagonal cracks are considered in equilibrium. Experiments were then conducted to verify the validity of this model. The experimental and analytical values have been found to be in good agreement and the proposed model is thus capable of predicting not only the strength but also the angle of twist, the steel strains and the concrete strains throughout the loading history. The concrete cover and the reinforcement ratio are also found to have significant effect on the change of shear flow.