This paper presents an easily comprehensive method of shakedown analysis of two-span beams and symmetric three-span beams with a moving load when taking account of bending and shear. The original problem to be dealt with is a nonlinear mathematical programming due to a nonlinear interaction of bending moment and shearing force on the ultimate strength of cross section. Adoption of Mises yield condition reduces this problem to a quadratic programming. Well-known conception of quadratic inequality is introduced to find the analytical solution of the problem. Numerical results for the beams with various span-ratios, loading conditions and strengths of cross sections clarify the shakedown characteristics, particularly the influence of shearing force on shakedown loads.

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This paper presents an experimental investigation on the buckling strength of stub channel columns under repetitive compression to determine reasonable cross sections of steel sheet piles against the repeated driving force by diesel hammer. The tests were performed under the pseudo-static condition using microcomputer-based servo-controlled testing system to find the deteriorating properties of steel sheet pile models undergoing the large elasto-plastic deformations under repetitive compression.
Through the study, the deteriorating properties of the sheet pile model were clarified and found to be influenced by the width-thickness ratio, aspect ratio of the flange plates, and the relative dimensioning of the web and flanges.

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This study presents an experimental investigation on the strength of thin-walled steel box beam-columns of the T-shaped steel bridge piers under constant axial thrust and repetitive bending moment simulating earthquake excitations being applied, however, in the static condition. The steel box beam-column specimens had flanges with or without the longitudinal stiffeners.
From the tests, the elasto-plastic behavior, the ultimate strength, the deteriorating and hysteretic properties are clarified. The effects such as the rigidity of the flange stiffeners, the magnitude of the axial force on the load-carrying capacity and the failure types of the specimens are investigated.

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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.

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Structural design optimization will be more convenient to formulate the design problem with discrete variable than it would be if the variables were assumed to be continuous. In order to solve a structural design problem with discrete variable only, two completely different techniques, 1) Integer gradient direction, which is later supported by subsequential search interval technique and 2) Modified Rosenbrocks orthognalization techniques have hybridized. Rosenbrocks original procedure is a well established method to solve continuous variable optimization problem; but to suit to discrete variable problem solution some modifications are needed and reported here. By this hybridizing most of the practical difficulties, usually, encountered in the discrete optimization can be overcome. Details of the techniques are discussed and by their combination a solution code has been generated. A constrained problem is first converted into a sequence of unconstrained problem by use of interior penalty function and then solved by the generated code. The efficiency of the generated code is revealed by solving several test problems.

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This study is to estimate statistically the life time of bridges and to analyse the reason of demolish and renewal. Data sources are the ledgers of bridge in Niigata prefecture, from which the numbers of remaining bridges and demolished ones were took out in order of newly built year. Total of remaining bridges are 4333 and demolished ones are 44 at 1986.
Using terms of reliability theory, the “probability density function of failure” is supposed to follow a weibull distribution from graphic analysis, and by the presumed reliability function, the life expectancy of steel bridge are estimated at some 35 years and of reinforced concrete bridge are at some 54 years. Concerning reason of demolish, using information theory, the contributed ratio of information are calculated. Political or functional reason are superior to physical reason.

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In the following paper, the vibration of an initially deflected rectangular plate under a sinusoidally time-varying inplane moment is examined from the point of view of dynamic instability. The equation of motion describing the large deflection of the initially deflected plate is analyzed by the Galerkin method. The resulting equations for time variables are integrated by using the Runge-Kutta-Gill method. The dynamic instability regions are analyzed by the small deflection theory of a thin plate, neglecting nonlinear terms. The amplitudes of unstable regions are determined by large deflection theory.
Numerical results are presented for various shapes and magnitudes of the initial deflection. The effect of the initial deflection on natural frequency, dynamic instability and amplitudes are discussed.

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Presented in this paper is a study on the creep and relaxation behavior of the composite girders with the precast prestressed concrete slabs using a simple linear visco-elastic model for the concrete slab and by making use of the Laplace and its numerical inverse transforms in view of the principle of correspondence to the linear elasticity.
The comparison of the analytical results with those of long-term experiments on precast prestressed slabs and composite girders specifically scheduled and conducted by the authors have shown that upon determination of the visco-elastic constants from the prestressed concrete slab tests, the creep and relaxation behavior of the precast prestressed composite girders presented herein can be reasonably well predicted by a simple linear visco-elastic model.

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First of all, size and change location of cover plates which compose variable box cross sections adopted in fixed-end steel arch ribs are examined using their core-moments analyzed by a first-order-elastic analysis. Then, strain behavior at ultimate states of the arches with several patterns of the variable cross-sections are discussed using an ultimate strength analysis. Relationships between the ultimate strengths of the arches with variable cross-sections and those of arches with uniform cross-sections are also investigated. Based on the results a practical estimate on their relationships is carried out. Finally presented are design provisions which are able to take into account the effects of the variable cross-section on the ultimate strength.

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It has been reported that fatigue cracks were often initiated at the connections of cross beams to main girders in plate girder bridges. In this paper, the relation between the local stresses which induced the fatigue cracks and the three-dimensional behavior of plate girder bridges is formulated by the results of the stress measurement of an actual plate girder bridge and its three-dimensional finite element analysis. The obtained equation reveals the influential factors for the occurrence of the local stresses.

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A constitutive equation for buckled plate components is established based on the effective width concept to account not only for the reduction of effective area but also for a sudden drop of axial stiffness at the instant of buckling. Based on this, the updated Lagrangian FEM analysis is performed to predict the interactive column and beam-column behavior of built-up steel sections with local buckling, and is proved accurate by the comparison with the tests. The existing interactive design formulae have been examined through the analysis, and some practical implications are made.

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Elastic instability and the nonlinear finite displacement behavior for spatial thin-walled members under displacement-dependent loads are investigated. The displacement-dependency is reflected on the load stiffness matrix, of which the nonsymmetry indicates the nonconservative loads. A general formulation to derive the load stiffness matrix is presented. As important examples, the follower force and the wind forces are treated, and their load stiffness matrices are given explicitly. The mass matrix of thin-walled mambers is also derived to examine the dynamic instability. The nonlinear finite element analysis as well as the static and dynamic instability analyses are made as computational examples for the follower force and the wind forces, and some interesting features are discussed.

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In this paper, a discrete method for analyzing the problem of elasto-plastic bending of a rectangular plate is proposed. The solutions for partial differential equation of rectangular plate are obtained in discrete forms by applying numerical integration.
An incremental variable elasticity procedure has been used for the elasto-plastic analysis of the rectangular plate. As the applications of the proposed method, elasto-plastic bending of rectangular plate with four types of boundary conditions are calculated.

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Upon an existing nonlinear theory of thin-walled beams for truly large displacements, linearized governing relations are rigorously developed on a general equilibrium after any large displacements. Apart from those in that nonlinear theory, another set of parameters are employed for the infinitesimal variations under the same kinematic field to develop a normalized formulation. Any bucklings of thin-walled beams arising after large displacements can be put exactly on the present tangent equations: as an unprecedented example, the flexural buckling of an open-cross-section beam subject to finite torsion and compression is analyzed.

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This paper proposes a new method of frequency response analysis of probabilistic structures using FEM to evaluate the stochastic dynamic behavior of structures with uncertain parameters. It presents some numerical examples including verification by Monte-Carlo Simulation (MCS). The frequency transfer function H (ω) of displacement of a system is expanded into the first-order Taylor series at the mean values of input parameters. Then a function similar to the frequency transfer function of a SDOF system is specified to interpolate each input parameter axis. Using these specific interpolated frequency transfer functions, the mean and standard deviation time history of response can be obtained.

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A numerical method using transfer matrix technique is developed to obtain solutions for space rods considering finite displacements. The present method is characterized by the point that the numerical solutions are directly derived from the highly nonlinear governing equations with Lagrangian expressions. The governing equations are based on the theory of finite displacement with small strains and no restrictions are made on the magnitude of displacements.

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The development of the tension field and the collapse mechanism of shear panels isolated from plate girders are numerically investigated by the finite element method. Special attention is paid to the influence of the rigidity of flanges and the boundary conditions of one panel. It is then recognized that no plastic hinge appears in flanges even in the ultimate state, and that a collapse mechanism is formed when the yielded zones propagate completely in the diagonal direction of the panel. Furthermore, discussed are the relationships between the configuration of the tension field or the inclination of the tensile principal stress and the anchor action by the sided members or the gusset plate action.

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A method for synthesizing strong-motion accelerogam from small earthquake records is presented with aid of the faulting source model. It is derived by extending the spectra relation satisfied in a point source model to ones in the faulting source model. The important terms involved in the method, namely, the scaling law of source spectra and the number of sub-faults are obtained statistically from the past strong-motion accelerograms. The method is applied to several representative earthquakes occurred in Japan, and it is shown that the synthesized accelerograms by the method agree relatively well with the observed ones in the points of amplitude, duration and spectra characteristics.

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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.

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Certain structures have the vibration modes of closely-spaced natural frequencies. The galloping behaviour of such a structure is studied. A cable-stayed bridge tower whose the natural frequency of the in-plane second mode is close to that of the in-plane first mode is employed as the case study. The structure is modeled as a linear two-degree-of-freedom system with proportional damping, and nonlinear quasi-steady wind force is assumed. An asymptotic modal analysis on galloping is conducted. The results indicate that the galloping of this tower is the steady-state motion either in one of the two modes, depending upon the initial disturbances, and that the coexistence of two modes in galloping, i. e. multi-mode galloping, is unstable. However, for structures with certain properties, e. g. unsymmetrically distributed mass, only the multi-mode galloping is stable. These results agree well with the observations in wind tunnel experiments.

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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.

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Bifurcation behavioral characteristics of a cone-shaped axisymmetric elastic space truss made of n elastic members with n-axes of symmetry are studied. Equilibrium equations of the truss are investigated using cylindrical coordinates to verify the existence of 2n bifurcation paths. The number of paths increases proportionally to the member number n. The equilibrium equations show this increase of bifurcation paths by the vanishing of lower-order terms, resulting in non-vanishing terms with higher-order nonlinearity. The geometric symmetry of the truss results in rotational symmetry of the equilibrium equations and of the bifurcation paths.

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This paper is concerned with the analysis of free flexural vibration of rectangular plates by the finite difference transfer matrix method.
In this method, the algebraic computations are conducted by the transfer matrices which are formulated with the use of the ordinary finite difference equations for the differential equation of plate vibration.
The proposed method is efficient to reduce the size of the coefficient matrix of simultaneous equation in the ordinary finite difference method and finite element method. Some numerical results are also presented to prove that the proposed method has the wide applicability and possibility of future development of structural analysis.

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This paper presents a dual approach for the optimal elastic-plastic design of largescaled skeletal structures using the sensitivity analysis. Herein, the sensitivity analysis is to find the sensitivity coefficient of the behavior variable (e. g., deformation) with respect to design variable. The optimal elastic-plastic design method is developed by separating the design process into the three parts, i. e., the structual analysis, the sensitivity analysis and the optimization by dual approach. The main feature in the proposed method is to use the sensitivity coefficient of the elastic-plastic deformation found analytically and, as such, the design calculation can be efficiently performed for the large-scaled structures. The validity of the proposed method is confirmed by the 10-bar truss structure and the application of the approach is examined by the steel-made Sabo dam structure. This method can control the both constraints of the ultimate load and the elastic-plastic deformation and, therefore, it is very useful for the design such as the steel-made Sabo dam structure subjected to debris flow.

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There are few studies on the ultimate strength of steel plates under in-plane combined loading, and their basic strength curves in the design specifications in many countries are still based on the elastic buckling theory using relevant safety factors. Evaluation in the ultimate strength is essential to promote the ultimate limit-state design method. This paper presents the ultimate strength of plate panel under in-plane stress gradient. Based on the analytical results, the ultimate strength formulas for uniform compress and pure bending are proposed, respectively and the interaction formula for the combined loading of compression and bending are then proposed.

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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.

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This paper clarifies the ultimate strength properties of longitudinally stiffened continuous plates simply supported by transverse stiffeners with sufficient flexural rigidity under uniaxial compression. By means of the elasto-plastic finite displacement theory, in which much reduction of degree of freedom of analytical models and computer time can be greatly expected by introducing a technique similar to the usual modal analysis making use of generalized coordinates into the conventional finite element method, many models of stiffened plates with various values of parameters are efficiently analized. Moreover, the numerical results are compared with the strength curves specified by several design codes, and then the safety margin included in these design codes are discussed.

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A large number of studies have been carried out for predicting and calculating the ultimate strength of plate girders under patch loading. In 1983, a modified theory of Roberts and Rockey's one was proposed by Moriwaki et al. with taking account of the web buckling strength. That theory is enable us to predict the most accurate values of the ultimate strength, but is applicable under limited conditions. In this paper, an accurate calculation method based on new mechanism models is developed with taking account of coexisting bending stress and shearing one, which is existing under more usual conditions.

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By processing statistically the data of initial deflection obtained from measurement of stiffened plate members in steel box girder bridges recently fabricated in Japan, its statistical properties can be made clear. On the basis of the initial deflection data, the ultimate strength curve corresponding to the probability of nonexceedance of 5% can be provided. Finally, the conception of determining the allowable values as well as the procedure of test measurement for the initial deflection of stiffened plates are presented.

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In this study, the transmission mechanism of impulsive force of a falling rock on a sand layer was investigated by means of Cundall's discrete block method. At first, a falling rock and a sand layer were modeled by elements assembled of rigid cylinders, springs and dashpots, then effects of basic parameters such as spring and damping constants on the impulsive force were discussed under the numerical analysis as a two dimensional problem. Secondly, to explain the real behavior better, the discrete block model was extended to a three dimensional problem using the character of the sand based on experimental results. Finally, it was shown that the transmission mechanism of impulsive force by a falling rock in this method agrees with that in experimental results on various conditions.

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Bending moment due to geometrical nonlinearity in a main girder should be checked on designing cable-stayed girder bridges. Even though the employment of nonlinear analysis by an electronic computer is powerful, much time is also inevitable for carrying it out.
In this paper, a formula to estimate the bending moment due to nonlinearity is proposed and also dominant parameters which have a close relation to nonlinear behavior of the girder are summarized. This simple formula is useful for designers' judgement whether nonlinear effect should be taken into account or not beforehand. In addition, it is available for selecting a bending rigidity of the girder of long-spanned cable-stayed girder bridges at preliminary design stage.

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From the pointview of degrees of anchoring, cable-stayed bridges are classified into three types, i. e., self, fully and partially anchored systems. In the partially anchored cable-stayed bridges the expansion joints which do not transmit the axial forces at all are inserted in main girders.
This paper presents the application of multilevel optimal design to cable-stayed bridges with these three types of anchorages. First, optimal design of the partially anchored systems are made for such design parameters as optimal locations of expansion joints, moment-transmitting ratios of expansion joints and ratios of tower height to center span. Secondly, each cost of three types of anchored systems is compared. The resuits indicate partially anchored systems are most effective for long-span cable-stayed bridges.

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In this paper, the validity of straight beam approximations for curved thin-walled members is examined by a theoretical investigation and numerical calculations on geometrical nonlinear analysis. For the purpose of the present report, geometrical non-linear quantities of a straight beam assemblage as well as an exact circular member are given by reducing the length of straight elements to infinitesimal. Next, the governing differential equations for lateral-torsional buckling of circular arches are derived by using the above quantities. Moreover, the new generalized displacements for the rotations and torsion satisfied the compatible conditions between adjacent elements are proposed for the geometrical nonlinear analysis.

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This paper presents the experimental researches on the coupled behavior of lateral-torsional buckling and web buckling of transversely stiffened plate girders. The cross-sectional dimensions of all the six specimens were proportioned to prevent from local torsional buckling of compression flange, and the web width-thickness ratio was kept constant being equal to 200 for mild steel which is over the current JRA upper limit, 152. Then the effect of preceded web buckling on the ultimate strength of girders failed by lateral-torsional buckling is investigated. In-plane bending strength was also examined. The test results are also compared with those for girders with the web width-thickness ratio smaller than the JRA limit.

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Double side web-gusset welded joints whose main plate thicknesses are changed and a single side web-gusset welded joint are examined using finite element stress analysis. As a result, differences in stress distribution between these joints are revealed, and it becomes clear that shell finite element analysis does not provide sufficient accuracy for such three-dimensional joints. And their fatigue lives are calculated by fracture mechanics. The results indicate that these fatigue lives are almost the same.

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The dynamic responses of highway bridges to moving vehicles are investigated theoretically and experimentally taking account of the road surface roughness. To verify the rationality of both theoretical analysis and analytical models of bridges and moving vehicles, the analytical results are compared with the experimental ones obtained by dynamic field tests on a simple girder bridge with span length of 22.2m. With strict regard for the influence of eccentricity of moving vehicles on dynamic response of bridges, the simultaneous differential equations for the coupling vibration of bending and torsion are derived by means of modal analysis. It can be considered that the two-degree-of-freedom sprung-mass system with one front axle and two rear axles is more realistic as a model of heavy dump truck than the one-degree-of-freedom system usually used.

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This paper deals with the ultimate strength of straight and curved parallel steel box girders as a new monorail girder system. First, simplified formulas for ultimate strength of monorail girders are derived. Next, single and parallel beams of 1/15 scale under two concentrated loads are tested under simple and 3-span continuous conditions to investigate the ultimate load behavior and to check up the simplified formulas. Lastly, the test of two straight box girders and three curved parallel box girders of 1/3 scale having cross beams at the both ends only are carried out. From the test result, it is clear that the parallel steel box girders having only the end cross beams with sufficient rigidity can be adopted for the monorail girders.

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In the analysis of dense instrument array data obtained by independent triggering and recording systems, it is inevitably necessary to understand the accuracy of the data. Such requirement is particularly severe when ground strains induced during earthquakes are evaluated from differential ground displacements at several observing points. Errors associated with numerical integration of acceleration records at low frequency range and difference of sensitivities between instruments are likely to develop unrealistic ground strains. This paper presents experimental analysis on the effect of lower cut-off frequency of instrument correction filter, number of bits of AD converter and its sampling interval on accuracy of calculated displacement. And reliability of relative displacements evaluated from the records by plural instruments is also presented.

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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.

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In this paper, a Monte Carlo simulation method, which is able to evaluate practically the post-earthquake restoration process of road transportation system, is proposed. The simulation model is divided into three phases; 1) Assessment of damage state of network, 2) Performance evaluation of system included in traffic flow analysis, and 3) Recovery process of damaged network. The restoration problem is separated in two parts, emergency restoration evaluated by considering only connectivity between nodes, and rehabilitation works affected by traffic control. The structural and functional restoration are defined by various useful measures. The present method is then applied to evaluate the performance of road transportation system in the Izu Peninsula during the post-earthquake period. The structural and functional restoration processes, restoration order and traffic volume, as influenced by repair progress, are examined within the context of some constraints such as available manpowers and materials, and an optimum strategy for system restoration is quantitatively discussed.

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While the conventional seismic hazard analysis incorporates estimation of a single ground motion intensity parameter, it is often required in engineering application to estimate not only intensity parameter, but also other ground motion parameters, such as, predominant period, ground motion duration, etc.…. For the purpose of such an extension, the use of “hazard-consistent magnitude” and “hazard-consistent distance” is proposed. They are defined as conditional mean values given that the ground motion intensity exceeds the level specified by the annual probability of exceedance. Other ground motion parameters are determined as such corresponding to the hazard-consistent magnitude and the hazard-consistent distance. In this manner, one can determine all parameters to characterize a site ground motion on the basis of a single risk parameter.

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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.

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One of the problems to be clarified today is how to determine the values of cable stay forces to be introduced when designing the prestressed concrete cable stayed bridges. In the previous study, the authors proposed a method of optimization of cable stay forces where the minimum strain energy criterion was adopted from the structural point of view. Considering the economic aspects of the design, this paper presents another criterion based on the minimum cost. It also discusses a comparison between two criteria. The result shows that the minimum strain energy and minimum cost criteria give almost the same cable forces and costs when span lengths are adequately proportioned.

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