A number of experimental research works on the strength and ductility capacity of structures have been carried out in the past, which showed that the ductility capacity was strongly affected by loading condition. As far as such a repeated loading as earthquake motion is concerned, the design based on ductility factor is not always reasonable. The authors have proposed that the energy absorption capacity of structures is wellsuited index for seismic safety. The purpose of this study is to investigate the energy absorption capacity of structures quantitatively. A series of five reinforced concrete columns were tested under four types of repeated loading. The results developed in this paper is intended to use in estimation of seismic safety.

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When a thin-walled plate girder is subjected to repeated bending, it is possible that fatigue cracks may be initiated at the toe on the web side of fillet welds connecting the compression flange to the web. They are caused by the secondary bending stress produced by out-of-plane movement of the web under repeated in-plane bending, due to its unavoidable initial deflection. In this paper, first, the relation between in-plane bending stress and secondary bending stress is formulated. Secondly, substituting the fatigue strength of fillet welds subjected to secondary bending stress into the relation, the fatigue strength for the above fatigue cracks is expressed in in-plane bending stress. It is given as a function of the web slenderness ratio, and the influence of various factors on the fatigue strength is discussed.

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We clarify the complexity of large earthquakes by considering the ground motions of short-period range. First, an approach is applied to three large earthquakes in Japan by which the accelerograms of a large earthquake are synthesized from the accelerograms of a small one. As a result, it is shown that this approach can be applicable to some degree, but a larger earthquake is more complicated. Next, an inversion method applicable to the analysis of the source rupture process corresponding to short-period range is proposed and is applied to the 1968 Tokachi-oki, Japan, earthquake. It is inferred from the obtained results that this earthquake has a complicated source rupture process and has source directivity even in short-period range. It is thought that this inversion method is exceedingly effective.

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A study of behavior of curved plate girders under bending is made, emphasizing mainly the interactions between the flange plates and the web plate. The analyses are carried out by using finite element method based on the finite displacement theory. In this paper, the behavior of curved plate girders under bending is described, such as out-of-plane displacemnent of web plate, in-plane stress distribution and corresponding effective web width, resisting moment of girders and so on. The results shows that so called vertical buckling of flange plate does not arise from loss of the bending capacity of the plate girder. Moreover discussions about the more reasonable boundary conditions of the web panel as partial structural element for analyzing curved plate girders are described.

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A simplified separation technique of body and surface waves in strong motion accelerograms have been proposed. To confirm the dispersion characteristics of surface waves the evolutionary power spectrum have been examined for Japane typical accelerograms. The parameters t_d, and f_d, in time and frequency domain, respectively, have been defined as the separation parameters. To make sure of importance of separation, ground strain caused by body and surface waves have been analyzed for original data and its separated body and surface waves. It has been pointed out that the separated surface waves should be used spcially for estimation of local ground strain.

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In this paper the application of the computer program SUBSSIP-2D (Substructure method for Soil-Structure Interaction Problem: 2-Dimentional Analysis) is made for the seismic analysis of a three-span continuous girder bridge on multiple foundations of deep grouped piles and wall types. The SUBSSIP-2D is developed based on the substructure method, which first evaluates the subgrade impedance at the specified foundation nodes and the effective seismic input motions to them, and then establishes the inertial coupling between substructure and superstructure. The detail comparison is presented among solutions from various modelings and methods of analyses to derive the useful design considerations for bridges dealt with herein.

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This paper presents the formulas to compare the cost of cable-stayed and suspension bridges. Three types of cable-stayed bridges with full, self and partial anchorages and two types of suspension bridges with full and self anchorages are considered. With the cable-stayed bridges, fan, harp and semi-harp types are treated. The structural components counted in cost comparisons are superstructures (cables, hanger ropes and steel in main girders), towers and anchorages.
The numerical calculations are conducted varying the number of hangers and stays, span sag ratio, the locations of expansion joints in partially anchored cable-stayed bridges and the cost of anchorages. The numerical results in this paper show that partially anchored fan type bridges are the most suitable for long spans.

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This study presents a sequential linear programming approach for the optimal design of skeletal structures satisfying simultaneously both elastic and plastic design criteria at the service and ultimate load levels, respectively. The paper also examines the effective range of the ultimate load constraint by determining the upper and lower bounds of the effective load factor. The design method develops a minimum weight design focused on the merit of plastic design by a linear programming. Three examples of truss and frame are designed to illustrate the features and scope of application of the approach.

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A simple method is developed for calculation of inelastic response spectra for arbitrarily predetermined values of ductility and damping. Period-dependent Ductility & Damping Reduction Factor (DDRF) is defined as a scaling factor that convert 5%-damping elastic response spectra into an inelastic response spectra for desired damping and ductility. It is formulated as a product of two functions interrelating the ductility, damping and natural period, and a period-band-dependent matrix of regression coefficients which are statistically quantified on the basis of Japanese strong motion data set. Influence of site effects on DDRF is studied by classifying the strong motion records according to the soil condition classification employed in the Japanese Earthquake Design Specifications for Highway Bridges. On this basis a closed-form statistical model is proposed for prediction of a site-dependent inelastic response spectra for a given soil condition, ductility and damping.

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Design criteria of two-hinged, parabolic, steel arches based on the ultimate limit state design concept are presented. The design criteria on the planar ultimate strength are formulated for arch ribs. The ultimate strength design criteria are specified by critical cross sectional forces and critical stresses analyzed by the first order elastic analysis. Variable, cross sectional effect of arch ribs is also discussed from a viewpoint of the ultimate strength designing.

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A method of limit analysis which combines the features of the lower and upper bound approaches is outlined. In this method, the collapse load of a structure is expressed as a function of a set of kinematic and static variables which are subject to constraints resulting from an assumed collapse mechanism and yield conditions. The true collapse load is obtained by minimization with respect to the kinematic variables and maximization with respect to the static variables. The method is illustrated with simple examples. Application is made to evaluate the shear strength of reinforced concrete beams. It is concise as compared to separate upper and lower bound analyses. It also allows the minimization and maximization processes to be carried out in any order, thus enabling the collapse load to be calculated by the easier way.

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For rational reliability based structural design, it is important to accomplish the target probability of failure as accurate as possible. From this standpoint, this paper presents a probabilistic basis for the fractile-based structural design, and demonstrates the advantage of the method. Numerical examples indicate the superiority of the proposed fractile method to the second moment method. It is also noted that, by the independent determination of the design points from the linearization procedure, the proposed method has proved much simpler than the improved second moment method proposed by Rackwitz et. al., retaining its accuracy at a similar level.

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Bannosu Viaduct one of the Honshu Shikoku Bridges, neighboring to the Bisanseto Suspension Bridge, is panned to carry 4 lane roadways and 4 railway lines. This viaduct has the high piers, about 40-70m, and the pile foundations deeply penetrated into the comparative soft ground.
The behavior of these structures during an earthquake, therefore, is affected by the dynamic characteristics of foundation-pile systems.
The design of the structures considering earthquake-proof and the running stability of railway cars during the earthquake is required.
In particular, to secure the running stability of railway cars, it is important to design the viaduct having a definite range of dynamic characteristic. The viaduct must be designed to avoid resonating with the ground vibraion.

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Iwagurojima Bridge, which comes under the Honshu-Shikoku Bridge project, is a cable-stayed bridge with a main span of 420m. In this bridge, designed to be of a highway and railway combination type, fatigue behavior due to train load will pose an important problem. In order to prove the appropriateness of the fabrication procedure for this bridge, a specimen with dimensions almost equal to the transverse chord of stiffening truss, was trially fabricated. This specimen was then subjected to a static torsional loading test and a bending fatigue test. The objectives of these tests were to investigate the fatigue behavior of different weld joint details. These results reflected on the practical design and construction.

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The design of steel box girder bridges under unsymmetrically placed live loads involves consideration of intermediate diaphragms that are required to limit crosssectional deformation and distortional normal stresses. In this paper, the required spacing and stiffness of such intermediate diaphragms are examined by performing a parametric study based on Beam Analogy.
The results of the present parametric study yield a series of simplified design procedure that accounts for estimating diaphragm spacing and stiffness that are required to limit not only distortional stresses but also cross-sectional deformation.

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The present work is concerned with the membrane action in reinforced concrete slabs subjected to point-loading after cracking. Much attention is focused on the characteristic stress flow of membrane effect caused by point-loading. In a finite element crack analysis, the crack patterns are well simulated and the associated principal directions of membrane forces are calculated. Plotting of both these figures for each load step reveals the strong dependence of the stress flow of membrane forces on the corresponding crack pattern.

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This paper is intended to clarify the seismic response characteristics of the caisson-pier during earthquakes by use of observed results. The main obtained results are as following: 1) the (acceleration) response of pier depends on the epicentral distance, and is dominated by the contribution of higher mode when the epicentral distance is short. 2) the frequency characteristics of caisson and pier are almost similar to those of the basement and the superstructure respectively. 3) the time-dependent property of the frequency characteristics in the response of caisson and pier appears when the frequency of acceleration of the basement is time-dependent.

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This paper presents the result of multiple regression analysis of absolute acceleration response spectra with damping ratio of 5% of critical. Analyzed were 394 horizontal strong motion acceleration records obtained at 67 free field sites in Japan from 88 earthquakes with focal depth less than 60km. Because sensitivity of the Japanese SMAC accelerograph is appreciably low at the high frequency range, instrumental correction was performed on the original data. Each pair of two orthogonal horizontal components was combined in time domain to get the maximum value of absolute acceleration response spectra on the horizontal plane. The records were classified into three groups due to subsoil condition. Empirical formulae of attenuation of absolute acceleration response spectra with 5% damping ratio are proposed for three subsoil conditions.

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In this paper, the most general higher-order equations of one-dimensional static and dynamic theories for generally anisotropic elastic beams are proposed by expanding the displacements of infinite Power series with respect to the transverse coordinate of the beam.
Several beam theories which were proposed previously, can be deduced by the particular cases with employment of the lower-order terms of our theory and with specialization of the constitutive equations.
On the other hand, we apply the previously proposed plate theories including the effect of transverse deformations to the beam analysis, and examine the special theoretical and numerical charachteristics of the various beam theories through the application to some static and dynamic problems.

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An experimental study is presented on the local and overall interaction strength of welded box columns stiffened by longitudinal ribs and diaphragms. The column crosssections are composed of plates with relatively large width-thickness ratios so that local plate buckling is supposed to occur before the attainment of the overall column buckling. The test program consists of (1) six eccentrically loaded column tests, (2) four centrally loaded stub-column tests, and (3) two residual stress measurement tests. Based on the test results, an empirical design formula is proposed to predict the interaction strength.

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The objective of this paper is to assess the effects of initial irregularities on the seismic response of cylindrical tanks. Such out-of-roundness induces hydrodynamic pressure components which are circumferential high order modes and neglected in current design assumptions. Seismic response formulas are derived for cylindrical tanks having arbitrary initial irregularities from Lagrange's kinematic equation using natural frequencies, vibration modes and the hydrodynamic pressure. The hydrodynamic pressure in an irregular tank is evaluated by using velocity potential function. Natural frequency analysis is done by means of the transfer matrix method taking into concideration the initial hoop stress.
The effect of ratio H/D (H: liquid height and D: tank diameter)and shape of initial irregularities are examined by numerical calculations.

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This study presents a quasi-static approach using a matrix method based on the linear programming (LP) for the elastic-plastic analysis of a plane curved buried pipeline subjected to forced ground deformation. The actual buried pipeline is initially modelled as a discrete pipeline-ground system, in which pipe and ground spring elements are supposed to have elastic-plastic behaviors, respectively. The incremental deformation analysis is formulated as a LP problem. Herein, the objective is to maximize ground deformation increment during the successive yielding of ground spring or pipe element, while simultaneously satisfying the conditions of compatibility, equilibrium, yield and plastic flow as constraints. From the results of numerical examples, it is found that this method is very useful to evaluate the plastic strain and plastic rotation which are necessary for the seismic design of buried pipeline.

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In order to study the dynamic behaviour of underground pipelines, the earthquake observation has been continued on an underground pipeline since 1977. Out of over twenty earthquakes observed since the installation of instruments, the Miyagiken-Oki earthquake, the Izuhanto-Tohooki earthquake, and the Chibaken-Chubu earthquake were taken up as examples. A closer investigation by evolutionary spectra analysis and phase velocity analysis was made to make clear the relation between the strain measured on the underground pipeline and the ground motion.
The method of the seismic response analysis of underground pipelines was proposed taking account of the results of above-mentioned earthquake observation. To prove its effectiveness, the strains obtained by using this method were compared with observed ones. In result was proved the effectiveness of this seismic response analysis method.

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The greatest concern of bridge engineers in the world is maintenance, repair and rehabilitation of bridges. Many bridges, which have been constructed in the age of high growth of economy, sustain the damages by increase of heavy traffics. They need repair and/or strengthening. Characteristics of repair and strengthening works are to be done under loading and vibration. There are few studies in relation to welding to members in service condition though the use of welding in repair and/or strengthening works has many advantages.
This paper describes some experimental and analytical studies on the effect of welding under loading on the deformation behaviors of plates.

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This paper describes model vibration tests to find effects of softening characteristics of ground on an underground tank with water 60% or without water during severe earthquakes. For this study, a new model material-a polyethylene and salad oil mixture was developed which has superior reproductiveness of softening characteristics of ground.
Using this material and a shaking table, this dynamic interaction of ground-tank-liquid combined system was investigated. By comparing underground tank embedded in soft reclaimed lands and in rather rigid grounds of two layers, the dynamic behaviors of the tank were clarified. As the results, the underground tank during severe earthquakes are influenced greatly due to the softening of the surrounding ground, and the strains of the tank do not increase in direct proportion to the input intensity since the damping constant of the ground including viscocious hysteretic and radiation dampings increases.

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A simplified technique for calculation of the dynamical ground compliance for an arbitrary-shaped rigid foundation is presented. This numerical method is based on a reduction of integral equations to linear algebraic equations by subdividing the contact area into subregions. Following points are mainly improved:
(1) in order to enable analytical integrations, Green's functions are approximated to power series or linear functions;
(2) the contact area is subdivided into triangular-shaped subregions; and
(3) linear distribution of the contact pressure is assumed in each subregion.
In order to discuss an accuracy of this method, circular and square foundations resting on an elestic half-space are examined.

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This paper studies an efficient method of identification of dynamic properties such as natural frequencies ω^(j), modal damping coefficients β^(j) and participation factors P^(j)₁ at the i-th mass, of a multiple degree of freedom linear system on the bases of using microtremor records which are measured at the first floor and at the roof in a fourstorey reinfoced concrete building. The EK-WGI method which was previously proposed by the present authors is used for the solution of a system identification problem. As a result, dynamic properties of the first mode and the second mode can be estimated from this method. Then, it is found that this method is more useful tool for the identification than the response function which is a common approach to estimate dynamic properties.

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The characteristics of the duration, total power, and rms value of strong earthquake ground motions are investigated with the aid of the wave propagation theory and statistical technique. It is made clear from some theoretical estimations how the duration and its related parameters are affected by the soil layer conditions. A new multiple regression analysis which includes not only the earthquake factors but also the local site conditions as its independent variables is developed and applied to the duration and its related parameters using strong-motion earthquake records. By combining the theoretical and statistical results, semi-empirical expressions are derived in order to predict the duration and its related parameters.

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This paper presents the shear strength of the horizontally curved plate girders based upon the experimental studies on 10 model girders by alternating radii of curvature, aspect ratio and slenderness ratio of web plates as well as stiffness ratio of transverse and longitudinal stiffeners. From these tests, the buckling strength of curved girder subjected to shear is inquired in comparison with ordinary straight girders. The postbuckling strength of curved girder is, moreover, clarified and the contributions of transverse and longitudinal stiffeners are made clear. Finally, the substantial factor of safety against the allowable shear strength provided with Japanese Specification for Highway Bridges are discussed in details.

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Observation is conducted at a soft surface layer with sloping base to clarify the effects of lateral inhomogeneity on seismic waves. It is found from the observed and computed seismograms that the scattering Rayleigh wave is strongly produced in the surface ground near the sloping base. Thus, the amplitude of the ground strain is large and the effects of the Rayleigh wave caused by lateral inhomogeneity should be considered on design for underground structures with large horizontal dimension.

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In the process of engineering planning and design, the Bayes' theorem has been used as a useful approach which provides the framework or procedure for incorporating engineering judgement with observation data and systematic updating of information. Based on discussions about some examples of the posterior probability problem in some literatures and the Bayesian estimator in the sampling theory, the following conclusions are drawn:
(1) It is necessary to understand clearly the premise of the Bayes' theorem.
(2)The application of the Bayes' theorem for the objective probability problems yelds no appreciable effects.
(3) The Bayesian estimator in the sampling theory plays a meaningful role only ffor the limited cases.

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For the analysis of sloshing of liquid in a storage tank, it is important to consider relatively long-period ground motion properties expected at the construction site, and to establish a rational analysis method. Furthermore, it is rational to account for non-deterministic and non-reappearent properties of earthquake waves when the establishment of earthquake input model and response analyses are carried out. In this paper, a “fault model” which is an effective simulation method of long-period ground motions in seismology. Then, an earthquake input model was expressed by a nonstationary autoregressive model compatible to the simulated motions, and the analysis was effectively carried out by the use of a recursive covariance approach.

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This study presents a sequential linear programming approach for the optimal elastic plastic design of truss structures under the ductility factor and the ultimate load factor constraints. Little or no attempt has been made to generally cast the optimal elastic plastic design of skeletal structures. The method is first fomulated by the SLP primal and dual problems for the optimal elastic-plastic design using the holonomic elastic plastic analysis and the limited ductility constraints. Then, a sensitivity analysis based on the shadow cost concept is applied to select the yielding membes and to introduce their plastic deformations. Truss structures are designed to illustrate the applicability of the approach.

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An optimum design method of truss based on dual theory, linear approximation and suboptimization of member element is presented. In the practical design problems of truss, several original design variables and constraints related to a member element are condensed into one primal variable and single artificial constraint respectively by suboptimization of member element. Then the design problem is transformed into a sequence of approximate primal problems of convex and separable form by linear approximation concepts. The convex problems are solved by dual method, in which dual function is maximized by using quasi-Newton algorithm on the dual variables and the primal variables are decided directly by explicit expressions of the dual variables. Due to the sharp nonlinear constraints imposed on member elements, move limit restrictions on the design variables are required to converge successive solutions to the optimum. Application of the envelope method based on optimality criteria and linear set of equations are also discussed to estimate appropriate initial values of the primal and dual variables respectively. The efficiency and reliability of the design method presented are demonstrated by giving numerical results for large scale trusses.

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A new discrete model, RBSM, for the slipping problem of the joints up to the state of major slip is developed. A joint element separated by imaginary vertical plane, which includes bolt axis, is assumed to be consisted of four half rigid bodies connected by two elongation springs κ_e and a shear spring κ_s. The spring κ_e has the same quantity as the elongation stiffness of the plate with bolt holes, and κ_s has nonlinear properties that the shear force, when it reaches critical shear force against local slip, holds the same value of critical one, The initial shear-spring constant κ_s0 is determined by setting the total shear strain energy in the spring equally to the one in the plates with two compensation factors φ and φ. The theoretical solution of load-displacement relation and major slip load was verified by comparing the theoretical results with the results of tests carried by Honshu-Shikoku Bridge Authority.

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We formulate the general higher-order theory of plates under the assumption of displacement and stress components which satisfy exactly the boundary (loading) conditions of upper and lower surfaces of the plate. The results of this theory include the both cases of bending and stretching behaviours of the plates. It is shown that the recently proposed theories of second-order by Reissner and Koga can be derived as a special case of our formulation with employment of a few lower-terms.
Numerical results for the case of torsion of a rectangular plate under the several order theories with truncated terms are compared with the exact solution of elasticity.

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It is known that out-of-plane vibrations of suspended cables are observed under inplane forcing. This fact is caused by the geometrical nonlinearity of cables, Single-degree-of-freedom approach for this problem was used in the preceding work. In the present work, out-of-plane vibrations of cables are studied by using multiple-degree-of-freedom approach because cables are continuous system. Nonlinear inplane responses and corresponding out-of-plane vibrations are analyzed by the harmonic balance method, Unstable regions where out-of-plane vibrations occur are obtained, The results of numerical examples show that unstable regions of out-of-plane vibrations whose modal shapes are similar to those of inplane modal shapes are wide and that simple parametric resonances are signficant compared with combination resonances.

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The dynamic effect of bridges under moving vehicles must be investigated to the decision of impact factor in the rational design of highway bridges, This dynamic effect is defined by the word of the dynamic factor in this study, and is distinguished between the dynamic factor and impact factor written by design specifications. The dynamic factor of single-span bridges under the equivalent vehicle load to design live load (L-20) is calculated, Numerical examples are presented to obtain the information of the dynamic factor of highway bridges consolidated the multi-span continuous bridges and the single-span bridges. Finally, the dynamic factor based on the response of deflection and bending moment of highway steel girder bridges is suggested by a function with the parameters of span number and span length.

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This paper shows the fundamental solutions of displacements and stresses of an elastic half-space due to harmonic loads acting in the interior of the half-space. The solutions shown in this paper can be used as the fundamental solutions in the Boundary Element Method. As numerical example's the applicable extent of the solutions of displacements and stresses derived in this paper is discussed in comparison with the ones obtained by the superposition of an elastic free-space solutions. The influence of non-dimensional frequency ωH/V_s is also discusse

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