The normal stress distribution and cross-sectional deformation by distortion in single span curved box-bridge-girders have been investigated. An analytical modeling by so-called Beam on Elastic Foundation (BEF) analogy for the distortion is verified experimentally by testing programs. On the basis of the parametric studies by the BEF analysis, a spacing provision by which the distortional stress can be kept within the level of secondary stress is developed. Design examples specified by the proposed provision are also presented.

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System modal identification for structures is a fundamental problem in structural dynamics. The identified natural frequencies, damping ratios and mode shapes can be used to better understand the behaviour of structures, modify structures, design control system for structures, and can also be used in direct analysis of structures. A time domain method for identification of modal parameters for a test structure using free vibration responses is presented in this paper. The method in based on the multidimensional autoregressive model of a vibrating structure. The method is efficient with computing time and has the advantage of being able to identify very close natural frequencies and highly coupled modes. A numerical example and a test case are used to illustrate the usefulness and results of the method.

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Corrosion deterioration characteristics of the structural steel bridges, especially plate girder bridges are studied in this paper. The parts of bridges that are severely corroded are also investigated. Emphasis is placed on the prediction of corrosion (based on the steel exposure test, paint life, and corrosion ratio) of painted bridge members. The final aim is to find the effect of corrosion on the strength of painted bridge members.

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In this paper, a new formula to predict the ultimate shear strength of a plate girder is proposed on the basis of the numerical analysis. The analysis of an end panel isolated from the whole structure can describe the stress distribution in the shear panel sufficiently. A stress distribution model in the ultimate state is constructed by generalization of the numerical results. In order to show its validity, the predicted strength by the proposed formula is compared with those by Basler and Rockey et al., and also with the available experimental data.

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Tuned Liquid Damper (TLD) utilizing the motion of shallow liquid for absorbing and dissipating the vibrational energy is studied with emphasis on liquid motion. A mathematical model based on the nonlinear shallow water wave theory is presented to describe the liquid motion in a rectangular tank. Liquid damping is evaluated semianalytically and is included in the formulation. Mechanical properties of TLD are also experimentally investigated using the shaking table. It is found that the liquid motion in TLD is strongly nonlinear and reveals a hardening-spring property even under small excitation. Good agreements between the simulation and the experimental results are shown when no breaking wave occurs. The model presented in this study is expected to serve as a tool for TLD design.

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Dynamic stability problem of an annular sector plate subjected to in-plane dynamic moments at the radial edges is examined. The basic equation is reduced to a set of ordinary differential equations by applying a Galerkin method, and transformed into an eigen-value problem by using the harmonic balance method. The stability of the system can be directly determined from the sign of the real parts of the eigen-values.
The dynamic unstable regions composed of both simple parametric and combination resonances, which contain the secondary as well as the primary unstable regions, are obtained for the annular sector plates with various boundary conditions and geometrical parameters. The effect of a static moment on the unstable regions is also examined.

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The interaction between rectangular Tuned Liquid Damper (TLD) and structure is investigated both experimentally and theoretically. A TLD-structure interaction model is developed where the dynamic interaction force is theoretically evaluated by applying the nonlinear shallow water wave theory. Good agreements are found between the experimental results and the theoretical simulation within the range where no breaking of wave occurs inside the TLD. Effectiveness of TLD is demonstrated for sinusoidal forced excitation. An example of TLD design procedure is also given using the TLD-structure interaction model.

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A new method for analyzing the fracture of concrete structures is proposed in which concrete is considered a granular assembly. Because concrete is a complex, extremely heterogeneous material, it is difficult to analyze it's failure properties by the Finite Element Method (FEM) in which concrete is considered a homogeneous, continuous medium. We have developed a Modified Distinct Element Method (MDEM) that can be applied to the problems of fracture of concrete structures. In the MDEM the respective major constituents of concrete, gravel and mortar, are represented as circular particle elements and nonlinear springs, called pore-springs. We have used the MDEM to simulate the dynamic fracture behavior of concrete structures. The numerical results obtained are in good agreement with the seismic damage recorded during past earthquakes.

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The static ultimate strength analyses of the tower-cable system of Akashi-Kaikyo Bridge are performed for the investigations of the planar and spatial behaviour of the structures subject to a variety of the combinations of the vertical dead and live loads, and the horizontal wind loads both in the directions of perpendicular-to-bridge axis and bridge axis. The obtained ultimate loads based on three different loading paths are compared with the design loads specified in the current codes of huge towers. The nonlinear dynamic responses of the planar tower and tower-cable models are obtained to examine the safety of the superstructures of Akashi towers against horizontal ground motions of the 1940 El Centro record with variable amplitudes up to four times the design acceleration specified in the codes.

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Elasto-plastic out-of-plane buckling strength of through type and half-through type arch bridges are analyzed by a finite element method which is capable of considering finite displacements and yielding of materials. Examining the numerical results and using an analogy between an arch and a column, we propose a method to determine the slenderness parameter for arch bridges. A designer can use the slenderness parameter to obtain an ultimate stress for arches by substituting it into a column strength formula. The predictions by the proposed procedure are shown to be fairly good correspondence with all of numerical results.

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In order to examine the properties of fatigue crack initiation and propagation from weld cracks which were created at high temperature and also to make clear the influence of weld crack angle on the above mentioned properties, fatigue tests were performed on the specimens containing the weld cracks of various orientations. The material used was JIS SM50A steel. Weldings were done by submerged arc processes or metal-inert-gas arc processes. The specimens were bending-type which contained cracks on the edge, and tension-type which possessed cracks on the center. The angles between crack orientations and applied stress direction were 90, 60, 30 degrees in the bending-type specimens, and were 90, 60, 45 degrees in the tension-type specimens.

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A new type of parallel wire strands were developed for stays on cable-stayed bridges. A strand consists of slightly helically twisted wires with high fatigue resistant sockets. The results of fatigue tests for these socketed cables were presented. A design non-dimensional S-N curve was proposed for these new cables. Stays may suffer considerable stress fluctuation when cables oscillate due to winds or vehicles on the bridge. Cable normal and secondary bending stresses due to the oscillation were obtained analytically with some consideration on the effect of support conditions. Fatigue lives due to random traffic were investigated by a simulation method for the three-span cable-stayed bridge. Cables show different fatigue lives depending on the position of the bridge and the shape of influence lines. A simple method was then proposed to predict fatigue damages and proved effective.

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The reliability index is usually utilized for structural design problems. Relations between design results, such as configurations, and the reliability indices in accordance with the Advanced First Order Second Moment (AFOSM) method, are numerically investigated with the help of some fundamental problems and practical examples. In general, the AFOSM method contains some intrinsic errors. When the index value is large the error in the failure probability increases significantly, even if the error in the index is relatively small. It is explained that the design result is not affected to the same degree as the error in the failure probability by the error in the index, but it is usually affected to the same or somewhat larger degree as the error in the index. It is preferable to use the reliability index rather than the probability by which the design results are indirectly affected.

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An analysis for thermal-bending stresses in an annular sector plate with the moderate thickness is carried out by the theory of moderately thick plates, together with the thermoelastic displacement potential. The temperature field in the plate is considered a steady-state prescribed to surface temperatures on the top and bottom faces and on all the edges, of the plate. Mechanical boundary conditions on the top and bottom faces and on the edges are considered stress-free and simple support. A three-dimensional elasticity solution as a particular solution and a plane and generalized plane stress solutions as a homogeneous solution are used. Numerical results for thermal-bending stresses and displacements in the plate are presented. The influence of the thickness-width ratio on the stresses is examined.

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The reliability based economic evaluation of structures is usually carried out to minimize the expected total life cost of structures, including initial cost C_i and failure cost p_fC_f The minimization is performed using the principle of minimum total cost. But the expected total loss cost which is to be minimized lacks consideration of serviceability or life term of structures. In this paper, interest rates are considered into the evaluation of expected total loss cost in order to translate the cost of failure to present worth for comparison with the initial cost. In order to calculate the expectation of reliability during the life term of structures, a safety reduction function is also proposed.

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Long life corrosion fatigue tests were carried out using web-gusset-type fillet welded joints and 3% NaCl solution. In corrosive environment, fatigue cracks initiated from the bottom of corrosion pits formed along the weld toe and led specimens to failure at such a low stress range as half of the fatigue limit in air and the S_r vs N_f relationship had a linearity with a slope of about -1/3 in the range of N_f=5×10⁵-10⁷ cycles on a logarithmic graphpaper. Corrosion fatigue life of fillet welded joints could be accurately estimated by assuming that corrosion pits start to grow from the facet-like initial crack and by using da/dN vs ΔK relationship including corrosion pit growth rate vs ΔK relationship.

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Fixed-end restraint effect of arch ribs on the over-all, in-plane ultimate strength of deck type steel arch bridges is studied by an accurate nonlinear finite element approach. This approach takes into consideration the two important factors on nonlinearities, namely, geometric and material. The interaction between bending moment and axial thrust, the changes in deflection mode, and the progress of yielding and unloading zones with load level until the ultimate state are throughly examined. The load-deflection behavior, until the stability limit load is reached, has also been analyzed by elastic theory. Special characteristics of the local member failure of arch rib between the posts are finally investigated.

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Empirical scaling of Fourier Amplitude Spectra in terms of the Modified Mercalli Intensity (M. M. I.), local soil conditions (“rock”, stiff soil, and deep soil) and local geologic conditions (basement rock, intermediate sites and sites on sediments) are presented. It is suggested that both soil and geological site effects should be used together in estimation of the site specific Fourier amplitude spectra.

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The purpose of this study is to investigate a method of quantitative estimate of the elastic input energy E_ie and hysteretic energy E_hp of SDOF structures subjected to strong earthquake motions. In this study, numerical response analyses for hi-linear SDOF structures were carried out by the use of artificial earthquakes and recorded ones. From the examination of analytical results, it is found that a good correlation can be seen between the energy response spectrum E_s for E_ie and E_hp and effective Fourier amplitude spectrum F_se for each input earthquake. Also the difference in values for the ratio of the square root of the E_sk to F_sek, at any natural period T_k, is seen to be substantially reduced amongst the earthquakes. Considering these results, the authors derived regression equations for the mean value of this ratio, √E_s/F_se, for the artificial earthquakes relating to structural parameters, i. e., natural period T, damping factor h, yield strength ratio R and secondary slope p.

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Vibration characteristics of motor vehicles and driver's reaction during an earthquake are studied through questionnaire to the drivers who were in driving in a region with the JMA seismic intensity of V during the Nihon-kai-chubu Earthquake of 1983 and the Chiba-ken-oki Earthquake of 1987. Emphasis is placed on driver's recognition of earthquake, the reason why drivers recognized the earthquake and driving situation during the earthquake.
It is concluded from the study that degree of driver's recognition of an earthquake highly depends on driving situation. Approximately fifty percent of the total drivers immediately recognized the outbreak of the earthquake from the abnormal vibration of vehicles, followed by swinging of electric poles and street signs, and vibration of houses.

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We report a procedure by which structural parameters and input ground motion are identified from measured responses only. We have assumed that the coda of the response time history represents the free vibration response of the structural system. Because the coda is not effected by the input ground motion, we can first identify such structural parameters as the masses, damping coefficients and spring constants from this part of the record. Input ground motion then is estimated from the full record and the identified parameters. The identification and estimation are made with the Kalman filter. To verify the effectiveness of this procedure, we have simulated the responses of a linear, three-degree-of-freedom system for different earthquake inputs and made estimations using the simulated responses as observed records. The estimated accelerograms, the identification of which usually more difficult than the identifications of velocitigrams and displacementgrams, are in good agreement with the recorded ones for the actual earthquakes.

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In many plate girder highway bridges, fatigue cracks occur at the connections of cross beams to main girders. In this paper, the structural parameters governing the cracking at the cross-beam connections are presented. Then, the relationship between the parameters and the cracking at the cross-beam connections is investigated for the plate girder bridges on a route of the Hanshin Expressway in Osaka, and it is shown that the deformation of a concrete slab due to running vehicles has a great influence on the cracking at the cross-beam connections.

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Sub-parametric strip elements based on the discrete Kirchhoff theory were proposed for the bending analysis of thin plates with arbitrary shape. In this paper, a general formulation of the above-mentioned strips is shown by the use of new condensed displacement functions, in which the static condensation of stiffness matrices is not required. The new functions are derived from an analytical elimination of the internal degrees of freedom in the displacement functions of the parent elements using the Kirchhoff constraint conditions. The present method contains the ordinary bending strip elements and the bending analysis of thin plates with arbitrary shape could be easily performed by much the same algorithm as in the common finite strip methods.

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In this study, human-response exposed to bridge vertical vibration was investigated through monitoring of 100 persons on Ohshima Bridge and shaking table. In the shaking-table test, the frequency and amplitude of vibration were changed in the range of 0.2-1.0Hz and of 1.0-10cm respectively.
The amplitude—frequency characteristic curves for human-response exposed to the vibration obtained here shows the roughly agreements with several previous results.

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In this paper, the stress transfer mechanism at the pile head joint was studied by FEM. And the stress distribution modeled for safety check was also investigated. In the numerical analyses, debonding and slip on the interface between pile and footing were considered. And also, the effects of the interface friction, the axial load and the embedded concrete depth into pile on the stress transfer were investigated. Based on the results of the analyses, some proposals about the stress evaluation for safety check were made.

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Different from the frames with rigid or pinned connections, the critical behavior of the semi-rigid frames is rather complicated due to the inelastic property of flexible connections. Thus, up to the present, no accurate method has been developed for its analysis. Herein, we present an accurate method which precisely takes into account the inelastic critical behavior with special emphasis on bifurcation. Further, with this method, rectangular frames with semi-rigid connections are analyzed to examine their critical behavior.

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This paper deals with the applicability of Maskell's theory to porous plate and truss girder through which air stream can blow, and also to hexagonal section. The applicability was certainly proved for all sections within the range of blockage ratio studied in this test. The blockage effect is not negligible even at 5% blockage ratio. Its effect is especially large for the section which has large porous ratio. To make the correction method practical for various types of sections, the general expression of the blockage factor was attempted. From the results of this test, the generalization was successfully carried out by introducing drag coefficient defined by model outlined area in place of model projected area.

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Steel pipe piles constructed in marine environment have been damaged bittely by corrosion after long term. Damage is concentrated in steel pipe pile at sprash zone. Some steel pipe piles are lack of strength which is necessary for external forces. Repair work is required to such piles. Some repair methods are proposed for corroded steel pipe pile. Repair method by reinforced concrete coverage is one of effective methods and used in some repair works. But design method of this repair work is not enough arranged. Bending loading test and push out loading test are carried out to know mechanical properties due to bending moment and axial force and to confirm applicability of a conventional design method. Through loading tests, ultimate strength, crack development, deformation and so on of test specimen are investigated.

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The cable-stayed bridges having the new structural system such as the Annacis Bridge, stiffened by the plate girder and with precast concrete slabs, have been interested from a viewpoint of economy. It will be more necessary for the Annacis type bridges as well as the ordinary type bridges to estimate the natural frequencies in the initial stage of design in order to check the aerodynamic stability.
In this paper, the effect of cable stiffness on the natural frequencies of the cablestayed bridges is investigated with respect to the relation between a cable-stayed bridge and a beam on the elastic support for their dynamic behaviour. And the simplified method of estimating the natural frequencies of the continuous type cable-stayed bridges with the various girder and cable stiffness is newly proposed for the aerodynamic resistant design.

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In the paper, the basic column strength curves are investigated analytically by the finite element technique. At first, the imperfection sensitivity function for column strength is introduced and the various coefficient in the function are numerically identified by a finite displacement elasto-plastic analysis with both geometrical and material imperfections. And using a number of imperfection sets generated by Monte Carlo simulation from the measured imperfection data, the strength distributions of steel columns with several representative cross-sections are evaluated from a probabilistic views. The theoretical results are compared with the experimental buckling strength database. Finally, the mean strength curves and the resistance factors for two column groups are proposed.

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In the design of bridge structures, it is necessary to account for aesthetic feature in addition to safety and economy. However, it is not easy to deal with the aesthetic factors in a quantitative way. In this paper, an attempt is made to apply the concept of fuzzy sets for the aesthetic design of bridges. As a typical type of bridge, pi-shaped bridge is employed. In order to examine and discuss the aesthetic characteristic of pishaped bridge, a survey was conducted, in which a set of questionnaires were distributed among experienced bridge designers. Based on the results obtained from the survey, several design factors are investigated using membership values as a comparative measure. It is concluded that the fuzzy set theory is useful for introducing aesthetic factors in the structural design, because it can treat them in a mathematical or quantitative manner.

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In order to evaluate the fatigue strengths of friction-type bolted joint with punching holes, fatigue tests are performed. The surface of the hole, micro-structure and hardness of the steel near the hole are also observed. The test results indicate that the fatigue strengths of joint with punching holes are fairly lower than that with drilling holes, because the surface of punching hole is rough and contains small cracks due to shear deformation.

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Materials such as timber, concrete, rock and soil exhibit a strain softening behavior after reaching a peak stress in compression tests. The present paper is concerned with deflections of elastic-plastic strain softening timber beams. The theoretical method for calculating the deflections due to bending and shear is developed, using the virtual work principle for beams. For Japanese cedar, the simplified bi-linear σ-ε relationship with a linear falling branch is used, according to compression and tension tests. The shearing stresses of timber beams in the elastic-plastic range are also presented. The numerical solutions obtained from the presented virtual work principle are compared with the test results, and the accuracy and the efficiency of this method may be verified.

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This paper presents both experimental and analytical approaches for the shear resistance force of the fill materials in the steel made Sabo structure by using cylindrical concrete element model. At first, the experiments have been performed by applying the horizontal load to the top of the simple shear steel frame with cylindrical concrete elements. The effects of arrangement of fill materials are examined on the movement of an element and the shear resistance force-displacement relation. Then, the shear resistance analysis is performed by introducing the displacement incremental analysis into the distinct element method. By using the input data determined by the simple tests, it has been found that the computational results are in good agreements with the experimental ones.

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Gravitational stiffness in torsional oscillation of suspension bridge is discussed, and it's effect on the fundamental frequency of torsional mode is investigated theoretically with a parameter of span length. It is found that the effect of gravitational stiffness becomes larger with the increase of span length and that the gravitational stiffness should be taken into account in order to estimate accurately natural frequencies of extremely long-spanned suspension bridges. The three dimensional frame model with gravitational stiffness is also discussed for the analysis of suspension bridges.

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An experimental investigation on friction behavior of saddle with horizontal friction plate was done using a prototype. On basis of the results, an analysis model was constructed. Friction mechanism of the saddle of a real suspension bridge was analyzed by the model. As the result, the mechanism was made clear. Furthermore, the result was adopted for the design of Tokyo Port Link Bridge. As an example, a reasonable design frietion coefficient was established for the bridge.

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When flat-based cylindrical tanks are acted upon by earthquake forces, the bottom plates slide partially on the foundations. The influences of this partial sliding have been not clarified in previous studies.
In this paper the authors deal with the tank sliding behaviors through their experiment and analysis, such as displacements, friction forces and stresses in bottom plates and shells. The experiment was among a series of static tilt tests using a very large model with 9.6m diameter and 8m height. The analysis was conducted using non-linear three-dimensional shell and plate finite elements with consideration of slide and separation between the bottom and foundation.

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A coupled finite element and boundary element method in time domain is presented for the anti-plane strain and the plane strain wave fields. The wave equation is transformed into an ordinary differential equation with respect to time in FE region and that in BE region is transformed into a recurrence procedure with respect to time step. Basic equations in these regions are coupled by using the method of weighted residuals, and a recurrence procedure similar to the Newmark's beta method is obtained. This procedure is a scheme to solve BE region and FE region under the same time increment.

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This paper deals with the estimation of total energy put into structures under earthquakes. Using stochastic models of earthquake motion, the authors studied the relation between the total input energy and such parameters on ground motion as the maximum acceleration, duration time, the integral of squared acceleration and predominant period. As a result, the mean of input energy E can be expressed by E=mZ²_maxC_tT_gS_E or E=mPT_gS_E, where Z_max the mean of maximum acceleration, C_t is a factor directly related to duration time, T_g is predominate period, P is the mean of the integral of squared acceleration and S_E, called as normalized input energy spectra, is a non-dimensional scalar depending on the distribution of power spectrum of earthquake motion and independent of the scale of the earthquake motion. The normalized input energy spectrum is also studied with actual earthquake motions. As a design spectrum, S_E-T₀relation can be represented by the bilinear model.

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If the ground where a manhole is constructed is susceptible to liquefaction during earthquake, the manhole may float up straight or cant. A series of model shaking tests were conducted 1) to investigate the failure phenomena due to liquefaction, and 2) to test the effectiveness of four types of manhole stabilization techniques against liquefaction, such as surrounding with crushed grain and sheet pile or dewatering to the bottom level of the manhole, compared with a manhole employing no stabilization technique.
Based on measured accelerations, excessive pore pressures, and observed floating up and settlement, this paper describes the effectiveness of stabilizing techniques. Surrounding a manhole with crushed grain and sheet pile or dewatering to a depth at the bottom of the manhole was found to be effective.

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An analysis of the earthquake response of embedded rigid structures using a simple rigid body-ground spring model is presented. The model considers embedded rigid structures in horizontal linear elastic layers. The system is idealized as a rigid body supported by ground springs and excited by the free field displacement through the ground springs. The applicability of the model was confirmed by comparing with results of FEM analysis, earthquake observations and experiments. It was found that the model was effective for estimation of the dynamic earth pressure on, and the dynamic response of, the embedded rigid structures.

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Strong motion records are often used as the ground motion inputs in the earthquake analysis and design of structures. In particular, for the design of underground structures, not only the time history at any particular point on the Earth's surface but also the space-time variation of the ground motion is needed. A method is developed for generating an artificial and simulated space-time variation which is characterized by a given cross-correlation function and includes a recorded strong ground motion at a point. Some examples of the application of the proposed method are given, and it is shown that a good convergence is obtained.

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Considering the possibilities of fatigue cracking of the stiffening chord members, periodic inspections appear essential. In this case, cracks need to be detected and measured by non-destructive testing. With the aim of clarifying the applicability and adaptability of non-destructive testing system, cyclic loading test was carried out of the large scale box sectional specimen coated with the paint. Under the cyclic loading, 46 cracks at the different weld joint were detected using the non-destructive testing system which consists of two stages: the preliminary examination through the paint film and a precise examination after removal of paint film.

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This paper is concerned with cable vibration dampers for increasing the structural damping of stay cables in cable-stayed bridges. Complex eigenvalue calculations have to be worked out in designing the details of cable vibration dampers. Although advancing computer technology has made complex eigenvalue calculation an easy task, calculations for all cables in cable-stayed bridges will require the great number of computational cost.
Therefore, in this brief paper, the effects of cable vibration dampers on the structural damping characteristics are investigated by means of complex eigenvalue calculations using cable model with the length of 200m. Practical estimation method are also proposed on the basis of these analyses in order to reduce the computational cost of complex eigenvalue calculation.

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