From an economical point of view minimizing the sum of the expected value of loss caused by disasters and the construction cost, this paper describes a probabilistic method for estimating the optimum yield shear force coefficient of hysteretic structures in consideration of the influence of variation of the structural energy absorption capacity and the input ground motion, and discusses the effects of the structural energy absorption capacity, the input ground motion and others on the optimum yield shear force coefficient. Finally, the optimum distribution of shear force coefficient under the optimum design based on structural reliability theory is proposed.

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As buildings have become higher, it is likely to find the wind loads that is equal to or even greater than the design seismic loads. Also, response control systems by hysteretic damping of steel have been developed for the aim of the response control or the damage control during seismic excitation. Then the subject that structural members yield under wind loading will become more important on structural design. In this paper, to assure the safety of buildings with the yielding members under wind loading, inelastic response characteristics, e. g. the distributions of the fluctuating displacement, the maximum displacement, the absorbed energy and so on, under across-wind loading are investigated quantitatively through time history response analyses by using a single-degree-of-freedom system. And a stochastic method of estimating the inelastic responses under wind loading so as to be available for the evaluation of fatigue-damage is proposed on the basis of the zero-crossing peak-value distribution. It is confirmed that the predicted inelastic responses almost agree with the results of simulation.

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In the earthquake resistant design of RC buildings, it is necessary to evaluate damage of structures both by maximum displacement and by energy dissipation. In this study, damaging potential of earthquakes to structures is estimated by total input energy, and damage of structures is evaluated by damage index considering both maximum displacement and dissipated hysteretic energy. From results of parametric inelastic response analyses using simulated earthquakes, it is found that earthquake response pattern of structures can be represented by a parameter based on energy response. It will be possible to establish a design concept of RC buildings considering damage limits.

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Overturning of furniture and human behavior in dwellings during the 1993 Kushiro-oki earthquake was surveyed through an interview method. By describing a mess in each room and patterns of human behavior in the order of time sequence, it was able to make clear that human ability to evacuate strongly depends on the severity of floor response in a dwelling. For example, under the even small tremors beneath of 200 gals refugees cannot walk over a speed of 0. 8m/sec and it takes about 5sec to take an evasive action as supporting furniture, defending oneself, and protecting a child. These values obtained by the investigation could be useful for evaluating seismic casualty risk potential.

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We estimate ground motions from the record observed at the JMA Kobe station in the Sannomiya district in Chuo Ward, Kobe, where heavily damaged buildings were concentrated during Hyogo-Ken Nambu earthquake, and use them to examine the damage distribution of buildings. We use a two-dimensional finite element method to model local topography, shallow sub-surface layers, and a deep basin structure formed by the Rokko faults. The resultant ground motion without holocene layers has peak accelerations or velocities well exceeding 800 cm/sec^2 or 100 cm/sec, respectively, in the narrow zone 750m away from the fault. These peak values could be more on the surface since holocene layers would amplify them. Therefore, we carry out nonlinear analyses of holocene layers with five representative sites to estimate surface ground motions after we verified our scheme by comparing the results of the nonlinear analysis with surface records at Fukiai Gas supply station in Chuo Ward. Then, we evaluate maximum ductility response of buildings which are subjected to ground motions with or without holocene layers. Variation of ductility responses with respect to the distance from the fault shows good correspondence with the area of damage concentration. These results suggest that both a deep basin structure and shallow holocene layers have to be taken into account to simulate the strong ground motion and hence to explain damage concentration in Kobe during the Hyogo-ken Nambu earthquake.

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A numerical method is presented for computing ground surface displacements in radial and transverse directions that are induced by a harmonic horizontal point force acting on a three-dimensional layered elastic half-space. The contribution of the residue of the Rayleigh and Love poles and the branch line integrals, i. e., that of surface and body waves, to the ground displacements is computed for two-layered media. Its variation with the S-wave velocity ratio and Poisson's ratio of the media as well as the distance and frequency of the source is examined.

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Structural shape optimization always adopts structural analysis. For such a reason. the solution of a shape optimization always depends on the loading pattern (loading cases), and it is not so easy to obtain a unique optimum solution for a structure subjected to different loading cases. By weighting function method. the present paper promotes a multicriteria optimization method to maximize the rigidity and minimize the volume (the total volume of all members) of a tension structure subjected to different loading cases. With a purpose of minimizing the nodal displacement vector and the volume, a nonlinear programming method is adopted in the analysis to find the optunum nodal coordinates, member section areas and the distribution of prestresses. A tensegrity frame is taken as a numerical example. and the results show 24. 5% reduction in the volume and that some of the nodal displacements can be reduced 10%, or 30% of their initial values.

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An important characteristic of membranes is that they cannot support compressive stresses since they have almost zero bending rigidity. Therefore, when compressive stresses exist in a membrane structure, wrinkling occurs. In this paper, four examples of wrinkling on membrane structures of revolution are analyzed as a bifurcation buckling problem by using conical frustum finite elements considering geometrical nonlinearity. Post-wrinkling behavior is examined by following bifurcation paths. Illustrative examples are l)a hemispherical shell under meridional tension, 2)a spherical shell under external pressure, 3)an inflated membrane of ellipsoid and 4)a circular membrane under inplane torsion. In the circular membrane, results obtained by using quadrilateral elements and Mikulas's theoretical solution are also shown in order to discuss their applicability to the analysis of wrinkling.

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About 2000 wooden structures were surveyed through 81. 6 ha, the seismic intensity was over 7, in Higashi Nada ward in Kobe-city where had been seriously damaged by the Hyogo-ken-Nanbu earthquake on Jan. 17th '95. The problems of the traditional Japanese post and beam wooden structures houses of two stories or less are not only pointed out, but also the cause of mechanism of collapses were determined according to the close investigation of 185 units through the seismic destruction area. It is recognised that quite numbers of the small and narrow houses with dry-wall exterior finish collapsed among many other Japanese traditional wooden structures with mud-wall exterior finish. The primary cause of collapses of these houses was that the structural planning was ignored on their floor planning.

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Recent experiments on lap splices failing in side split mode have revealed two important facts : (1) Yield strength of shear reinforcement does not affect strength of lap splices much ; and (2) Shear reinforcement increases strength of lap splices linearly at least up to p_w = 2. 4%. But why? This paper presents a hypothesis to answer the questions : a stirrup bar and its neighboring concrete constitute a small triangular beam, which covers lapped main bars. Thus, the strength of lap splice is affected by the flexural strength of the triangular beams, not by the yield strength of shear reinforcement. Shear reinforcement increases strength of lap splice linearly until the lapped main bars are completely covered by the triangular beams.

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In this present report, we describe a fundamental study about an automatic design of the hollow-section. The substance is estimate method in the size of effective hollow-section of the bending failure preceding type, namely this method uses equation of the web-flange simultaneous failure and equation of α determination taking in corner reinforcement coefficient(φ). Hence making good use of the merits of these two equation, we made the specimen of hollow-beam to be proved the theory by experiments whether is estimated falure type. And we made experiments of hollow-beam. As a result, the calculated values is generally in a fairly good agreement with the experimental values.

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In this paper, static and dynamic response analyses using a matrix method were systematically performed, in order to investigate the hysteretic behavior of prestressed concrete frames. On the basis of these analytical results, we presented a restoring force characteristics model for the prestressed concrete frames with different prestress levels. Furthermore, dynamic response analyses using this model were carried out, the parameters of which analyses were the cracking and yielding points on the envelope curve, the stiffness of the unloading curve and the natural periods with respect to the initial stiffness and to the secant stiffness at yielding. Taking these analytical results into consideration, an equation was proposed for predicting the substitute damping of the prestressed concrete frames.

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The corner portion of a cold press-formed square tube was the subject to be tested. We conducted tensile tests with fan-shaped test pieces and sub-divided small test pieces. As a result, many detail data concerning the mechanical properties for each part of corner portion was recorded. Small test piece's strain in plastic region was obtained by means of measuring diameter at the neck. The fan-shaped test piece's theoretical stress-strain curve was composed from small test piece's measured stress-strain curves, using the sum total of the stresses of the same strain. This theoretical curve was very consistent with the fan-shaped test piece's measured stress-strain curve.

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The authors have already proposed a basic law that governs damage distributions in elastic-perfect plastic shear-type models as a function of structure's strength distributions. In this paper, one quarter of the energy input due to ground motions is assumed to be absorbed first by plastic deflection in one direction, and then the rest of energy is assumed to be distributed throughout the following reversals of plastic deflection according to the damage distribution law. Thus the concentration of plastic deformation in one direction, and the maximum and residual deformations in one-degree-of-freedom systems with various kinds of force-deformation curves are determined in a quantitative manner.

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The purpose of this study is to evaluate the plastic deformation capacity of high strength steel beams. It is evaluated by two categories, which are the local buckling of the compression flange and the ductile fracture of the tension flange. The effect of width-thickness ratio and length of specimens on the collapse form are investigated by experiments and numerical analysis. The plastic deformation capacity of considering the collapse form high strength steel beams is shown by the flange width-thickness ratio. Finally, the line of demarcation between local buckling and ductile fracture are shown by width-thickness ratio.

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In order to evaluate the ultimate earthquake resistance of multi-story steel frames, inelastic response analysis based on the realistic behavior of steel members are carried out. Analytical models are designed by the ultimate strength design method based on the individual Ds-values of members, and the parameters of the models are the shape of panel zone and Ds-value of each member. The main conclusions are followings ; 1) By realizing the strength distribution corresponding to the individual Ds-values of members, overall collapse mechanism can be formed. 2) When the overall collapse mechanism is realized, the ultimate earthquake resistance of frames is mainly determined by the deformation capacity of column bases.

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Variations of the fire resistance of concrete walls were numerically analyzed using a model of heat and mass transfer. The analysis was made in two steps. In the first step, the material properties such as thermal conductivity and density were estimated based on the mix design. Then, in the second step, the values are used in the model of heat and mass transfer, which gives the estimate of fire resistance time. By repeating this procedure, the variation due to the mix design of concrete was quantified. In a similar way, the variation due to the change of initial water content was also quantified. As a result, the effect of mix design dominates the variation of fire resistance of concrete. The effect of initial water content is small compared with that of mix design. Thus the effect can be approximated by a liner relationship as 3. 3 minutes per 1% change in initial water content in case of 70 mm thick walls. By using this result, a diagram was presented to show the range of acceptable mix design for the required fire resistance time.

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A probabilistic framework is presented to evaluate the load effects of wind-waves and seaquakes on a large floating island at a specific offshore site. Both long-term and short-term descriptions of loading are constructed. The long-term description of loading is given by the occurrence rates of each load intensity. On the other hand, the short-term description of loading is given by the spectral density functions in terms of each load intensity. For each load intensity, the stochastic response analysis of a large floating island is carried out on the basis of a wet-mode superposition approach and stationary random vibration theory. The site-specific responses which are conditional on the corresponding return periods are calculated. Numerical examples are presented to discuss the load effects of wind-waves and seaquakes on the large floating island with mooring system at different offshore sites.

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