A new non-stationary spectrum termed 'energy input rate spectrum' is formulated in order to assess when, at which frequencies, and how much damage potential is contained in a seismic wave. This spectrum indicates the energy input rates per unit mass exerted by the effective ex-citation forces acting on viscously damped linear oscillators with various natural frequencies. This spectrum is mathematically equivalent to Page's instantaneous power spectrum smoothed along the frequency coordinate by a set of spectral windows, which are the real parts of complex frequency velocity response functions, for the oscillators. Especially in the case of no damping, the spectrum is identical to Page's instantaneous power spectrum. The advantages of this spectrum are that the damping constant influences only on the smoothness along the frequency coordinate, and that it can follow the abrupt changes of non-stationary signals. This spectrum is suitable for the visualization of the non-stationary seismic damage potential distributed along the frequency-time coordinates.

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The effect of horizontal tied rebars concentrated in slabs instead of cotter rebars for precast reinforced concrete shear walls was studied. To investigate the seismic behaviour and the resisting mechanism to the lateral force, loading tests and FEM analytical studies were carried out for. Multi-story specimens which had different arrangements of rebars in the vertical joint between a cast-in-place column and a precast panel. Major conclusions are as follows: (1) The shear wall has a good deformation capacity and a strength if horizontal tied rebars are sufficiently arranged in slabs instead of cotter rebars. (2) It is necessary to reduce the capacity of wall reinforcements when the shear wall has horizontal tied rebars instead of cotter rebars. (3) It is able to pursue the experimental load-displacement curve by FEM analysis using bond elements which have stiffness in only one direction. (4) The resisting mechanism of the shear wall with sufficient horizontal tied rebars turns into the truss mechanism in each story.

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In this paper, the characteristics of multi-story reinforced concrete frames subject to lateral loads are studied in consideration of the effects of elasto-plastic behavior of beams, columns and walls. Those members subject to bending moments are replaced by member-models with varying plastic zones, which have, restoring force characteristic of Tri-Linear type between bending moment and curvature. The structural behavior of the uniform frames are obtained from elasto-plastic three-moment equations and three-deflection equations. We especially described the ultimate capacity, the ductility, and the collapse mechanism of the walled frames.

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Recently, many kinds of fibre rods for concrete reinforcement have been developed in Japan. Generally fibre rods are characterized by elastic behaviour, high strength, low rigidity, and low bond strength to concrete. To improve bond strength, the authors employed a braiding process in manufacturing fibre rods. Flexural tests of partially prestressed concrete beams using braided aramid fibre rods (main reinforcement and prestressing tendons) were conducted. The test results demonstrated that prestressing was effective for reinforcements which had the properties of high strength and low rigidity. Because aramid rods are perfectly elastic, beams had three flexural failure modes namely concrete crashing, breaking of the tendons, and breaking of the main reinforcement. The paper also discusses the effects of prestressing force, strain compatibility condition between rods and concrete, and variation of material properties on the strength and failure modes of the beams.

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There are many difficulties in the nonlinear statical analysis for the collapse of structures. In the case of considering the discontinuity of the mechanical behavior of a materials, further hardships will obstruct to obtain a good solution because of the abrupt dropping of the strength. All structural problems which many researchers had treated as statically should have a dynamic effect tacitly such as the inertia force of the own weight of deforming structural element. At the critical or limit point, the inertia term will help to solve the equlibrium eqations. In this paper, a comparison between statical analysis method and dynamic is done, and three numerical examples show the effectiveness of the dynamic method. 1. Yielding and breaking analysis of straight bar 2. Snap through problem of reticulated space truss 3. Material and geometrical nonlinear analysis of double-layered space frame

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Yield stress of steel pipes became higher than that of plates because of work hardening; however, the apparent yield stress lower than that of the expected because of residual stress. And also in case of hot dip zinc galvanized steel pipes, thier deformation behaviors are alternated comparing with the raw materials since residual stress is partially released through the galvanizing. This study quantitatively realized the effects of the galvanizing to compressive deformation behavior by residual strain measurements, tensile strength tests, and compressive strength tests of the series of short columns. Furthermore, we propose the limited, value of thickness to diameter ratio of hot dip zinc galvanized steel pipe.

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The purpose of this paper is to make clear the elasto-plastic deformation and fracture behaviours of wide flange steel encased reinforced concrete (SRC) columns subjected to combined bending and shear under constant compressive axial force. Firstly, monotonic tests are carried out to clarify the effects of shear span ratios and b/t ratios of encased steel. Then, a macro-model is developed for deformation analysis, and the interactions between R/C part and Steel part are discussed. The validity of proposed analysis is verified by comparing with the test results.

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An unified and effective method, which enable one to trace the elasto-plastic; finite deformation behaviors and to evaluate the so-called shake-down limits considered on the geometrical non-linearity, of structures subjected to repeated variable loads, is presented. It is assumed that the domain of the variable loads is given as a hyperpolyhedron and the instantaneous loads move arbitrarily inside the prescribed load domain during the loading time. Likewise, the domains of the the response displacements, strains and stresses of the structures under the above loading are also supposed to be the hyperpolyhedra, vertex of which are the extreme responses corresponding to those of the polyhedric load domain, respectively. Under these assumptions, basic equations governing the relations between the parameter: P^* (which denotes the magnitude of the load domain) and each of the extreme responses, are derived, in which the well-established total Lagrangian formulation is employed to introduce the finite de-formation effects. Elasto-plastic, finite deformation analyses of the plane truss structure composed of 11 members are performed, and show that the present approach might be very advantageous and effective for investigating the plastic-collapse behavior of structures and structural elements, such as offshore structures, under repeated variable loading.

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It is well known that seismic response of a transmission steel, tower is affected by the reactions of the neighborly towers connected with overhead wires. We have applied the frequency response method as the seismic response analysis to investigate characteristics of towers connected with overhead wires. This method is effective to easily ex-amine the response characteristics affected by phase differences and-stiffness of the-neighbors. And also this method needs less calculation time, since we can execute the unit tower model which has the spring elements taken into consideration of the effects of overhead wires. Then, we find that the response regions can be restricted by the present analysis method, which is compared with the multi-mass-points model analysis. Under the general condition, we also limit the response reagion by using the simultaneous phase analysis. Consequently, based on results of the present analyses, we proposed the modefied aseismatic design method including the general idea of "story-moment".

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This paper deals with the nonlinear random response of the single-degree-of-freedom system with elasto-plastic hysteretic characteristic, when subjected to Gaussian white excitations. The analysis aims at finding the approximate solutions for displacement, velocity, ductility factor and cumulative ductility factor in closed forms. The displacement is decomposed into the shift of the center of oscillation and the deformation about its displaced center. The former is regarded as the diffusion process and estimated by the random walk theory. The latter is evaluated by taking account of the equivalent frequency together with the concept, of the energy balance. The approximate solutions are compared with the digital estimates. The agreements between the both are satisfactory in most cases. The relations between the ductility factor and the cumulative ductility factor are investigated. The relations between the maximum elastic and inelastic responses are examined.

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This paper describes a theoretical study concerning soil-structures dynamical interaction problems in the case of embedded structures in an alluvial medium. The analysis is performed on basis of the two-dimensional wave propagation theory. In this paper are derived the sets of govering equations of soil-structure interaction system subjected to base rock excitation and the analytical expression for the sway and the rotation spring constants of sub-side soil ground when the basement wall vibrates rotationally. The following results have been obtained in this study, 1) Interaction effect of pore water gradully increases with lower permeability of aggregate body, however coupling effect between porous elastic solid and pore water is getting decrease with its higher permeability. 2) K^-_<RS>≒0.4 K^-_<SS> and K^-_<RR>≒0.6K^-_<SR> Where K^-_<SS> and K^-_<RS> mean spring constant of sway and rotation due to the horizontally vibrating basement wall and K^-_<RR> and K^-_<SK> mean spring constant of rotation and sway due to the rotationally vibrating basement wall, respectively. 3). Maxwell-Betti-Lamb's reciprocal theorem is verified in any frequency range because the rotational spring constant under condition of the basement wall to be horizontally excited equals to the sway one under condition of the basement wall rotationally excited.

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A Self-balancing adaptive control is newly adopted for the active adjustable stiffness system. The basic control effect is explained from the dynamical response results of a DIB analytical simulator as the dual frequencies property and the energy accumulation property by changing the stiffness in each quarter cycle. The control effect is demonstrated by the DIB seismic response spectra. The relation between the necessary magnitude of the active stiffness devices and the obtained reduced response values is quantitatively evaluated.

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A seismic-response-controlled structure was realized in Tokyo in August, 1989 for the first time in the world. Because this structure is a very slender ten-story office building, the Active Mass Driver (AMD) system has been installed to actively suppress vibrations caused by medium earthquakes and frequent winds. By June, 1990, the building had experienced about ten earthquakes, during which measurements were taken of the response of the structure and the control system. These measurements are simulated by a numerical analysis to represent the interaction between the structure and the control system. By comparing the uncontrolled responses calculated without the AMD System, the effectiveness of the AMD system is assessed.

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Analytical derivation of the impulse response functions and time-domain response analysis by the Duhamel integral are presented for single and multi-story building frames with biaxial stiffness eccentricities. The impulse response functions are derived in closed-form expressions through the Laplace transform of the equations of the coupled lateral-torsional motion and analytical solutions for the coupled responses to white noise and wind-induced force excitations are obtained. Analytical results and numerical examples show that the beat oscillations caused by the combination of responses of closely spaced modes dominate in the coupled response when the frames have small stiffness eccentricities and specific values of mass-inertia radius to stiffness radius ratio so that the natural frequencies are close. The analytical solutions presented in this paper are used to study the wind-induced vibration of high-rise buildings.

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This paper deals with the differetial settlements of houses on soft ground. Through the measurements of differetial settlements of more than two hundred houses on the soft ground around Suwa Lake, the effects of N-value of ground and type of foundation on the settlements are investigated. The main conclusions are summarized as follows : 1) If the N-value of ground is not less than three, the differential settlement hardly exceed 60mm, irrespective of type of foundation. 2) If the N-value is less than three, the settlement is influenced by the type of foundation. In the case where the foundation is the continuous footing, which is not reinforced concrete, the rate of houses, of which differential settlement is more than 60mm, is 37 %. On the other hand, the rate is 12 % in the case of pine pile foundation. 3) The inhabitants are hardly conscious of the diffrential settlement of houses as long as the settlement does not exceed 60mm.

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Framed Foundation is made to confine lateral movement of the soil under the footing and in-crease the bearing capacity of the ground. This paper describes a theory on the bearing capacity and consideration on the load-settlement behavior of Framed Foundation. The conclusions are summarized as follows. (1) The relationships between load and settlement of the footing, the distributions of settlement and axial force of inside soil at the model test are expressed exactly by using authors' theory which is led by finite deference method. (2) On the bearing capacity, influence of the frictional resistance and the point resistance of frame, are small, and the compressibility of inside soil and subsoil are dominating. The bearing capacity of Framed Foundation is equal to the spread foundation which depth is equal to that of frame. (3) The settlement of the footing is sum of compression of inside soil and settlement of subsoil. The distributions of settlement of the ground can be shown as Fig. 11 and Fig. 12 in compliance with the depth of frame.

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The creep buckling behavior of steel tee columns was studied experimentally and theoretically at high temperatures. The tee column specimens with width-to-thickness ratio b/t=10 were subjected to various constant load with eccentricities at high temperatures from 500 to 550℃, and all of them failed by local buckling of the tee stem. The lateral deflection and contraction curves of the columns versus time were obtained and it was clarified how the load, eccentricities and temperatures affected the creep buckling behavior of tee columns. The test results were also com-pared with the values of nonlinear analysis by the finite element method which adopted the mechanical model of structural steel at high temperature propesed by authors. Consequently the validity and efficiency of the present analytical method were examined by the experimental results.

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