The influence of the short cut fiber on the fracture parameters of high strength mortar matrix was investigated in order to obtain a basic information on the fracture behavior of high-strength fiber reinforced concrete(HFRC). Three-point bending tests on pre-notched mortar beam specimens which containing short cut fibers were performed. Various kinds of short cut fibers were used for the specimens. Fracture parameters of the specimens were analyzed based on the poly-linear approximation analysis of the tension softening diagram with the data of a load-load point displacement curve. As the results, the use of short cut fibers was significant on the improvement of the toughness of high-strength mortar, and the appropriate fiber which improving the toughness of high-strength mortar was clarified. The fracture parameter proposed in the paper, such as toughness modulus(T.M.) , R-curve, was effective on estimating the toughness of fiber reinforced cementitious composites.

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In this study, the stress transfer mechanism and the joining properties between concrete and alkali resistant glass fiber reinforced cement (GRC) panel which had deformed surface, was investigated by experiment and numerical analysis. The strain compliance, which was definded as a ratio of the strain on GRC panel to that on concrete, was proposed as an index to estimate the joining properties between GRC panel and concrete. This was because when the load increased, several behaviors occured on the joining interface of the specimen could not be understood by loading-displacement relations. Before reaching the maximun load, the damage had occured on the joining interface, but the specimen would not be broken suddenly. For explaining the behavior on the joining interface, the model, stress transfer element was considered to be effectual.

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To consider aeroelastic instabilities of prismatic high-rise buildings in strong winds, unsteady aerodynamic forces must be investigated as the external forces acting on buildings. In the previous paper we presented the characteristics of fluctuating pressures on side face of the oscillating square prism (depth-breadth ratio D/B=1). This paper presents the characteristics of fluctuating pressures of other two type rectangular prisms, which are flow reattachment model (D/B=2) and complete separation model (D/B=0.5). And the comparison of three type prisms(square and two type rectangular prisms) is discribed. The characteristics of the pressures on the lower parts of square prism are similar to that of D/ B=0.5 rectangular prism, on the other hand the characteristics of the pressures on the higher parts of spuare prism are similar to that of D/B=2 rectangular prism.

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In order to investigate the aeroelastic instability of a rectangular cylinder in uniform flows, the three-dimensional flows around an oscillating cylinder with depth/breadth equal to 2.0 in heaving mode are computed by means of the direct finite difference method. It is confirmed that the computational results of oscillation behaviors as a function of the Scruton numbers or the initial state of the displacement are in good agreement with experimental ones even in nonlinear regions of the vortex-induced oscillations, the galloping and so on. Also the time variations of the response and the unsteady aerodynamic forces are investigated in order to understand the characteristics and the physical mechanism of various unstable oscillations.

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In evaluating dynamic reliability of structures with consideration of uncertainties included in structural properties and excitation characteristics, the gradients of the conditional failure probability with respect to the uncertain parameters are needed. In this paper, in order to avoid the difficulties in obtaining the gradients, a procedure of extensive FORM com- bined with Response Surface Approach is proposed, in which the performance function is approximated by a second order response surface and solved by FORM. The influences of parameter uncertainties are discussed and it has been proved through some examples that the proposed method has advantages in both computational efficiency and precision.

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This is a report of experiental investigation to get the relationship between mental-perspirasion of human bodies in the building and damping capacity of the building. To obtain the mental-perspiration the cooperator of many young male and female placed on the shaking table were applied. And the table were drived by the responses waves of malti-stories building distarbed by earth-quakes. Conclusion, judging from the volumes of measured mental-perspiration, increasing of damping ratios make decrease the mental-perspiration and optimum damping ratios are proved more than 30 percent.

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Site-dependent response spectra accounting for soil nonlinearity are at Grst estimated and then simulated accelerograms compatible with prescribed response spectra are generated. Inelastic response analysis for different idealized structural systems subjected to simulated accelerograms is performed, focusing on the effect of local soil conditions and input motion intensity on normalized drift response. Results presented in this study indicate that for relatively long period structural systems increasing softness of soil deposit is associated with increasing spectral response. This general tendency becomes less visible for relatively low level of yield acceleration and high level of input motion intensity.

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System identification using a transfer function obtained from the spectral ratio for buildings during microtremors and with soil-structure interaction has advantages and disadvantages. The advantages are that the vibration modes and dynamic characteristics of the buildings themselves can be obtained under small wind velocity conditions. A disadvantage is that the wind force deforms the spectral ratio. This paper describes a study of this phenomena. Three factors were studied: the existence of upper input forces, simultaneous upper and lower input situation, and relation (dependence or independence) between two input forces. Furthermore, it was explained mathematically that the relative magnitudes of base movements due to the upper and lower input forces control this phenomena.

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For future earthquake disaster prevention and hazard mitigation, it is very important to predict in advance the earthquake motions from hypothetical earthquakes which may occur with high possibility. Based on the investigation of seismic activities near the Ashigara Valley, two kinds of M7-class earthquakes; an inter-plate earthquake and a plate-fracture earthquake, are assumed in this paper. The ground motions induced by the above two earthquakes are predicted at nine observation stations by using the empirical approach. The maximum velocities of the ground motions at Odawara are about 80 cm/s at the rock surface and about 160 cm/s at the sedimental layer surface. The velocity response spectra from the nearfield surface motion are almost as strong as the ones from the record of 1995 Hyogo-ken Nambu Earthquake at Kobe Marine Meteorological Observatory.

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As the basis for seismic microzoning on damage of wooden houses, the spatial distribution of the population of wooden houses should be evaluated. In this study, a procedure to estimate the population of wooden houses with different construction age is proposed using the Grid-square Statistics which is a nation-wide CIS database on Population Census of Japan. The populations of households at different periods, together with the empirical relations of populations of house-holds and wooden houses, are used to estimate the populations of wooden houses. The results from the procedure proposed are verified using the GIS data in Kawasaki and Yokohama cities.

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An inverse problem formulation is developed for finding that set of member bending stiffnesses of a representative elastic building frame which would exhibit a specified set of member-end fibre strains including geometrically nonlinear effect under a set of design vertical and horizontal loads. A new perturbation procedure is developed by regarding all the unknown stiffnesses and field variables as functions of a multiplier on those vertical loads which would result in P-⊿ effect and the effect of deteriorating column stiffnesses. The procedure enables a designer to directly reserve a desired level of safety against the yield strain.

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The optimal shape for dynamic buckling of shallow arches subjected to up-and-down excitations is studied. First, we introduce basic equations of the arches of two-degree-of freedom by assuming that the thickness of the arches vary continuously along the span direction. Second, we analyze "the critical input acceleration" which can cause dynamic buckling by use of the total potential energy approach for step excitations and the equations of motion approach for sinusoidal excitations. Consequently, we investigate the optimal shape by searching the local maximum point on the curve of the critical input acceleration with the thickness.

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The method to determine the members to be initially stressed on beam string structures has to be discussed to effectively reduce the control forces or energy. This study treats the problem of optimal arrangement of actua- tors on beam string structures by using hybrid genetic algorithms combined with heuristic algorithms. Genetic algorithm based on the principle of genetics and natural selection is efficient for such problems, since it is possible to obtain the global optimum solution without using function gradients. The performance of the hybrid algo- rithms for solving the optimum arrangement problems is illustrated by the results of numerical simulations.

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Large flexible space structures are generally lightly damped due to low structural damping in materials and the lack of damping such as air drag. Induced vibrations of large structures have long decay period that can lead to instability or other problems. Recently active vibration control of such structures with closed loop systems consisting of sensors, actuators and controllers have drawn much attention. Piezoelectric material responds to mechanical forces and generates an electric charges/voltage(called direct piezoelectric effect). An electric field applied to the material induces mechanical stresses or strains (called converse effect). In the present paper, the sensing and vibration control of an elastic shell with a top distributed piezoelectric sensor and a bottom distributed actuator layer is investigated. "A laminated piezoelectric shell element" by the finite element method is formulated and a few numerical examples in sensing and vibration control of piezoelectric shells are presented.

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In this paper, a new type of hybrid structure which consists of both cable members and rigid structures is proposed, while the following items are studied. (1) Classification of stable and unstable hybrid structures. (2) Introduction of pre-stress for initial stiffness and stability. (3) Stress and displacement analysis under static loads. (4) Vibration analysis. (5)In order to examine the validity of the theoretical analyses, an experiment on the hybrid structure model was done as follows: 1) the introduction of pre-stress and, 2) measurement of response under static loading

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Twelve reinforced concrete beams were tested in order to investigate the shear resistant behavior of high strength concrete. The experimental variables were the target concrete strength (σ_<BO>=100, 60, and 30 MPa), the amount of stirrup (p_w=0, 0.3, 0.6, 0.8, 1.0 and 1.2%) and its arrangement. Test results showed the following remarks:(1)The increase of concrete strength does not bring proportionally the increase of the shear strength of the member; (2)The measured stress distribution of longitudinal bar shifts to tension compared with flexural theory; (3)The number of stirrup legs does not influence the shear strength significantly; (4)The shear strength calculated by AIJ-A method was a little overestimation for concrete strength higher than 70 MPa and that calculated by Beta method was a little more conservative.

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The behavior of reinforced precast concrete beam with lap splices in bottom bars in flexural plastic hinged region is described. The results from 17 bending and shearing test specimens are presented. The main variables studied are the construction method, the way to overlap bottom bars, the lap length, the position of lap splices, and space, and yield strength of transverse reinforcement. In this paper, the structural behavior of the beam and the property of the lap splices are made clear. The results show that the beam with lap splices in flexural plastic hinged region shows good ductility by taking proper measures.

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This paper describes effects of factors on strains at buckling of longitudinal reinforcement within confined concrete subjected to uniaxial compression. Experimental variables employed in this study were ratios of lateral reinforcement pitches to specimen diameters (S/D), an index of confining stress (Psσsy), yield strength of the lateral reinforcement (σsy), compressive strength of plain concrete (Fo), and shapes of the lateral reinforcement. Test specimens were cylindrical specimens with 200mm diameter and prismatic specimens with sections of 200 × 200mm, both of which were 600mm in height and without cover. The following conclusions can be obtained mainly. 1) Clear definition on strains at buckling of longitudinal reinforcement are proposed on the basis of axial force decrease of longitudinal reinforcement calculated from data of lateral deformation of the reinforcement. 2) Because buckling of longitudinal reinforcement is considered to depend on behavior of confined concrete, variables which make mechanical performance of confined concrete higher, such as smaller pitch and larger amount of lateral reinforcement, lower concrete strength, etc, increase the buckling strains.

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Seismic test on 12-story T-shaped coupled shear wall has been conducted under the U.S.- Japan cooperative structural research project on composite and hybrid structures. Objectives of this test are to investigate restoring force characteristics of coupled shear wall, and carrying shear force ratio of tension and compression side walls. In this test, load-transducers were inserted at center of coupling beams to measure axial and shear forces of them. Main results from this test are followings; (1) shear force and varied axial force of each wall are measured, (2) maximum shear force of this system is dominated by the deflection capacity of coupling beams, and its structural drift is 1/67 radian(deflection at the 12th floor / 12-story height), (3) the ultimate deformation capacity of the wall in this system is confirmed up to the structural drift of 1/25 radian.

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Experimental and analytical investigations were conducted to understand the structural behavior of the spirally confined lap splice for precast concrete structural walls. In the behavior model of the lap splice, the flow of forces was idealized as in a plane truss. The results of nonlinear analyses using constitutive response models for truss members agree well with the experimental results. Failure occurs when the distribution of bond stress between concrete and winding sheath becomes even throughout the length. As the lap length increases, the lap splice tensile strength increases because the concrete portions providing bond resistance increase. Reducing the spiral steel pitch and increasing the concrete cover enhance the maximum local bond resistance and hence the tensile strength due to an increase in the maximum strength of triaxially confined concrete struts.

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After Southern Hyogo-Prefectural Earthquake, many cases of brittle fracture were observed at structural members made of high strength thick steel plates. However, it is not investigated about brittle fracture of structural members as far as we know. This paper represents quantitative evaluation of elastic-plastic fracture toughness JiC and fractographic examination of a high strength steel HT780 for applying to structural members. The results show a higher value of elastic-plastic fracture toughness J!C of HT780 compared with the conventional steels. A new method to evaluate toughness at transition temperature region is also proposed.

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The computation of system reliability which is affected by many interacting failure modes of frame struc- tural system presents considerable difficulty and expense. In this paper, a practical procedure is proposed, in which a performance function which is independent to failure mode is defined and a response surface is employed to approximate the performance function, FORM is used to compute the failure probability corressponding to the limit states. It is found that the proposed procedure have good efficiency and enough accuracy, and the difficulty in both the failure mode identification and the failure probability computation can be avoided.

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The space truss is subject to failure by the member buckling of compressive chord members. After buckling, a member loses most of its strength, shedding force to neighbor members. This causes spreading member failures and a progressive collapse, which could take only seconds to develop. We propose a method to control collapse mechanism to improve the plastic deformation capacity of the space truss. The method is to use the compressive chord members with eccentric joints in space truss. We clarified the structural properties of this space truss by experiment and numerical analysis.

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In order to verify the aseismic performances of mixed frame structures, tow story - two span frame type specimens were tested. In this paper, the effects of differences of beam-column joint details on the aseismic performances were discussed. From the experimental results, the effects of the differences of the beam-column joint details were investigated on the differences of story stiffness, ultimate strength and hysteresis loops. The aseismic performances of the joint details of the through beam type was less excellent than those of the through column type. For the verification of the test results, the frame analysis of the test specimens were carried. The analytical results for the stiffness, yield strength and hysteresis loops gave a good agreement with the experimental results.

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Three dimensional transient analysis of temperature field for a steel beam installed beneath a ceiling and exposed to a localized fire source has been done. A general-purpose finite element code ANSYS was used for the calculations. Experimental heat fluxes to the beam surface were applied as boundary conditions. A correction method is proposed to derive net heat flux from incident heat flux data. In order to verify the simulations, correspondence has been examined on the temperature field between the data of former experiments and the results of analysis. The satisfactory agreement between the experimental and the calculated results confirms the effectiveness of the finite element method for determining the temperature field in the structural members exposed to a localized fire.

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