One of the most useful methods of enhancing the flexural ductility of beams reinforced by high strength fiber rebars is to get tensile co-operation of matrix To discuss such a point of ductile flexural behavior, direct tension tests, flexural tests and related analysis were executed The followings are concluded 1) A reasonable agreement is observed between the model prediction and experimental data for direct tension tests and flexural tests, supporting the validity of the proposed model 2) The important properties of matrix for ductile flexural behavior are tension softening behavior and pullout behavior of short fiber bridging cracks before the crack openings become 0 11mm

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Autogenous shrinkage and thermal expansion/contraction due to hydration generate complex stress in high-strength concrete structures at early age. However, there are few investigations on the stress induced by autogenous shrinkage under realistic temperature histories in the structures, or mechanical properties of the young, high-strength concrete for the stress analyses. This paper presents developments of Young's modulus and tensile creep coefficient of the concrete and their prediction models. The autogenous shrinkage stress in concrete specimens under semi-adiabatic conditions were also measured. The stress calculated based on the mechanical properties taking a maturity law into account agrees well with the simulated stress in the structures. These results show the prediction models and the calculation method are very useful for the stress analyses in high-strength concrete structures.

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The temperature rise of the concrete in early age affects on long term strength development of concrete in the structure between the age of 28 and 91 days. In this study, comparison between the compressive strength of control specimen subjected to standard curing at 28 days and the compressive strength of core specimens taken from structural members was made, and observations methods of evaluating the concrete strength in structure were discussed. When the maximum temperature of the concrete in the structure exceeds 60℃, the concrete strength in structure may be lower than the compressive strength of the 28 days standard curing specimens.

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This paper presents the evaluation method of floors with bare feet. The first, in order to obtain slip resistance of floors with bare feet, the new slider of O-Y-PSM (Slip tester developed by author in former research) was developed by author, and the physical value C.S.R・BF (Coefficient of Slip Resistance with Bare Feet) was established. The second, sensory test was carried out to make the evaluation scales of slipperiness of floors using with bare feet. Finally, it was showed that C.S.R・BF corresponded to the evaluation scales, and the evaluation method of slipperiness of floors with bare feet was presented by means of correspondence.

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A damage prediction model is presented to evaluate the seismic performance of multistory buildings. A distributed element model is used as the basic model The damage evolution is controlled by two internal parameters of each element in the distributed element model : maximum and cumulative ductility factors The damage model is capable of reproducing a wide spectrum of deterioration with ductile as well as brittle behaviors. The damage model can be also used to relate stiffness degradation to strength deterioration. The damage model is verified by comparing with published experimental results on RC, S and SRC test specimen and with past seismic damage data of existing buildings. The applicability of the damage model is presented to predict the seismic damage against possible future earthquakes in a stochastic manner.

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As a building becomes higher and more slender, its natural frequency becomes lower due to the insufficiency of stiffness comparable to the building height. In the case of installation of the hysteretic damper, although the building has a damping performance, the natural frequency tends to shift lower due to large response. Consequently, the velocity of oncoming wind is apt to reach the critical range for the onset of vortex-induced oscillations. In order to realize detailed investigation by the wind tunnel technique, we present the experimental device, consisting of a stick model amd a yielding rod for a high-rise building with hystefetic damper. After grasping the fundamental characteristics of dampers, we discuss aero-elasto-plastic behavior of a tall building near resonant region to vortex-induced oscillations.

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The analysis of structural reliability under load combinations has been studies for evaluating the probability distribution of the maximum value of the combined loads over a given time period, and up to now analytical methods for the evaluation of the load and resistance factors of structures has been derived. This paper presents a new analytical method in the evaluation of the safety index and the load and resistance factors of structures with resistance deterioration due to load history or aging under load combinations consisting of dead, live, snow, wind and earthquake loads, applying the advanced first order and second moment method with the statistics of the resistance of structural element which has survived up to time τ, instead of evaluating the exceedance probability of the maximum value of combined loads. The expected value of the load and resistance factors is suggested, and the effect of strength deterioration on it is described with numerical examples.

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Pile stresses during an earthquake comprise stresses due to mertial force of the structure and due to soil response. This paper presents the practical evaluation method for the latter stresses σ_K, and it describes the analysis method of the soil response when the maximum acceleration of the earthquake input motion at the soil surface is given and the applicability examination of the method. The first natural period and the first modal damping factor of the soil deposit are employed for the estimation of the response of the soil, and the nonlineanties of the strata are incorporated. The extension of siuk nonlinearities by the proposed method gives good agreement with that by the more rigorous procedure such as SHAKE The proposed pile stress analysis method is based on the transfer matrix method. Five kinds of soil conditions are set, and the correlative studies are done comparing with the rigorous method. When the soil contains the weak stratum, the stresses by the proposed method show the slightly poor agreement. Judging from the practical seismic design, the proposed method has the enough applicability.

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The response of a foundation during earthquakes, which includes the effects of inertial and kinematic interactions, is referred to as an effective input motion It expresses the total interaction effects during earthquakes and is regarded as one of the key factors in the soil-structure interaction study This paper discusses characteristics of the effective input motions extracted from earthquake observations of 19 events recorded at a large scale shaking-table-foundation and the surrounding soil. The main findings obtained in this study can be summarized as follows (1) The characteristics and magnitudes of effective input acceleration motions compared to the surface ground motions depend greatly on the frequency components included in the earthquake ground motions (2) The ratio of the vertical effective input motions to the surface ground motions becomes slightly larger than that for the horizontal components (3) The vertical motions at the sides of the foundation due to the rocking motion become as much as a quarter of the vertical ground motion on the soil surface (4) The results of the effective input motions obtained by the analysis of small to mid ground motions differ in magnitude from those obtained for strong around motion records of the Hyogo-ken Nanbu earthquake, but show the similar in tendency

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From an economical point of view, It is one of a design criterion that, the building structure's allowed to respond inelastic behavior to some extent, under the condition of non-severe damage of structure and no loss of lives, against the disastrous earthquakes Speaking of Kobe earthquake, the severe damages are concentrated to unexpected beam-column connections in some steel structures Such buildings should have been designed to disperse the damages, on account of increasing the capacity for absorbing earthquake energy In this paper, sizing techniques under static horizontal forces focusing on ductility factor of members are presented Plane frame examples are demonstrated by proposed techniques, with minimizing total weight of steel volume

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The first author proposed in the past a technique of minimum-norm stress analysis to choose a design stress field in equilibrium with ultimate design loads. This paper reformulates the technique based on the sum of weighted square stress that represents designer's dissatisfaction to a stress field chosen. As for a beam-column member, weights for squares of bending moment anj axial force are proposed on the basis of an elliptic approximation of yield surface. Also, another interpretation is presented that the technique is equivalent to perform a linear-elastic stress analysis on a rigid-body spring model of a frame. Then a designer can draw any desirable situation about the resistance and the deformation rate of plastic portion, and its secant flexibility can be used as tentative dissatisfaction weight at each portion. This technique has a potential to accept an arbitrary designer's strategy in the ultimate limit state design of frames.

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In this paper, predicting settlement for buildings with mat foundation supported on the diluvial stratum is described by considering the rebound of the ground. Building a structure on ground subject to load removal, such as through excavation, results in eventual deformation of the ground, varying from rebounding caused by excavation to settlement due to the building load. The settlement of a structure is influenced by both the rebound caused by excavation and the weight of the structure. In this report, firstly cyclic consolidation characteristics of diluvial clay are described. Based on those characteristics, we calculated the rebound of ground and the settlement of a building with mat foundation including basements, and described subsequent effects on the construction.

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Although cables are the most popular structural material for tension structures, high-strength steel rods are also used as tensile members. However, because of the fact that these rods were origmally developed as pre-stress members and temporary members, performances against high-stress cyclic loads have not been cleared yet. Also for the typical pin-block connections, ultimate or fatigue strengrth including eccentric pin are yet to be clarified. In this paper, above characteristics are confirmed by tests and analyses, followed by discussion on the performance of the overall system.

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The purpose of this study is to analyze the elasto-plastic response considered geometric nonlinear behaviors for two analysis models with different boundary conditions, and is to investigate dynamic characteristics of single layer lattice domes subjected to vertical earthquake motions that are TAFT-UD and KOBE-UD. In particular, the aim of numerical analysis is to obtain the maximum acceleration of input earthquake motions to lead the collapse of domes in this dynamic analysis. Analysis models are two kinds of domes with pinned supports and radius direction roller supports. The following results were found through numerical experiments. 1) The deformations of collapsed domes hardly change by different static safety factors and vertical earthquake motions. 2) Since the magnitude of collapse acceleration correlate closely with natural periods of domes and spectrum of vertical earthquake, it is not always in proportion to the values of static safety factors.

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A new seismic retrofit technique utilizing PC bar prestressing was proposed as one of techniques in order to prevent shear failure and improve ductility of RC columns in the previous paper by authors The purposes of this investigation are to evaluate the lateral capacity and to propose the design method of RC columns retrofitted by PC bar prestressing as external hoops on the base of cxpenmental test results under the combination of cyclic lateral forces and a constant axial load whose level to concrete cylinder strength ratio is 0 2 These test results consist ofa total of 31 specimens whose failure modes are shear, flexural and bond failure ones As a result, if seismic retrofit technique by PC bar prestressing is designed so that shear and bond strength of the retrofitted columns can overcome their flcxural strength, a desirable seismic performance may be expectcd for seismic retrofit of RC columns

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In the previous paper, we clarified that in the frame structure lateral deformation of the beams connected to columns is restricted by those columns, and it is possible to reduce these buckling length Then we assume that boundary conditon of these beam is warping fixed. But in the case of beams connected to H-shaped column, the torsional rigidity of beam-to column joint is small, so we can hardly expect effect of warping restraint at the edge. In this paper, we investigate the lateral buckling length of the beams prevented warping deformation by beam-to column joints

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This paper presents a seismic design procedure to estimate the ductility demanded of beams in strong column - weak beam steel frames. Critical parameters that control the earthquake response of steel frames are characterized and incorporated into the equivalent SDOF representation. Maximum and cumulative plastic rotations induced into beam-ends are derived in explicit forms as functions of these parameters, and accuracy of the estimated rotations is demonstrated through the comparison with numerical results.

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We suggested tangent modulus which reflected on plastic region and yield stress, then estimated plastic deformation capacity by width-thickness ratio of flange which was modified by this factor However, though we examined about members under pure bending stress, we didn't examine about members with moment gradient. Then ih this study, we examined the possibility to adapt our suggested method for members with moment gradient. And we examined that difference of moment gradient influence plastic deformation capacity of members Lastly we attempted to estimate plastic deformation capacity of members by modified width-thickness ratio besides moment gradient

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We've examined steel encased reinforced concrete buildings whose column bases were severely damaged due to 1995 Hyogo-ken Nanbu earthquake. We've deduced the tension force due to overturning moment has caused these damages through statistical analysis of the data. We've also proposed the models to estimate the shear coefficient C_B equivalent to the overturning strength of the building Those buildings which suffered severe damage at their column bases had C_B values less than 0.5 and/or had C_B value lower the shear coefficient C_O values which are estimated summing the shear strength of the columns and walls. Those buildings whose tensile strength of the column base overwhelms that of the column itself could also avoid the damage of the column base.

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The load resistance of laminated glass to a special pressure record obtained from a wind tunnel test was investigated by the reliability design method using the FEM and failure probability theory. In the stress analysis of the rectangular float laminated plate glass comprised of polyvinyl butyral interlayer, the interlayer was modeled as a linear visco-elastic material. The results showed that the allowable pressure of failure probability of 0.001 was 0.8 to 1.1 times larger than that of monolithic glass at 20℃ and 0.6 to 1.0 times larger than that of monolithic glass at 50℃ for flexibility ratio (length of short dimension / total glass thickness) ranging from 56 to 222.

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