The authors have proposed a viscoplastic suspension element method to simulate the flow behavior of fresh concrete. In this paper, a new method developed by supplementing the elasticity into the analytical model, that is called visco-elasto-plastic suspension element method (VEPSEM), is proposed. This analytical method is a dynamical one used a non- continuum model, and can be applied to the simulation of failure peculiar to brittle materials such as concrete. Some examples of analytical results obtained by the visco-elasto-plastic suspension element method are shown herein.

View full abstract

This paper presents the quantitative value corresponding to human sense on accuracy on the subjects of various sizes and forms of tiles. Firstly, the sensory scale relating to accuracy of finishing of the tiled walIs employing the sensory test was constructed. On the other hand, the geometric measurement on accuracy of finishing of the tiled walIs was carried out. Secondly, the quantitative value was established from the relationship between the result of the measurement and the sensory scale. The quantitative value is what developed from another quantitative value established in the former report on the subject of one tiled wall.

View full abstract

The double slab space composed of foundation slab and footing beams is often used as a heat storage tank of airconditioning system. The temperature of the tank water is about 45 degree of centigrade in winter and about 5 in summer. This hot and chilled tank water causes thermal stresses in the reinforced concrete basement structure. In order to study on the thermal behavior of structures due to heat storage tank, a long term temperature measurement (about one and a half year) of a office building in Tokyo was carried out. The temperature was measured for the water, foundation slab, exterior and interior footing beams, slab and exterior wall of machine room, and so on. From the measured data, the mean temperature and temperature gradient of cross section of member were derived. Unsteady static heat conduction of the building and surrounding soil was analized by 2-dimensional finite element method. The analidcal results were good agreement with the measured data.

View full abstract

The scaling factors in different semi-empirical methods were examined by the numerical approach for the same condition of the fault models. The results clearly showed that the methods had been improved to be consistent with the ω^2 model for the seismic source spectrum. Based on both the numerical and theoretical approaches, it was found that the randomness of the arrival times of the motions from the fault elements should be taken into account for the evaluation of the actual scaling factors in the syntheses.

View full abstract

Pile foundation responses during strong earthquakes are greatly affected by nonlinear soil-pile foundation interaction. Centrifuge test results indicated that pile responses in liquefied sand change due to large ground displacement and excess pore water pressure buildup. In this paper a practical numerical model is proposed which consists of lumped masses and nonlinear soil springs taking into account pile group effects. The soil springs modified at each step according to the relation of lateral load-displacement of the pile and the changing effective stress in the free ground. Earthquake responses of a structure on pile foundation in liquefiable soil deposits are analyzed using the numerical model. The effects of the inertial and kinematic interactions on pile responses are investigated. Analytical method to evaluate pile stresses induced by earthquake is also discussed.

View full abstract

This paper studies theoretically on basic characteristics of torsional vibration of 1-story linear system with uniaxial eccentricity subjected to translational ground motions. Basic characteristics mainly of the torsional component is made clear by deriving mathematical expressions for participation vectors and acceleration magnification factors. Based on these magnitudes of vectors and factors new indices for the dynamic torsional effect are proposed. Proposed simple indices are effective for torsional vibration not only in the ordinary case of large eccentricity but also in the extraordinary case of small eccentricity. These indices also show good agreement with damages of structures in past earthquakes.

View full abstract

This paper investigates the fundamental characteristics of ratio between horizontal and vertical spectra(H/V-R) of short-period microtremors and elucidates its relationship with ground amplification. In addition, the paper investigates the possibility to predict earthquake ground motion using spectral ratio. The results are summarized as follows: 1) Clearly observed peaks in H/V-R fairly correspond to the 1st mode of ground amplification due to S-wave propagating above bedrock which is a relatively strong reflection boundary. 2) H/V-R can be simulated in 2-dimensions by FEM considering surface waves generated by ground noise. From the numerical simulation of single layer model, it is considered that the abovementioned relationship is valid in the range of impedance ratio exceeding 2-3. 3) H/V-R can be efficiently used to estimate the relative strength of earthquake motion in case of minor changes in ground conditions.

View full abstract

In this paper, we discuss dynamic stability of an elastic rod with damping terms subjected to nonconservative loads by using the boundary element method for a regional division type. The used damping terms are the internal damping (Voight-Kelvin type) and the external damping (viscous type). We air adray proposed the numerical method for dynamic stability analysis without damping terms. Our derivation of integral equations is based on an inverse formulation of a canonical form. The resulting discretized form has a coefficient matrix of a whole system with a sparse property which is the same characteristic as a conventional finite element method. We apply this methodology to the dynamic stability analysis of elastic rod system with damping terms under nonconservative forces. The well-known nonconservative stability models for the elastic rod which are called Beck's problem, Leipholz's problem and are their similar ones are examined by our procedure as illustrative examples. The obtained numerical values exhibit a monotonic convergence behaviour according to number of divisional regions and Ziegler's jump phenomena. The results prove the effectiveness of the proposed numerical method.

View full abstract

It is of importance to investigate and predict the response of reinforced concrete structures to impact loading from the view point of disaster prevention at nuclear power plant facilities, and there is an urgent requirement for establishment of design methods against the impact of aircraft and/or its engine. The authors proposed a numerical approach for assessing local response characteristics by the high-velocity impact of deformable missiles, and the results of numerical analyses were verified by that of full-scale impact tests using real engine body (GE-J79) reported by Muto et.al. The relation between the crash strength of engine body and the limit thickness of perforation was calculated and illustrated in this paper.

View full abstract

The present paper specifies fundamental vibration characteristics of the suspension membrane structure. Quadrilateral and approximate hyperbolic parabolic shaped membrane models are experimented to examine free vibration characteristics under several initial applied tensile forces or initial applied amplitudes. From these experimental results, it is obtained that the vibration characteristics strongly depends on the initial applied amplitude, and added mass of the air is necessary to be considered in analyzing on the experimental data. Displacement response wave forms obtained from the experiments are also examined by nonlinear response analysis. From the analytical result, it is possible to clarify the vibration characteristics qualitatively. Consequently, by the analysis it is examined influence of initial state of the membrane shape on its vibration characteristics; therefore, it is predicted how state of shape is necessary to check its vibration characteristics in the design process.

View full abstract

Dynamic elasto-plastic behavior of long span structures has been investigated by performing time-domain earthquake response analysis. However, such a numerical simulation is not suitable to examine thoroughly the overall. characteristics of the obtained solution related to various parameters. The purpose of this paper is to discuss the nonlinear dynamics of the long span structures with geometrical and material nonlinearities based on the frequency-domain periodic solution. In this approach, we obtain the resonance curves, which are closely related with the resistant capacity against dynamic load, by applying equivalent linearization technique and harmonic balance method. The elasto-plastic shallow triangular frame, which is originally the example of the so-called Williams' toggle frame, was analyzed in order to examine the typical characteristics of the long span structures. As a result, the significant properties of the elastoplastic vibration were revealed clearly in the form of the resonance curves.

View full abstract

A new construction method, in which a structure is built by lifting concrete waffle slabs along built-in columns, is being proposed. In order to realize such a procedure, the stress transfer mechanism at the slab-to-column joint has been experimentally investigated. The results indicate: (1) that the ultimate strength of the slab-to-column joint is represented by the strength when slipping occurs at the slab capital at which the slab is attached to the column by cast-in-placed concrete; (2) that the ultimate transfer of moment at the joint, when only lateral load is applied, is equivalent to the sum of the ultimate flexuial moments and torsional moments that acts on the side of the column, and the added moment by shear friction on the joint resulting from the dowel action at the flexural reinforcement; and (3) that the ultimate transferring moment, calculated based on this stress transfer mechanism, agrees favorably with the experimental result.

View full abstract

The effects of the specimen size and aggregate size on the inelastic stress-strain behavior of plain and confined concrete were examined. The following statement can be drawn from the study. For air cured plain microconcrete in which the size of aggregate is reduced in proportion to the size of a specimen, the compressive strength increased and the descending portion of stress-strain curve showed more brittle behavior with increasing size of specimen or aggregate. The compressive strength of confined concrete increased with increasing size of specimen when cured in air. On the other hand, the size effect was almost negligible in water cured specimens. The stress-strain curve of confined concrete showed more brittle behavior with increasing size of specimen and degree of such size effect depended on the spacing of hoops.

View full abstract

Different arguments have been proposed from various institutes on post installed anchor pull-out strength calculation. There are many typical formulas to calculate pull-out strength of post installed anchor. In this paper, the calculation formula for the maximum pull-out strength of the metallic expansion post installed anchor has been derived from estimation of maximum resistance by gathering statistically influential factors based on many experimental data within a scope of expansion anchor failure exclusively limited to concrete failure, and from a safety factor on calculated values given by probability theory under a hypothesis with experimental values and calculated values ratio distribution pattern taken as normal distribution because of dispersion of the experimental values.

View full abstract

A method of perforating to steel plate by punching is superior to drilling method in working time and cost of maintenance. The punched hole is, however, prohibited from applying to high strength bolted joint by JASS 6. The reasons can be said that the proper punched hole shape and the metallurgical effects of shearing may have influenced on the mechanical properties of perforated steel plate in elongation capacity, fatigue strength, as well as relaxation behavior of fastened bolt, slip load in a friction type bolted joint. We, in this paper, investigated those mentioned properties through experiments and F.E.M. analysis. Further, we make it clear the suitable punching condition and applicable portion of steel structure.

View full abstract

This paper presents the analytical studies to estimate the elastic stress distribution of beam flange connected to the box type steel column to H beam connections using finite element method, when the connection is subjected to the severe earthquake loading. In this paper 44 various cases about beam to column connection are caluculated by FEM analysis. It is found that stress distribution of beam flanges is affected by not only shea lag phenomenon but also local flange deformation by bending moment and axial stress of column. Finally, suitable design formulas are recommended.

View full abstract

Bending test of cold press-formed square steel pipes having four different thicknesses, 28, 32, 36, and 40 mm, was done, entirely resulting in brittle fracture in the welded section connected to a piercing diaphragm plate. It was found that brittle fracture can take place even under monotonic loading as well as cyclic loading, and that a fibrous crack triggering the brittle fracture can be generated at the weld toe of the press-bent corner even though the weld toe is smoothly finished and the weld heat input is restrained in a small amount. The fracture-governed plastic ductility of the four beam-specimens varied in a wide range from 2.5 to 9.7. Such a high uncertainty and an involvement of very low deformability may be attributed to the lack both in strain ductility and notch toughness in the material.

View full abstract

The surface roughness of actual shot-blasted treatment at the steel fabricator is investigated. The roughness measurement and the slip tests were performed to evaluate the influence of nonrusted surface roughness on the slip coefficient. The results of these static tests are summarized that the roughness of the shot-blasted surface for ordinary treatment condition are greater than 50S and these slip coefficients usually exceed the minimum value 0.45 required by the AIJ Specifications. The dynamic slip test under cyclic loadings were also conducted. The test parameters are the surface roughness, the rate of the slip strength to the yield strength of the joint and the sinusoidal frequency. The fluctuation of the slip strength and the bolt clamping forces, and the hysteresis characteristics are discussed.

View full abstract

In order to simplify a beam-column joints for concrete costing, and constructions in a mixed structure, the details of joints with reinforced concrete clumns and steel beams were developed in authors' previous experimental study. In order to investigate the shear resisting mechanism of the joints, it is necessary to cosider internal stress transfer mechanisms based on the analytical study. In this study, 3-D non-linear finite element analysis was performed to investigate the shear behavior of the joints. The analytical results gave good agreements with the test results. The effective area of concrete and steel in the joint was evaluated by observation of analytical principal stress distributions. From the analysis, it was found that the shear strength of the joints was influenced by the section details of beams and columns. Finally, the shear strength of the joint were investigated by carrying out the numerical tests.

View full abstract

The present paper is concerned with the wave response on relaxation moored two floating type architectures in coastal zone. On evaluation of wave response of floating bodies, the effects of hydrodynamic interaction and reflection wave due to quay were discussed by using the numerical results. Furthermore, the responses on motion and tension of mooring line were calculated by numerical simulation considering the nonlinearity of wave exciting forces and mooring system, and the nonlinear effects on motion and tension of mooring line were made clear.

View full abstract

This paper aims to apply the seismic deformation constrained design method, developed by the authors, upon frame-steel plate shear wall system, which is clearly indicated in the tide. However there are no description on their applied results of this method on frame-steel shear wall system, which shows a very complicated non-linear behaviors at their early loading stage through the buckling of compression field. Under cyclic loading the hysteresis loop show hard-spring type. If the term, steel-plate shear wall, is used, some description may be treated at their application. If not, the term, steel-plate shear wall, may not be adequate as the title of this paper.

View full abstract

The writers appreciate the discusser's interest in their paper. The use of steel-plate shear walls appears to provide a feasible and better solution to a design problem of a building frame from the structural, architectural and economical points of view. In the current design practice, it is generally recognized that elastic buckling of such steel plates should be prevented even under severe earthquakes and plates of moderate thickness or those with adequate stiffeners should be utilized. Although a few papers recommend the use of thin and unstiffened steel plates as seismic resistant walls due to their significant increase in strength in the postbuckling range, further research appears to be required due to still insufficient data on their mechanical characteristics especially in the cyclic inelastic range. In the original paper, the ratio of bending stiffness of a shear wall to its shear stiffness had been determined adequately in order to characterize a property of steel-plate shear walls of practical dimensions installed in a moment-resisting frame. It had also been clearly stated that a new finding is that a new elastic seismic-deformation constrained design method can be constructed for steel-plate shear wall-frame systems via an inverse formulation.

View full abstract