The consistency of fresh concrete is generally evaluated Theologically by using theBingham model expressed with yield value and plastic viscosity. In this study, the slump test is discussed from the rheological point of view, which is the standard method for testing the consistency of fresh concrete. The theoretical curve of slumping-time relation is obtained as a function of the rheological parameters of concrete such as yield value and plastic viscosity. The estimating method of yield value and plastic viscosity of materials from the experimental slumping curve and slump-flowing curve is proposed.

抄録全体を表示

The characteristics of strain measurement obtained from the embedded-type concrete strain gages was examined by the tests on concrete specimens subjected to the following conditionsrdrying shrinkage, instantaneous and gradual temperature changes, sustained loading over 2 weeks, and monotonically increased short-term loading. The results of the tests, where the uniform strain distribution was anticipated, showed that the internal strain readings of embedded gages were mostly 10-20% larger than the external strain readings. . A finite element analysis was performed to verify that this difference was caused by the local concentration of concrete stress around the embedded gages.

抄録全体を表示

This paper discusses the H^∞ structural control design, in particular with the emphasis on (l)the selection of design criteria and (2)the construction of reduced order controller. To treat the first problem, the control effects provided by three kinds of the proposed design criteria are compared to find the most favorable one. As a solution to the second problem, the controller reduced with properly selected weighting functions in the frequency domain is proposed, providing the same control effect of the full order controller.

抄録全体を表示

An evaluation methodology of design earthquake motions based on design lifetimes of buildings and on site-related earthquakes is proposed. The method involves a procedure for evaluating possible earthquakes and earthquake motions according to the available information and to the state-of-the-art knowledge. Earthquakes which should be considered for the structural design are intensively discussed on the basis of the latest knowledge in seismology, earthquake engineering and geology. To evaluate the earthquake motions for a particular site, the characteristics of the seismic source, the propagation, and the ground conditions are taken into account. An application result of this method to a super highrise in Tokyo whose design lifetime is taken 100 years shows the effectiveness of the method.

抄録全体を表示

This paper describes a theoretical study concerning soil-structure dynamic interaction problems on an alluvial medium. The dynamical characteristics of a poroelastic half space are investigated using an analytical model based on theory of aggregate body. There are some permeability ranges which are unable to be qualitatively explained explained by behaviors of both perfectly elastic body and Voigt-type viscoelastic one simulated by using the characteristics of the body waves traveling in the aggregate body. The value of imaginary part of Dynamical Ground Compliance corresponding to radiation energy through a sub-soil ground, is large in high permeability range, on the other hand, it becomes small in low permeability range, because the relative particle velocities between the porous elastic body and the pore water decreases in this range.

抄録全体を表示

The Green's function in a viscoelastic medium for a body force moving with constant velocity (hereafter called the Moving Green's Function : M. G. F.) is interesting for various applications in elastodynamics, e.g. 3-D wave propagation analysis of 2-D structures and analysis of ground motion due to vehicles. This paper first describes two different methods for calculating the M. G. F. in 3-D layered media. Analytical solutions in the infinite wavenumber integral form and discrete form solutions based on the thin layer element method are calculated. Next, the validity of these methods including numerical codes are verified through comparisons of the results of the two methods and also those of a past paper. The wave propagation characteristics in 3-D layered media due to loads moving with different velocities are then discussed as an example analysis.

抄録全体を表示

The active vibration control of a linear structure with uniaxial eccentricity is presented. The 2DOF objective structure is actively controlled by the only one control force under an earthquake excitation. Based on the pole assignment method, the state feedback control law is represented in a closed form as a function of the modulus of eccentricity, the spring radius ratio, the location of the controller, and the damping factors as the control target. Uncontrollability means that a participation factor for a control force is zero at the center of torsion in each vibration mode. Velocity-feedback control could only reduce the vibration in either the lateral or torsional direction, though the control aims to increase the damping of the structure. The sign of the feedback gains changes at the centers of torsion as the location of the controller moves. The inefficient control is indicated by the values of the gains increasing near the centers of torsion. The resonance curve shows the optimal location of the controller for simultaneously reducing vibrations in both directions by the only one control force.

抄録全体を表示

This paper describes earthquake simulator tests of a 1/2.5-scale model of an existing base-isolated, three-story reinforced-concrete building. Two types of high-damping rubber bearings and one type of lead-rubber bearing were used in these tests. Moderate and extreme input motions were applied to the model to study the ultimate behavior of the isolated structure. Dynamic analyses were conducted to simulate the response to both moderate and extreme input tests, using a previously-developed analytical model. Good agreement between the experimental and analytical results was obtained, and the analytical model was confirmed to be suitable for representing the mechanical properties of bearings.

抄録全体を表示

In our previous paper we had estimated engineering bedrock waves, in which local site effects of surface geology are removed, by using strong motion records of 18 earthquakes observed at 12 boreholes sites deployed in the 20km X 20km region in Sendai. The objective of this paper is to represent acceleration Fourier spectra of the engineering bedrock waves by the statistical model which reflects recent seismological studies. First we modeled the spectra which takes account of the amplification factor from the seismological bedrock to the engineering bedrock on to Boore's model, in which source spectra are modeled by the so-called ω^<-2> model with a high-frequency decay parameter fmax. Second we identified the model parameters by the step-by-step identification method proposed in this study and carried out regression analyses for these identified parameters. As a result, we successfully obtained a physically meaningful new statistical spectral model for engineering bedrock waves which reflects the characteristics of the source, path and site for the Sendai region.

抄録全体を表示

Atmospheric temperature change and solar radiation are the main factors causing thermal expansion and contraction of R/C buildings. In this paper, the effect of the above factors is investigated using non-steady-state heat conduction analysis and three dimensional elastic analysis, and the temperature for thermal stress analysis of the A-wing of the Faculty of Engineering, Hokkaido University is estimated. The thermal movement obtained from the estimated temperature shows a good agreement with the measured movement. Structural damage of 1-story frames subjected to repeated temperature change is also discussed.

抄録全体を表示

It is important to estimate vertical stresses and displacements by a distributed load in the ground for the analyses of building structure. To consider this problem, generally buildings and ground are assumed to be onehalf infinite continuous elastic body and Hindi in's solutions are valid. So Hindi in's first solutions about vertical stresses and.displacements in the ground are integrated for a linearly distributed rectangular load. And the calculating method by using figures is originated for these equations. Calculations of these integrated equations are performed and the results of calculations are discussed.

抄録全体を表示

It is known by the few examples that the structures with raft foundation possess the great efect of suppression to differential settlements. We suspect that this factors are the rigidity increase of superstructure by the raft' s stiffness and the load dispersion by the large area of contact on the ground. I n this paper, we have proposed the practical analysis method for structures with raft foundation. This method is considered the interactive behavior of a soil-structure system and the non-linear property of superstructure and soil. On the case that the differential settlements of structures with raft foundation occured, we discuss the distribution of contact pressure and the stress of superstructure including the foundation beam and the mat slab by the use of numerical example.

抄録全体を表示

The horizontal load tests and the 2-D non-linear finite element analysis were performed on the beam-column sub-assemblages in order to investigate the mechanisms of beam-bent bar anchorages in R/C wall column and beam joints. It has been recognized through the parametric analysis that the mechanisms of beam-bent bar anchorages are mainly attributable to the bond resistance and the compressive resistance at the inside of the hooked bend. It has been also understood that the authors' model of anchorage can lead to the way to describe the strength of anchorage and the bent bar slippage.

抄録全体を表示

Effects of variables, such as development length of reinforcing bars, kinds and compressive strength of grout, etc., on bond stress-slip relations of reinforcing bars in splices having grout-filled coupling sleeves of electric resistance welded steel tubes. Following main conclusions are obtained. (1) In pre-yield regions of reinforcing bars in splices with the same grout, the bond stress-slip relations which are considered to be almost similar are obtained. (2) Assumption of different constant bond stress in both pre- and post-yield regions of reinforcing bars in the splices leads equations to estimate practically both load capacities and failure modes of the splices.

抄録全体を表示

A new effective hysteretic damping device for improving the seismic resistance characteristics of a X-braced frame structure, in which the seismic energy is absorbed into the plastic deformation of the perforated steel plate in the device, was proposed in the authors previous papers. In this paper, the low-cycle fatigue characteristics of the present damping device are investigated. The applicability of the fatigue relation and the linear accumulation damage rule to the device is confirmed through constant amplitude and high-to-low block loading tests. Also, the life prediction expression of the present device is shown and its availability is verified by non-stationary amplitude fatigue tests using the deformation time history of the hysteretic damper in the on-line computer-actuator control test. It is clarified that the accumulation damage value of the damping device is small in the responses of the building with proper dynamic structural characteristics under a severe earthquake ground motion (with about 60 kine in the maximum ground velocity), and thus the present device has enough energy absorption capacity.

抄録全体を表示

Accelation data which had been measured in a vibration test of a full scale 3-story steel frame structure, are integrated to get displacement data, and relations between shearforce and displacement are gotton. Using this relation, an effect for damping, horizontal stiffness, and energy absorption of building on earthquake, which are brought by nonstructural members, are studied. On strong earthquake, shear force was decreased to 80%, and horizontal stiffness is increased to 150%, by nonstrucural members. And it is also confirmed that nonstrucural members influence on a distribution of energy absorption on the limit earthquake.

抄録全体を表示