Harutoshi Kobayashi

Rectangular mindlin plates on elastic foundations

Abstract Rectangular plates on Winkler foundations are analysed on the basis of Mindlins thick plate theory. The plates are simply supported on the two opposite edges and the other two edges may be arbitrarily restrained, e.g. simply supported, clamed or free. Solutions are presented in the Levytype single series forms, of which forms must be distinguished into three different forms depending upon the properties of plate materials and the modulus of foundation. The effects of shear deformation are first showed numerically for the deflections and strees resultants at major points of the plate. Furthermore, the twisting moment and shear force distributions along the edges and centre lines of the plate are illustrated graphically to demonstrate the principal difference between Mindlins plate theory and classical thin plate theory.

Elastic small deflection analysis of annular sector Mindlin plates

An analytical method is developed for the bending response of annular sector Mindlin plates with two radial edges simply supported, and exact solutions are presented in the form of Levy-type series. Several different boundary conditions on the two circular edges are considered, viz. simply supported-simply supported, clamped-clamped and free-free. Numerical results for the case of uniform loading are presented to indicate the effect of shear deformation on the deflections and stress resultants at various points in the plate. Twisting stress couple and transverse shear stress resultant distributions along and near the edges of the plate are illustrated graphically, and the principal differences between the results predicted by Mindlins plate theory and classical thin plate theory are discussed in detail. Results obtained with the present exact analysis may serve as references for approximate solutions and, especially, as a ‘shear locking’ test for thick plate finite element analysis.

Multispan Beams on Linear Viscoelastnc Foundations

ABSTRACT ABSTRACT The solutions of the quasistatic bending problems of the multispan beams on the linear viscoeiastic foundations of the Kelvin, Maxwell, and Standard linear solid types are presented. The method of solution is developed by using the eigenfunctions found in the free lateral vibration problem of the multispan beam and by utilizing the correspondence principle between the linear elastic boundary value problem and the linear viscoeiastic one. Numerical results for the variations of the deflection in space and time are illustrated for a three-span beam on the viscoeiastic foundations of the Kelvin, Maxwell, and Standard linear solid types.

Impact Fracture Analysis Of ReinforcedConcrete Rock Sheds

Numerical analyses of impact fracture problems of reinforced concrete rock sheds are carried out using Rigid Body Spring Model (RBSM) within a frame theory. The rock sheds considered here are of a type of portal frame whose roof is covered with sand cushion. A number of numerical simulations are executed under various loading conditions such as weights of rock-mass, rock fall-heights, collisions angles of rock-fall and so on. Two types of failure mode are observed, one is bending failure mode and the other is shear failure mode due to diagonal cracks of concrete. From the numerical results obtained, the difference between the statical and the impact (dynamical) characteristics of the rock sheds are discussed.

Basic Study on Shear Capacity of CFT Members with a Large Width-thickness Ratio of Steel Plate

This study is intended to investigate the shear capacity and shear failure mode of the concrete filled steel tubular (CFT) members with a large width-thickness ratio of steel plate. Six specimens used have a square cross section and 200 or 250 of width-thickness ratio of steel plate. The beam specimens simply supported were tested, in shear-span ratios ranging from 0.75 to 2.0, by a two-point loading method. Only the specimen with 0.75 of shear-span ratio showed a clear shear failure mode. The shear capacities of these specimens amounted to 4.61 times as large as the values predicted by the current codes of CFT members in which the shear capacity assumes to be yielded by only steel section. Discussions are made on the shearing rate of shear strength into steel section and core concrete. And it is suggested that the shear capacity of CFT member may exceed the simply cumulative strength of steel webs and core concrete by virtue of a confinement effect.

A Method Of Dynamic Nonlinear Analysis ForRC Frames Under Seismic Loadings

The paper presents a method of seismic nonlinear response analysis for RC frames designed as a bridge pier. Rigid Body Spring Model (RBSM) is adopted as a numerical model, in which material nonlinearity is introduced into springs between adjacent rigid bodies. Moment-curvature relations of RC members are derived from numerical integration on their cross sections according to nonlinear stress-strain relations of steel and concrete, and Bernoullis assumption. Assemblage of element matrix equations through a similar procedure to an ordinary displacement method leads a fundamental equation of motion under seismic loadings. An explicit time integration scheme is used for solving the equation of motion.

Model Test Verification On Structural FailureModes Observed In Hyogo-ken Nanbu Earth-Quake 1995

Main concern is placed on the effect of vertical thrust from the bottom of footing on a viaduct pier column failure. Small scaled model tests were carried out using an underwater explosion method. In the method, a pulse-like vertical thrust was induced to the bottom face of footing by an explosion of a thin steel wire or a thin aluminum foil charged with high voltage in water. Specimens of RC pier models with a circular, a square or a rectangular column cross section were made by plaster or cement mortar with steel wire reinforcements. Furthermore, specimens of steel tubular pier models were also made of aluminum. Parametric tests were carried out concerning surcharge mass, charged voltage and capacity of condenser. Discussion was made by comparison of the observed failure modes in the Hyogo-ken Nanbu earthquake with those in the test models.