Keiichiro Sonoda

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.

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.

Embossed Steel Plate-Concrete Composite Member Subjected to Bending and Shear

Two point loading tests of twenty three simply supported open-sandwich beams which consist of concrete and embossed or plain steel plate with headed studs, were carried out. Two types of embossed plates were used, namely checkered and ribbed types. Ultimate loading capacities and failure modes were examined in relation to the types of steel plates, stud spacing and shear span ratios. Methods to predict the shear bond strength of an open-sandwich beam are discussed.

Load carrying capacity and safety check of prestressed concrete rock-shed

本研究は, PC落石覆工の耐荷力評価と安全性照査方法について解析的に考察したものである. まず最初に, PC落石覆工全体系 (落石―サンドクッション―落石覆工) の衝撃応答解析法として, 個別要素法と剛体ばねモデルを併用した方法を提示した. 次に, 落石条件を徐々に厳しくしながら応答解析を行い、PC部材断面が終局モーメントに達したときをPC落石覆工の破壊とみなすことにより, その耐荷力評価を行った. さらにエネルギー的観点に基づく安全性の照査法として, エネルギー基準による3種類の方法を提示し, 各手法め妥当性について実物大PC落石覆工を対象に数値的に検討を試みた.

RELIABILITY OF EPOXY BONDED STEEL PLATE METHOD FOR REPAIRING DAMAGED RC SLABS OF BRIDGE

Epoxy bonded Steel Plate Method is a reinforcement method for repairing cracked and damaged RC slabs of bridge. In the method, a steel skin plate is adhered to the bottom surface of damaged concrete slab with epoxy resin.The aim of this paper is to examine the reliability of this method. Model slabs were tested under the repetition of truck wheel loading in both the states before and after repairs. From various observations on deflection-growth, cracking in concrete, and strain-increase in steel bar and skin plate, it is concluded that the method is fairly reliable even if the repair is done at the stage of so severe damage as to cause diagonal tension (shear) cracks in the concrete section of slab.

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.