Abstract of RIIS Report ( SH-1961-1 )

National Institute of Occupational Safety and Health, Japan

Impact Strength of Wire Rope (1st Report)

SH-1961-1-1

E.AKIYAMA, T.KONDO, T.HAKAMAZUKA and S.TONSYO

: For the prevention of wire rope accidents, not only the static strength but the impact strength of rope is essential factor. To study it, we made a new type of shock load testing machine. A large steel disk, weight 1,700 kg, revolves about a horizontal axis. Both sides of the disk fit up with two claws, which keep inside usually, but project from the disk only at the testing time. A wire rope test piece, previously extended by the proper static load, is struck onitsholder by the claw, and broken down. The shock load of rope at the impact moment, is measured with the strain meter, and recorded on the oscillograph together with the elongation of rope.
We tested flawless wire ropes, under the different shock speed and the different test piece length. Besides, we tested various kinds of intentional damaged ropes, and compared with flawless ropes. We certified that damaged ropes are more weakened on the impact strength than the static strength.

On the Compressive Strength of V-Beam

SH-1961-1-2

Yoshitada MORI

: The straight bar of V-beam which is mainly used for a yieldable support of a tunnel buckles by a compressive force, usually sooner than a ordinary buckling bar.
    This phenomenon seems to be based on the fact that the bar of V-beam buckles by both torsion and flexure.
    The investigations concerning the torsional and flexural buckling of a bar of open thin-walled section with one symmetrical axis have done by many persons.
    In this report, the compressive strength of four types of V-beam on the market has been calculated on the theory of torsional and flexural buckling, on the assumption that V-beam has a open thin-walled section with one symmetrical axis.
    In the result, the thinner the wall of section, the smaller the moment of inertia of section around the symmetrical axis in relation to the other moment of inertia, and the shorter the bar, the more is effect of torsion on the buckling strength. In such a case that the wall of section are thick and both moments of inertia of section are equal to each other, this effect can be considered to be negligible.

On Shearing Strength of Kanto-Loam

SH-1961-1-3

I.MAE

: Shearing strength of soil is the most important factor for analysis of stability of earth slopes and of man-made cuts.
    There are many testing methods to measure shearing strength of soil, such as direct shear test, triaxial compression test, unconfined compression test and vanetest etc.
    The purpose of this series of test is to determine shearing resistance of Kanto-Loam, and to find out the difference between direct shear test and unconfined compression test.
    The values of cohesion C and angle of internal friction φ determined from the results of direct shear test, and the values of unconfined compressive strength q_u from the values of unconfined compression test are shown in the following.
    angle of internal friction φ = 15° - 30°
    cohesion                   C = 0.7 - 1.5 kg / cm²
    unconfined compressive strength q_u = 1.5 kg / cm²
    Theoretical relation between unconfined compressive strength q_u and angle of internal friction φ and cohesion C is expressed by the equation
    q_u = 2 C tan (45° + φ/2 )
Substituting φ and C which are the value from the results of direct shear test in above equation, the value q_u that are named converted unconfined compressive strength are obtained.
    The value q_u must be equal to the value q_u theoretically, but the ratio of the value q_u to the value q_u is
    q_u / q_u = 0.4 - 0.6
    This discrepancy in these values may be caused by difference of shearing processes in these tests, and of size of specimens for test, as specimens have many seams in them.

Theoretical Consideration on Buckling Strenth of Tubular Pole Scaffold

SH-1961-1-4

Yoshitada MORI

: Since a tubular pole scaffold around the outside of a building under construction is usually tied to the building at many points, no displacement of the scaffold in the direction normal to the surface of the scaffold occurs at a connecting point, while at another point the scaffold tends to move in such direction when no crosswise bracings.
    On some assumptions this scaffold can be regarded as such a lattice with many spans and layers, that no moment is transmitted from member to member at a panel point.
    In this report the buckling problem of this lattice when it buckles normally to the surface of the lattice, by the vertical load acting on only a upright, has been treated as a characteristic value problem of differential equation, and in a general case only the critical load equation has been induced, but in some simplified cases the actual solution of the critical load has been acquired; instead of the critical load P the value m in the following Eulerian expression has been acquired, since m is independent on the dimensions of the member of the scaffold.
    P = π² EI / m² l²
where E is the modules of elasticity of the material, I is the moment of inertia of the section of the member, and l is the vertical distance between a ledger and an adjoining ledger.

JNIOSH

Abstract of RIIS Report ( SH-1961-1 )

National Institute of Occupational Safety and Health, Japan

Impact Strength of Wire Rope (1st Report)

On the Compressive Strength of V-Beam

On Shearing Strength of Kanto-Loam

Theoretical Consideration on Buckling Strenth of Tubular Pole Scaffold

Other Publications