Report of the commissioners appointed to inquire into the application of iron to railway structures

Abstract

Rq)ofl of ~he Ommissioners ,qppointed to Inquire into the .3Tplication of Iron to Railway Structures.*From the infonm ~ion supplied to us, it appears that the proportions and tbrms at present employed for iron structures, have been generally derived from numerous and careful experiments, made by subjecting bars 0fwroug!~t or east iron, of different forms, to the action of weights, and thence determining by theory and calculation such principles and rules as would en, able these results to be extended and applied to such larger structures aild loads as are required in practice. But the experimentsLwere made by dead pressure, and only apply therefore to the action of weights at rest. On the contrary, from the nature of the railway system, the structures employed therein are necessarily exposed to concussions, vibrations, torsions, and momentaff pressures of enormous magnitude, produced by the rapid and repeated passage of heavy trains.These disturbing causes, in smaller degree, have always occurred in structures connected with mill-work or other mechanism. But the effects upon their stability have not been found greater than could be met t)y increasing the dimensions of the parts without especially inquiring into the exact principles upon which such increase should be made. Thus~ we are infbr,ned that the dimensions of cast iron girders, intended for sustaining stationary loads, such as water-tanks and floors, are usuallyso propor-tioJ~ed that their breaking-weight shall be three times as great as the load they are expected to carry, or in some cases four or five times as great. llut when the girders are intended for railway bridges, and therefore sub-" From the London Civil Engineer an(i Architect'

Hatfield Memorial Lecture 2007 Railways and materials: synergetic progress

“…It was the failure of such a bridge over the Dee at Chester in 1847 20 which nearly caused the premature and ignominious end to the engineering career of Robert Stephenson, but more importantly led to the appointment of a Royal Commission to inquire into the use of iron in railway structures. 21 The Commission report contains a wealth of detail of the then current knowledge of iron and details some important experiments which led to the idea of an elastic limit and tests on large beams which were the first fatigue tests on structural members.…”

“…It is worth recalling the twin advantages of rail transport: that of speed and the ability to haul large loads with modest tractive effort. When the railways were introduced speeds in the order of 30 to 50 km h 21 were an astounding increase on the maximum speeds possible by foot or horse traction. This great speed unified countries (indeed, many would claim that the day's return journey made possible by the railway defined the size of many European states), enabled news to be disseminated, allowed food and mail to be distributed, necessitated the introduction of a standard time and initiated the institution of fish and chips.…”

Aesthetics versus function: the fall of the Dee bridge, 1847

“…When, however, the depressions produced by the machine were made equal to one-half of the ultimate deflection, the bars were actually broken by less than nine hundred depressions. 8 Although the term was not then used, the experiments demonstrated the problem of low cycle fatigue as well as the idea of a fatigue limit. However, they also introduced the erroneous idea that the structure of the metal changed fundamentally, repeated flexure producing 'a peculiar crystalline fracture and loss of tenacity'.…”

Vehicle Response to Kinematic Excitation, Numerical Simulation Versus Experiment

“…A moving load's effect on transport structures has been observed in literature since 1849. After the collapse of the Chester Rail Bridge in England in the year 1947, civil engineer R. Willis and mathematician G. G. Stokes published work [1,2] in which they tried to clarify the cause of the accident and a method for solving equations of motion describing the problem. Subsequently, a flood of articles appeared that tried to solve the problems of moving loads analytically, with varying degrees of applicability.…”