A Stability-Based Target Displacement for Direct Displacement-Based Design of Bridge Piers

P-Δ effects can cause instability if they are not properly accounted for during the design of bridge piers and other structures. When a bridge pier is designed with the Direct Displacement-Based Design Method, P-Δ effects are evaluated at the end of the design process and compared to the flexural strength of the pier to find a stability index. If the stability index exceeds the specified value, the design must be repeated, iteratively reducing the target design displacement. This article presents a model that when used at the beginning of design (without knowledge of strength) allows the estimation of the maximum lateral displacement that a bridge pier can sustain without exceeding the specified value of the stability index, therefore eliminating the need for iteration. The examples that are presented prove that the model is accurate and very useful for design of extended pile bents.     

The Idea of Epilepsy as a Disease Per Se

In the 1850s Delasiauve and Russell Reynolds independently introduced the idea that the previously more inclusive concept of “epilepsy” should be restricted to that of an idiopathic disease manifesting epileptic seizures not caused by detectable brain pathology. This idea was rather widely accepted, though with some modification, over much of the next century. However there was increasing opposition to the idea from those, including John Hughlings Jackson, who perceived that all epileptic seizures must be symptoms of underlying brain disease. With increasing identification of structural brain pathology in what had been regarded as instances of idiopathic epilepsy, the latter view has increasingly prevailed.     

Samuel Tissot’s Traité de l’épilepsie—250 years old

A quarter of a millennium ago, Samuel Tissot (1728–1797), a Swiss physician who had achieved a substantial European reputation, authored a monograph entitled Traité de l’épilepsie. The book was translated into several European languages and appeared in various editions over the following 70 years, although an English-language version was never published. In his Traité, Tissot provided a thorough account and critical analysis of the previous relevant literature concerning epilepsy, added data from his own experience in practice, and raised issues, some of which remain important today. The appearance of the book was propitious, occurring during the period of the European Enlightenment, when medicine was increasingly divesting itself of ancient modes of thinking and veneration for the opinions of great names from the remote past. At least in Western Europe, the Traité de l’épilepsie became an intellectual launching pad for the considerable expansion in knowledge of epilepsy that occurred over the century or longer that followed its publication.     

A ‘German Invasion’? Irish Rural Radicalism,European Integration,and Irish Modernisation, 1958–73

Land hunger was a pervasive feature of Irish rural society which had not disappeared with the attainment of national independence. Rural agitation for land redistribution was conducted by many small indigenous farmers and it acquired an extraordinary anti-German tone after 1960. This was partially fuelled by a wave of international media speculation about Ireland as a base for Nazis eluding justice, but it was also driven by the notable success of Irish agencies in attracting German investment to Ireland. Consequently, the land question spilled into Irish efforts to attract Foreign Direct Investment (FDI) and Ireland's application to join the European Economic Community (EEC). Governments were slow to respond to the demands of the rural radicals: heavy-handedness against foreign landholdings might endanger Ireland's international reputation at the very time that the country was seeking to shake off an anti-progress and insular image. Militant republican involvement in land agitation stirred additional concern. When the Irish Land Commission compulsorily purchased the properties of a handful of West Germans in 1969, the Bundestag of the Federal Republic of Germany (FRG) debated the matter. This ostensibly served as the rationale for vandalism, arson, and bomb attacks against foreign-owned farms and properties at a critical point: Northern Ireland was careering out of control and Dublin's priority was to join the EEC. The government defended the right to private property and it could not halt the EEC's liberalisation of agricultural land purchases after 1970: membership of the EEC was the overriding strategic objective. In sum, land ownership had formed part of the bedrock of Irish nationalism since at least the nineteenth century and Irish adaptation to the liberal international economy generated predictable resistance. The linkage between land ownership and national citizenship was not unique to the Irish, as the Danes, the Dutch, and several countries bordering West Germany experienced comparable difficulties in the 1960s and the 1970s.     

Cortical epileptogenesis and David Ferrier

There was an increasing medical interest in the localization of representation of function in the cerebral cortex after Broca in 1861 identified a cortical area that appeared responsible for expressive speech. By the late 1860s, John Hughlings Jackson—based on clinico-pathological correlations mainly in persons with focal motor seizures—had reasoned that contralateral somatic motor function was represented in another area of the cortex. This localization was supported by Fritsch and Hitzig (1870) in experimental cortical stimulation studies in dogs. These authors also reported producing events resembling contralateral motor convulsing in their animals. Their work, and Jackson’s ideas, prompted David Ferrier, in Great Britain, to begin a program of cerebral cortical stimulation studies in various vertebrate species, trying to locate cortical sites of representation of functions other than expressive speech and motor activity. In his initial report of his investigations (1873), he noted that appropriately sited Faradic stimulation evoked immediate or delayed contralateral focal motor seizures, some of which evolved into generalized convulsions. On this basis he reasoned that focal motor and generalized seizures were expressions of the same disorder; that nearly all epilepsies originated in the cerebral cortex and not in the lower brain stem, as hitherto thought; and that the clinical pattern of epileptic seizure phenomenology depended on the function of the cortical site of origin and the extent and direction of spread of seizure activity in the brain. He not only provided experimental verification for Jackson’s reasoning about epileptic seizure mechanisms but expressed the ideas a good deal more clearly than Jackson ever managed to do. Ferrier’s achievement in this regard has tended to escape notice, lost sight of because of the great importance of his investigations into localization of cerebral function.     

Fiber-Based Modeling of Circular Reinforced Concrete Bridge Columns

This article presents the application of fiber-based analysis to predict the nonlinear response of reinforced concrete bridge columns. Specifically considered are predictions of overall force-deformation hysteretic response and strain gradients in plastic hinge regions. This article discusses the relative merits of force-based and displacement-based fiber elements, and proposes a technique for prediction of nonlinear strain distribution based on the modified compression field theory. The models are compared with static and dynamic test data and recommendations are made for fiber-based modeling of RC bridge columns.