A curved shell finite element for the geometrically non-linear analysis of box-girder beams curved in plan
A four-noded curved shell finite element for the geometrically non-linear analysis of beams curved in plan is introduced. The structure is conceived as a sequence of macro-elements (ME) having the form of transversal segments of identical topology where each slice is formed using a number of the curved shell elements which have 7 degrees of freedom (DOF) per node. A curved box-girder beam example is modelled using various meshes and linear analysis results are compared to the solutions of a well-known computer program SAP2000. Linear and non-linear analyses of the beam under increasing uniformly distributed loads are also carried out. In addition to box-girder beams, the proposed element can also be used in modelling open-section beams with curved or straight axes and circular plates under radial compression. Buckling loads of a circular plate example are obtained for coarse and successively refined meshes and results are compared with each other. The advantage of this element is that curved systems can be realistically modelled and satisfactory results can be obtained even by using coarse meshes.
Experimental Study on Steel Beams Curved in Plan
This paper is concerned with the ultimate load behavior of I-beams curved in plan. Results obtained from experiments on two sets of I-beams (one comprising rolled sections and the other built-up sections) are presented. The test results for deformations and ultimate strength are found to be in good agreement with the corresponding values predicted by using the elastoplastic finite-element analysis. The effects of residual stresses and radius of curvature to span-length ratio ( R /L) on ultimate strength are considered. Each beam was subjected to a concentrated load applied at an intermediate point where the beam was laterally restrained. Test results indicate that the load-carrying capacity decreases with the decrease in the R /L ratio.
Comparison of Binaural Release from Forward Masking in Animals and Humans. Electrophysiological Studies
Evoked potentials in the inferior colliculus and auditory areas of the cortex were studied in anesthetized guinea pigs and long-latency auditory evoked potentials (LAEP) were studied in waking humans using sequential binaural presentation of pairs of clicks – the masker and the masked signal – with a variable interval between them, to provide the conditions needed for the psychophysical phenomenon of direct forward masking. Introduction of phase differences between the masker and the masked signal led to decreases in suppression of responses to the masked signal and to faster recovery of the reaction types recorded. The greatest relative differences between response magnitudes to antiphase and synphase masked signals were seen at the beginning of the recovery process, and were 1.6, 1.5, and 1.4 respectively for responses from the inferior colliculus, auditory area of the cortex, and LAEP at stimulus intensities of 50–65 dB sound pressure level, differences subsequently decreasing to zero. There was a positive correlation between this measure and the stimulus intensity. The greatest differences between the time at which the recovery process ended for responses to antiphase and synphase masked signals were 4, 250, and about 2000 msec respectively for the inferior colliculus, auditory area of the cortex, and LAEP.