Nonlinear analysis of earthquake fault rupture interaction with historic masonry buildings

The response of historic masonry buildings to tectonic ground displacements is studied through analysis of a simple yet representative soil-foundation-masonry wall system. A nonlinear 3D finite element method is developed and employed to reproduce the strong nonlinear response of the rupturing soil, as well as the masonry structure. Following a sensitivity analysis of the effect of the exact location of the structure with respect to the emerging fault, the paper discusses several characteristic mechanisms of soil-structure interaction and evaluates the associated structural distress. The observed failure pattern and the consequent structural damage are shown to depend strongly, varying from minimal to dramatic, on the exact position of the structure relative to the fault. Alleviation of tectonic risk through foundation enhancement/improvement is investigated by considering alternative foundation systems. Results highlight the advantageous performance of rigid embedded and continuous foundations as opposed to more flexible and isolated supports indicating that foundation strengthening may provide important shielding against settlement and structural drift

Capacity of grillage foundations under horizontal loading

Grillage foundations are an alternative to solid surface mudmats for supporting seabed infrastructure, offering improved hydrodynamic performance and savings in foundation material. Recent research has demonstrated that grillages can be designed to have similar vertical bearing capacity to a mudmat with the same footprint. This is extended herein by: (a) determining grillage performance under horizontal loading at constant vertical load (V-H); (b) the application and development of existing plasticity-based models for predicting performance; (c) comparing the V-H behaviour with surface mudmats; and (d) discussing the implications for design. Experimental tests were conducted in sands over a range of densities and in two different modes, representing different installation procedures. In over-penetrated tests, the foundations were installed to achieve a vertical bearing capacity V 0, followed by horizontal loading at a constant vertical load with V &lt; V 0. In normally penetrated tests, foundations were installed to V 0 before horizontal loading at constant vertical load with V = V 0. Both normalised V-H yield surfaces and a plasticity-based simulation model are presented for use in design. Laboratory-scale grillages offer improved horizontal capacity in loose and medium-dense sands and similar horizontal capacity in very dense sand, compared with surface mudmats. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees. http://www.icevirtuallibrary.com/content/journals</p

Bridge-Pier Caisson foundations subjected to normal and thrust faulting:physical experiments versus numerical analysis

Surface fault ruptures can inflict serious damage to engineering structures built on or near them. In the earthquakes of Kocaeli, Chi-chi, and Wenchuan a number of bridges were crossed by the emerging normal or thrust faults suffering various degrees of damage. While piles have proved incapable of tolerating large displacements, massive embedded caisson foundations can be advantageous thanks to their rigidity. The paper explores the key mechanisms affecting the response of such bridge foundations subjected to dip-slip (normal or thrust) faulting. A series of physical model experiments are conducted in the National Technical University of Athens, to gain a deeper insight in the mechanics of the problem. The position of the caisson relative to the fault rupture is parametrically investigated. High-resolution images of the deformed physical model is PIV-processed to compute caisson displacements and soil deformation. A novel laser scanning technique, applied after each dislocation increment, reveals the surface topography (the relief) of the deformed ground. 3D finite element analyses accounting for soil strain-softening give results in accord with the physical model tests. It is shown that the caisson offers a kinematic constraint, diverting the fault rupture towards one or both of its sides. Depending on the caisson's exact location relative to the rupture, various interesting interaction mechanisms develop, including bifurcation of the rupture path and diffusion of plastic deformation.</p

Performance of Cotton Varieties Tested in Alabama, 1992

Caption title. Cover title: Performance of Cotton Varieties Tested in Alabama, 1992. "March 1993.

Performance of Ryegrass Varieties in Alabama, 1997-98

Cover title. "July 1998.

1994 Alabama performance comparison of small grain varieties for forage

Title from cover

Performance of soybean varieties in Alabama, 1992

Title from cover. "March 1993.

Performance of ryegrass varieties in Alabama, 1996-97

Title from cover. "July 1997.

1997 Alabama performance comparison of small grain varieties for forage

Title from cover

1994 Alabama performance comparison of small grain varieties

Title from cover