Cross-sectional optimization of cold-formed steel channels to Eurocode 3

Cold-formed steel structural systems are widely used in modern construction. However, identifying optimal cross section geometries for cold-formed steel elements is a complex problem, since the strength of these members is controlled by combinations of local, distortional, and global buckling. This paper presents a procedure to obtain optimized steel channel cross-sections for use in compression or bending. A simple lipped C-shape is taken as a starting point, but the optimization process allows for the addition of double-fold (return) lips, inclined lips and triangular web stiffeners. The cross-sections are optimized with respect to their structural capacity, determined according to the relevant Eurocode (EN1993-1-3), using genetic algorithms. All plate slenderness limit values and all limits on the relative dimensions of the cross-sectional components, set by the Eurocode, are thereby taken into account as constraints on the optimization problem. The optimization for compression is carried out for different column lengths and includes the effects of the shift of the effective centroid induced by local buckling. Detailed finite element models are used to confirm the relative gains in capacity obtained through the optimization process

Detachment analysis of dehumidified repair mortars applied to historical masonry walls

An innovative laboratory procedure for the pre-qualification of repair mortars is described. The tested mortars are suitable for use with new dehumidified plasters applied to historical masonry walls. Long-term plaster detachment frequently occurs because of the mechanical incompatibility of mortar. The procedure consists of the application of static loads to mixed stone block-mortar specimens with particular characteristics, in terms of geometry and adhesion at the interface. A numerical simulation based on the cohesive crack model was used to follow the experimental data, in order to describe the evolutionary phenomenon of detachment as a function of a small number of parameters. The methodology is currently being used at Sacro Monte di Varallo Special Natural Reserve (UNESCO heritage site) in Piedmont (Italy

Numerical dynamic analysis of stiffened plates under blast loading

Using the general purpose finite element package Abaqus, an investigation has been carried out to examine the dynamic response of steel stiffened plates subjected to uniform blast loading. The main objective of this study is to determine the dynamic response of the stiffened plates considering the effect of stiffener configurations. Several parameters, such as boundary conditions, mesh dependency and strain rate, have been considered in this study. Special emphasis is focused on the evaluation of midpoint displacements and energy of models. The modeling techniques were described in details. The numerical results provide better insight into the effect of stiffener configurations on the nonlinear dynamic response of the stiffened plates subjected to uniform blast loading

Quantum Smoluchowski equation: Escape from a metastable state

We develop a quantum Smoluchowski equation in terms of a true probability distribution function to describe quantum Brownian motion in configuration space in large friction limit at arbitrary temperature and derive the rate of barrier crossing and tunneling within an unified scheme. The present treatment is independent of path integral formalism and is based on canonical quantization procedure.Comment: 10 pages, To appear in the Proceedings of Statphys - Kolkata I

Mechanical Behavior of Steel Pipe Bends; An Overview.

An overview of the mechanical behavior of steel pipe (elbows) is offered, based on previously reported analytical solutions, numerical results, and experimental data. The behavior of pipe bends is characterized by significant deformations and stresses, quite higher than the ones developed in straight pipes with the same cross section. Under bending loading (in-plane and out-of-plane), the main feature of the response is cross-sectional ovalization, which influences bending capacity and is affected by the level of internal pressure. Bends subjected to cyclic in-plane bending exhibit fatigue damage, leading to base metal cracking at the elbow flank. Using advanced finite-element tools, the response of pipe elbows in buried pipelines subjected to ground-induced actions is also addressed, with emphasis on soil-pipeline interaction. Finally, the efficiency of special-purpose finite elements for modeling pipes and elbows is briefly discussed. © 2016 by ASME

Investigation of progressive damage and fracture in laminated composites using the smeared crack approach

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97056/1/AIAA2012-1537.pd