Search results for "Structural engineering"
showing 10 items of 1998 documents
Numerical modelling of fatigue crack initiation and growth of martensitic steels
2010
This paper presents a numerical simulation of micro-crack initiation that is based on Tanaka-Mura micro-crack nucleation model. Three improvements were added to this model. First, multiple slip bands where micro-cracks may occur are used in each grain. Second improvement deals with micro-crack coalescence by extending existing micro-cracks along grain boundaries and connecting them into a macro-crack. The third improvement handles segmented micro-crack generation, where a micro-crack is not nucleated in one step like in Tanaka-Mura model, but is instead generated in multiple steps. High cycle fatigue testing was also performed and showed reasonably good correlation of proposed model to expe…
Crack growth in fillet welded steel joints subjected to membrane and bending loading modes
2020
Abstract The present paper presents the results from extensive studies of the fatigue damage evolution in fillet welded steel joints subjected to Constant Amplitude (CA) stress under membrane and bending loading modes. The welded joints in question are F class details (category 71) with plate thicknesses ranging from 25 to 32 mm. The steel quality is a medium strength carbon manganese steel. Crack growth histories for the shallow semi-elliptical shaped cracks emanating from the weld toe are obtained by an Alternating Current Potential Drop (ACPD) technique. These growth histories are presented in detail and modelled by Linear Elastic Facture Mechanics (LEFM). The calculations follow the rec…
Mapping and assessing coastal resilience in the Caribbean region
2015
Assessing the vulnerability and resilience to coastal hazards is a critical worldwide issue, especially for hurricane-prone coastal regions such as the Caribbean. However, the development of a useful metric for vulnerability and resilience assessment has a lot of challenges. Cartography and GIS analysis can contribute effectively to the solution of the issue by integrating natural and human data layers for assessment, mapping, and visualization. This paper uses the new Resilience Inference Measurement (RIM) model to assess the resilience of 25 countries in the Caribbean region to hurricanes. The RIM indices of the countries were computed using three variables representing three dimensions: …
Effect of the indentation process on fatigue life of drilled specimens
2015
Design and manufacture of mechanical elements are strongly influenced by the evaluation of the residual stresses due to their effects on the material strength. This paper presents numerical and experimental results performed on AW 6082-T6 aluminum alloy drilled specimens when the hole is created after a bilateral indentation process. The plastic deformation induced by the indenters creates a compressive residual stress field around the hole, which persists after the drilling operation. Several numerical analysis have been carried out in ANSYS APDL explicit solver for different indentation depths and hole diameters in order to evaluate the compressive circumferential stresses, optimal proces…
Simplified analytical model for flexural response of external R.C. frames with smooth rebars
2018
In this paper an analytical model in a closed form able to reproduce the monotonic flexural response of external RC beam-column joints with smooth rebars is presented. The column is subjected to a constant vertical load and the beam to a monotonically increasing lateral force applied at the tip. The model is based on the flexural behavior of the beam and the column determined adopting a concentrated plasticity hinge model including slippage of the main reinforcing bars of the beam. A simplified bilinear moment-axial force domain is assumed to derive the ultimate moment associated with the design axial force. For the joint, a simple truss model is adopted to predict shear strength and panel …
Regulation and efficiency: the case of European railways
2001
Abstract During the long period of regulation of the railway system in Europe (1950s–1990s) the companies notably improved their levels of productivity. However, parallel to this, the state of their financial accounts also significantly worsened. In order to explain this fact we have estimated both cost and revenue frontier functions, calculating the losses associated with both cost and revenue inefficiencies as well as inefficiencies on the cost side. The results obtained show the existence of significant potential losses of revenue, which can be explained above all by the strong policy of regulation and intervention reigning in this period. A better commercial policy and a supply adapted …
Price dispersion, competition, and the role of online travel agents: Evidence from business routes in the Italian airline market
2014
Abstract In this article, using data from the Italian airline market, we study the role of online travel agents (OTAs) in driving price dispersion as compared to the effect of airlines’ websites. Specifically, we investigate how distinctive factors between OTAs and airlines’ direct channels influence price dispersion. We find that after controlling for OTAs’ features related to airline competition, price dispersion should be lower in the OTA channel relative to airlines’ direct channels. On the other hand, we also find that OTAs’ features related to the presence of airline competition play in favor of higher price dispersion in such indirect channel.
The importance of the inland leg of containerised maritime shipments: An analysis of modal choice determinants in Spain
2011
Abstract While most of the studies that address competition between road and rail transport focus on national or international non-maritime shipments, there is practically no empirical evidence on the modal choice determinants of the inland leg of maritime shipments. This paper intends to fill that gap by estimating a modal choice model between road and rail transport on the inland leg of Spanish containerised maritime freight shipments, using a mixed logit model and stated preference techniques. The results obtained confirm the vital role that frequency plays in the relative competitiveness of rail transport and also provide subjective values of transport attributes that are deemed essenti…
Virtual element method for computational homogenization of composite and heterogeneous materials
2020
Abstract In this study, a two-dimensional multi-region framework, based on the use of the Virtual Element Method (VEM), is developed for computational materials homogenization and applied to different classes of widely employed heterogeneous materials. The VEM has recently emerged as a powerful generalisation of the Finite Element Method capable of dealing with very general polygonal mesh elements, including non-convex or highly distorted elements. Such features are appealing for the treatment of problems whose analysis domains present complex or statistical morphological features, which would generally require careful and time-consuming mesh/data preparation and regularization. In this wor…
Numerical and Experimental Analysis of the Frictional Effects on 4ENF Delamination Tests Performed on Unidirectional CFRP
2015
Abstract Progressive delamination in composite materials under static or fatigue loading condition are, in many structures, one of the predominant cause of failure. In the paper, an accurate study of quasi-static delamination growth under mode II loading condition is conducted. Several experimental tests are performed on composite laminates consisting of unidirectional carbon/epoxy layers. Four-point end-notched flexure (4ENF) test is employed in order to characterize the mode II interlaminar fracture toughness. The R-curve is obtained by means of optical and numerical determination of crack tip position. The energy release rate and the crack length are calculated through experimental deter…