Dynamic actions on bridge slabs due to heavy vehicle impact on roadside barriers

The use of roadside safety barriers in Italy has changed in recent years: the number of installed devices has increased, and so have their stiffness and resistance. These changes were necessary because early barrier design was inadequate to contain and redirect heavy vehicles. The change in barrier design led to an increase in stiffness and resistance; consequently, the action transferred to the structure by the device increased. The need for resistance on the bridge slabs can be too high because the peculiar action of the roadside barriers was not adequately taken into account in the oldest bridge design codes. In addition, characterizing the actions transferred to the bridge slab is difficult because of the dynamic nature of vehicle impacts on roadside barriers. Given the impossibility of performing a full-scale laboratory test for every bridge deck, the use of computational mechanics applied to dynamic impact/interaction problems is one of the best ways to establish these actions in the project phase. Research was conducted into the use of a three-dimensional finite element model of the bridge slab-barrier-vehicle system to perform a numerical simulation of the impact, according to the procedure used for the roadside barrier homologation crash test, described in the European Standard EN 1317

Analysis of pavement condition survey data for effective implementation of a network level pavement management program for Kazakhstan

Pavement roads and transportation systems are crucial assets for promoting political stability, as well as economic and sustainable growth in developing countries. However, pavement maintenance backlogs and the high capital costs of road rehabilitation require the use of pavement evaluation tools to assure the best value of the investment. This research presents a methodology for analyzing the collected pavement data for the implementation of a network level pavement management program in Kazakhstan. This methodology, which could also be suitable in other developing countries’ road networks, focuses on the survey data processing to determine cost-effective maintenance treatments for each road section. The proposed methodology aims to support a decision-making process for the application of a strategic level business planning analysis, by extracting information from the survey data

Traffic dynamic effect on road bridge joint

In road engineering, also a well realized bridge expansion joints always creates a discontinuity in the road surface. This unevenness produce very important dynamic load increase due to the moving heavy vehicles. The dynamic component of wheel forces depends on the road pavement profile, the functional characteristics of the vehicle (geometry, mass and stiffness distribution, tire and suspension type, operative speed, etc.) and structural characteristics of the bridge superstructure (span length, geometry, static scheme, natural frequencies and damping). The dynamic actions can produce a general decay of the structure and local breaks near the biggest pavement unevenness for example near the Highway Bridge Expansion Joints (BEJ) and could decrease or cancel the skid resistance between road and tire, with dangerous consequences on traffic safety. Generally, it is recommended to consider the dynamic actions between the vehicle and the road. The definition of these actions is possible by means of the analysis of vertical accelerations measured, for example, on a heavy vehicle axle running on the joint. An innovative approach for solving the problem of dynamic interaction between heavy vehicle and BEJ is presented, taking advantage of the all purpose explicit finite element code LSDyna. The proposed model allows to determine, varying the parameters of the test vehicle (load, geometric dimensions and speed), of the JOINT unevenness dimensions (amplitude and wavelength) and of pavement modulus, the stresses and deformations on JOINT and of each pavement layer due to dynamic actions generated by vehicle motion. The model allows to also determine the accelerations on the vehicle, to verify the Ride Quality of a uneven pavement

Development of a HGV FEM for road safety analysis

In the last years roadside safety design, in particular for passive systems, was greatly improved with the possibility to use computational mechanics. Computational mechanics is based on the use of complex finite element codes, that allows the virtual reproduction of real world problems. Regarding roadside safety, the design phase was, until now, based on the use of simplified analysis, unable to describe accurately the complexity of vehicle impacts against safety hardware. To build a FE model for an impact problem many elements are necessary: • Model geometry. • Constitutive laws of the materials. • Links (rigid, cinematic, etc.) between bodies or part of them. • Definition and characterization of contact surfaces. This set of information is needed for each different body involved in the event; making the development of a complete model very much demanding, but once a part (subset) of the entire model has been accurately validated by the comparison with real experimental data, it can be used again and again in other analogous models. Our goal was to build and validate a FE model of a Heavy Goods Vehicle (HGV). We chose this kind of vehicle because it wasn't available and because it was useful to test the containment of the barriers, and to study the dynamic interactions between vehicle and road pavement. In particular, this vehicle can be used to test the safety barriers according to EN 1317 standard, for the H4a class of containment. It reproduces a FIAT-IVECO F180 truck, a vehicle with 4 axles and a mass of 10.5 ton (30 with the full load). The model (12337 elements and 11470 nodes) was built for and is ready to use with LS Dyna FE code from Livermore Software Technology Corporation

Finite Element Modeling of Aircraft Gear Interaction with Cement Concrete Pavement

Computational mechanics applied to dynamic impact/interaction problems is nowadays possible. This approach can be used to Jet the gear and pavement interact in a more complex and realistic way; the FE analysis evaluates either the contact forces and the stresses on the pavement and aircraft gear. This paper describes the development of a 30 Finite Element Model of a cement concrete pavement/joint system and an Airbus 300 gear. The code used to perform all the analysis was LS-DYNA v.950d, a nonlinear explicit Finite Element Analysis code. In order to examine the effects of the joint bump height and aircraft speed, two different pavement models were used, with and without dowels, running a total of 16+16 simulations (4 different speeds, 4 different bump heights for each model). The doweled joint model has been used to evaluate the joint Load Transfer Efficiency, the non-doweled model results have been compared to the values calculated using the Westergaard's theory

Localized scleroderma unius lateri and Borrelia burgdoferi infection

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Parental Risk Attitudes and Children's Secondary School Track Choice

It is well known that individuals' risk attitudes are related to behavioral outcomes such as smoking, portfolio decisions, and also educational attainment, but there is barely any evidence on whether parental risk attitudes affect the educational attainment of dependent children. We add to this literature and examine children's secondary school track choice in Germany where tracking occurs at age ten and has a strong binding character. Our results indicate no consistent patterns for paternal risk preferences but a strong negative impact of maternal risk aversion on children's enrollment in upper secondary school

Characterisation of the Cell Line HC-AFW1 Derived from a Pediatric Hepatocellular Carcinoma

Current treatment of paediatric hepatocellular carcinoma (HCC) is often inefficient due to advanced disease at diagnosis and resistance to common drugs. The aim of this study was to generate a cell line derived from a paediatric HCC in order to expand research in this field. We established the HC-AFW1 cell line from a liver neoplasm of a 4-year-old boy through culturing of primary tumor specimens. The cell line has been stable for over one year of culturing and has a doubling time of 40 h. The tumour cells have an epithelial histology and express HCC-associated proteins such as Alpha-fetoprotein (AFP), Glypican 3, E-cadherin, CD10, CD326, HepPar1 and Vimentin. Forty-nine amino acids in exon 3 of β-Catenin that involve the phosphorylation sites of GSK3 were absent and β-Catenin is detectable in the cell nuclei. Cytogenetic analysis revealed large anomalies in the chromosomal map. Several alterations of gene copy numbers were detected by genome-wide SNP array. Among the different drugs tested, cisplatin and irinotecan showed effective inhibition of tumour cell growth in a proliferation assay at concentrations below 5 µg/ml. Subcutaneous xenotransplantation of HC-AFW1 cells into NOD/SCID mice resulted in fast growing dedifferentiated tumours with high levels of serum AFP. Histological analyses of the primary tumour and xenografts included national and international expert pathological review. Consensus reading characterised the primary tumour and the HC-AFW1-derived tumours as HCC. HC-AFW1 is the first cell line derived from a paediatric HCC without a background of viral hepatitis or cirrhosis and represents a valuable tool for investigating the biology of and therapeutic strategies for childhood HCC

A Different Look at Lenin's Legacy: Trust, Risk, Fairness and Cooperativeness in the Two Germanies

What are the long-term effects of Communism on economically relevant notions such as social trust? To answer this question, we use the reunification of Germany as a natural experiment and study the post-reunification trajectory of convergence with regard to individuals' trust and risk, as well as perceived fairness and cooperativeness. Our hypotheses are derived from a model of German reunification that incorporates individual responses both to incentives and to values inherited from earlier generations as recently suggested in the literature. Using data from the German Socio-Economic Panel, we find that despite twenty years of reunification East Germans are still characterized by a persistent level of social distrust. In comparison to West Germans, they are also less inclined to see others as fair or helpful. Implied trajectories can be interpreted as evidence for the passing of cultural traits across generations and for cooperation being sustained by values rather than by reputation. Moreover, East Germans are found to be more risk loving than West Germans. In contrast to trust and fairness, full convergence in risk attitude is reached in recent years