Improved Equivalent Frame Analysis Method for Flat Plate Structures in Vicinity of Edge Columns

This paper proposes a modification to the ACI 318-02 equivalent frame method of analysis of reinforced concrete flat plate exterior panels. Two existing code methods were examined: ACI 318 and BS 8110. The derivation of the torsional stiffness of the edge strip as proposed by ACI 318 is examined and a more accurate estimate of this value is proposed, based on both theoretical analysis and experimental results. A series of 1/3-scale models of flat plate exterior panels have been tested. Unique experimental results were obtained by measuring strains in reinforcing bars at approximately 200 selected locations in the plate panel throughout the entire loading history. The measured strains were used to calculate curvature and, hence, bending moments; these were used along with moments in the columns to assess the accuracy of the equivalent frame methods. The proposed method leads to a more accurate prediction of the moments in the plate at the column front face, at the panel midspan, and in the edge column. Registered Subscribers: View the full article. This document is available as a free download to qualified members. An electronic (PDF) version is available for purchase and download. Click on the Order Now button to continue with the download.

Modified stiffened panel analysis methods for laser beam and friction stir welded aircraft panels

The introduction of advanced welding methods as an alternative joining process to riveting in the manufacture of primary aircraft structure has the potential to realize reductions in both manufacturing costs and structural weight. Current design and analysis methods for aircraft panels have been developed and validated for riveted fabrication. For welded panels, considering the buckling collapse design philosophy of aircraft stiffened panels, strength prediction methods considering welding process effects for both local-buckling and post-buckling behaviours must be developed and validated. This article reports on the work undertaken to develop analysis methods for the crippling failure of stiffened panels fabricated using laser beam and friction stir welding. The work assesses modifications to conventional analysis methods and finite-element analysis methods for strength prediction. The analysis work is validated experimentally with welded single stiffener crippling specimens. The experimental programme has demonstrated the potential static strength of laser beam and friction stir welded sheet-stiffener joints for post-buckling panel applications. The work undertaken has demonstrated that the crippling behaviour of welded stiffened panels may be analysed considering standard-buckling behaviour. However, stiffened panel buckling analysis procedures must be altered to account for the weld joint geometry and process altered material properties. © IMechE 2006.

General rules for predicting where a catalytic reaction should occur on metal surfaces: A density functional theory study of C-H and C-O bond breaking/making on flat, stepped, and kinked metal surfaces

To predict where a catalytic reaction should occur is a fundamental issue scientifically. Technologically, it is also important because it can facilitate the catalyst's design. However, to date, the understanding of this issue is rather limited. In this work, two types of reactions, CH4 CH3 + H and CO C + 0 on two transition metal surfaces, were chosen as model systems aiming to address in general where a catalytic reaction should occur. The dissociations of CH4 - CH3 + H and CO --> C + O and their reverse reactions on flat, stepped, and kinked Rh and Pd surfaces were studied in detail. We find the following: First, for the CH4 Ch(3) + H reaction, the dissociation barrier is reduced by similar to0.3 eV on steps and kinks as compared to that on flat surfaces. On the other hand, there is essentially no difference in barrier for the association reaction of CH3 + H on the flat surfaces and the defects. Second, for the CO C + 0 reaction, the dissociation barrier decreases dramatically (more than 0.8 eV on Rh and Pd) on steps and kinks as compared to that on flat surfaces. In contrast to the CH3 + H reaction, the C + 0 association reaction also preferentially occurs on steps and kinks. We also present a detailed analysis of the reaction barriers in which each barrier is decomposed quantitatively into a local electronic effect and a geometrical effect. Our DFT calculations show that surface defects such as steps and kinks can largely facilitate bond breaking, while whether the surface defects could promote bond formation depends on the individual reaction as well as the particular metal. The physical origin of these trends is identified and discussed. On the basis of our results, we arrive at some simple rules with respect to where a reaction should occur: (i) defects such as steps are always favored for dissociation reactions as compared to flat surfaces; and (ii) the reaction site of the association reactions is largely related to the magnitude of the bonding competition effect, which is determined by the reactant and metal valency. Reactions with high valency reactants are more likely to occur on defects (more structure-sensitive), as compared to reactions with low valency reactants. Moreover, the reactions on late transition metals are more likely to proceed on defects than those on the early transition metals.

Parenting practices in Northern Ireland: evidence from the Northern Ireland Household Panel Survey

The impact of parental child-rearing practices on child outcomes has been the subject of much research and debate for many years. Studies carried out within a variety of disciplines and across a number of different countries in the world have indicated that parents tend to use a different pattern of rearing their sons than their daughters, and that child-rearing practices are related to the gender of the parent, as well as to the age and developmental stage of the child. However, there has been little research in Northern Ireland on child-rearing behaviours. In order to address this shortfall, this paper presents an analysis of parents’ perceptions of their interactions with their children. Data from Wave 3 of the Northern Ireland Household Panel Survey were analysed to explore aspects of ‘‘negative’’ parenting practices (arguing, yelling and use of physical punishment) as well as ‘‘positive’’ parenting practices (talking, praising and hugging). The participants were all parents (aged 16 years and over) with children under the age of 16 years living in the same household. Each parent reported his/her interaction with each child (up to a maximum of six children), and in total 1,629 responses were recorded. The results of the research supported previous findings from the United Kingdom and elsewhere, and indicated that the parenting styles of respondents in Northern Ireland were indeed related to the gender and age of the children and to the gender of the parents. The survey found that parents in Northern Ireland tend to have a harsher, more negative style of parenting boys than girls and that children in their teenage years have fewer positive interactions with their parents than younger children. The same parents and children will be followed up in 2007 in order to provide a longitudinal analysis of parent/child relationships in Northern Ireland.

A panel of single locus minisatellite DNA probes for application to problems in salmonid aquaculture

Eleven minisatellite DNA locus specific probes, isolated from Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) partial genomic DNA libraries, were tested for cross-hybridization to eleven other salmonid species, i.e. sockeye salmon (Oncorhynchus nerka); coho salmon (O. kisutch), chum salmon (O. keta); pink salmon (O. gorbuscha); chinook salmon (O. tshawytscha); rainbow trout (O. mykiss); brook trout (Salvelinus fontinalis); Arctic charr (S. alpinus); grayling (Thymallus thymallus); huchen (Hucho hucho); pollan (Coregonus autumnalis). Simple single locus profiles for each of these species were revealed by, from two to ten SLPs. These markers are likely to be of great value in addressing several problems in aquaculture of these species.