Soil structure interaction of integral abutmentb bridges

Integral Abutment Bridges (IAB) are defined as simple or multiple span bridges in which the bridge deck is cast monolithically with the abutment walls. Integral abutment bridges are becoming very popular due to its good response under seismic loading, low initial costs, elimination of bearings, and less maintenance. However the main issue related to the analysis of this type of structures is dealing with soil-structure interaction of the abutment walls and the supporting piles. The interaction between the structure and the adjacent soil media is essential in analysis, and gives a better prediction of the structural behavior compared to the analysis of the structure alone. Large varieties of soil constitutive models have been used in studies of soil-structure interaction in this kind of structures by researchers. This paper is an effort to review the implementation of finite elements model which explicitly incorporates the nonlinear soil and linear structural response considering various loading condition and finite element models

Masonry units bound with waste vegetable oil – Chemical analysis and evaluation of engineering properties

Masonry units with attractive environmental credentials can be produced from waste aggregate materials and vegetable oils. Heat curing at low temperatures induces chemical changes in the binder which stiffen the block and afford them a compressive strength which can be compared to existing blocks and bricks. This method allows use of 100% waste materials, which far exceeds the level of replacement possible in traditional concrete and clay matrices. To better understand the chemistry of the vegetable oil binder at different stages of the curing process a range of experiments have been performed including infrared spectroscopy, liquid chromatography and mass spectrometry. Results show production of chain-shortened and oxygenated derivatives and the nature of reactions based on curing time and physical environment of the binder. Compressive strength and mass loss are dependent on curing time and the altered molecular architecture of the oil, but other physical properties are independent of the chemistry and reliant on physical concerns such as aggregate selection

Predicting the tensile creep of concrete

Over a four year period, six phases of testing were performed to observe the influence of age at loading, applied stress level, mix composition and relative humidity on the tensile creep of concrete. From these investigations it was possible to develop a model which allowed the prediction of tensile creep based on a knowledge of the compressive strength of the concrete (determined at the age of loading), the applied stress level and the relative humidity. Subsequently, this model was validated using the results from three independent investigations. Compressive creep as well as tensile creep was also obtained. This allowed a comparison of compressive creep with tensile creep and illustrated that on the basis of equal stresses, tensile creep is on average between 2 and 3 times greater than compressive creep (the maximum ratio is in excess of 8). For this investigation, however, on the basis of stress/strength ratio the difference between tensile and compressive creep is less significant. Considering a simply supported flexural reinforced concrete element, the investigation suggests that it is unwise to consider actual compressive creep equal to actual tensile creep as is often the case in design practice

Employee involvement and participation : developing the concept of institutional embeddedness using WERS2004

It is widely accepted that employee involvement and participation (EIP) is a key component of the high commitment bundle of HRM, but that it can take a range of forms in practice. Much of the analysis to date has either treated different forms of EIP as a single construct or has measured EIP by virtue of its presence or absence alone. Drawing on earlier work based on the data from WERS1998 examining the link between various forms of EIP and employee outcomes such as job satisfaction and organisational commitment, the authors re-apply and extend these ideas to data from WERS2004. In particular they develop the concept of institutional embeddedness, in order argue that both the depth and breadth of EIP have important associations with commitment though not with satisfaction. This association held for workplaces employing 25 or more workers, and here it was apparent that the more that employees are involved at workplace level – through a wider number of EIP practices that are held more frequently and include opportunities for workers to have their say – the more likely it is that investments in EIP will reap the reward of organisational commitment. For smaller establishments, given that they tend to operate with relatively few formal schemes, it is likely that managers in these workplaces find alternative ways in which to engage the workforce, and that informal EIP offer similar levels of embeddedness in these situations. A clear implication to be drawn from the findings is that, in a context of lower levels of formality within organisations (large and small), line managers are more than ever the key link between HR policy and the embodiment of actual practice at the workplace