State-of-the-art of spatial arch bridges

The paper describes a new form of bridge called a spatial arch bridge. This bridge type was developed in response to the demand for landmark structures, which have started to appear in the modern urban landscape to provide a symbol of originality, innovation and progress. Spatial arch bridges are defined as bridges in which the vertical deck loads produce bending moments and shear forces not contained in the arch plane, owing to their geometrical and structural configuration. Moreover, the arch itself may not be contained in a plane. The different variables and geometries that create such a structural configuration have been studied and classified. A wide compilation of examples of this bridge type has been made in chronological order, according to their construction date, from Maillarts first concrete spatial arch bridges to the latest designs and materials

Rock mass characterization using MWD data and photogrammetry

Measurement while drilling data are produced in enormous quantity in underground and surface mines across the world. The data comprise parameters recorded during the drilling process, including penetration rate, rotation pressure, feed pressure, percussive pressure, damping pressure and flush pressure. MWD data are shown to be very useful for rock mass characterization, blasting applications and geological modelling of the rock mass. In this study, an open pit mine in Austria was selected for data collection as a part of SLIM project. The MWD data collected from drilling rigs were processed to identify different zones of rock mass, i.e. weak, fractured or competent rock. The results were compared to 3D images obtained by close-range terrestrial digital photogrammetry for validation; which showed a close agreement with each other. The method can be used to characterize the rock and to modify the charging of explosives in the boreholes for improved blasting results.ISBN för värdpublikation: 978-0-367-33604-2, 978-0-429-32077-4</p

Empirical functions for dependent variables in cutback furrow irrigation

Water scarcity and the high consumption of water resources in agriculture have strengthened the need to manage and optimize irrigation systems. Among surface irrigation systems, furrow irrigation with cutback is commonly used because of its potentially higher irrigation efficiency, lower costs and relative simplicity. The performance of this system is affected by various management and design variables, and hence different management scenarios should be evaluated before it is applied in practice. For this purpose, empirical functions for the performance evaluation indices are useful. This paper employs sensitivity, dimensional and regression analyses in the development of empirical functions for application efficiency, deep percolation, runoff and distribution uniformity. The proposed functions were evaluated using a numerical zero-inertia model and field measured data. Coefficients of determination for Ea, Dr, Rr and Ucc were calculated to be 0.90, 0.91, 0.90 and 0.84, respectively. These values indicate that the proposed functions enable the performance indices to be predicted satisfactorily. Values for the indices calculated using the developed dimensionless functions showed a very good agreement with both the outputs of the zero-inertia model and values calculated from measured field data. As the functions were general (not site and irrigation specific) and explicit, they could prove to be of practical significance in both conventional and optimal design and management of free draining, graded furrow irrigation systems with cutback flows