Civil Engineering

Within this article it will be shown how the cable factor of deviated bundle tendons and accordingly the pressure between prestressing steel elements and duct can be determined exactly. The knowledge of the maximum pressure between strand/wire to the duct of a bundle tendon is important both to estimate the danger of fatigue fracture of the prestressing steel due to fretting corrosion when using corrugated steel ducts and to estimate the imprints into polyethylene ducts of bondless tendons. Polyethylene ducts serve as corrosion protection hulls for tendons. Especially for bondless tendons, it is necessary to limit the wear of the ducts to ensure the corrosion protection of the steel, the durability of the tendon and the tensioned structure. In the past, graphical methods had been applied as well as costly and time-consuming simulations of the arrangement of strands or wires in a duct with the help of small-scale models. For configurations other than the tested ones or for a higher number of wires in a duct these results cannot be used. That is why the authors developed two numerical approaches of how to arrange strands/wires in a duct (approach A: "Nonlinear Optimization", approach B: "M-PDS-algorithm"). After finding an optimal arrangement it is possible to determine the cable factors and thus the maximum pressure by he help of a two-dimensional truss calculation. Finally, two approaches for estimating the maximum cable factor are presented. They are reducing the calculation effort to different extents. The first approach is based on hydrostatic analogy. The second one is a simplified method that allows the quick estimation with the help of the relevant parameters in a short formula. In contrast to the exact solutions only the maximum value of the cable factors can be found, but not the pressures between strands/wires or the remaining pressures between strands/wires and duct, [1]. Nevertheless, with the help of the tools which are presented herein, the curvature design of deviated tendons can be reconsidered. In addition to that, they can contribute to a qualified assessment of the durability and efficiency of existing post-tensioning systems or to their development.

This paper provides an economical geodetic method for damage recognition on a pre-stressed concrete bridge built in the sixties. Numerical models based on Finite Elements (FE) analyses have shown that for the affected object a complete surveying of the bottom surface is necessary. Based on reflectorless electronic distance measurement (R-EDM) and a combination of a self-developed software application and motorized tacheometry a highway bridge with a length of 600 m is therefore scanned with 2800 points with a precision of 1-2 mm twice a year. Numerical simulations are used to minimize temperature and other environmental effects on the deformations of the bridge. Tests concerning accuracy and error estimations of R-EDM are discussed. Afterwards the technical realisation of the fully automated measuring process is explained in detail. Apart from the prismless measurements more than 60 prisms placed on the structure are surveyed as well in order to determine the horizontal movement of ...

The derived nature of transportation demand implies that enhancement of mobility per se is not a reasonable goal for transportation policy; instead, improved mobility is desired to the extent that it furthers accessibilityÐa goal that can be achieved through a variety of measures. The paper uses the mobility±accessibility distinction to distinguish different implementations of congestion pricing. A mobility-based congestion pricing promises to alleviate congestion but threatens to deteriorate from overall regional accessibility as it accelerates metropolitan deconcentration. In contrast, accessibility-based congestion pricing avoids acceleration of sprawl by incorporating policies to ensure that drivers tolled off roads are replaced with residents and travelers arriving at previously congested areas by other means. q

This paper describes a one-dimensional finite element code for debris flows developed to model the flow within a steep channel and the stopping conditions on the fan. The code allows the systematic comparison of a wide variety of previously proposed one-phase flow resistance laws using the same finite element solution method. The onedimensional depth-averaged equations of motion and the numerical model are explained. The model and implementation of the flow resistance relations was validated using published analytical results for the dam break case. Reasonable agreement for the front velocities and stopping location for a debris-flow event in the Kamikamihori torrent in Japan can be achieved with turbulent flow resistance relations including "stop" terms which allow the flow to come to rest on a gently sloping surface. While it is possible to match the overall bulk flow behavior using relatively simple flow resistance relations, they must be calibrated. A sensitivity analysis showed that the shape of the upstream input hydrograph does not much affect the flow conditions in the lower part of the flow path, whereas the event volume is much more important.

The paper presents the new international Master Programme "Environmental engineering" at the Technical University of Munich (Technische Universitat Munchen, TUM). In addition to the classical study course of civil engineering, this programme offers new opportunities especially for students who are more interested in natural science and/or in engineering sciences beyond civil engineering. Particularly for future environmental engineers with a specialisation in water issues, the TUM offers three special study lines: (1) Urban Environments and Transportation with focuses on drinking-water supply, wastewater treatment, and waste management; (2) Environmental Hazards and Resources Management with focuses on flood modelling and management, geo risks, and propagation of pollutants; and (3) Environmental Quality and Renewable Energy with focuses on water-resources management, water reuse, and hydropower. The future concept aims to couple research and teaching more closely, so that...