The Effect of Flange Length on the Distribution of Longitudinal Strain during the Flexible Roll Forming Process

Flexible roll forming is an advanced sheet metal forming process which allows the production of variable cross-section profiles. In flexible roll forming process, nonuniform transversal distribution of the longitudinal strain can cause the longitudinal bow, which is deviation in height of the web over the length of the profile. To investigate the effect of flange length on the transversal distribution of the longitudinal strain, FEM simulations are conducted with different flange length for three blank shapes; trapezoid, convex and concave. The result shows that the longitudinal strain and longitudinal bow decrease with increasing flange length for a trapezoid and a concave blank. For a convex blank, the longitudinal strain and longitudinal bow increase with increasing flange length. To validate FEM simulation result, numerically obtained longitudinal strain has been compared with experimental results.

Research on Utilization Characteristic and Management Issue of Asphalt Pavement of Airfield Runway on Highway

According to advantages of airfield runway on highway, at first the building effect and significance are analyzed, and then the utilization characteristic of asphalt pavement of airfield runway on highway is discussed through the aspects of transit load type, wheel imprint transversal distribution, traffic volume and service requirement, etc, in combination with practical situation of prevailing of asphalt pavement in China. In order to provide reference to management and maintenance of asphalt pavement of highway-runway, and satisfy the service requirement of vehicle and airplane, related discussion issues are proposed, such as pavement evaluation index system, performance comprehensive evaluation, residual service life prediction, evaluation system software, external quality evaluation method, etc.

Reinforcement of Timber Floors-Transversal Load Distribution on Timber-Concrete Systems

In this paper the transversal load distribution in timber-concrete systems is analysed and discussed. The analysis is based on experimental and numerical results obtained for real scale timber-concrete systems. Two situations are considered: a timber-concrete floor for a multi-storey building with dimensions of 3.39mx3.48m in plan view and a road bridge deck with dimensions of 5mx14m also in plan view. In both situations the systems were designed to the loads required by the European codes. The effect of the transversal load distribution was experimentally assessed by imposing concentrated loads in various locations, eccentric to both transverse and/or longitudinal direction. Additionally, FEM models were developed to describe the mechanical behaviour of the two composite timber-concrete systems. The results obtained with both methodologies are presented and discussed. Based on this discussion conclusions are drawn regarding the amount of transversal distribution that can be expected in this type of reinforcement solution.

The St Venant Zone Extent of the Self-Balancing Longitudinal Elastic Stress

In the gaps between cells within continuous groups of rolling mills, as a result of local temperature and mechanical factors, longitudinal elastic stress may arise in the strip; this stress is the sum of uniform and self-balancing components. These components affect metal flow in the deformation source. According to the St Venant principle, the influence of the self-balancing component declines with increasing distance from the point of action. The longitudinal and transversal distribution of the self-balancing elastic stress in the strip was analyzed as well as the maximum distance between the deformation source and the point of elastic stress in the strip at which the self-balancing component still affects the plastic deformation of the metal, i.e., the extent of the influence zone of the self-balancing component. The results of this analysis will be useful for a design of new flatness control methods and devices.

Calculation of Shear Lag in Cantilever Box Girder with Constant Depth

The physical explanations both of positive or negative shear lag are given in this paper. The shear lag effects occur attributing to the abrupt change of shear stress at junction upper the web. The abrupt change of shear stress or called shear stress jump changes the stress magnitude of the flange bending stress, which attenuates gradually at increasing distances from the web. Meanwhile, the abrupt change of shear stress from zero to the flange shear stress also influences the bending stress state at the centerline of the slab. The method to determine the shear lag has given, which is based on the Euler-Bernoulli elementary theory of bending. Considering the transversal distribution of the shear stress at the junction upper the web, the real flange bending stress could be calculated all on the section.