Tropical pseudolinear and pseudoquadratic optimization as parametric mean-payoff games

We apply an approach based on parametric mean-payoff games to develop bisection and Newton schemes for solving problems of tropical pseudolinear and pseudoquadratic optimisation with general two-sided constraints.Comment: 30 pages (with appendices), 9 figure

Seismic Performance Assessment of a Pin-bearing Restraint System for Curved Bridge

The traditional restraint systems limit the deformation of curved bridge under temperature load, which results in radial and tangential secondary internal forces in the bridge. This paper proposes a pin-bearing restraint system (PBRS) for curved bridge, which can relax the rotational deformation of curved bridge under temperature load. Its configuration and working mechanism are illustrated. The finite element model of a curved bridge with PBRS is established using ANSYS software, and nonlinear time history analysis is conducted. The pounding force and pounding number between pin and slot under ground motion are analyzed. The pin stiffness, the gap and the ratio of upper structure mass to lower structure mass are selected for parametric study. The results show that the pounding force and pounding number present dramatic changes with pin stiffness. As the pin stiffness increases, the pounding force presents a logarithmic linear tendency, and the pounding number shows a reduce tendency. Gap has little influence on pounding force and pounding number. The radial pounding force and pounding number increase with the increase of mass ratio

Welding-induced Residual Stresses in U-Ribs of a Steel Bridge Deck

To calculate the welding-induced residual stresses in U-ribs of the steel deck plate and conduct quantitative analysis of influential factors, the U-ribs of steel deck plate of Xinghai Bay Bridge was taken as the research object. In the ABAQUS finite element software, the local models of U-ribs of steel deck plate were established. Nodal body force loads, i.e., heat generation rate, of the double ellipsoidal heat source models were applied via the compiled subsidiary Dflux program. The welding process of the v-groove welds was simulated, to obtain the residual stresses distribution in the top plate and U-rib plates. The influence of thickness of top plate and angle of welding groove on the residual stresses in the U-ribs were studied. The results show that the welding-induced residual stresses calculated by the numerical method proposed in this paper agree well with the experimental data. The maximum residual stresses in the top plates and the U-rib plates all occur near the welds, which exceeds the yielding limitation of the material. As the thickness of top plate increases, the maximum values of residual stresses in the top plates and U-ribs increase. However, with the increase of groove angle, the maximum values of residual stresses in the top plates and U-rib plates decrease

An evaluation method for corrosion fatigue life of steel structure considering mechanical factors

Steel structures in corrosive environment are often subjected to coupling effect and damage caused by corrosion and fatigue. This paper proposed a new assessment method to study corrosion fatigue life of steel structure, including the effect of cyclic loading and corrosion damage. Based on mechanical factors, the corrosion depth of structure under cyclic loading at different time intervals was defined by a mathematical model for corrosion damage. A finite element model was established to calculate structure damage. Finally, the cumulative damage could be obtained by Miner guidelines to assess the fatigue life. Comparing traditional methods, the coupling effect of corrosion and fatigue were taken into account by this new method. According to this new method, the results showed that the calculated corrosion rate was faster, and the corrosion fatigue life shorter. Corrosion fatigue could cause more damage to structure than was expected. Furthermore, this method was convenient and practical for assessing/estimating the corrosion fatigue life of normal steel structure