Influence of Long-term Climate on Fatigue Life of Bridge Pier Concrete and a Reinforcement Method

This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers, considering the long-term climate. The paper suggests a method to predict the low-cycle fatigue life by demonstrating a thermal-fluid-structural analysis of bridge pier concrete according to long-term climate such as temperature, velocity and pressure of air and water in the process of freezing and thawing in winter. In addition, it proposes a reinforcing method to increase the life of damaged piers and proves the feasibility of the proposed method with numerical comparison experiment

Semi-analytical study of transient electroosmotic flow of Maxwell fluids in nanochannels grafted with a strong polyelectrolyte layer having layered distribution of charges

We theoretically study transient electroosmotic flow of general Maxwell fluids through polyelectrolyte grafted nanochannel with a layered distribution of charges. By applying the method of Laplace transform, we semi-analytically obtain transient electroosmotic flow from Cauchy momentum equation and Maxwell constitutive equation. For nanochannels grafted with polyelectrolyte layers having different layered distribution of charges, we study the influence of dimensionless relaxation time, dimensionless polyelectrolyte layer thickness and dimensionless drag coefficient on transient electroosmotic flow. We verify that adjusting charge distributions of the layer can control intentionally the direction of the flows as well as strength of electroosmotic flow

A nonlinear local equivalent stress method in stress analysis of concrete gravity dam

When the stress state of the structure is analyzed by the finite element method (FEM), the stress at the stress concentration points such as the dam’s heel and toe gets infinitely larger as the element size decreases. In order to overcome this defect, many equivalent stress methods of normal stress have been proposed to convert the FEM stress into equivalent stresses on the boundary between the dam and the foundation. This paper proposes a nonlinear local equivalent stress method that reflects the mechanical equivalent conditions and material continuity in the areas near the dam’s heel and toe and proves that the stress state obtained by the nonlinear local equivalent stress method is close to the actual stress state through calculation experiment. Keywords: Stress analysis of dam, Finite element method, Stress concentration, Equivalent stress method, Nonlinear local equivalent stress method, ANSYS, MATLA