The crack causes of certain bridge tower are explained on the basis of the synthetic analyses of the crack character, material properties, structural specialties, environmental conditions and changes, and the analytical calculations.
Further discussion is made regarding the key issues in pier design, such as bearing structure, expression method and criterion of the degree of pre-stress forces, location of anchor strings, percentage of pre-stressed and non-prestressed reinforcement, causes for cracks and crack control, and so on and on.
This direct observation indicates that one of the primary causes of cracks in laser welded Au-coated materials is due to the segregation of Au in the final stage of solidification.
The presence of the crack causes higher order modes to be generated, which in turn influence the properties of the standing wave set up inside the waveguide.