CAPACITY OF COLUMNS WITH SPLICE IMPERFECTIONS

This paper which discusses fracture mechanics and design, lists the factors that control the susceptibility of structures to brittle fracture, and outlines fracture criteria and the effects of temperature, loading rate and thickness. The paper also outlines a fracture control plan, discusses AASHTO material toughness requirements, and comments on fracture tests of welded beams. The primary factors controlling susceptibility to brittle fracture are: material toughness, flow size, and stress level. The factors involved in the development of failure criteria include service conditions, desired level of performance and margin of safety, and possible modes and consequences of failure. There are 2 general parts to fracture criterion: general test specimens to categorize the material behavior, and specific notch toughness value or values. A fracture control plan consists of identification of the factors contributing to fracture, establishment of the relative contribution of the factors, determination of the relative effeciency and trade-offs of various design methods and recommendation of specific design considerations. It is observed that the following factors are effective in improving service life: reduction of tensile design stress, reduction of initial flaw size, and increase of material thickness.