Mid-spliced end-plated replaceable links for eccentrically braced frames

摘要

Eccentrically braced frames (EBFs) can be re-used after a major seismic event by replacing the link members. Recent years have witnessed the development of numerous replaceable links. Among various details developed for this purpose, extended end-plated replaceable links are found to be the most efficient. The use of these links enables the engineer to minimize the size and the weight of the part to be replaced. In addition, the performance of end-plated links is similar to that of conventional links. Research reported to date has shown that end-plated links have disadvantages in terms of removal and replacement. Large axial forces can develop within the link member. Removal and replacement operations may require the use of hydraulic jacks to push the ends of the collector beams and the flame cutting of the links to gradually release the residual stresses and deformations. More important are the difficulties associated with link replacement under residual frame drifts. A novel detachable, replaceable link is proposed in this study which employs a splice connection at the mid-length of the link. The splice connection consists of channel sections welded to both parts of the replaceable link. The detail employed provides an erection tolerance which facilitates easy removal and enables replacement under residual frame drifts. Proof-of-concept testing of the proposed links was performed on 3 specimens where the type of force transfer in the splice connection was considered as the prime variable. All specimens failed at link rotation angles that were significantly higher than the link rotation angle required by AISC341 and demonstrated the potential of the proposed link concept. Complementary finite element parametric studies were conducted to validate the design procedure developed for the proposed replaceable link concept.