ABSTRACT
Steel structures are critical in resisting cycling loading due to the locations of high- stress concentrations. A large number of existing steel bridges suffer from ageing and fatigue issues and need to be retrofitted to increase their fatigue life. Disasters and catastrophes may happen if deteriorated components are not appropriately strengthened. Methods of retrofitting steel elements to increase their fatigue lives include drilling holes, stitching, welding steel plates, cold expansion and FRP composites. In this paper, these strengthening methods are described in detail and their efficiency in fatigue resistance is considered. In addition, prestressed carbon fibre reinforced polymer (CFRP) and shape memory alloy (SMA) strengthening methods are two techniques currently used in strengthening steel structures against fatigue loading. This paper identifies the advantages and disadvantages of each approach, including their duration and performance. Finally, some suggestions are made for future studies.
