Static strength of doubler plate reinforced X-joints under out-of-plane bending

Experimental and numerical studies conducted by the authors have shown that the provision of a doubler plate at the connection between the brace and the chord can significantly improve the static strength of circular hollow section (CHS) joints. The size of the plate, however, may have important effects on the strength of the reinforced joints. Such effects on CHS X-joints subjected to in-plane bending have been investigated and reported by the authors. As part of an overall research effort, this paper presents the results of an investigation on the static strength of doubler plate-reinforced CHS X-joints loaded by out-of-plane bending. It is found that the ultimate strength of a CHS X-joint reinforced with appropriately proportioned doubler plates can be up to 290% to its un-reinforced counterpart. Based on the numerical results, a strength ratio function has been derived to estimate the ultimate strength of doubler plate reinforced CHS X-joints subjected to out-of-planebending.