A self-anchored suspension bridge with a large span arrangement (210+600+200) m is designed for urban railway in the city Chongjin of China. The deck system of the bridge also has some special features. A rubber layer between the concrete slabs and the orthotropic steel deck is used to absorb the vibration energy. In order to study the fatigue behaviour of the orthotropic steel deck, a finite element model is established, and the weld in the rib-to-diaphragm region is modelled by the oblique shell element. After the reference stress was defined, the stress influence lines of the details were calculated, and then the stress ranges were counted by the rain-flow method. The nominal stress method was adopted to assess the fatigue behaviour of the concerned part. Apart from that, the circle form cut out was compared with the key form used in this bridge. Due to the stress dispersing in the concrete slab, the results show that the stress ranges keep at a relatively low level in the details of the two cut out forms. The key form of a cut out is eventually adopted because it is easy to assemble the ribs and diaphragms with a relatively large weld tolerance. (C) 2016 The Authors. Published by Elsevier Ltd.