Optimized design of deck longitudinals and permanent means of access structure at transverse bulkhead

The oil tanker is composed of double shell and single main deck, so the local high stress problem at the joint of deck longitudinals and transverse bulkhead is obvious, which is a threat to hull safety. In order to realize lightweighting design and satisfy the structural safety assessment as well, theoretical calculation, cargo hold structural strength analysis and local structural strength analysis were carried out. Optimized design method of permanent means of access (PMA) structure was provided in this paper. The discontinuous PMA does not participate in the deformation of transverse bulkhead, so its own weight is lighter and there is no stress concentration problem of itself. Continuous PMA participates in the deformation of transverse bulkhead, which can reduce the maximum stress by 42.5% of deck longitudinals and reduce 180 tons of structural weight in the cargo hold area. But there is a problem of stress concentration in the structure itself, which needs to be paid attention to in the progress of design. This paper can provide reference for design of other similar structures.