YUTHDANAI PETCHDEMANEENGAMCIVIL & ENVIRONMENTAL ENGINEERING2012-04-302012-04-302011-09-16YUTHDANAI PETCHDEMANEENGAM (2011-09-16). Plasticity-Induced Fatigue Crack Closure For Structural Steels In Offshore Applications.. ScholarBank@NUS Repository.https://scholarbank.nus.edu.sg/handle/10635/32487This thesis investigates experimentally and numerically the plasticity-induced fatigue crack closure (PIFCC) behavior in S355 offshore structural steels through large-scale in-plane bending fatigue tests of circular hollow section (CHS) X-joints and small-scale fatigue tests of C(T) and M(T) fatigue specimens. The full-scale testings investigate the fatigue performance of the tubular joints fabricated using the enhanced partial joint penetration (PJP+) weld with different applied load ranges, post-weld surface treatments, residual stresses, and overload tests. The small-scale testings examine the effects of in-plane constraints (specimen type) and out-of-plane constraints (thickness and side-grooving). The numerical study utilizes the node-release technique to simulate the fatigue crack closure and to compute the crack opening load. The PIFCC effect in fatigue specimens appears to be strong whereas remains negligible for full-scale tubular joints with surface cracks under constant-amplitude loading.enPlasticity-induced fatigue crack closure, fatigue cracks, tubular joints, enhanced partial joint penetration welds, overload, node-release techniqueThesisNOT_IN_WOS