The nonlinear response of the hull girder to global loads is treated in this chapter. These include torsional loads, the result of major damage leading to loss of longitudinal strength of part of the hull girder, and hull girder collapse. In the case of torsional loads, of critical importance is the position of the shear centre, and this depends on hull girder geometry (closed or open section). The effect of structural arrangements is then described in relation to longitudinal warping. The effect of discontinuities is discussed and design issues are considered. Combined and coupled horizontal bending and torsion are treated next. The next section deals with the determination of reserve strength of the hull girder following damage. The approach followed by a classification society to calculating residual strength is described and the use of IACS Common Structural Rules in calculating residual strength of oil tankers is presented. The topic of the last part of the chapter is the ultimate strength of the hull girder in longitudinal bending. The need to calculate ultimate strength is discussed, followed by the calculation of ultimate strength using a simplified, upper bound approach. Progressive collapse analysis is presented and this allows for the gradual spread of elasto-plastic behaviour in individual stiffened plate elements of the hull girder.