The last three years have witnessed many maritime accidents (like “Costa Concordia”, “Mol Comfort”, “MV Smart”, etc), which led to serious consequences including the loss of human life and asset and environment pollution. In order to mitigate loss, maritime emergency response requires time-saving. So, a fast numerical tool is very important for supporting decision making and related engineering work in emergency case. Currently, most fast numerical modeling method is either by manually laboriously building or requires 3D or 2D AUTO CAD drawing, which is very difficult to obtain in emergency situation. Thus this thesis is aiming to propose a fast numerical method based on limited information from emergency situation. Based on the fast numerical model, structural analysis, weight estimation, etc, can be assessed, thus supporting decision making and engineering work. In consistent with the emergency situation, global longitudinal bending strength is analyzed based on the fast numerical model in the present work. This thesis is divided into 3 parts: rapid numerical method and a corresponding numerical tool for container ship; verification of this numerical tool in global structural response and longitudinal ultimate bending strength assessment for container ship; longitudinal ultimate strength assessment for other types of structure like OT, BC, FPSO, etc. Firstly, in this thesis, a global data structure for storing ship geometric information from available drawings after emergency situation is developed in this thesis. Based on this data structure, a rapid numerical modeling method is developed in the present work. Then, a corresponding rapid numerical tool in container ship is produced. Secondly, the fast numerical tool is validated in structural response of global FE model of container ship. And the failure mechanism of container ship under sagging is investigated by both numerical model and analytical model. Based on it, the longitudinal ultimate bending moment is obtained by the generated fast numerical model. Finally, for other type of ship structures like OT, BC, FPSO, etc, the failure mode of the structure under pure bending is investigated by nonlinear finite element analysis. Based on the failure mode, a simplified method for assessing ultimate bending moment by NLFEM is proposed and validated with experiment result and ISSC benchmark study. This validated fast numerical tool for container ship can be used for structural analysis, structural weight estimation etc, and thus supporting engineering in emergency case. And the generic fast numerical method can be further applied for other types of ship structure, like OT, BC, FPSO etc. A corresponding simplified NLFEM method can be used for assessing maximum bending capacity and thus supporting lifting engineering work.