The Analysis And Design Of Blast Wall On Offshore Platforms

Blasts are a credible topsides structural design consideration; they are low probability incidents with possibly severe consequences. A blast occurs if the circumstances of a hydrocarbon release permit the build-up of an explosive mixture of hydrocarbon gas, or vapor and air, followed by a delayed ignition. Profiled barriers have been increasingly used as blastwalls in typical offshore topsides modules to provide a safety barrier for working personnel and critical equipments. This paper presents the study on the design and analysis of stainless steel profiled barriers subjected to blast load, the main contents are as follows:1) Research on the modal approximation method, introduce the equivalent single-degree-of-freedom (SDOF) systems, which were developed to approximate the structural response, a beam model is applied in the analysis to represent the corrugated panel, the relationship between the central deflection of the corrugated panel and the external distributed load is concerned.2)Introduce the design guidance Technical Note 5(TN5) issued by the Fire and Blast Information Group, give a basic procedure for designing blast walls in accordance with this guidance, and finally provide an example on the design of blast wall by TN5.3) Carry on a study about the nonlinear property of corrugated panels by using FEM software ABAQUS/Explicit. The study considers 3 different profiled barrier sections, distinguished by the depth of the sections in accordance to the Technical Note 5 (TN5) issued by the Fire and Blast Information Group, and subjected to dynamic loadings. A comparison on the responses of the blastwalls obtained from both TN5 and NLFEA methods are given. Then comparisons on the responses of the blastwalls using different materials and different loading description are made. The design overpressures and duration are selected so as to represent realistic values that results in either an elastic and plastic response of the blast barrier. A simple research on strain rate effect is conducted. And the sensitivity of peak displacements, plastic strains and dissipated energy to mesh density and loading are also investigated.4) A finite element model is built by using Ansys 10.0, which is a complete structural model representing the topsides of a TLP (tension leg platform). Plate elements representing blast panels were added for application of blast overpressure. Detailed discussions of blast wall design, analysis methodology, modeling, load development and analytical result are presented .Equivalent nonlinear static analyses are performed, and dynamic load factors are considered to account for the dynamic nature of blast loading.