Case study

Blast resistant design

The challenge

Control buildings and other critical structures on oil refinery sites must be blast resistant to ensure that people and critical equipment are protected. Our client builds the fully fitted out blast resistant modules, including control buildings and substations, in parts to be shipped to site. There are often requirements for large open spans, which means that the roof structure and connections are particularly critical. Our skills and experience mean we can produce a building which meets all the strength requirements but is as light as possible and easy to construct, enabling our client to win projects in a competitive market place.

Our involvement

Initially we carried out scoping calculations on the building which enabled our client to enter a competitive bid and win the work. We were then awarded the contract to carry out the outline design and supporting blast and code assessments for the building. Using the structural form we proposed at the bid stage, a finite element model was produced and analysed under the blast loading defined by the operator. A full dynamic analysis was carried out for each wall facing the blast, which showed that the building was efficiently designed, with some plasticity but deflections within allowable levels. The finite element model was also used for the transportation analysis, since lifting the half sections of building places large loads on the structure. Since the building was to be manufactured in the UK and shipped to Australia, an assessment of the fatigue damage from transportation and shipping loads was carried out. The building had to meet Australian structural steelwork codes, so a set of calculations were prepared demonstrating compliance under the required environmental loads, including the extremely high wind speeds for North Western Australia.

Extra added value

By building good relationships with our client and keeping them informed of the direction of the design, we ensured that when it came to construction, there were no hold ups. This enabled the client to produce the building on schedule for shipment to Australia. Our blast design skills have be applied to numerous applications such as concrete structures, offshore steel structures and pressure vessels for both internal and external blast.

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Figure 1: Full building dynamic finite element blast assessment

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