Department of Architecture and Civil Engineering

Effects of blast loading on structures

At a glance

Funding body: University of Bath studentship
Researcher: Phil Isaac
Supervisors: Antony Darby (lead), Tim Ibell, Mark Evernden
Dates: 2009-2012

Abstract

The threat of terrorism has increased the need for engineers to have confidence that buildings can withstand the significant loads experienced during a blast event. The destruction of load bearing columns can lead to the more serious problem of progressive collapse, it is therefore important that suitable strengthening techniques can be developed to avoid column failure.

The rapidly time varying nature of a blast load means that analysis through traditional static methods is no longer accurate. Traditional analysis of this problem has tended to focus on the use of dynamic analysis techniques and the favoured approach has been the equivalent Single Degree of Freedom (SDOF) method. However, doubts have been raised over the accuracy of this method in predicting the behaviour of columns with low amounts of transverse reinforcement. These columns have been shown to fail through diagonal shear at both ends. As shear displacements are difficult to predict it is of little surprise that challenges in applying the SDOF model have been raised. This has lead this current research project to focus on alternative methods that may be able to better predict failure modes and the peak loads that can be carried by the column.

This research project plans to focus on the use of energy methods for analysis with the premise that the energy delivered by the blast must be equal to the energy dissipated by the structure. Energy can be dissipated in many forms depending on the mode of failure and a major challenge of this project will be determining the parameters that dictate the mode of failure. It is hoped that once an accurate understanding of the behaviour of a column is understood, a suitable fibre reinforced polymer (FRP) retrofit scheme can be developed. This will again be based on energy principles which will lead to a consistent approach to analysing an existing column and improving its behaviour under blast loading.