Keywords: transient loading, impact, seismic, computational, spreadsheets.

This paper introduces a range of analytical tools which can be used to assess the potential response of a structure to transient loading including seismic and impact loading. These analytical tools can be implemented on charts (action diagrams) and spreadsheets for facilitating their application in practice.

The use of response spectra and the acceleration-displacement action diagrams are illustrated in the paper as low-tier design tools. Simulations of the time-history of the displacement of single-degree-of-freedom systems that can be implemented on spreadsheets are introduced. This simulation technique is further extended for analysing the response behaviour of two-degree-of-freedom systems which represent the interaction of a projectile and the targeted structure both of which are represented by a lumped mass. Screen dumps of the animation of the impact actions are displayed along with the time-histories of the internal forces developed during the impact.

Many commercial computer packages are capable of analyzing the response behaviour of a structure, a member, or a component to the environmental, or man-induced, hazards of wind, waves, earthquakes, impact and explosion. Simple manual calculations (that are assisted by electronic calculators and/or design charts) are as important in terms of providing benchmark references to the engineer of the order of magnitude of the response parameters for comparison with results obtained from the computer. Structural engineers are mostly equipped with the skills of analyzing simplified structural problems using basic engineering statics in order that checks can be undertaken on the computer output from full-scale structural analyses for static loadings. The overall trends in the changes of the response parameters to variations in the geometry of the structure and the loading patterns can also be inferred from simple manual calculations.

Few engineers have the skills to undertake their own checks on analyses involving transient loadings which can be the response to impact loads or ground shocks. Codes of practice often resort to the use of equivalent static loading which may give misleading results.

This paper provides an introduction to some useful concepts which yield approximate, and realistic, solutions to dynamic problems.

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