Seismic design for temporary works: Recommendations for a Temporary Works forum NZ design note

Abstract

The Temporary Works forum NZ (TWf NZ) aims to improve construction safety by addressing risk in the design and execution of temporary works. Anecdotal evidence suggests that seismic actions on temporary works are often inadequately considered by designers, or not considered at all. Similarly, many principles associated with robust seismic performance are not being followed in temporary works’ design.

In this paper the seismic design of temporary works is examined to establish best practice, and to inform the development of a TWf NZ Guidance Note. The paper includes a literature review to establish international practice and current NZ code requirements, a discussion on seismic risk relating to temporary works, and discussion on the principles of efficient design as it relates to seismic performance of temporary works. Case studies explore how these principles have been applied on projects, some of which have been tested by earthquakes.

From our literature review and case studies, our recommendations for a TWf NZ design note are summarised as follows:

• The design process for all temporary works must consider earthquake loading and consequences of failure. This is a requirement of the NZ Building Code. NZS1170.5 provides the necessary seismic parameters for temporary works design. Consider elevated importance level where consequences of failure are high. Consider parts and components loading when appropriate.

Principles of robust detailing and design for uncertainty are as important for temporary works as they are for permanent works design. Where possible, capacity design principles should be applied in temporary works design to reduce the risk of brittle failure.