Damage Resistant Design

Introduction

Damage resistant design, also referred to as damage avoidance or damage control design, represents a new seismic design philosophy gaining acceptance amongst structural engineers the world over.

Modern approaches to seismic design have generally emphasised ductile building behaviour during earthquakes that prevents building collapse and loss of life but at the expense of controlled damage. Following severe shaking this damage can potentially render the building beyond economic repair.

The limitations of this approach are clearly evident in the aftermath of the 22 February 2012 earthquake. Christchurch experienced a seismic event of a severity even its modern buildings were not necessarily designed for, and which produced unprecedented soil liquefaction and lateral spreading.

While moderately aged reinforced concrete and reinforced concrete masonry buildings generally suffered structural damage they did not collapse (with two tragic exceptions). However, for a considerable number the damage meant demolition was inevitable.

Damage resistant design using concrete systems offers a means to design buildings that go beyond “life safety” to also allow for “building survivability”. Through the use of post-tensioned rocking walls or rocking column/beam joints in the form of PREcast Seismic Structural System (PRESSS) and the recently developed non-tearing joints (slotted beam) design, or elastomeric and sliding bearings in the form of base isolation, damage resistant design is an increasingly affordable option for structural engineers to create the next generation of New Zealand buildings.


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“Professionally its really important that we exhibit best practice all the time, and I believe this [damage resistant design] is becoming best practice.”

ALISTAIR CATTANACH
DUNNING THORNTON CONSULTANTS