Seismic design of acceleration-sensitive non-structural elements in New Zealand: State-of-practice and recommended changes

Abstract

Acceleration-sensitive non-structural elements not only constitute a significant portion of a building’s component inventory, but also comprise components and systems that are indispensable to the operational continuity of essential facilities. In New Zealand, Section 08 of the seismic loadings standard, NZS 1170.5: Earthquake Actions, and a dedicated standard, NZS 4219: Seismic Performance of Engineering Systems in Buildings, address the seismic design of non-structural elements. This paper scrutinizes the design provisions for acceleration-sensitive non-structural elements in NZS 1170.5 and NZS 4219, and provides an international perspective by comparing with the design provisions for non-structural elements specified in ASCE 7-16, the latest ATC approach and Eurocode 8. This is followed by a detailed discussion on the improvements required for component demand estimation, the need for design criteria that are consistent with performance objectives, definition of realistic ductility factors, and recommendations for the future way forward in the form of an improved design procedure and its application through a new seismic rating framework.

Monotonic testing of brace assemblies for piping systems and considerations for capacity design

“…Rashid et al [6] includes a detailed discussion on the need for capacity design of brace assemblies and the relevant design approach. Here, the results from testing are used to support the arguments made in Rashid et al [6] in favor of capacity design.…”

“…Rashid et al [6] includes a detailed discussion on the need for capacity design of brace assemblies and the relevant design approach. Here, the results from testing are used to support the arguments made in Rashid et al [6] in favor of capacity design. First, the testing reveals that in all the rigid brace assemblies, except for variant 3 with PACs under compression, failure or damage was confined to the attachment components and nothing of significance happened in the brace elements.…”

“…New Zealand standards addressing the seismic design of non-structural elements allow reductions in the design force by relying on the ductility capacity of their seismic resisting elements [3,4]. Research has shown that seismic demands on acceleration-sensitive NSEs can be significant if resonance occurs between the supporting structure and the components attached to its floors [5][6][7][8][9]. Such demands can be reduced for the purpose of design by utilizing the ductility capacity of seismic restraints using empirical relationships between acceleration or force demand and ductility capacity [10].…”

Seismic performance characterization of fire sprinkler piping systems through shake table testing

“…Seismic demands on sprinkler piping systems should be estimated using a reliable yet simple procedure that can account for the dynamic characteristics of the system and the interaction between the piping system and the supporting structure. Current standards in New Zealand do not include any guidance on the determination of displacement demands on acceleration-sensitive systems that are also sensitive to displacements, for example, piping systems (discussed in detail in Rashid et al [11]). Future updates to these standards should include guidance on the determination of displacement demands, such as through the specification of a floor displacement spectrum, so that design decisions regarding bracing and clearance can be made based on the dynamic characteristics of the system and anticipated demands, rather than empirical guidelines.…”

Seismic design of buildings: Where to next?

“…Hence, seismic performance of non-structural elements (SPONSE) needs to improve in order to minimize financial loss in future earthquakes. Unsurprisingly, awareness of the importance of SPONSE research has significantly increased in NZ in the recent years [1][2][3], and researchers are striving to identify and amend the inherent weaknesses in the current design and installation practices [4][5][6][7] and to develop low-damage solutions for key NSEs [8][9][10][11].…”