AS3600 section 14 for Buildings classified as EDC1

[Ross P]

I have a query relating to structures less than 12m high, and classified as Earthquake Design category 1 (EDC1).

My understanding is that if a structure is categorised as EDC1, in accordance with AS1170.4 section 5.3, then the structural elements do not need to comply with AS3600-2018 - Design for Earthquake Actions. Section 14 of AS3600 does not expressly state that section 14 does not apply to structures categorised as EDC1, however I would like further comment. If a structure is EDC1, then sections 5.2 and 5.3 are applicable, and a static force of 0.1Wi is applied to the structure.

Thanks in advance.
Ross

 

[rapt]

Have you read AS3600-2018 section 2.1.2?

 

[Ross P]

Thanks rapt,

I think you have pointed me into the right direction. AS3600-2018 section 2.1.2 clarifies the use of section 14 for structures designed for earthquakes using AS1170.4.

In the case of a structure categorised as EDC1, base shear Fi = 0.1Wi, and members are designed and detailed in accordance with section 14.4 and if structural ductility factor greater than 1, the code directs one to other parts of the code such as sections 14.5, 14.6 or NZS codes etc.

any further comments welcome.

 

[Reo-Checka]

Hi Ross P,

It's not that an ECD1 structure would not need to comply with AS3600-2018, but that clause 5.3 of 1170.4 is based on a theory that does not model the behaviour of a structure that is <12m under earthquake loads.

You are still in compliance with AS3600-2018.



ReoChecka

https://reochecka.com.au/

 

[Ross P]

I have been in contact with Scott Menegon and John Wilson (Swinbourne Uni), and quote Scott's comments below,


Hi Ross,
EDC 1 has no specific requirement to design the structure for ductility. If you refer to the commentary of AS 1170.4 (published by AEES), under Clause C5.3 with respect to EDC 1 it says “In this category there is no need to specify the ductility to be achieved by the structure”.
However, despite this, we would still strongly encourage detailing RC structures for a ductility factor of 2 even when designing them as an EDC 1 type structure. Further, please note that the commentary to AS 1170.4 is currently under revision and will be updated this year, which will include advice strongly encouraging designers to detail EDC 1 RC structures for a limited ductile classification.
Hope this helps.
Kind regards,
Scott


Hi Scott,
This does help, and thank you for your reply. I am in the “design and Construct” industry, and builders have been used to constructing wall elements with 150 thick precast with a central layer of class “L” reinforcement.
It is now looking like (with respect to earthquake restraining elements), that precast walls will become a minimum 180mm thick, with two layers of “N” class reinforcing bar. I do think that further communication with engineers and especially builders will be required to make sure that this is understood and will become the norm as we continue to develop robust earthquake detailing.
Ross

Hi Ross,
I broadly place precast walls in two categories: 1. Warehouse walls that support a light weight structural steel roof; and 2. Walls that are supporting a suspended concrete slab in a single or multi-storey building. I think the continuation of using 150 thick panels with central mesh is OK in the former, obviously if the system is designed appropriately. However, in the case of the latter, I believe there is no place for them and they should be a minimum of 180 thick with two faces of N grade bars (non-load bearing façade panels not included).

The CIA is currently organising a national seminar on the topic (earthquake detailing for RC buildings), which I think will be held in April this year. Hopefully this will help, communication wise with the industry as you mention.

Kind regards,

Scott