The investigation found almost half the warehouses had panels that were poorly anchored at the base. File pic Photo: 123RF
Engineers investigating the design of warehouses have found almost half are done poorly and there is a threat to people from their heavy concrete walls falling over.
Their new report, coming eight years after warehouses in Masterton sparked investigations, listed a host of serious design shortcomings.
Engineering New Zealand's study of 20 warehouses was sparked by the poor earthquake design of six buildings in Masterton.
The deficiencies detected revolved around how the buildings hold together - their "connections" - and inadequate attention to what is holding their heavy concrete panel walls up - their "load paths".
Read the full report (PDF: 4MB)
"The deficiencies could mean concrete panels - typically found on the external walls - become dislodged during an earthquake, presenting a potential risk to life safety," Engineering NZ said.
It found 45 percent of panels were poorly restrained from falling inwards or outwards.
Also, 45 percent have concrete panels that were poorly anchored at the base.
This was found "frequently", despite concerns raised about such anchors after the Canterbury quakes of 2010-11.
Engineering NZ said it would send the report to regulators.
It was unclear what was happening with the 20 warehouses studied.
"In some cases, engineering designs have not addressed key structural design elements, including those that ensure load paths and detailing [that] are able to withstand seismic activity," the report said.
"In some examples, design engineers had incorrectly drawn or omitted critical details in their design of warehouses, such as the restraint of large concrete panels, which may present a life safety risk should they collapse during an earthquake."
The deficiencies are nothing new: "Such issues appear to have been present in the building system for some years," the report said, citing official findings in 2013 and 2016.
Long list of errors
Often the panels were secured using non-seismic bolts, which is substandard.
Out of all the designs, only one had key information about how to resist buckling.
Roof bracing typically was inadequate.
"There were incomplete load paths, eccentric cleat design, and bracing missing completely."
In several designs, key details were missing altogether.
Some had foundations that were too small.
"Designs did not typically allow for concrete shrinkage and movement."
Engineering NZ's sole recommendation in the report was that engineers were educated better, and it would be working on a technical design guide.
'Not isolated'
The Masterton buildings were all warehouses, flagged as a worry in 2015, leading to censure of chartered engineer Kevin O'Connor in 2021. They had brittle connections and heavy, precast concrete panels "likely to be unstable in a moderate to large earthquake".
Their owner, the Masterton Lands Trust, protested at how long it took ENZ to get around to a punishment the trust said was too weak.
It has taken till now, eight years on, for the wider inquiry to report back.
"The results suggest those issues relating to poor design and internal quality control seen in the Masterton buildings are not isolated," the new report said.
The regulator of the building code, the Ministry of Business, Innovation and Employment, distanced itself from the study, saying ENZ was better placed to discuss it.
"We expect that Engineering New Zealand will follow up with the owners of the buildings identified in its report and relevant local councils," national manager of building system assurance, Simon Thomas, said in a statement.
"It is worth noting that [the] investigations were solely focused on design plans, there were no in-person assessments of the buildings."
Thomas welcomed the move to educate engineers better.
The ministry's focus was on improving the building regulatory system to provide policy and technical advice "to meet current and future needs", he said.
The 20-warehouse study found:
- 45 percent had poor concrete panel anchorage, 32 percent average, and 23 percent good
- 45 percent had poor restraint on panels that is meant to keep them from falling (32, 23);
- 41 percent had poor bracing detail (36, 23)
- 41 percent had poor bracing capacity (41, 18)
- 32 percent had poor connection details (50, 18)
- 23 percent had poor foundation design (23, 55)
- 23 percent had poor baseplate connections (18, 59);
- 23 percent had poor restraint against buckling (32, 45).