Hurricane Cannon tested at Diamond Head Crater

University of Hawai'i researchers have built a specialized cannon that fires two-by-four timbers into walls and doors.

(Image: The University of Hawai'i's Hurricane Cannon, within the “windborne debris test facility” inside Diamond Head Crater. Credit: Ian Robertson.)

They will use it to test the ability of Hawai'i structures to withstand the kinds of forces generated by hurricanes. The first test is scheduled today (Aug. 19, 2010)

Anyone who has seen the power of items driven by hurricane winds knows what that's about. Entire roofs skating through the air like a Frisbee. Sheets of corrugated roofing whizzing across the landscape at shoulder level. Stuff embedded in solid walls.

The cannon is the work of Mānoa professors Ian Robertson and H. Ronald Riggs of the Civil & Environmental Engineering Department. Their device, which looks like nothing so much as a giant potato gun, was constructed with support of Hawai'i State Civil Defense.

It will fire nine-foot two-by-fours at up to 80 miles an hour.

It's not the first such cannon to be developed. Some of the early work in the field was performed at the Texas Tech University at Lubbock. Among their findings was that a “2 × 4 in. plank perforates the face shell of unreinforced concrete masonry at about 65 mph.”

One target of the Hawai'i research will be the kinds of wall systems proposed for safe rooms. These are armored rooms that can be built into a home, where residents can be sheltered from the kinds of flying debris that would readily smash through windows and plywood walls.

Safe rooms on Kauai, where the community has recent experience with hurricanes Iwa and Iniki, qualify homes for property tax breaks.

The goal of the Hurricane Cannon with respect to safe rooms is to work with structural engineer Gary Chock of Martin & Chock to help develop economical designs for safe rooms that can be used in Hawai'i homes.

Another goal is to publicize the cannon, in hopes its work will help convince people to build safe rooms.

“By informing residents of Hawaii about the potential threat of windborne debris during future hurricanes, it is hoped that this facility will encourage retrofit of existing homes through the addition of opening protection or saferooms. Residents without such protection or whose homes do not have hurricane connectors, will be encouraged to evacuate to state designated shelters,” said a fact sheet issued by Robertson.

"Windblown debris is a major risk to life and limb as well as to property damage during strong-wind events. Ian and Gary are perfectly suited by education and practical experience to study this critical element of public safety," said C. S. Papacostas, professor and chair of the University of Hawai'i Civil & Environmental Engineering Department.

© Jan TenBruggencate 2010