UNR lab designed to withstand largest quakes in history

The earthquake lab at the University of Nevada, Reno, can replicate any earthquake on record even the biggest ones in history to see whether buildings and bridges can survive the shaking.

The first challenge facing the designers and builders of an expansion to the earthquake lab, then, is this: How do you build a structure that doesn't collapse itself when it's delivering some of the most severe jolts known to mankind?

And then the second, and closely related issue, becomes this: How do you build something that strong with its masses of steel and concrete in such a way it maintains the extremely close tolerances that are required by seismological researchers when they perform rigorous scientific research in the lab?

The answer is beginning to take shape as a hillside is cut away on the west side of Evans Avenue near the UNR Quad.

Clark and Sullivan Construction of Sparks is the general contractor on the $18 million project, which has been funded largely with a $12.2 million grant from the National Institute of Standards and Technology in the U.S. Department of Commerce. BGJ Architecture + Engineering of Reno is handling the design and engineering.

The 23,000-square-foot lab is an expansion of the existing seismology lab next door. That 20-year-old laboratory is busy nearly constantly with testing ordered by engineering firms and other researchers.

The first task facing Clark and Sullivan was fairly routine: Moving 6,000 yards of earth, enough to fill more than 200 dump trucks, from the hillside next to Evans Avenue. That work was complicated by a requirement to drill pins 20 feet deep from the face of the hillside and under the street to keep the slope stable.

Also fairly straightforward will be construction of an auditorium on the north side of the expanded laboratory, an auditorium that will take advantage of the site's natural slope.

Construction of the lab itself, however, is anything but a conventional construction job.

The building will house four massive shake tables. At 14 feet by 14 feet, each is bigger than the kids' bedrooms in most suburban tract homes.

Massive hydraulic actuators controlled by computer software can shake the tables to replicate any known earthquake.

And the lab doesn't track merely the effects of earthquakes on bridges and buildings. The new facility will allow scientists and engineers to track, for instance, the effects of earthquake waves as they move through soil under the foundation of a building.

To withstand the punishment that it will be inflicting upon itself along with the punishment it will hand out to the materials it is testing, the new laboratory relies on massive amounts of steel-reinforced concrete.

The floor of the lab, for instance, will be constructed with 711 yards of concrete to be delivered in 70 cement trucks during a pour that is estimated to last 10 full hours.

That work is complicated by the need to maintain very close tolerances on the floor, says Pelin Eldeleklioglu, a project manager with Clark and Sullivan.

Once the shake tables are installed, they will be aligned to a tolerance of less than 0.001 inch, even across a 100-foot space.

Says Patrick Laplace, a laboratory manager at the UNR facility, "We need a very flat, very accurate floor or we wouldn't be able to meet our alignment requirements. We use a very expensive laser than can hold tolerances of 0.0001 inch to do this."

Similarly close tolerances are required on hundreds of holes in the concrete walls and floor that will be used to hold experiments in place.

Laplace explains:

As researchers prepare an experiment in the earthquake lab, they attach 20,000-pound cubes of concrete with holes they look just like gigantic Lego blocks to the floor or to the walls.

Across the floor of the lab, holes are laid out in a 2-foot-by-2-foot grid. (They're created by the use of a specially developed form at the time the concrete is poured.) The Lego blocks and the big shake tables have exactly the same hole pattern, allowing them to be shifted to any position in the laboratory.

When it's time to install the shake tables or Lego blocks in place, researchers use post-tensioning rods similar to those used in bridge construction. Instead of torquing a bolt, researchers use a hydraulic jack to stretch the rods to 100,000 pounds. They tighten the nut on the post-tension rod and release the jack clamping the Lego block of shake table firmly to the floor or wall.

Obviously, the holes need to line up to allow the post-tension rods to run through the floor or the wall as well as the shake table or the floor.

"The accuracy of the hole alignment is very critical since our shake tables move very accurately. We can control the position of the shake table and a 100,000-pound specimen to several thousandths of an inch," says Laplace. "This makes for a very unique floor and wall build requirement, quite different than a typical warehouse or garage."

The holes in the concrete walls and the 3-foot-thick floor also need to be perfectly plumb.

"The challenging part of this job is going to be all those sleeves," says Steve Jessop, Clark and Sullivan's project superintendent.

One of the few major building projects under way in northern Nevada this summer, the earthquake lab is project to employ as many as 100 workers at its peak. The job is scheduled for completion next year.

In the past 10 years, the Center for Civil Engineering Earthquake Research at UNR has landed more than $38 million in grants and contracts from across the world. The center and its earthquake lab employ about 20.

The additional facilities will allow the lab to handle a greater number of contracts, says Ian Buckle, its director.