Shiling Pei is from the Republic of China, where he likely suffered from wood deprivation. Concrete is the material of choice. Except for ancient buildings, there are few, if any, wood frames, he says. Source: ENR
Pei is not only a wannabe woodworker. He has been researching timber building systems for years. “I consider myself an experimentalist,” says Pei, also a licensed civil engineer in California.
His latest wood research in resilient performance-based seismic design is historic. As principal investigator for the National Science Foundation’s Natural Hazards Engineering Research Infrastructure TallWood Project, Pei is leading a team that tested a resilient 10-story “rocking-wall” frame, composed of vertically post-tensioned cross-laminated-timber, on an outdoor shake table at the University of California San Diego. The 112-ft-tall specimen was the tallest full-scale structure ever tested on a shake table, says NHERI.
The shaking simulated the 1994 Northridge quake, a magnitude-6.7 temblor in Los Angeles. Then it ran Taiwan’s 1999 Chichi quake, a magnitude-7.7 temblor.
The specimen sustained no damage, except to steel clips that can be replaced, says Pei, and it performed exactly as expected, returning to its plumb position after rocking. “We found a cost-effective and practical way to build a tall wood building that is almost earthquake proof,” he says.
The unbuilt 12-story Framework, designed by LEVER Architecture and KPFF, is the model for the specimen. “Ling had the most difficult position of all,” says Reid Zimmerman, a structural engineer on the NHERI team and technical director at the Portland, Oregon, office of KPFF. “He led a large, diverse team,” including six universities, “to design, supply, fabricate and construct the tallest shake-table test in the world,” he adds. And Pei leveraged multiple funding sources and numerous supplier donations while building consensus.
Thomas Robinson, LEVER’s founding principal and a NHERI participant, says the rocking wall is “probably the most innovative structure put on a shake table in our lifetime.”
Pei’s research focuses on multi-hazard mitigation through performance-based engineering, numerical modelling of structural dynamic behaviour and large-scale dynamic testing. “There’s something very addicting to testing large structures,” says Pei, who has a Ph.D. in civil engineering from Colorado State University.
Pei first studied bridge engineering as an undergraduate at Southwest Jiaotong University, in China. He arrived in the US in 2003 to study structural engineering.
It was a time when academia was interested in the seismic performance of wood structures, in the aftermath of the Northridge quake. There were few fatalities but the number of wood structures with severe damage was high, Pei says. “We thought wood could do better,” he adds.
The “sweet spot” for the resilient rocking system is three to six stories, says Zimmerman. LEVER, with structural engineer Holmes, is currently designing a three-story office building with a timber rocking wall. If built, it would be the first wood rocking wall, other than the specimen.
Timber rocking walls are not in the code, making it more difficult for engineers to use the system. Pei and Zimmerman hope to change that. They are co-leading an effort to write a proposal for the 2028 update of ASCE/SEI 7, Minimum Design Loads and Associated Criteria for Buildings and Other Structures. Toward that, Pei has to have the NHERI report finalized by the summer of 2025.
