Concrete Left Standing

They’re not going to huff and they’re not going to puff, but researchers at the University of California at San Diego (UCSD) are wielding 10 huge hydraulic jacks that could easily bring a shoddily constructed house down. The team is using the jacks to subject a 60-percent-scale model of a five-story concrete building to a series of simulated earthquakes; like the third little pig, they believe they’ve got a better building technique that will keep their structure standing.

The testing is the culmination of a 10-year collaboration between universities, industry and the National Science Foundation to develop seismically sound structures using prefabricated, or “precast,” concrete. Builders generally prefer precast to poured-in-place concrete-it’s cheaper and faster to erect. What’s more, factory fabrication allows for better quality control and frees a project from the whims of the weather. But conventional precast construction is susceptible to damage from earthquakes, and building codes have traditionally frowned upon its use in earthquake-prone areas such as the West Coast.

That could all be about to change. UCSD Professor of Structural Engineering Nigel Priestley, who coordinates the collaboration, says that the results will form the basis of new design recommendations and ultimately new building codes. Tests will give data on four different systems for connecting columns and beams, two approaches to flooring and one method of connecting wall panels. Researchers will simulate several earthquakes of increasing intensity by pushing on the structure with the hydraulic actuators.

The researchers expect the tests to show that-if the right methods are used-the precast concrete systems actually perform as well as, or better than, those dictated by existing codes.