Vicki Sauter

Transcription

♫MUSIC♫ VOICE OFF CAMERA: Six, five, four, three, two, one…start! MILES O'BRIEN: On a hot, late-summer afternoon at Georgia Tech's Structures Lab, it's time to get shakin'... (Machine Noise) This is no act of nature. It's a highly controlled, carefully calibrated shake test, and this building is wired to the hilt. REGGIE DESROCHES: What we're really concerned about the two to five story buildings that are used for office buildings, apartment buildings, any sort of structure that you might find very, very common in the U.S. MILES O'BRIEN: With support from the National Science Foundation, structural engineer Reggie DesRoches and a team at Georgia Tech want to document how older reinforced concrete buildings respond under moderate-to-strong earthquake conditions, and validate how to best retrofit them to withstand a temblor. (machine rattling) REGGIE DESROCHES: The goal of the project is not only to understand how they behave, but also look at ways to retrofit them, to rehabilitate them so that they perform much better and don't collapse in an earthquake. MILES O'BRIEN: The Georgia Tech team built this concrete structure with their shake-test plans in mind. It's divided into four sections so that each could be rigged for different retrofits and more tests could be done. The shaker itself is a portable unit attached to the building's roof. REGGIE DESROCHES: What it does is it imposes a load laterally onto your building, representing what would happen in an earthquake. MILES O'BRIEN: On the day we visited, a bolt needed to stiffen the structure came loose during the first strong test. No big deal. They quickly fixed it and were back in business. The retrofits varied; mixing combinations of mortar, high strength steel rods, and carbon fiber sheets that wrap around the columns and pillars. Another was a brace using a "shape memory" alloy to keep the structure strong and stiff. Even under hard shaking, it barely moved at all. REGGIE DESROCHES: We tried several different retrofits, all of them worked to a different extent. This project was focused on trying to find a way to do it that's less disruptive than the current approaches. Meaning, we don't have to perhaps evacuate the building for months or years on to retrofit it. It doesn't change the look of the building dramatically and it's fairly easy and economical to do. MILES O'BRIEN: DesRoches wants to give building owners looking to upgrade the information they need to choose an effective retrofit. REGGIE DESROCHES: I think many people think there's nothing you can do about an earthquake other than hope it doesn't happen while you're in the building. In fact, there are ways, fairly straightforward ways that you can retrofit a structure, so that either it doesn't collapse, whereas it would if it wasn't retrofitted or has much better performance. (machine rumbling) MILES O'BRIEN: Tests like these done now and the retrofits that will follow could mean a huge difference going forward, making older structures in quake zones safer than ever before. For Science Nation, I'm Miles O'Brien.