When Northeastern professor Jerry Hajjar thinks about the future of building design, he envisions a booming new industry that hinges on sustainability. This means dismantling aging buildings and reusing the components in new structures, rather than leveling the buildings and starting from scratch.
“The basic concept is this: At the end of the useful life of a building, instead of demolishing it and recycling the materials, we think about whether we can deconstruct it and refabricate,” said Hajjar, chair of the Department of Civil and Environmental Engineering.
Hajjar has teamed with Mark Webster, a structural engineer at the firm Simpson Gumpertz & Heger, to explore this new approach to building design with a $250,000 grant they recently received from the National Science Foundation to begin their work.
It’s called design for deconstruction.
“The primary part of a steel building that’s not deconstructable is the composite concrete floor slab, which is poured integrally with the steel girders on which it sits,” Hajjar said. But his team proposes the use of new technologies such as removable clamps instead. For example, precast concrete planks could sit on top of the steel girders, held in place with clamps, he explained.
Testing whether such deconstructable building designs can withstand extreme forces will be done in the new Laboratory for Structural Testing of Resilient and Sustainable Systems, or STReSS lab, at the George J. Kostas Institute for Homeland Security in Burlington, Mass.
The lab is the first of its kind in the Boston region. “It’s a powerful lab,” said Hajjar. More than 400 tie-down anchors span the 2,000-square-foot “strong-floor,” each capable of withstanding 200,000 pounds of force.
The design-for-deconstruction project represents a new direction for Hajjar’s work, which has traditionally focused on the structural impact earthquakes and other extreme events have on steel buildings, bridges and other infrastructure.
“I prefer to think of it as augmenting our earthquake research,” he said. “We’ve been developing new systems to make structures safer, more economical and more secure. A long overdue component for structural engineering is sustainability.”
To that end, Hajjar’s lab is also looking at integrating new materials — like steel foam — into building design that can improve energy efficiency. If buildings were designed with sustainability in mind — not just from an architectural perspective but also the engineering perspective — their impact on the environment could be significantly reduced, he said.