Collapse Resistant Frame Structure With Autoadaptive Response Characteristics

Collapse Resistant Frame Structure With Auto Adaptive Response Characteristics UM File # 1893 Background: To reduce collapse and catastrophic failures collapse-resistant building or bridge structures typically include interconnected columns and beams that are formed of steel or steel-reinforced concrete. Because steel/reinforcing steel may be characterized as exhibiting \"elastic/plastic\"" behavior the columns and beams of such known frame systems may likewise be expected to exhibit \""elastic/plastic\"" behavior. Thus once the elastic strain limit of such columns and beams are exceeded the behavior of such columns and beams is essentially governed by the rotation of a concentrated region of plastic deformation (the formation of a \""plastic hinge\""). In this regard variations of plastic hinge formation and frame members have been explored but further improvements are needed to for frame systems with improved collapse-resistance and self-centering capabilities after undergoing large deformations relative to known steel and steel-reinforced concrete frame systems. Technology Description: Researchers at the University of Michigan have developed a frame system for use for example in an earthquake-resistant building or bridge structure. In particular the lowermost columns are formed of a material that exhibits quasi-elastic behavior in response to seismic excitation while the beams of the frame system are formed of another material that exhibits elastic/plastic behavior. In this way quasi-elastic flexure of the columns under seismic loading will cause plastic hinge formation in the beam ends to dissipate the rotational energy without significant plastic hinge formation in the column bases. The column material is an engineered cementitious composite (ECC) matrix reinforced with fiber-reinforced plastic (FRP) to provide a relatively-high flexural strength member having a relatively-lower flexural stiffness and higher elastic deformation limit while the beam material is an ECC matrix reinforced with mild steel rebar to provide a relatively-lower flexural strength member featuring high energy-absorbing capacity. Applications: Collapse-resistance and self-centering structures"