Research Areas

The Thin-walled Structures group, and Professor Schafer, work across these broad categories of research:

Structural Engineering Structural Stability Structural Reliability
Thin-walled Structures Cold-Formed Steel Structures Steel Structures
Experimental Mechanics Computational Mechanics Structural History & Art
Building Structures Wind Tower Structures Solar Support Structures
Natural Hazards Engineering Adaptation and Resilience Sustainability

This may seem like a lot of areas – but they are all closely tied to Structural Engineering and the desire to utilize engineering intelligence to create structural efficiencies that enable better outcomes for people. Below we provide more insights on our group’s interests and contributions in all these areas.

Structural Engineering is the broad field in which the group works. Our efforts generally focus on building structures and more recently wind tower support structures, but the group has worked on bridges, towers, racks, cars, buried structures and numerous other structural systems. Professor Schafer is a Fellow of the American Society of Civil Engineers – Structural Engineering Institute.

Structural Stability is the consideration of buckling and geometric nonlinearity in the performance of structures – our group contributes in this area extensively and Professor Schafer is a past Chair of the Structural Stability Research Council.

Structural Reliability is the consideration of uncertainty in the design of structural systems, our group has worked in this area primarily in relation to cold-formed steel framing and system reliability, with works such as this one. Recognizing the need for robust statistical characterization of inputs we have performed fundamental work on imperfections and residual stresses in cold-formed steel members to better inform stochastic models and reliability studies. With the modern focus on ML and AI, the Thin-walled Structures group finds themselves working more in this area in recent years.

Thin-walled Structures are the class of structures in which stability and geometric nonlinearity of the components that form a section typically drive the response. The group works broadly in this area and Professor Schafer is past North American Editor of the journal Thin-walled Structures. The team has worked on thin-walled structures comprised from plastics, aluminum, cold-formed steel, hot-rolled steel, stainless steel, wood, bone, and more. We all call ourselves the Thin-walled Structures Group, because the set of knowledge around thin-walled structures is core to all that we do.

Cold-formed Steel Structures are comprised of lightweight steel members formed to shape at room temperature from coil steel typical 1-3mm thick and are used in buildings, racks, metal building systems, support structures and more. The group has authored large portions of the governing U.S. standard for cold-formed steel structures and originated the Direct Strength Method of design (review article one and two). Professor Schafer is the Founder and Director of the Cold-Formed Steel Research Consortium. He is the past Chair of the Cold-Formed Steel Engineering Institute and the ASCE Committee on Cold-Formed Steel. He serves on the American Iron and Steel Institute committees that created the U.S. Standards for cold-formed steel design. He Chairs the ASCE 8 committee that creates the standard for Cold-Formed Stainless Steel Structural Members. Everyone that works in the Thin-walled Structures Group learns a little or a lot about cold-formed steel.

Steel Structures are comprised of heavier rolled shapes and plate are are used widely in buildings, bridges, and the broader civil infrastructure. Professor Schafer serves on the American Institute of Steel Construction committee that creates the U.S. standards on hot-rolled steel design and Chairs the Task Committee on Member Design, he is also Vice-Chair of the committee on stainless steel structural members. Principles of sustainability drive even heavier structural steel solutions to examine efficiencies – and often bring them into the realm of thin-walled structures.

Experimental Mechanics are foundational to the study of thin-walled structures and the group maintains a testing laboratory that has performed studies on cold-formed steel walls, joist-stud assemblages, beam-columns, columns, beams, scale models for wind turbine towers, fastener assemblages, and materials testing. We developed a unique laser scanning rig for geometric imperfection characterization and a completely unique multi-axis testing rig for full wall testing under multiple actions (compression, shear, out-of-plane bending). We are constantly looking to implement new technology and capabilities into our experimental mechanics portfolio.

Computational Mechanics that encompass geometric and material nonlinearity are necessary for the study of thin-walled structures. Our group is best known for its contributions to cross-section elastic stability analysis and the application of the finite strip method and development of the constrained finite strip method. See CUFSM. We also work extensively in geometric and material nonlinear collapse analysis modeling primarily with ABAQUS and OpenSees.

Structural History is an important aspect of structural engineering education and Professor Schafer has specific interests in this area. He has collaborated with the National Park Service on covered wooden bridges and performed independent research on the contributions of John Wellborn Root to the development of the steel skeletal skyscraper in Chicago. Structural Art is a means to critique our built environment, and through assessment of social, scientific, and symbolic significance determine the great works of structural engineering. Professor Schafer taught about Structural Art in the course Perspectives on the Evolution of Structures for over 15 years. The notion that full evaluation of structural success requires examination across multiple criteria (e.g. social-economy, scientific-efficiency, and symbolic-elegance) was first provided to Professor Schafer as an undergraduate at the University of Iowa and formed the genesis for a life-long interest in structural engineering not as only “structural response,” but the role of structures in resilience, sustainability, disaster mitigation and a variety of related areas.

Building Structures are a long term focus of the group’s research. Our group’s expertise is greatest in steel building structures, particularly cold-formed steel framed buildings. Our team focuses a great deal on building design i.e, the engineering design process focused on creating a safe final form given extreme uncertainty and the inability to prototype and test at scale. Professor Schafer has a deep interest in this area as an educator and an engineer and spends a significant amount of time working on codes and standards for buildings. Our team is also interested in building construction which is evolving with the growth in panelized and fully modular construction. Professor Schafer is keenly interested in the application of thin-walled structures growing from the member (e.g. a thin-walled lipped channel) to the subsystem (e.g. panel or module) to the complete structure (e.g. the punched tube lateral system for high-rise buildings). Our upcoming shake table testing on a 10 story building its just one example.

Future Energy Structures consist of the infrastructure to support alternative energy solutions: solar support structures, and wind turbine towers are two examples that our research group has expertise and research efforts within. In both cases the critical supporting structure is thin-walled and our groups expertise can be used to optimize and improve efficiency in these important structures. The group is interested in other alternative energy structures and ideas, including the solar chimney.

  • Wind Tower Structures are commonly formed from thin cylindrical steel towers. Our team is keenly interested in the stability and strength of these towers – and increasing their structural efficiency and the accuracy of design predictions. In cooperation with ROSEI we combine our groups expertise with a wide group of wind energy experts. We are actively performing testing, modeling, and developing software in this space. In the last two years this hade become one of the most active areas for the group.
  • Solar Support Structures are commonly formed from uniquely configured cold-formed steel and hot-rolled steel parts. These structural members are often proprietary in nature, and place demands on the steel shapes that are not common in building structures – particularly torsion. We are working to improve the efficiency of these structures and to increase the role of the structural engineer in their design. 

Natural Hazards Engineering – Earthquake Engineering is critical to the advancement of structural engineering, and our group has worked extensively to advance the seismic design of cold-formed steel structures. We performed the first full-scale shake table test on a cold-formed steel framed building, authored a major rewrite of the AISI S400 Specification, and continue to work extensively to advance our understanding of buildings as complete systems – including the interaction of lateral and gravity systems as well as vertical and horizontal lateral force resisting systems. The group is involved in seismic performance-based design efforts and considers earthquake engineering as an important starting point for advancing multi-hazard engineering and building structural system design in general. See CFS-NEES, SDII, and more; including our forthcoming 10-story stake table testing. Wind Engineering has become increasingly important to our research group as our efforts have expanded into wind tower support structures – and the group is working on the reliability of offshore wind installations during hurricanes and generally has a growing interest in wind engineering.

Adaptation and Resilience – is the broad and increasingly important areas that address the ability of a system (material, building, city) to adapt and recover from shocks and hazards. Our group’s expertise begins at the structural level and relates to the selection of systems for buildings and structures that are more robust to hazards and damage; however, our interests are broader and include collaborations with those interested in (a) the broader infrastructure that forms the physical backbone of cities and (b) the social-technical interactions that comprise community-level resilience.

Sustainability is the broad concept of meeting today’s needs without compromising the needs of future generations. This broad principle is at the corse of the Sustainable Energy Institute that Professor Schafer directs and has become a primary motivation for all of our structural engineering research. We seek efficiency in all we do, to minimize the impact of our structural solutions – to engineer is not just to make something safe, but to make it safe and ensure that precious materials and energy are cherished and minimized.