Research Abstracts Online
2008 - March 2009
University of Minnesota Twin Cities
Institute of Technology
Department of Civil Engineering
PI: Henryk K. Stolarski
Co-PI: Arturo Schultz
Nonlinear Analysis of Spandrel Beams
Precast, prestressed concrete spandrels have been widely used in the perimeter of parking ramp frames. They support precast, prestressed concrete doubles-tees and are connected to column corbels at their ends. It has been commonly believed that spandrels are so stocky that stability considerations can be neglected. However, the advance of materials technology in construction has enabled engineers to produce more and more slender spandrels. Therefore, a detailed evaluation of stability limit requires for precast, prestressed concrete spandrels.
Recently, full-scale tests of precast, prestressed concrete spandrels have been conducted at North Carolina State University. The main objective of this study was to evaluate the need for closed stirrups in the slender spandrel web. The test results showed that the spandrel ends are significantly affected by torsion and shear. Furthermore, for all spandrel specimens the maximum lateral deflections were approximately two times larger than the vertical deflections. Based on these results, it might be concluded that slender spandrels are prone to lateral stability problems in some cases. In this project, the researchers use the finite element formulation to investigate behavior of spandrel beams assuming various design options. The real, nonlinear behavior of concrete as well as actual distribution of reinforcement and prestressing steel will be included. The combined effect of shear, torsion and bending has to be taken into account, which makes the analysis and the design of spandrels relatively complicated. The researchers hope to come up with better design rules, leading to beams with improved strength and stability properties.
Bulent Mercan, Graduate Student