Finite Element Study of Shear Behavior of Spandrel Ledges and Comparison with PCI Shear Design Provisions

Abstract

Punching shear failure of spandrel ledges has been observed by many researchers and heightened concerns have been raised questioning the safety level of the PCI shear design provisions for beam ledges. This paper presents non-linear finite element analyses conducted to model the behavior of prestressed L-shaped spandrel beams. Special emphasis was given to the behavior of the ledge at the end regions of the spandrel, where punching shear controls the design. The accuracy of the finite element model is demonstrated by comparing the predicted behavior to the results of one major test by another researcher. The influence of different parameters included in the PCI shear design provisions for beam ledges is discussed. The analysis is extended to illustrate the effect of other parameters including the prestressing level, hanger reinforcement and the amount of debonded strands at the end regions of the spandrel beam. Results of the analyses showed that the PCI shear design provisions for spandrel ledges are dangerously unconservative. The provisions do not account for key parameters, which affect the punching shear behavior.

Keywords

finite element analysis ledges punching shear prestressed concrete

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