|Principal Investigator: ||Rigoberto Burgueño, Ph.D.|
|Research Assistant: ||Kedar M. Bhide|
|Funding Agency: ||University of California, San Diego|
|Period: ||January 2001 – December 2002|
Recent research efforts on the characterization of concrete filled FRP tubes have provided considerable knowledge on the axial and flexural behavior of these members. The promising results have also motivated the use of these members for piles and beams in short and medium span bridges. However, there is a significantly lack of knowledge of on the shear behavior FRP/concrete composite members. The objective of this research work was to develop a rational analytical approach that would allow evaluation of the shear load-deformation response of concrete filled circular FRP composite tubes. The specific tasks included: a) development of an analytical procedure for the shear force distribution between concrete and the FRP shell; b) modeling the shear behavior of the FRP-confined cracked concrete; c) include extension/shear coupling effects of anisotropic FRP shells into existing axial/flexural models; d) validate the analytical model by comparing to available experimental data; and e) conduct parametric studies.
Figure 1. Shear Stresses in Concrete Filled FRP Tube
An analytical method to evaluate the shear load–deformation behavior of composite and non-composite concrete filled circular FRP tubes was developed. The procedure extends previously validated models for the axial/flexural behavior of FRP/concrete tubes to include anisotropic FRP behavior and integrates a smeared shear modulus of cracked concrete and the conditions of equilibrium, compatibility and shear force transfer across cracks stipulated by the modified compression field theory. The analytical results were found to be in satisfactory agreement when compared with available experimental data from large- and small-scale tests with composite and non-composite connection detailing, respectively.
a) Shear Force-Strain Response (Comp.)
b) Shear Strain Profiles in FRP Shell (Comp.)
|Figure 2. Comparison of Analysis Results with Experimental Data|
The analysis results provide considerable insight on the shear behavior of hybrid FRP/concrete members, particularly regarding the contribution of the concrete core. The concrete infill was shown to considerably influence both the shear strength and stiffness of the hybrid member and carried more than half of the vertical shear load in the composite system.
Concrete filled fiber reinforced polymer (FRP) tubes have been recognized as an efficient hybrid concept for structural members that use FRP reinforcement as a stay-in-place structural form. Resent research projects have led to a good understanding of the axial and flexural behavior of this system and its excellent performance has led to applications as beam, pier, and pile components. However, the shear response of concrete filled FRP tubes has so far been only preliminarily addressed. The analytical procedure and results presented in this paper address this gap in our understanding of the shear response of concrete filled FRP tubes.
- Bhide, K.M., "Shear Response of Concrete Filled Circular Fiber-Reinforced Polymer Composite Tubes", Masters Thesis, Michigan State University, East Lansing, MI, 2002.
- Burgueño, R., and Bhide, K.M., "Shear Behavior of Concrete Filled Circular FRP Tubes", to be presented at the 2004 ASCE Structures Congress.
- Burgueño, R., and Bhide, K.M., "Shear Response of Concrete Filled FRP Composite Cylindrical Shells", submitted to ASCE Structures Journal, August 2003.