Shear strength of large frp-reinforced concrete beams without shear reinforcement

Abstract EN

The understanding of size effect on the concrete shear strength of members (beams and one-way slabs) reinforced internally with fiber reinforced polymer (FRP) bars is of fundamental and practical significance in order to expand the use of FRP bars in new structures.

This paper examines the effect of depth on shear strength of slender beams longitudinally reinforced with either glass-fiber-reinforced polymer (GFRP) or carbon-fiber-reinforced polymer (CFRP) containing no shear reinforcement.

Also a number of methods for FRP shear design were selected and reviewed and design methods are proposed.

The database of this research, which consists of 174 data, covers a wide range of variables affecting the shear strength, including concrete compressive strength, FRP reinforcement ratio, shear span-to-depth ratio (a/d), and member depth.

The specimens were simply supported and tested in three or four point bending tests.

The specimens were analyzed using ACI 440-06, BISE-99, CSA S806-02, JSCE-97 guidelines and the proposed methods.

One of the proposed method is a modified version of Bazant and Yu (2005b) which was originally proposed for steel-reinforced concrete members.

The results indicated that the ultimate shear strength of FRP-reinforced beams is size-dependent and Bazant's law (1984) which was modified by Kazemi and Broujerdian (2006) can best describe such size effect.

The comparison study showed that the aforementioned design methods give conservative predictions with the proposed and the BISE-99 methods being the most accurate.

However, when considering the percentage of unconservative predictions, the JSCE-97 and ACI 440-06 design methods are superior to the other methods.

A modified version of Kazemi and Broujerdian (2006) equation was also proposed and its prediction and simplicity is comparable to that of ACI 440.1R-06 equation